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Spinner too short? or Saito engine shaft too long?

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Spinner too short? or Saito engine shaft too long?

Old 02-06-2021, 01:17 PM
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MattKennedy
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Default Spinner too short? or Saito engine shaft too long?

I need some advice/guidance. I am in the middle of a building a kit (Sig Kadet Sr.) and plan to use a new Saito .62 I've purchased. Sig recommends a 2" spinner. So after much looking I bought a Dave Brown Vortech 2" "standard" aluminum spinner. Dave Brown recommends their "short" adapter nut for spinners under 2.5" so that is what I bought to go with.

I just received the spinner and adapter nut so I thought I'd check to see how they fit together on the engine. So I first removed the Saito washer, prop nut and lock nut. I then slipped the spinner backing plate all the way down the engine shaft until it was against the brass-colored non-removable spacer (with the knurled face - sorry not sure what this is called). I then spun the adapter nut onto the end of the threaded engine shaft as far as it would go. It spun easily until it bottomed out so I'm pretty certain it was all the way on even though it is only finger tight. I then put the spinner cone itself over the adapter nut and screwed the retaining screw through the tip of the spinner cone and into the adapter nut. First photo below shows the pieces I am referring to. The second photo shows the issue.

Here is the problem. The spinner cone is still about 1/4" short of reaching it's backing plate. It would seem I'd either need a longer spinner cone or a shorter threaded shaft on the engine. I've done a lot of searching and haven't read anything like this. I am surprised as it doesn't seem like I'm using overly small or large engine or spinner. . This is the shortest adapter nut Dave Brown has available and it is really pretty short - just under 3/4" total. A longer adapter nut would only push the spinner further away from the backing plate.
Thoughts?

Thanks for the help!
-Matt


Last edited by MattKennedy; 02-06-2021 at 04:11 PM.
Old 02-06-2021, 02:08 PM
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DGrant
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... or maybe a shorter prop-nut that has a center-thread for screwing spinner cones on. You'll have to measure the depth of the spinner cone, and compare that to the length of your crank/prop-nut/prop when that's assembled. That should tell you if that prop-nut assembly is too long. Occasionally these can be shortened, just with a Dremel cut-off wheel, as well as the spinner-screw that sometimes needs to be trimmed, so it's tight when the spinner cone is firmly seated too. Don't tighten that spinner cone too much though, you can warp that backplate by tightening the cone on too tight. Firm is good for a cone, but extreme tight isn't good for the cone or backplate.

Maybe some pics too might help.. I'm only imagining... but a 1/4" discrepancy/space seems quite a bit.. especially if they told you it would work and it's the shortest nut they have.
Old 02-06-2021, 02:24 PM
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RCFlyerDan
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Originally Posted by MattKennedy View Post
I need some guidance on something. Unfortunately, explaining is going to be difficult without photos but I'm new and haven't yet reached the necessary number of posts required before I can post photos. So here goes.

I am in the middle of a building a kit (Sig Kadet Sr.) and plan to use a new Saito .62 I've purchased. Sig recommends a 2" spinner. So after much looking I bought a Dave Brown Vortech 2" "standard" aluminum spinner. Dave Brown recommends their "short" adapter nut for spinners under 2.5" so that is what I bought to go with.

I just received the spinner and adapter nut so I thought I'd check to see how they fit together on the engine. So I first removed the Saito washer, prop nut and lock nut. I then slipped the spinner backing plate all the way down the engine shaft until it was against the brass-colored non-removable spacer (with the knurled face - sorry not sure what this is called). I then spun the adapter nut onto the end of the threaded engine shaft as far as it would go. It spun easily until it bottomed out so I'm pretty certain it was all the way on even though it is only finger tight. I then put the spinner cone itself over the adapter nut and screwed the retaining screw through the tip of the spinner cone and into the adapter nut.

Here is the problem. The spinner cone is still about 1/4" short of reaching it's backing plate. It would seem I'd either need a longer spinner cone or a shorter threaded shaft on the engine. I've done a lot of searching and haven't read anything like this. I am surprised as it doesn't seem like I'm using overly small or large engine or spinner. . This is the shortest adapter nut Dave Brown has available and it is really pretty short - just under 3/4" total. A longer adapter nut would only push the spinner further away from the backing plate.
Thoughts?

Thanks for the help!
-Matt
Matt,

A prop is more thick then where the spacer is located on the shaft. So, you need to mount the prop that you will be using. I think that you are trying to describe the prop hub for the thing with a knurled face.
Old 02-06-2021, 03:00 PM
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MattKennedy
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I really need to post those photos. It will make the issue so clear. Counting down...think I have like 3 or 4 posts to go...
Old 02-06-2021, 03:34 PM
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I responded to your question on another forum, but I got to thinking that you might check that there isn't any
trash, or metal shavings in the spinner nut. That's unlikely, but still worth checking 4 Stroke engines typically
use larger props then 2 stroke counterparts. Larger props have thicker hubs, and that's the reason your shaft
is a little long for your spinner. You might call the manufacturer and explain your problem, and they might have
a solution. They might have a special short nut, or they might modify one for your application?
Old 02-06-2021, 04:13 PM
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MattKennedy
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Photos now posted in original post. I have also emailed the manufacturer.
Old 02-06-2021, 07:51 PM
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DGrant
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Yeah, that cone is too shallow. Putting a 2" center-screw aluminum spinner on an engine this size is always a crap-shoot, when dealing with depth, and even the prop-notch can be difficult to fit correctly.

Do know, on that Saito, being a four-stroke, you need to run a jam-nut/prop-nut, really for your own safety. Note the original nuts with that engine probably were a prop-nut, then a jam-nut that seats and tightens to the prop-nut. That's for your own safety. A jam-nut is always recommended on four-strokes. If you ever have a four-stroke back-fire and throw a prop off, you'll know why you should always use a jam-nut/prop-nut. Don't leave that out.

Is it easy finding all the correct components to make it right?... nope. It is possible though.

A 2" aluminum center-screw spinner is actually small, and is a tough one to get fitted right, if it's even possible. Why do you need a 2" spinner?... is it for a cowl mating?.. I might suggest Tru-Turn spinners as well. Just Google them if you're curious. In my experience, they offer far more options and information for spinners of this sort then anyone... and they have many different shapes and sizes, and will custom make spinners/backplates as well. It's all they do, and they haven't changed in the 30yrs I've been using them. DaveBrown on the other hand isn't nearly as keen on spinners, although they offer somewhat of a variety. Tru-Turn makes spinners in every size, from very small electric styles, to giant scale and beyond. So if DaveBrown products doesn't come through, check out Tru-Turn, they will for sure help you.

Also, be aware not all prop-hubs are the same thickness. A MasterAirscrew resin/plastic prop has a very thick hub, whereas a Xoar or Falcon wood prop has a thinner hub and is overall thinner. So if you get your prop on, and there's only a thread or two left to put the nuts on, your prop might be a bit thick... again it's not easy sometimes to find compatible components, but it is possible, and well worth it, because with the props/engines it boils down to safety. Good luck with it.
Old 02-07-2021, 02:53 AM
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1200SportsterRider
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Here is the Tru-Turn version of that set up, you might want to upgrade to a 13 x 6 or a 13 x 7.
Here are my numbers for a 62 turning a12 x 6 three blade:Saito .62 MA 12x6 3B 10% full syn. 10,150 1,850.



Last edited by 1200SportsterRider; 02-07-2021 at 03:06 AM. Reason: Add content.
Old 02-07-2021, 07:15 PM
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MattKennedy
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Thank you all for the feedback and advice. At this point, given the advice I've received here and elsewhere, I'm going to return this spinner and bite the bullet and call Tru Turn and have a chat with them about the various options. From what I've read they are very good at providing a complete solution for a very specific setup. If they can't recommend something I'll fall back to a fancy prop nut of some sort.

Thank you all again!
-Matt
Old 02-08-2021, 04:16 AM
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MattKennedy
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A couple of additional things I wanted to share.

Dgrant - I loved your comment, "Is it easy finding all the correct components to make it right?... nope. It is possible though." Honestly, that's how this entire build has felt to me and is exactly how I've viewed it. So I'm taking your comment and making it my official motto for the remainder of this build.

1200Sportster - great photo. Great looking plane!

-Matt


Old 02-09-2021, 03:51 AM
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Thanks and don't forget about the larger prop, the 62 can handle it easily.
Old 02-09-2021, 10:54 AM
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MattKennedy
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Just a quick update in case someone else might benefit from this info down the road. I ended up returning the Dave Brown spinner. I called Tru Turn and explained the setup. They recommended their "Ultimate" style spinner which is longer/deeper and they believe would accommodate my setup. They also recommended their "wide mouth" version of this spinner which has slots that will accommodate the APC props I want to run without custom slotting. Lastly, they told me the spinner and adapter nut would be returnable if it didn't fit. $51 total ($10 shipping).

Thanks,
Matt
Old 02-09-2021, 08:53 PM
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DGrant
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Perfect! The Ultimate style is my favorite, and lends well to many models. Your plane will be clean clean!!

The "wide mount" cut might be the "Menz" cut, that also lends well to wider prop blades, and wider notch that won't ever be noticed. They're good. There's several options for new, and even old spinner set ups. If you have an old cone you want to fit to a newer engine, you can get new backplates. If your cone is damaged yet your backplate is fine, you can get a new cone. It doesn't matter if stuff was made 20yrs ago, if you know what you need, they can make to fit for any TT component. Great company.

You'll be pleased I'm sure... and moreso safe. It's well worth the wait. I'm so glad it's working out for you. You'll do great! Enjoy your plane!

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