Cutting a Keyway into Motor Output Shaft

[garrett1308]

Picked up another hustler (a 980 this time) that came with 2 spare vanguard 18 motors. Only problem with them is the output shaft is threaded, not keyed. Is there a way I could lock down the keyed clutch to the threaded shaft? Or would I need a new keyway cut. If a new keyway is in order, what are yall's suggestions to going about that?

[Noel Woods]

Any good machine shop can mill down a tapered shaft and install a keyway.

[Nubs]

A bit harder to do it while its still in the block but it can be done..

Don't think its a tapered shaft

[john swenson]

i have cut a 1/4'' keyway on a shaft with a small cutting wheel on a dremal tool. i marked the width with the key, then slowly ground the slot, checking as i went. if you take your time you can get it almost exact. mine has held for many years. hope that helps. johnboy va.

[dirtdobber]

I worked in a machine shop once upon a time, and occasionally we would have to cut a keyway by hand as Johnboy described. We would take a piece of angle iron and lay it along the shaft as a straight edge to scribe a line down the shaft representing each side of the keyway. We would grind out the keyway slightly narrower than the needed key width and then use a piece of square tooling stock (square piece of high speed steel or something similar...like lathe bits are ground from) and use the square stock to actually chisel, by hand, the keyway to final width. This gets the precise width.

Check with a machine shop, though. They may be able to mill your keyway without removing the crank from the engine.

[garrett1308]

Thanks guys, I'll take them both to a shop and see what they say on Thursday. If they can't, then I'll be doing it by hand.

[Nubs]

I've cut a few on a horizontal mill with the crank installed, just need to lock the flywheel to the table.

[garrett1308]

Got the keyways cut now. Where I work, we have a Bridgeport mill stashed in a corner. Forgot about it till the other day. Locked the motors down at the bases and went at it. Figured that a light passes on the shaft would keep the output shaft from trying to turn, and it seems to have worked for both of them.

Thanks for yalls help

[Nubs]

Nice...

[garrett1308]

New problem. The output shaft on the motor does not have a tapped hole to run a bolt in to keep the primary clutch from walking. I was able to drill it fairly easily with a used dewalt drill bit (there was a pre-existing hole in the shaft, but was very shallow), but I am unable to tap it. I am using a harbor freight tap set, which is probably why I am having trouble, but I'd think that a brand new tap would be able to cut at least one thread out. The tap is getting stripped.

Any ideas?

I've heard carbide taps work, but I've also heard that they break fairly easily.

[Nubs]

a good hardware store tap like a Hanson will cut fairly easy, the crank is cast iron so if pilot hole is right for the tap your good. go a turn or two and back it out etc..

[john swenson]

if you had any extra shaft sticking out past the clutch, 1/2'' ? you could use a 2 piece clamping collar on the shaft. otherwise, maybe drill the hole on the motor shaft hole 1/4 '' or 3/8'' diameter.take a grade 8 bolt that size, cut the head off and then cut the smooth part of the bolt long enough to fit into the hole so the threads stop at the end of the motor shaft. then drill thru the motor shaft and bolt and secure with a roll pin that is ground flush with the shaft. now you have a threaded bolt to put washers on if needed and a lock nut to secure the clutch on. just make sure you use a long enough bolt to stick out far enough with threads. maybe this will help ... let us know or maybe someone has a better idea. johnboy va.

[dirtdobber]

Garret forgive me if I'm telling you things you already know, but you have to use exactly the right size drill bit to correctly tap threads. To tap a 3/8 hole, you do not use a 3/8 drill bit...use a 21/64. If you used a bit that is too far undersized, it's going to be really tough to cut the threads because you will be trying to remove too much material.
Also, make sure you are not using a bottoming tap. A bottoming tap is designed to cut closer to the bottom of a blind hole. A standard tap has more taper and starts easier when cutting threads. Also, make about a 1/4 turn cutting and back out a 1/4 turn then cut another 1/4 turn and back out 1/4 and so on until you reach the bottom of the hole. Keep the tap oiled, even if its just motor oil. Finally, if you have a T handle tool, use it. If you are using a crescent wrench or something like that it's hard to keep a tap straight. The T handle will keep you from torqueing the tap to one side.