Testors Engine Propeller

batjac wrote:For my Testors engines I just drill out the hole on a Cox 5x3 safety prop.  I make sure to mark the props with "WM" for Wen-Mac, since they're the same as a Testors.  Works fine for me.

The Marked Mark

Yep. That's what I did on this Testors Albatross, when the original prop got broken in a botched hand launch\crash.

I recall Bernie had quite a few original Testors props in stock some time back. Not sure if he still has any.

Chancey, The Testors .049 engines have a 6-32 threaded crankshaft which measures .161" diameter. A #20 (decimal/inch) machinist-drill has a .161" diameter.

Alternately.. a 4.1mm metric drill has a .1614" diameter.. and would also be a good choice.

Either of these drill-sizes are what you'd want to use to enlarge a propeller's hub-hole to fit your Testors .049 engine.

Don't drill the hole oversize.. or else you'll likely have a propeller that's off-center and out-of-balance after it's mounted.

Don't re-use the propeller on a Cox .049 engine once it's been drilled-out to fit the Testors engine's 6-32 shaft. Keep the propellers separate.. and marked for the engines that they fit. The Cox .049's 5-40 prop-screw is .039" smaller in diameter than the 6-32 size.

NEW222 wrote:Thanks roddie for all the information. I am glad I now know the size of the shaft as well. I do have those drill bits available to me to use also, so I will give it a go. Thank you.

Hey Chancey.. you're welcome my friend. It's imperative to keep precision measurements with model-aircraft applications.

Sorry but just saw this post:

https://www.ebay.com/itm/7824-Vintage-Testors-Model-Airplane-Prop-2-Blade-6-Propeller/371977064889?epid=22002738548&hash=item569b8f91b9:g:uAAAAOSwR2RaKs~8

https://www.ebay.com/itm/4100-5016-Vintage-Testors-Model-Airplane-Prop-2-Blade-4-1-2-Propeller/371977109433?hash=item569b903fb9:g:ptYAAOSwX3FaA4Xv