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Testors Engine Propeller

Post  NEW222 on Mon Jun 25, 2018 5:49 pm

Hi all. So, I recently came to aquire a Testors 8000 series engine. However, the main shaft is larger than that of a Cox engine. What propellers does one use, or is it safe to drill out a Cox or Master Airscrew propeller? Thanks in advance.
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Re: Testors Engine Propeller

Post  batjac on Mon Jun 25, 2018 11:15 pm

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
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Re: Testors Engine Propeller

Post  NEW222 on Tue Jun 26, 2018 11:19 am

Thank you.
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Re: Testors Engine Propeller

Post  TLAnderson on Tue Jun 26, 2018 9:00 pm

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.

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Re: Testors Engine Propeller

Post  Oldenginerod on Wed Jun 27, 2018 5:21 pm

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

Post  roddie on Wed Jun 27, 2018 7:38 pm

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.
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Re: Testors Engine Propeller

Post  GallopingGhostler on Wed Jun 27, 2018 8:09 pm

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

No longer shows on-line, my guess is he finally sold out.
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Re: Testors Engine Propeller

Post  NEW222 on Wed Jun 27, 2018 9:25 pm

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.
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Re: Testors Engine Propeller

Post  roddie on Fri Jun 29, 2018 12:05 am

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.
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