So I want to make a keyway..

[ttabbal]

I would like to cut a keyway into a pulley. Aluminum timing belt pulley like those in 3D printers etc.. Nothing really special. It might be nice to be able to do it in steel at some future point, but I don't need it right now. Not production, probably making 4 or so.

1) Buy the pulley with a keyway. Sure, it might exist and I'll look for it, but this is h-m, buying the right part isn't much fun..

2) Buy the right tool. Broaches are out there, can buy the sleeves or make them. I don't have an arbor press, but the hydraulic would probably work. A shaper could be fun, but I don't think that's in the cards.

3) Single point style on a machine like the lathe. I could make the tool easy enough. Not sure how to secure the spindle though. The PM1127 lacks a back gear and that seems to be how people usually do it. The back doesn't have an obvious way to accomplish it either.

The Bridgeport does have a back gear and a spindle brake. I would have to figure out a way to hold the brake engaged if the gear isn't enough. Is the quill up to being used like this? Running the table up and down would be a bit tedious.

The CNC router isn't as ridgid, but might be up to it once I rig a holder and tool to the Z setup. Speed would be better once I get the code set up for it. I'd probably have to hand code it. But I could manage that.

4) File it. Yeah, I don't want to.

5) Use an end mill and let the top of the keyway be round. I'm not sure if it has downsides other than cosmetic. I'd use a set screw against the key however it's cut.

Any options I'm not considering? Thoughts on what the best way to go would be?

 

[mmcmdl]

Buy a broach and be done with it .

 

[kd4gij]

If this is for a 3d printer a keyway will be over kill. A flat on the shaft and a setscrew would be enough. or a dimple in the shaft.

 

[JimDawson]

3) Single point style on a machine like the lathe. I could make the tool easy enough. Not sure how to secure the spindle though. The PM1127 lacks a back gear and that seems to be how people usually do it. The back doesn't have an obvious way to accomplish it either.

It shouldn't be necessary to put the spindle in back gear or otherwise lock it. There would be no rotational force on the spindle when single pointing the keyway. Worst case, use a ratchet strap around the chuck to secure it down to the bed, would work just like a band brake.

 

[ttabbal]

If this is for a 3d printer a keyway will be over kill. A flat on the shaft and a setscrew would be enough. or a dimple in the shaft.

It's actually for my lathe. I was using the printers as an example since people are generally familiar with them.

I'm thinking the broach is the best way, I just like to try to consider options.

 

[TakeDeadAim]

I agree with Jim, I have cut them in both the lathe and mill with a single point tool. My lathe has no back gear and I just put in the lowest speed and it went fine. You should have no problem with it moving while you cut.

 

[ttabbal]

I agree with Jim, I have cut them in both the lathe and mill with a single point tool. My lathe has no back gear and I just put in the lowest speed and it went fine. You should have no problem with it moving while you cut.

Thanks. I've seen people really worry about it, so I thought it was important. I like his strap idea too.

 

[TakeDeadAim]

Thanks. I've seen people really worry about it, so I thought it was important. I like his strap idea too.

I would really not worry about it. I have done it in 4140 in the mill and not had an issue, Steel and aluminum in the lathe with no issues. There is really no force that would cause the chuck to want to rotate

 

[RobertB]

I would really not worry about it. I have done it in 4140 in the mill and not had an issue, Steel and aluminum in the lathe with no issues. There is really no force that would cause the chuck to want to rotate

Yeah, unless you are making something like a timing belt pulley that requires precise key clocking there is no need to hold it. After the first cut the following ones will want to self center in the existing groove.

Having said that, it's worth doing for the fun of trying a new technique, but it's a bit tedious and you will want the broach when you want to do more.

 

[jcp]

a bit tedious and you will want the broach when you want to do more.

^^^^^^this^^^^