REV, please chill with the loctite

Last night our team attempted to remove the casing of the NEOs in order to press a pinion gear on. However, we were unable to remove a single casing. We had two motors where we got two screws out and the third bolt stripped, and one where all three bolts stripped. I believe that the hex head of the bolt is too small to properly withstand the force needed to break the loctite seal. REV, please use less or a lower strength adhesive so that teams can use your motors as directed.

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You will probably have more luck contacting them directly:

contact@revrobotics.com

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@Greg_Needel @JB1

I would warn against trying to disassemble the casing off the motor assembly. In the past removing the casing off a CIM motor has been considered “compromising the physical integrity of the motor”, and against the rules. This year R35 gives regulations as to the modifications you are allowed to do to a motor.

No where does it say you would be allowed to remove the casing of a motor, and then use that motor in competition. At best I would suggest to bring this idea to the FRC Q&A before continuing to physically disassemble a motor you would like to use in competition.

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Yet nowhere does it say you cannot disassemble the motor and reassemble it, without making any modifications.

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Question. Did you heat the threaded area before trying to disassemble? Because heat is definitely your friend in this situation.

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We did not heat it, but wouldn’t that cause the screw to expand, and therefore make it tighter?

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It will weaken the Loctite at quite a relatively low temperature because its a thermoset plastic.

Even if the screw expands, the adjacent threading will expand with it. Also, a threaded interface has plenty of room to expand without causing binding.

Edit: Henkle recommends heating to remove ‘red’ threadlocker(s): http://henkeladhesivesna.com/blog/how-to-remove-loctite-2620-red-threadlocker/

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The REV guide for press fitting a pinion specifically shows removing the case as the preferred method: http://www.revrobotics.com/content/docs/REV-21-1650-PG.pdf

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@Ryan_Dognaux So it is not actually disassembling the motor, the “can” that is coming off is more or less just a dust cover. The whole motor assembly not only stays intact, it also stays in place and aligned.

Correct. I was just wanting to make sure that teams knew they could do this and your previous statement was not correct.

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Yes if you heat it the screw will expand, however the size of the hole it is in will also expand and because it is aluminum it will expand at a higher rate, which I’m sure is a factor in the choice to use a high strength thread locker.

The problem is that you need to get the parts to 500 degrees to melt red Loctite brand thread locker. Getting it that hot would at least damage the paint and likely cause other damage as well.

On the other hand Red would not be indicated for such a small fastener or for such an application and the purple is what would be indicated for this application.

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I happened to take one apart a couple days ago and didn’t have much trouble with it. Since we never use tiny metric screws, the wrench I was using was basically brand-new. The loctite was not too obvious on the threads, but the residue resembled what I would expect from blue loctite (it also says to use blue in the instructions). Make sure you have a new, quality 1.5mm wrench.

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Same problem, different team!
FRC #1018 was working on this last night with similar results to report.
The REV process calls for a “high quality 1.5mm Allen key”

I suggest that it would be helpful to call out a specific part number of tool. If REV can please reply with the tool part number, that would help.

Has anyone tried to heat up the pinion to press it onto the shaft? Would heating sufficiently expand the gear so that it would slip onto the shaft?

Do the math, figure out how hot you would have to get the gear. Of course you’d need to know the press fit, so you’d need to be able to measure the bore and shaft size very accurately (ie. by using a small bore gauge). The expansion rates of metals are easy to find.

The best Allen wrenches IMO are the Wera Hex-Plus wrenches. These are the ones you see pictured in the guide:

We have also used and like Bondhus wrenches:

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+1 for the Wera wrenches. Have never stripped out a hex head with one of these.
Love the screwdrivers also.

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Also search McMasterCarr high torque L-keys. Don’t use the ball end for breaking loose the screw. The little Allen keys wear out. Best to keep a fresh set put away for these special occasions.

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We had a similar experience with both the beta and production NEO’s. You absolutely need a quality 1.5mm driver and a bit of heat to get them to budge. If you don’t mind damaging a driver, try to direct your heat source at the tip of the driver rather than the motor, just to prevent any waste heat from damaging the finish.

Rev uses Loctite Blue 242 (or at least recommends 242 for reassembly), which breaks down at about 482°F (or 250°C for NEO users outside of freedom-land)

I would recommend avoiding this process entirely, and to use keys and tooth lock washers for all of your pinion-retaining needs.

Anecdotally, I’ve had no issues removing the NEO motor casing, even with a shoddy allen key that came with my 3D printer. Firm, constant downward pressure and rotation make quick work of the thread locker.
For worn out allen keys, hitting the end on a belt sander or grinder works in a pinch.