NEO motor pinion keeps failing

We have a NEO motor for our shooting mechanism. On the shaft of the NEO motor we have a press fit pinion that drives an Andymark gearbox. However, after a few rounds of shooting the pinion becomes too big for the shaft, ie the shaft spins but doesn’t spin the pinion. When this first happened we replaced the pinion and it worked fine, but it happened again, in the middle of a match. Why is the pinion’s inner diameter getting stripped? What solutions do you all have?

use a tighter pinion. we’ve run into 6 pinions that ended up being unusable due to being not tight enough of a press fit. some of them didn’t even press they were just loose. you could also add an adhesive.

Which pinion is this specifically? The CIM Sport pinion?

Using loctite green retaining compound should fix this issue, but be warned. Very permanent. Let it fully cure before using it again.

specifically 680 retaining not 290.

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@Nadeem, which gearbox are you having issues with?

All, we actually found that Loctite 271 is far superior to the green bearing retaining compounds. When we were testing solutions to some 15T EVO pinion size issues, we wiped off the output shaft of the CIM but didn’t really do any surface prep to the pinion other than it had been on an off a shaft several times, removing some of the oil. We placed a ring of loctite around the inside of the pinion near one end and slid that end onto the shaft first which helped distribute the loctite along the shaft and pinion. After using the spacer tool to set the location of the pinion, We added just a little bit more loctite to the top edge of the pinion and allowed some of that to wick down between the pinion and shaft. We did our tests after 16 hours of cure time (recommended is 24 hours) and found a very similar holding strength to that of a proper press fit, approximately 4x the stall torque of a CIM (7.8 ft-lbs).

Green bearing retaining compounds were in the ~5 ft-lbs area before they stripped out.

Sincerely,
-Nick

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The different compounds are for different clearances