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HomeAircraftHelicopterMain Discussion › Gear Modulus Question
11-19-2011 03:17 AM  6 years agoPost 1
GMPheli

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W. Bridgewater, MA USA

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I am building a TSK MyStar 30. I want to convert the tail to TT drive from belt. I have a MyStar 60 TT drive that fits right in. Only thing is it has an 18 tooth gear that mates with the main gear, but I need a 16. My problem is figuring out the modulus of the teeth. From what I have read the modulus is the diameter divided by the # of teeth. This comes out to 1.119. If I go to Stock Drive products, they only list modulus of 1.0, or 1.25. Seems to me the modulus of most of the older helis is the same. Does anyone know what it is? I am thinking I could use an electric pinion gear. Needs to have a 5mm bore. Any help would be appreciated.

Thanks
Alan

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11-19-2011 05:37 AM  6 years agoPost 2
Dr.Ben

rrMaster

Richmond, VA, USA

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Safe money could be placed on the gears being mod 1.

Will an Evo 50 counter gear work?

Ben Minor

Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA

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11-19-2011 07:43 AM  6 years agoPost 3
Chuck Bole

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Tulsa Ok. U.S.A.

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WOW! TSK that brings back some memories..
post some pics when ya get it together please.
chuck

Team Synergy Field Representative / Thunder Power

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11-19-2011 03:50 PM  6 years agoPost 4
Countach

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Bismarck,ND

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The modulus is determined by the pressure contact area(pitch) which is going to be smaller than the overal dia.
http://en.wikipedia.org/wiki/Gear

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11-19-2011 05:47 PM  6 years agoPost 5
AirWolfRC

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42½ N, 83½ W

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You're on track but like Countach says, the modulus is based on the pitch diameter which is slightly smaller than the Overall Diameter.

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11-20-2011 01:35 AM  6 years agoPost 6
GMPheli

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W. Bridgewater, MA USA

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Thanks Dr. Ben! You are a wealth of information as always. Here is what I am dealing with. Does it look like an Evo pinion will fit to you? The belt drive is on the left with the 16T, and the tube drive on the right with the 18T.

Countach and AirWolfRC

Thanks, that explains a lot!

cgbole

I will post pics. Here is my TSK Blackstar gasser that I am also building

A TSK Kaiser Ace in waiting

My Kalt Omega Grand Prix

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