CRASHMISTER

My Feedback: (31)

Ive noticed on the RCU and other places , propellers drilled for specific motors. Can these be safely re-drilled? Obviously the wood ones would be weakened quite a bit. But what about the plastics and composites???? Pat. Actually what Im asking is drilled a second time With a whole new patern??? Seems to me safety issues aside you would be removing to much material . Prob make it pretty hard to balance the prop also. All in all seems like a bad idea to me but I hada ask. Pat.

voyager_663rd

Re-drilled? I presume you mean enlarging the hole? There are reamers specifically designed for that--metric and standard. For around $10 each. Not recommended to do it with a file or drum. Impossible to get it true.

Geistware

My Feedback: (16)

WHat I hav done is fill the holes with epoxy. Then re-drill holes in the propeller.
I have never had problems doing this with wood, plastic and CF propellers

mashp39

My Feedback: (1)

Why did you ever fill the hole and then redrill it?

Geistware

My Feedback: (16)

I purchased 2 propellers that had been drilled for a DA.
I have a BME. I filled in the holes and re-drilled them for the studs on both sides of the main shaft

redfox435cat

Are props really that much that you need to do this. Dude get another prop. The saftey and wellfar of those around you is worth a hell of alot more than a prop

Geistware

My Feedback: (16)

My propellers run from $50 to $85 each. If I can get 3 at half price, I can save $75 or more dollars. To me it IS worth it!

redfox435cat

I'm not going to get into a P!@@ match with ya but if can put a price tag on someone’s health that your simply hopeless. If you can afford a model that requires a 85 dollar prop then you can definitely budget for another prop. I can believe I even have to say this

Geistware

My Feedback: (16)

How is filling in holes in the hub a safety hazard?
I fill in six holes which has to make the propeller stronger.
I then drill two blind holes for my spinner bolt heads to fit into.
Then I balance the peopeller and install it on the engine.

If safety is a concern with respect to the hub, how about you guys who remove material from the propeller blade face to balance it. Now that is a safety issue to me.

Deadeye

Don'tcha just love unprovoked attacks? I would ignore him, Giestware.

FLYBOY

My Feedback: (11)

Guys, re-drilling a prop is not a bad thing. It is no way going to make it throw a blade if it is done right. Filling the hole in it doesn't make it stronger, it just fills it so you can drill it where it needs to be. Adding a round hole will not weaken it. Using a file on it can cause more problems cause you may get the hole elongated and it can move, but probably not enough to make a difference.

I use a drill guide for my big props cause I have to drill a bunch of holes to mount it. I think the hub uses 5 bolts instead of a center hole, so I too have to fill the center hole and re-drill.


redfox, I understand what you are saying, but your a little off the mark. I would be more worried about a scratch in a prop tip of a glass prop. It has more of a chance to throw that tip than re-drilling will ever have.

redfox435cat

Yea I probably sounded too harsh, but I've seen 5 of these big props thrown, 4 of them were repaired props from someone trying to save a buck. 2 missed someone by inches. It may have worked before but I asure you you got lucky. The epoxy and the prop materials do not have the same density, tensil strength or crush tolerance. When you try to repair it with any glue as soon as you cinch it down on the engine the prop crushes a little, the epoxy doesn't and usually splinters and is undetectable until you crank the engine and rev it. But hay it's stronger when you repair them

FLYBOY

My Feedback: (11)

repairing is a different story. re-drilling them to make them fit a new bolt pattern isn't a repair. If your talking repairing a crack or something like that, it would be ludicris. That would be a dangerous prop.

Many props have multiple hole lugs though. As long as the holes are clean and straight, they are no weaker than a single hole unless you use huge holes and leave no material left.

Richard39

My Feedback: (14)

Would using epoxy glued wood dowl pins in the holes make the process any safer? considering that the wood prop hub will compress when tightened...

kenh3497

Not that I know anything.... In my simple mind, this would be preferable to just filling the holes with epoxy.

Ken

Richard39

My Feedback: (14)

If the dowls are flush with the hub would that make a problem with the wood hub compressing even or allowing normal compression?

I have some wood props that compress up to 1/16 over time with continued tightening after each day of flying... of course maybe I am tightening too much or too much torque....

Oberst

Exactly. I've had to enlarge hole in my props and my reamers only goes up to a certain size. There are times when I need to use a short shaft spinner and need to drill into the prop in order to get the bolt down deep on the washer- and tight on the crankshaft. Early O.S. FS engines had a short shaft and if we wanted a Tru-Turn, we had to dig into the prop.

In order to be accurate with the drilling, and not throw off the balance too much- I use a drill press to make sure I get that perfect alignment.

So yes, I've drilled props for many years. I have yet to get a prop blade stuck in my forehead. Like Flyboy said, if you do it right you won't have any problems. If you don't have some sort of drill press, then I'd try getting one. Doing it with a hand drill is too difficult to get the hole accurate.

Hope I helped,

Pete

speedracerntrixie

My Feedback: (29)

Obviously we are talking about giant scale props with a 10mm center hole and 6 3/16" holes drilled to match the engine hub. IMO once a prop is drilled I would not fill the holes and drill for a different pattern between the pre-existing holes. Take the CF prop for example. It is made from a pre-preg CF material. What that means is that the material already has the epoxy in it and is stored in a freezer. When it's time for use, it's thawed, layed in the mold, vacuum bagged and cured in an oven at 250-275 degrees. That forms the outter shell, then epoxy saturated CF strands are laid in to fill the hub and edges. The molds are then joined together and heat cured again. When the prop is drilled a certain % of these strands are cut. The manufacturer designs the hub large enough to handle this. When one fills the holes with epoxy, it has different properties then what was used to originally make the prop so is of no value at all. When the second set of holes are drilled, the hub is weaked past designed paramiters and subject to failure. Wood props are simular as the wood grain is a natural fiber running from tip to tip and APC type props are a fiber reinforced plastic so the principal is the same.

jaka

Hi!
Of course you can use a reamer to enlarge a hole in a prop!
Of course you can use a round file to enlarge a hole in a prop!
Of course you can modify and file a prop to what shape you like!
...Provided you balance the prop afterwards!

Of course it's no use filling the holes in the hub with epoxy glue! Does not give added strenght in any way!

exeter_acres

My Feedback: (2)

The prop I'm using retails for $199.....

so yes...they are that much... and the hub is mostly resin anyways... so it is not a safety issue.. if done properly.