Turning a Pulley - Sequence of Operations?

For that size I'd drill and bore the hole, cut the groove and face one end of the bar, and part it off. When the set was done I'd reverse the chuck top jaws and face the other sides. (Actually I'd use a 1" collet).

I drill deep but bore only a little past the width of each blank because a long, thin boring bar deflects easily. I use a rule and a magnifier for low-accuracy jobs like pulleys rather than tediously setting the parting tool accurate to 0.001".

If I need accurate thickness I trim them on the mandrel. Take a light cut, measure, move the 29 degree compound twice the excess. Sin 30 =3D

Pulleys too large to chuck are harder. If possible I drill extra holes and drive from a faceplate. They are easiest to remove to reverse or check when they are pressed onto a mandrel, most solid when screwed to the faceplate. A compromise is to screw the blank on, rough the OD and bore the ID, then press it onto a mandrel for the finishing cuts.

If you don't have a mandrel the right size, you can tighten a coupling nut or a stack of hex nuts onto a full-thread bolt and turn to fit. Clamp the blank between the head and a nut, with some tubing or a socket as a spacer if necessary.

Jim Wilkins

Too much noise? Seems you were running the parting tool too fast. I just made one 1 1/2" dia and parted the groove using the parting tool to the bottom depth. I swung the tool post to 20 deg and cut the right side face with the parting tool to bottom of the groove. Then swung the tool post over to the other side to 20 deg and finished the groove on the left side. I made a 1 1/2" pulley with a 9/16" hole all in one setup. The groove I cut was 1/2 wide for an A belt. I bored the hole last. Took me about an hour and a half. I used a 16" South Bend lathe. Probably makes a big difference. Dan

Hmm ... this sounds as though you are making a pulley for flat belts, not V-belts. Is this the case?

If so -- the more common way to hold the belts centered is to skip the flanges entirely, and to simply crown the areas which you probably left flat. It would look something like this (within the limits of ASCII graphics): _ __ _ _____| | | |_____ (_____ | | _____) |_|__|_|

With two hubs. The parens are the closest that I can come to representing a crown.

The crown causes the belt to walk toward the highest spot. You'll find similar techniques used to keep a belt on a belt sander.

:-)

O.K. What are you calling a LH cutting tool? One which cuts on the left side of the tool, or one designed for cutting on the left side of the workpiece? The latter is the standard usage, FWIW, so a LH tool cuts on its own right.

Well ... first off -- I would go for a crown instead of a square groove with flanges. It provides less wear on the edges of the belt.

Now -- I would face and shape the first hub and bore with the stock held in the chuck. Part it off and turn it over to face and produce the hub on that side.

I would then mount it between centers on a very shallow taper arbor (I think about 0.002"/foot), and turn the OD and form the crown. I would probably use a file to form the crown, unless I had a radii turning fixture. If you have some radius gauges, aim for something like a 5/16" or 3/8" radius for a 1/4" wide belt which should give plenty of crown. You might be able to live with a larger radius.

Turning and filing the crown on an arbor between centers assures tha the pulley's OD is concentric with the bore.

If you're expecting to spin at high speeds, you probably want to true up the hubs and the facing while it is on the arbor, because there could be a bit of off-center from when you flipped it and gripped it in the chuck after parting.

Now to see what others have suggested.

Enjoy, DoN.

You could try bicycle sprockets and plated chain, too.

This photo shows one mounted on a simple hub: