10f Jackshaft Pulley Keyway

[cdhknives]

Upon disassembly I now see that the 4 speed pulley on the jackshaft has a keyway. I bought a D shaft as a replacement since all I saw were set screws.

Do I use the existing set screw on the flat of the D shaft (and forget the key) or do I put my jackshaft back together (no small trick, lots of burrs and shaft damage to drive over) and try and cut a keyway slot in my new shaft?

 

[pdentrem]

Not sure if the D shaft will be good enough. I would think it should be alright.

If you do not have milling machine or can get to one, you can either cut the whole slot or drill the ends of the slot and a row a holes joining the two ends and then remove the material between.
Pierre

 

[RJSakowski]

You will have less chance of slippage with the key. It seems that no matter how well you tighten set screws, on a high torque shaft, they will loosen over time and slip and gall your shaft. If you absolutely want to go that route, you can tighten the set screw down to mark the shaft, and drill a small pocket on the flat. There will be less chance of slippage that way. If at all possible, I would use a shorter set screw and run a second set screw in to lock the first one.

 

[wa5cab]

If the pulley has a keyway broached in it, most likely there is a set screw in line with it. If you use a longer set screw to tighten on the flat on the D shaft, it will be more prone to loosening than the one in the unkeyed pulley.

When you got your original assembly apart, did it have a square key or a Woodruff key?

 

[cdhknives]

I can't get the old key out. I have dinged it up good trying to get a hold of it, tap it out, torch heat it, etc.

Since there is no extra slot on either side, I'm guessing a plunge cut with a woodruff cutter... I dug up some old 1/8"x3/4" keys and a (too small, will have to grind down the keys in hand) cutter...I'll put it all back together AGAIN and see if I can cut a woodruff key slot with my milling attachment. I have not had good luck with my milling attachment...not very rigid even with the carriage locked down.

 

[wa5cab]

The usual solution to a stuck Woodruff key is a slightly blunted chisel on one end, then the other. The key isn't any good when you get it out but they are cheap.

I wouldn't recommend making a custom non-standard key. Key seat cutters are made for the key that they cut the seat for. Get the right key seater.

 

[cdhknives]

Oops...too late now. I have a 1/8"x1/2" diameter woodruff cutter and 1/8"x3/4" keys, so I made the slot 1/4" longer and ground a little off the nose to compensate for the depth difference. It fits...and should act like a rectangular key I would guess...