Many have read where I recommend using a torque wrench to set the torque value of propeller bolts. There are reasons for this.

Attached is a picture of a brand new propeller that ran for about 30 minutes. The hub had been drilled incorrectly, permitting a pre-load to be applid to the prop bolts when inserted becasue the holes were just fractionally tight. The bolts had been attached using an adjustable torque, battery powered, electric drill. Absolutely no accurate torque value was established prior to setting the limit stop on the drill motor. One of those "feels about right" situations. Same as what is often used by modelers and a hand held hex key. The end result is frightening, especially if you were the one on the business end of the propeller.

In this case, just about everything was done wrong. Something I fear may be much too common an occurance in the RC world. There will be a lot of comments from people about how this or worse could never happen to them because they have been doing RC for many years, have a calibrated wrist or elbow, or some other point of denial. This propeller was installed by an individual that is highly experienced and knew better, but in the interest of saving time and effort....

Some CF props have been reported to have "soft" centers, like some chocolates and some people. How do you tell and how should the tightening torque be adjusted if the centers are "soft"?

Thanks.

Richard

That was an expensive ouch

Until you pass the 120cc range, 65 inch pounds will hold them all. Few composite props have a true "hard "center. Most brands have wood core hubs. This particular brand usually has a solid plastic hub component, be it carbon or some other dense material. Clearly the hub composition does not meet the earlier standard. In this case the prop screws were noted after the fact as having been over torqued.

What actually caused the failure? Never mind I see they were over torqued.

I assumed the bolts did not clamp the prop fully leading to the torque load being transferred not through the hub, but through the bolts themselves. Fairly quickly this would destroy the laminate and result in the failure we see.

How exactly does over tightening cause the prop hub to fail like that?

@ TOM,
Thanks for posting.

@ Richard
Torque resistance of thepropis a requirement in an engine. If the soft center does not allow enough clamping force to achive the required torque resistance, that prop is not suited for the engine. Relaxing tightening torques is not the way to do it and will lead to desaster. Larger prop washers will increase clamping surface, and then 'maybe' will allow the required bolt tightening torque.
I would rather stay away from that brand prop.

This is a picture of the prop heart off an engine that was buried a foot deep in hard loam soil. The sides of the drilled holes show no sign of even touching the bolt threads.

Tom,

Is this the type of tool for the job? Seems that 65 inch pounds is the standard for rifle scope mountng rings.

http://www.snipercountrypx.com/pc-86...nch-drive.aspx

DR

Bolt torque is normally determined by the size and material type of the fastener, and the material it is threaded into. Can't do that with propellers because you have a hub composition/compression issue. A wood prop normally has a softer hub than a composite prop. Or at least should. One manufacturer found the previous out the hard way when they suggested a screw torque value in excess of 100 inch pounds for wood props with one of their engines. Crushed a lot of wood hubs...

Wood props can achieve maximum clamping force somewhere between 40 and 60 inch pounds, depending on the fastener, engine size, and hub density. Carbon props should achieve max clamping force in the area of 65 inch pounds. Their hubs permit greater screw torque without deforming the hub. Never exceed a fastener's maximum suggested torque value. From 60cc and down, 40-45 inch pounds works for both wood and composite props.

The link in the previous post cannot be accessed because it has been blocked by the administrator as "forbidden weapons". Seems the Second Amendment is not viewed kindly here. A standard inch pound torque wrench and 1/4"-3" drive hex keys works for everything that uses a multi bolt hub and allen head cap screws.

Pe:

Based on known usual hub compositions, we're talking about the same manufacturer. I will not post the makers name because it was a custom blade product.

Maby your broswer is funkey, I clicked on the link and went right to it.

Larry S

Torques in Nm. They stay 20% clear of the maximum boltproof torque, which could cause the bolt to fail
Sorry for the wide table. Somehow I cannot get it smaller.

<table border="0" cellspacing="0" cellpadding="0" width="1122" x:str="" style="width: 842pt; border-collapse: collapse"> <colgroup><col width="88" style="width: 66pt; mso-width-source: userset; mso-width-alt: 3218" /><col width="163" style="width: 122pt; mso-width-source: userset; mso-width-alt: 5961" /><col width="200" style="width: 150pt; mso-width-source: userset; mso-width-alt: 7314" /><col span="3" width="64" style="width: 48pt" /><col width="69" style="width: 52pt; mso-width-source: userset; mso-width-alt: 2523" /><col width="76" style="width: 57pt; mso-width-source: userset; mso-width-alt: 2779" /><col span="4" width="64" style="width: 48pt" /><col width="78" style="width: 59pt; mso-width-source: userset; mso-width-alt: 2852" /></colgroup> <tbody> <tr height="40" style="height: 30pt; mso-height-source: userset"> <td class="xl56" height="40" width="451" colspan="3" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; width: 338pt; height: 30pt; border-top: #d4d0c8; border-right: #d4d0c8"><font face="Verdana">Metric Max Bolt Torque (80%)</font></td> <td width="64" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; width: 48pt; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td width="64" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; width: 48pt; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td width="64" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; width: 48pt; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td width="69" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; width: 52pt; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td width="76" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; width: 57pt; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td width="64" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; width: 48pt; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td width="64" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; width: 48pt; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td width="64" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; width: 48pt; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td width="64" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; width: 48pt; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td width="78" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; width: 59pt; border-top: #d4d0c8; border-right: #d4d0c8"></td> </tr> <tr height="18" style="height: 13.5pt"> <td class="xl57" height="18" width="451" colspan="3" style="border-bottom: black 1.5pt solid; border-left: #d4d0c8; background-color: transparent; width: 338pt; height: 13.5pt; border-top: #d4d0c8; border-right: #d4d0c8"><font size="2">look up chart</font></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> </tr> <tr height="40" style="height: 30pt; mso-height-source: userset"> <td class="xl47" height="73" rowspan="2" width="88" style="border-bottom: #969696 1pt solid; border-left: black 1.5pt solid; background-color: #ffffcc; width: 66pt; height: 54.75pt; border-top: black; border-right: #969696 1pt solid"><font size="3">Diameter</font></td> <td class="xl50" width="363" colspan="2" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 272pt; border-top: black 1.5pt solid; border-right: black 1.5pt solid"><font size="3">Recommended Torque (N*m)</font></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> </tr> <tr height="33" style="height: 24.75pt"> <td class="xl26" height="33" width="163" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 122pt; height: 24.75pt; border-top: #969696; border-right: #969696 1pt solid"><font size="2">Class 8.8</font></td> <td class="xl28" width="200" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 150pt; border-top: #969696; border-right: black 1.5pt solid"><font size="2">Class 10.9</font></td> <td class="xl25" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"><font size="2">class12.9</font></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> </tr> <tr height="18" style="height: 13.5pt"> <td class="xl29" height="18" width="88" x:num="" style="border-bottom: #969696 1pt solid; border-left: black 1.5pt solid; background-color: transparent; width: 66pt; height: 13.5pt; border-top: #969696; border-right: #969696 1pt solid"><font size="2">4</font></td> <td class="xl27" width="163" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 122pt; border-top: #969696; border-right: #969696 1pt solid"><font size="2">2.9</font></td> <td class="xl25" x:num="" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"><font size="2">4.3</font></td> <td class="xl30" width="64" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696 1pt solid; background-color: transparent; width: 48pt; border-top: #969696 1pt solid; border-right: black 1.5pt solid"><font size="2">4.5</font></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> </tr> <tr height="18" style="height: 13.5pt"> <td class="xl29" height="18" width="88" x:num="" style="border-bottom: #969696 1pt solid; border-left: black 1.5pt solid; background-color: transparent; width: 66pt; height: 13.5pt; border-top: #969696; border-right: #969696 1pt solid"><font size="2">5</font></td> <td class="xl27" width="163" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 122pt; border-top: #969696; border-right: #969696 1pt solid"><font size="2">5.8</font></td> <td class="xl25" x:num="" style="border-bottom: #d4d0c8; border-left: #d4d0c8; 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border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> </tr> <tr height="18" style="height: 13.5pt"> <td class="xl29" height="18" width="88" x:num="" style="border-bottom: #969696 1pt solid; border-left: black 1.5pt solid; background-color: transparent; width: 66pt; height: 13.5pt; border-top: #969696; border-right: #969696 1pt solid"><font size="2">6</font></td> <td class="xl27" width="163" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 122pt; border-top: #969696; border-right: #969696 1pt solid"><font size="2">10</font></td> <td class="xl30" width="200" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 150pt; border-top: #969696 1pt solid; border-right: black 1.5pt solid"><font size="2">15</font></td> <td class="xl25" x:num="" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"><font size="2">16</font></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; 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border-left: #969696; background-color: transparent; width: 122pt; border-top: #969696; border-right: #969696 1pt solid"><font size="2">30</font></td> <td class="xl30" width="200" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 150pt; border-top: #969696; border-right: black 1.5pt solid"><font size="2">40</font></td> <td class="xl25" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> </tr> <tr height="18" style="height: 13.5pt"> <td class="xl29" height="18" width="88" x:num="" style="border-bottom: #969696 1pt solid; border-left: black 1.5pt solid; background-color: transparent; width: 66pt; height: 13.5pt; border-top: #969696; border-right: #969696 1pt solid"><font size="2">10</font></td> <td class="xl27" width="163" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 122pt; border-top: #969696; border-right: #969696 1pt solid"><font size="2">55</font></td> <td class="xl30" width="200" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 150pt; border-top: #969696; border-right: black 1.5pt solid"><font size="2">75</font></td> <td class="xl25" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> </tr> <tr height="18" style="height: 13.5pt"> <td class="xl29" height="18" width="88" x:num="" style="border-bottom: #969696 1pt solid; border-left: black 1.5pt solid; background-color: transparent; width: 66pt; height: 13.5pt; border-top: #969696; border-right: #969696 1pt solid"><font size="2">12</font></td> <td class="xl27" width="163" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 122pt; border-top: #969696; border-right: #969696 1pt solid"><font size="2">100</font></td> <td class="xl30" width="200" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 150pt; border-top: #969696; border-right: black 1.5pt solid"><font size="2">135</font></td> <td class="xl25" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> </tr> <tr height="18" style="height: 13.5pt"> <td class="xl29" height="18" width="88" x:num="" style="border-bottom: #969696 1pt solid; border-left: black 1.5pt solid; background-color: transparent; width: 66pt; height: 13.5pt; border-top: #969696; border-right: #969696 1pt solid"><font size="2">14</font></td> <td class="xl27" width="163" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 122pt; border-top: #969696; border-right: #969696 1pt solid"><font size="2">160</font></td> <td class="xl30" width="200" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 150pt; border-top: #969696; border-right: black 1.5pt solid"><font size="2">215</font></td> <td class="xl25" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> </tr> <tr height="18" style="height: 13.5pt"> <td class="xl29" height="18" width="88" x:num="" style="border-bottom: #969696 1pt solid; border-left: black 1.5pt solid; background-color: transparent; width: 66pt; height: 13.5pt; border-top: #969696; border-right: #969696 1pt solid"><font size="2">16</font></td> <td class="xl27" width="163" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 122pt; border-top: #969696; border-right: #969696 1pt solid"><font size="2">245</font></td> <td class="xl30" width="200" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 150pt; border-top: #969696; border-right: black 1.5pt solid"><font size="2">335</font></td> <td class="xl25" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> </tr> <tr height="18" style="height: 13.5pt"> <td class="xl31" height="18" width="88" x:num="" style="border-bottom: black 1.5pt solid; border-left: black 1.5pt solid; background-color: transparent; width: 66pt; height: 13.5pt; border-top: #969696; border-right: #969696 1pt solid"><font size="2">20</font></td> <td class="xl32" width="163" x:num="" style="border-bottom: black 1.5pt solid; border-left: #969696; background-color: transparent; width: 122pt; border-top: #969696; border-right: #969696 1pt solid"><font size="2">480</font></td> <td class="xl33" width="200" x:num="" style="border-bottom: black 1.5pt solid; border-left: #969696; background-color: transparent; width: 150pt; border-top: #969696; border-right: black 1.5pt solid"><font size="2">650</font></td> <td class="xl25" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> </tr> <tr height="18" style="height: 13.5pt"> <td height="18" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; height: 13.5pt; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> </tr> <tr height="17" style="height: 12.75pt"> <td height="17" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; height: 12.75pt; border-top: #d4d0c8; border-right: #d4d0c8">For the Imperial sized bolt torques, see notes below.</td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> </tr> <tr height="17" style="height: 12.75pt"> <td height="17" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; height: 12.75pt; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> </tr> <tr height="17" style="height: 12.75pt"> <td height="51" rowspan="3" colspan="6" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; height: 38.25pt; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> </tr> <tr height="17" style="height: 12.75pt"> <td height="17" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; height: 12.75pt; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> </tr> <tr height="17" style="height: 12.75pt"> <td height="17" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; height: 12.75pt; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> <td style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; border-top: #d4d0c8; border-right: #d4d0c8"></td> </tr> <tr height="33" style="height: 24.75pt; mso-height-source: userset"> <td class="xl56" height="33" width="1122" colspan="13" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; width: 842pt; height: 24.75pt; border-top: #d4d0c8; border-right: #d4d0c8"><font face="Verdana">US Recommended Bolt Torque</font></td> </tr> <tr height="18" style="height: 13.5pt"> <td class="xl41" height="18" width="1122" colspan="13" style="border-bottom: black 1.5pt solid; border-left: #d4d0c8; background-color: transparent; width: 842pt; height: 13.5pt; border-top: #d4d0c8; border-right: #d4d0c8"></td> </tr> <tr height="22" style="height: 16.5pt"> <td class="xl47" height="58" rowspan="3" width="88" style="border-bottom: #969696 1pt solid; border-left: black 1.5pt solid; background-color: #ffffcc; width: 66pt; height: 43.5pt; border-top: black; border-right: #969696 1pt solid">Size</td> <td class="xl50" width="1034" colspan="12" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 776pt; border-top: black 1.5pt solid; border-right: black 1.5pt solid">Recommended Torque</td> </tr> <tr height="18" style="height: 13.5pt"> <td class="xl53" height="18" width="363" colspan="2" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 272pt; height: 13.5pt; border-top: #969696 1pt solid; border-right: #969696 1pt solid">Grade 2</td> <td class="xl53" width="128" colspan="2" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 96pt; border-top: #969696 1pt solid; border-right: #969696 1pt solid">Grade 5</td> <td class="xl53" width="133" colspan="2" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 100pt; border-top: #969696 1pt solid; border-right: #969696 1pt solid">Grade 8</td> <td class="xl53" width="140" colspan="2" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 105pt; border-top: #969696 1pt solid; border-right: #969696 1pt solid">18-8 S/S</td> <td class="xl53" width="128" colspan="2" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 96pt; border-top: #969696 1pt solid; border-right: #969696 1pt solid">Bronze</td> <td class="xl53" width="142" colspan="2" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 107pt; border-top: #969696 1pt solid; border-right: black 1.5pt solid">Brass</td> </tr> <tr height="18" style="height: 13.5pt"> <td class="xl26" height="18" width="163" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 122pt; height: 13.5pt; border-top: #969696; border-right: #969696 1pt solid">Coarse</td> <td class="xl26" width="200" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 150pt; border-top: #969696; border-right: #969696 1pt solid">Fine</td> <td class="xl26" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">Coarse</td> <td class="xl26" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">Fine</td> <td class="xl26" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">Coarse</td> <td class="xl26" width="69" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 52pt; border-top: #969696; border-right: #969696 1pt solid">Fine</td> <td class="xl26" width="76" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 57pt; border-top: #969696; border-right: #969696 1pt solid">Coarse</td> <td class="xl26" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">Fine</td> <td class="xl26" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">Coarse</td> <td class="xl26" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">Fine</td> <td class="xl26" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">Coarse</td> <td class="xl28" width="78" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: #ffffcc; width: 59pt; border-top: #969696; border-right: black 1.5pt solid">Fine</td> </tr> <tr height="18" style="height: 13.5pt"> <td class="xl34" height="18" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; height: 13.5pt; border-top: #d4d0c8; border-right: #d4d0c8">#4</td> <td class="xl27" width="163" style="border-bottom: #969696 1pt solid; border-left: #969696 1pt solid; background-color: transparent; width: 122pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="200" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 150pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="69" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 52pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="76" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 57pt; border-top: #969696; border-right: #969696 1pt solid">5.2</td> <td class="xl27" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="64" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">4.8</td> <td class="xl27" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="64" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">4.3</td> <td class="xl30" width="78" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 59pt; border-top: #969696; border-right: black 1.5pt solid">-</td> </tr> <tr height="18" style="height: 13.5pt"> <td class="xl34" height="18" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; height: 13.5pt; border-top: #d4d0c8; border-right: #d4d0c8">#6</td> <td class="xl27" width="163" style="border-bottom: #969696 1pt solid; border-left: #969696 1pt solid; background-color: transparent; width: 122pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="200" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 150pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="69" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 52pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="76" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 57pt; border-top: #969696; border-right: #969696 1pt solid">9.6</td> <td class="xl27" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="64" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">8.9</td> <td class="xl27" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="64" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">7.9</td> <td class="xl30" width="78" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 59pt; border-top: #969696; border-right: black 1.5pt solid">-</td> </tr> <tr height="18" style="height: 13.5pt"> <td height="18" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; height: 13.5pt; border-top: #d4d0c8; border-right: #d4d0c8">#8</td> <td class="xl27" width="163" style="border-bottom: #969696 1pt solid; border-left: #969696 1pt solid; background-color: transparent; width: 122pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="200" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 150pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="69" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 52pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="76" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 57pt; border-top: #969696; border-right: #969696 1pt solid">19.8</td> <td class="xl27" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="64" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">18.4</td> <td class="xl27" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="64" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">16.2</td> <td class="xl30" width="78" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 59pt; border-top: #969696; border-right: black 1.5pt solid">-</td> </tr> <tr height="18" style="height: 13.5pt"> <td height="18" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; height: 13.5pt; border-top: #d4d0c8; border-right: #d4d0c8">#10</td> <td class="xl27" width="163" style="border-bottom: #969696 1pt solid; border-left: #969696 1pt solid; background-color: transparent; width: 122pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="200" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 150pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="64" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="69" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 52pt; border-top: #969696; border-right: #969696 1pt solid">-</td> <td class="xl27" width="76" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 57pt; border-top: #969696; border-right: #969696 1pt solid">22.8</td> <td class="xl27" width="64" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">31.7</td> <td class="xl27" width="64" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">21.2</td> <td class="xl27" width="64" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">29.3</td> <td class="xl27" width="64" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">18.6</td> <td class="xl30" width="78" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 59pt; border-top: #969696; border-right: black 1.5pt solid">25.9</td> </tr> <tr height="18" style="height: 13.5pt"> <td class="xl35" height="18" x:str="'1/4" style="border-bottom: #d4d0c8; border-left: #d4d0c8; background-color: transparent; height: 13.5pt; border-top: #d4d0c8; border-right: #d4d0c8">1/4</td> <td class="xl27" width="163" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696 1pt solid; background-color: transparent; width: 122pt; border-top: #969696; border-right: #969696 1pt solid">4</td> <td class="xl27" width="200" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 150pt; border-top: #969696; border-right: #969696 1pt solid">4.7</td> <td class="xl27" width="64" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">6.3</td> <td class="xl27" width="64" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">7.3</td> <td class="xl27" width="64" x:num="" style="border-bottom: #969696 1pt solid; border-left: #969696; background-color: transparent; width: 48pt; border-top: #969696; border-right: #969696 1pt solid">9</td> <td class="xl27" width="69" x:num="" style="border-bottom: #969696 1pt solid; 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Tom,

Try this one. Same product.....

http://www.opticsplanet.net/leupold-...ue-wrench.html

Those work, but typically are set to a single value. You end up buying a lot of expensive T handle torque wrenches if you have mulitple torque values. Very useful if you use the same value frequently though.

For about $20.00 most could run down to harbor Freight and pick up a torque wrence that is accurate enough for propeller screw torque. Perfect? Absolutely not, but were not spec,ing to serious production standards that require annual or semi-annual certification of precision tools

Pe, that photo tells the whole story. I was not familiar with how these props were manufactured. I've not seen a cross section of the hub of one of these props. There is very little material around the hub and, obvious now, it's not solid to the outside surface of the hub. Crushing the hub has serious consequences. The smaller carbon props that I'm familiar with are solid throughout.

While I'm not into engine in this size range I might one day try. Seeing the inside of the prop has made it very apparent that the clamping force is critical. I hope that if I try a carbon prop the manufacturer supplies appropriate torque specs and also takes into account different bolt sizes and how this translates to clamping force.

I've been really pleased with the Harbor Frieght 1/4" drive torque wrench.... I'm sure it's not accurate either, but like you said, much closer for our application than the alternative methods commonly used. Pat, I've never seen first hand, a prop like the one you posted. I'm glad I haven't.

I just ordered the 1/4" drive from Harbor Freight.

Adjustable to 200 inch .oz. Under $ 20 plus shipping.

Thanks guys !

I can attest to the fact that a number of torque devices period arent close to their adjusted values. I'm QA in a lab that certifies all makes and models of torque devices. A few of the bigger named tool manufacturers have some that stay within their required tolerances on a regular basis. Most of them require recertification every 3 - 6 months. The majority of them are made to within 4-6% of the adjusted torque value. Of course this is all for military stndrds. Like it was mentioned in a previous post, how accurate do we need them to be?
Stangevil29

I have both click type and bar type torque wrenches. I consider the bar type more cionsistent as it is not subject to any forces other than bending in measuring the torque. It may not be accurate though, as I have no way of testing that. I use the bar wrench to "calibrate" the clicker type wrench every so often, and especially if I am tightening a critical assembly. Just my redundent way of thinking.

Regards,

Richard

I usually drill the bolt holes slightly over sized, and rely on the center stud for positioning. I drill all of my props on a drill press.

The most common mistake I see with clicker type torque wrenches is not returning the tension adjustment to zero when not in use, I have seen mechanics with many years experience put their torque wrench back in their tool box still adjusted to a torque setting, which will cause inaccuracy very fast. ALWAYS return the the torque adjustment to zero after use.

there is so much info on the torque values of fasteners.

You show a chart for torque values for certain size hardware, but what alot do not know is that those torque values are not what the hardware is set for. the only way to properly set the correct torque for a bolt is to use a micrometer and measure the streatch of the bolt. you can have a torque value of lets say 45" lbs for a common 10-32 bolt/screw. the 45"lbs is a general torque value that will get you close but not exceed the correct value of the bolt when torque is applied fro from the head side of the bolt. A bolt can have two different torque values depending on where is torqued from head or nut side/threaded side. you also have to take in the fact of the shank resistence that the bolt is going thru in the prop or what ever material it is going thru. so that 10-32 bolt could use 45"lbs when torqued at the head side of it going thru a prop and be correct, but apply that torque on the nut side and it will be over torqued for the bolt.

torque wrenchs..... cheap one is better than none at all but you have to take care of them. You just cant torque your prop then throw the thing in the tool box. You need to treat them like they are made of glass. When you buy one MUST have it calibrated before first use to know it is accurate. When going to use it after is checked out you must set it to the torque value you will be using it at and then cycle the break over (click) of the torque wrench to "lube the head". This will give you most accurate torque that the torque wrench can give you. Torque wrench's have a useable range on them too. the general rule is to not use the torque wrench in its lower 20% of its range. a torque wrench that has a scale of 20-200" range at all. thats why they make a 5-50" one. Only has a useable range of 40-200, some will say the 20% is already in the scale but the torque wrench can not be accurate at all in the 0-20" then when done turn down to the torque wrench to it lowest value when storing it.

This is an excellent thread and the advice given by OP is worth its weight in gold! [sm=thumbup.gif]
THis thread should be made a "sticky"

Thanks!

Pe:

Since I was in a destructive mood today, and the fact another propeller was tossed with a different failure mode, I got to hacking up some propellers.

The prop you depicted is the same make as two that failed. The difference between yours and one of the ones that failed is ...nothing. Pics of a stock prop core are attached.

Over the counter production propeller with a fiberglass core. It just looks like carbon under casual inspection. The lay up has no "tow" to limit compression. The core strength is determined by the resin content. A 'dry' lay up (does happen) and core compression resistance is severely compromised. That was one of the failure factors in the prop in my first post. I'm starting to like the wood core composite props better. Just don't hunker down on the screws.

Now that I'm thinking about it, a PT or Air Models prop hasn't been failed yet. I hate it when one is missed. Got another mission

I got one of these last Christmas, and have been "educated" on how "un-calibrated" my fingers/wrist/elbow really ARE. Very lucky I never caused a prop failure during my "no torque wrench"living in denial days.

Now I am a believer.

Engineering 102:

When destruction of the third composition propeller in two days occurs, blame the propeller and engine hub design rather than admit you're doing something wrong. Argue with the guy that has 30 years more experience than you do how bolt clamping forces are inadequate to effectively secure a propeller. Describe how propellers should have a hard insert laminated into the prop at each bolt hole location. This in spite of the fact that thousands of people have been doing so every day with absolute success around the world. Then claim the engine makes more power than a "normal" engine with more violent combustion pulses. Use an associate engineer to reinforce your position.

When what you are doing fails to work, blame the product. Always blame the product....... Where does stupidity end for engineering brilliance to begin?

Common sense 101. Torque a fastener to the correct value and go play.

Here's a wood prop that came loose from a friend's plane this week. All 6 prop bolts sheared off; I think he failed to torque them down often enough. The spinner and center bolt remained intact and this allowed the spinner to chew into the prop. The spinner cut about 1/3 of the way through each blade before he got it shut down. This damage happened in about 30 seconds. The engine continued to run after the bolts sheared off.

The ones I have used so far all had sound hubs, with a hub core of polyester, filled with glass fibres and talcum powder. This gives the prop hub an excellent compression resistance, even when hot.
A dry lay-up that results in any form of delamination should be cause for warranty. This particular manufacturer has the hubs marked, so they can trace any error to the guy who made the prop.
I do not like wood cores so much. Wood compression strength is a variable that can hardly be controlled, unless it is resin impregnated under vacuum, or laminated using very thin hardwood plies. If inferior wood is used in the core of a carbon prop, failure can't be seen like in standard wood props, and a dry lay-up willcause delams as well.
I felt destructive too, so anoher two crash damage props was inspected. Clearly visible are the sound evenlayup, and the extra ring in the core, where the bolt holes are positioned. This particular 3-blade prop had the drilling done very tight (3D milling 4.9mm, M5 bolts). I normally drill 0.5mm oversize. In this case, all 6 bolts max torqued to M5 8.8 quality, at 10Nm. I normally use only 5 - 6 Nm on M5 prop bolts. With wood 3Nm, which already causes some crushing.