Advice on mk7 gear set screw problems

Hi guys ths problem s doing my head in

I'm using i3 extruders that use the mk7 gear pully to grip the filament

The problem I have is my stepper motor skips , filament stirs and skips the lot

I rip the extruder out and look at the gear and the hobbled gear has worked only a bit loose and moves around 1mm on the 5mm bolt

I have problems getting the m3 set screw to old good.

When I tighten down n the set screw I either round off the screw or the hex key.

If also tried tread lock

Only thing I can imagine is te m5 hex head bolt s soft metal and thats the problem

Any advise??

the best grub-screws are the black case hardened ones, the sorface finish helps it stay in there

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I grind a flat spot on the motor shaft where the set screw will set on it.

Rodney

yeah this is sitting on a M5 bolt as its the I3EXT extruder

i think iv got it solved now i went and blew £25 on a set of wera hex keys.

seemed to solve the problem..... so far