Hi there,
is it just me or are motor pulley grub screws extremely difficult to lock the pulley without destroying the screw. I mean forget about stainless steel. not a chance as it is too soft. I am going for the hardened ones and add Locktite and of course the key and all. but they are just rarely ever strong enough to hold the pulley to not slip of the shaft after a few rounds. sometimes they stay and all good but super often the just come off. It’s also very easy to break them if you go too tight and horray! you can drill them out and buy a new pulley. Has anybody a better solution or any tricks p their sleeves? this can’t be the actual answer to this mechanical problem. maybe drill out a bigger hole and use bigger grub screw? drill a hole in the shaft?
Agreed on all fronts. D shaped pulleys and motor shafts are less common but I have one on a setup and it’s been solid.
loctite 648 frw
no need for grub screws, or even keys
two solutions to this
Use blue loctite on the shaft as well as on the grub screw, combined with either:
- Having one flat side on the motor shaft align with the grub screw. this can be achieved by wrapping the motor to prevent shavings entering the can and filing a small flat spot where the screw can press against.
2., aligning your grub screw (preferably one with a pointy tip ( 
) ) and using a tiny drill to make a small indent into the shaft for the screw to lock into
also, with blue loctite, you will yield best results by letting it cure for at least 24hrs before riding and you’ll be sweet. these have always worked for me 
no way u depend on glue to not kill you on a hill yikes
i’ve run em on my mtb for the past ~200 miles no slop, nochanges all through SF(i run gear drives so there’s force in both rotational and, sliding along the shaft (axial and lateral?))
if anything you could run 648 and the key and it’s guaranteed to not move unless you torch it off
shit thats impressive stuff
ye, 648’s a retaining compound designed for “fusing” shafts and bores together
iirc when it cures , it turns jnto a sort of acrylic marerial, it’s wild
If you’re using helical gears, then yea, you’ve got both radial and axial loads, but if they are spur (straight cut) gears, the only significant force will be radial.
why inlove straight cuts
easier loads, moar noise, mor fun
ok, but how do you get it off when you have to?
you’d still need a grub screw though, no? or do they just grab better on d-shape?
I also saw some where the screw actually goes parallel to the shaft but not sure if I’d ever find the right size in that format.
Loctite as mentioned haha
blow torch and a lil bit of patience, and some leverageingnoff
I like this
#fuckgrubscrews
We’re getting married.
Yes, still need a grub, but the grub’s only job then is to resist sideways movement while the D shape completely resists all the crucial rotational forces.
When it’s feasible for me I will drill it out to bigger size and add a bigger screw. Even add a second or third on occasion. Also use wedged keys to prevent it from going towards the motor. I understand not everyone is capable of doing such works, or have the necessary tools to perform such, with that said if you need them fixed pm me. @billgordon nip pic is acceptable form of payment.
thanks guys, glad I’m not the only one banging my head on these. the keyways do a good job for the rotational (except for the occasional click/clack as there is a bit of play) will buy a decent pulley puller then and glue the f***ers on with locktite.
Ok so, here we go. My #1 solution for this problem:
-drill a F***ing little ding about 1/2 mm deep in the shaft. Seems to do the job really well.
-Glue grub screw in with locktite
-of course use keyway.
-exclusively steel pulleys and hardened steel grub screw. NO stainless grub screws.