I assembled a World Models T-34 and used an old spinner i had on hand. Well the spinner broke while doing the final assembling. I have another spinner but it is a different brand (DuBro) and it has an inset on the back of the backing plate. The cowl has already been positioned for the other spinner and the DuBro will hit the cowl if installed normally. Can i put a washer or two behind the backplate to space it more forward so it doesn't hit the cowl? What type of washer material would be the best since there are knurls on both the engine and spinner to tighten onto?

skeeter

no you can't. the washers will remove the friction from between the bakplate and the engine and the spinner will spin slower then the engine and possible destroy the knurling on the engine. put spacers or washers on the engine mount and firewall connection

Didn't think of that. Thanks for the tip!

skeeter

Can you not get another spinner like the one you broke?

Not sure what brand it was and i discarded it before i realized the difference. My local hobby shops that i've been to so far only carry the Dubro.

skeeter

I found some aluminum washers that are about 1/8 thick and knurled front and back at a local hobby shop that were designed just for doing this. Not a clue where the LHS got them, they bought out old shops and estate sales. I also have wood spacers with crocus glued onto the front and back that I made from different thickness ply that I use. These work very well but stand offs behind the engine or mount is a much better idea. The wood washers tends to compress when tightening the prop. I have never had a spinner come loose but I can see it happening.

Actually you can space out a spinner and have done it many times for just the reason you speak. One of my favorites is as old as model aviation itself and it goes like this: Use an old APC plastic prop (no wood props) cut the blades off and sand to a round blank. Now just use a bench grinder or face sander and thin down to the exact thickness you need and what you have avalible crankshaft threads for. I currently have two ships now in my fleet that are done this way One of them is a TT.61 pro. I am sorry but am completely befuddled and cannot post pictures with the new forum but would have otherwise. Also still unable to separate the reply into paragraphs but there is one other way to do what you want to do. That is simply use a propshaft extension from 'Fox Manufacturing' which are made in quarter inch increments up to three quarter inch. The three quarter inch extension is currently in use on one of my airplanes, John

Concerning the spinner/cowl spacing with various spinners. First with virtually all ARF's the included plastic spinners are most frequently simply the 'low bid at the time'. Iincluded spinners will often even not be the same from container load to container load so consistancey cannot be counted on and it at times it is even impossible to order an exact spinner from any given ARF and this even effect sometimes the big name ARFs. So here is a simple bit of info that will help you in the furture: Most of the Great Planes spinners tend to be designed with flush back plate and the spinner will go no further aft that the back edge of the propeller, Most of the Dubro spinners are designed with a recessed backplate and the spinner will protrude to the rear further than the others and this of course affects cowl/spinner spacing. So a little attention to the type spinner or brand you order can also solve the problem. John

Cut the center out of an old spinner Put a bolt through it and spin it in a drill against so 40 grade Aluminium Oxide paper.

Use a conventional steel washer but glue 120 grade W/D paper to both sides. Trim off excess.

I have used both with success.

I like Johns idea about the old prop cut down. I normally cut down an old spinner back plate as mentioned above. Either would work better and be lighter than a washer. Plus they will fit the crankshaft correctly.

david

Why not cut a piece of plywood and put it behind the motor mount and space it out. That is what I do.

It's actually easier than gluing the sandpaper to get friction. Get some open mesh sandcloth that plumbers use or either the sanders for drywall that are open mesh. It is rough on both side and very coarse, so all you have to do is cut a piece to fit and make a hole for the prop shaft. I use this stuff for spinner that have the plastic backplate and it's nearly impossible for them to slip.

Depending on how the thrust washer is attached to the engine you can put a spacer under the thrust washer to move it out. Some engines use a tapered collet and with that setup you can use a fairly thick washer. Some OS use the half crest to secure the thrust washer like the .46 I think you may be dealing with but can still be shimmed only to a lesser degree.

One of the problems I see with putting the spacer behind the engine mount instead of behind the spinner back plate is this. the cowl is cut specifically for the engine as it is currently mounted, if you put the spacer behind the engine mount, then the entire engine would move forward, and then the cowl opening might need to be enlarged. I think the spacer behind the spinner back plate would be much easier and cleaner option!

Craig.

Yes, I forgot about the cowl cutouts. At the moment they are just in the right place so I really don't want to mess with that. So many options mentioned for installing something behind the spinner. I will have to think about which would be the easiest for me at this time with what I have on hand.

skeeter