Tee Dee .020 Drive Plate Removal

Excellent reply, sosam117. I've never been a fan of pushing the
drive plate off by unscrewing the collet, regardless of engine size.
I use a smallish drill press vice with wood blocks, and hardened
allen cap screws. Sometimes after a short solvent soak, or a little
heat, and  it's foolproof.
Bob

Bob reassembling the drive plate by the prop screw is also not without a risk. So put some oil onto the splined end of the crankshaft and the screw threads  too to reduce friction and prevent the screw from snapping. A broken screw with its end stuck in the crankshaft without reach can mean the end of life for the crank..been there seen that...

While I am not a fan of removing the prop driver using the crankcase collet, it can be done. New parts and fits can make this method harder. I always use the prop screw to drive the crank off of the prop driver. I don’t use the actual prop screw though if at all possible. I usually use a hardened bolt.

All that said, you really don’t even need to use a washer (or floppy disc material in your case)in between the case and drive plate. I say this because a TD .020 is better suited to using a starter spring or your finger. Unless you have physical limitations then ok use a starter

It won’t cut your finger off…. Worst case small cut.

I agree with preferring a spring starter. I used electric starter on my hardest used Tee Dee 020 until a point of time when I had to put a washer between the drive plate and the worn collet. The engine otherwise is still a perfect and terrific runner so I invested in a red aluminum carb body with the spring peg on it, sold by Bernie, and use the spring starter instead of an electric one ever since. The engine, if well primed, will start after one or two flips with the spring.

For the same reason I changed the red plastic carb body on my most frequently used 010 with the pegged red aluminum option and am very satisfied at how efficient the spring starter on 010-s is..

I too use the collar to remove the drive plate it sometimes seems difficult with a little heat normally pulls out well I was scared once with a .010 but all went well I was because they are so small I was really scared of damaging it I agree with balogh the spring on the .010 works really great also the starter to be avoided if possible especially with the .020 and less But sometimes the starter is necessary as for the car the spring does not work My advice is to use a battery just enough:cox engine:  to start it no need to crank the engine at high speed wit a big 12v power therefore use the battery that is suitable for the size of the engine

dckrsn wrote:Excellent reply, sosam117. I've never been a fan of pushing the
drive plate off by unscrewing the collet, regardless of engine size.
I use a smallish drill press vice with wood blocks, and hardened
allen cap screws. Sometimes after a short solvent soak, or a little
heat, and  it's foolproof.
Bob

For pressing on the prop drive plate, I have a small arbor press that I use to press on the prop driver plates on all of the Cow engines. I made some fixturing so when I press it on the prop driver plate is perpendicular to the crankshaft.
The prop driver is inserted into the upper part of the press. (the part that comes down).
The crankcase and shaft is mounted to the bottom fixture.
It is a pin that slips into the back of the crankcase and there is a hole drilled in the pin to clear the pin on the crank.
So, it is a straight crank to prop driver plate press.

It is probably how Cox installed them at the factory initially?

Before I made the fixtures I used a socket head screw (which is hardened) to re-install the prop driver plate.
I changed to the socket head screw when the original Cox screw broke.
I was lucky to where the screw was sticking out of the crankshaft a 1/4 of an inch.

Well duh in pushing out the crank with the prop screw!! I’ve done that many times on Bees that I’m more familiar with…. I dreamed I read somewhere to do it with the collet on Tee Dees but maybe just my imagination…. It worked fine on the old engine..

Lots of wonderful ideas Thank you! I dug out an old small arbor press and made up some hard wood blocks….. Luckily I found a stainless screw the right thread and length (3-48?)…I gave it a push and it came out wit a pop, Not a smooth push off…. The splines in the prop driver are not cut as deeply as on the old engine…. I cleaned, oiled, Installed the thrust washer, And re-assembled using the stainless screw, a prop and washer…. It was a bit sketchy on pulling the drive back on, very tight….I used the screw like tapping something…. Small turn increments then back off and repeat…. Lots of oil…The old engine has .014” play when fully seated….That’s where I left the new one as well…

I agree it’s probably best to use a spring or finger but springs are hard to find… I think? PeeWee springs seem plentiful…. Plus this crankcase doesn’t have the pin to accommodate it

So why is it bad to use an electric stater? It looks like the thrust washer bears on the front of the collet/crank case….I can’t detect any rubbing of the lower end of the rod in the crank journal ..,The crank pin does not touch the back plate/tank on the inside….. I guess hydraulic lock from a flooded engine is the worst thing…..



Here is the stater I made…. Motor is from an old Tamiya buggy….Shaft hub from an old Erector Set gear…Terminating with 1/4” id surgical tubing…. Fits the .020 spinner nicely…..Pretty docile on 3 volts…

Thank you again for sharing your experience,

Robert

The trouble is that the thrust required to start is substantial and the thrust area is typically just the front of the case. If you can reliably start with minimal cranking, you'll probably be OK. I'm sure you've seen people grind on engines which were reluctant to start.

Something like this on a smaller scale would be ideal. https://www.greathobbies.com/productinfo/?prod_id=SUL635

That’s a neat little starter you built, certainly less invasive than I envisioned. It’s your engine after all so in the end do what you want.

They are just so easy to start with or without the spring that I wouldn’t have considered using a starter. I guess just keep an eye on it. If you notice that the crank play is increasing then you may want to re-think it. Keep in mind it’s not just the nose of the collet and case that gets ground down it’s also the backplate, pin and rod that takes a beating. The worst outcome is if the engine floods, if it hydraulic locks you are looking at a bent rod and a new piston assy. Not easy to come by although Pee Wees are plentiful.

Ron

Thanks for the replies…..I’ll practice hand starting the engine without the spring ….. I think ease of starting will be to have the engine in good mechanical shape, good hot plug and that just right prime….right compression, and etc..,

Part of building the starter was just tinker factor…. I had most of the stuff to do it…It wouldn’t turn the lightly oiled engine over one 1.5 volts….. It will weakly turn it thru compression at 3…. I tried to make it least aggressive as possible…

Robert

Can be useful:

https://www.coxengineforum.com/t11151-cox-020td-spring-starter

Also try to reshape a Pee Wee spring for TD.

Thanks for the link Levent….. Looks well thought out…
There’s a thread here on CEF somewhere that a gentleman was attempting to build some springs on a mandrel and a lathe…. Also a thread on RCG Free Flight on music wire annealing and tempering…,, I might plug all the info together and give it a go….I agree the spring is probably most effective/Safest for the engine….. My old engine started second try after cleaning up and using the factory spring…. It had not ran in over 20 years…

Also a little more nerdiness on the electric starter…. It pulls 5 amps on 3V…. 15 Watts…. That’s around 1/3 rd of the TD’s output power….. Current could go up a bit when you light the plug though….. Nothing really to compare to other than a ratio…,

Robert