pic: How will 3620 use this gear?

We drilled out the small octagonal hole and broached for 3/8" hex – both operations used a 3 jaw chuck on our lathe. Fitted to a scrap of hex shaft and a pair of am-0439 bearings, it just needs some side plates.

Neat, dual FPs! Are you going to add cooling air holes to the Front Plate?

Thanks! And yes, cooling holes will be needed. I am thinking 15/64" diameter, eight places on a 0.931 circle. Or something like that. :]

These motors do need air flow-through, or they’ll cook.

Also, the detailed dimensions visible on the drawing may not be correct – they are based on 0.8 module gear teeth – actual tooth size is more likely 32 DP. Also, they are based on a 19 tooth pinion, and our -9013 motors have 13 tooth pinions.

If your clearance hole for the pinion was smaller the motor will sit on the orange washer. Just need to use longer screws for the motor. Your air flow problem will be solved.


Yes, but how do you accurately locate the motor?

Let see. if that is the FP and the first stage from the FP gearbox you have a 13 tooth pinion and a 72 tooth driven gear that gives a speed reduction of 72/13 = ~5.54

Based on data from the FIRSt provided motor specs (http://www.usfirst.org/sites/default/files/MotorInfo4.1.pdf) the FP -9013 has a free speed of 16700 RPM. After this reduction that works out to ~3015 RPM. Gosh Richard, what could you ever want spinning that fast? :rolleyes:

I wonder if you put a wheel on that shaft what kind of surface speeds you could get?

My head seems to spin that fast, frequently. :wink:

Ba dum tsshh!! (you know, with drum and symbol):smiley: