Tool bit for V-Belt Pulley

A Few Questions:
I recently made a V-belt pulley but
with some difficulty because I had
trouble setting up a 20 degree angle
on the inside surface closest the
lathe head. I suppose I could turn
the pulley around but then it might
not run true.
Anyway, seems like I should be able
buy an off-the-shelf tool bit with
a snubbed 40 degree included angle.
Just plunge a certain depth and I'm
done. Is there such an animal?
Second, I could go for a smaller
belt but can't seem to find anything
smaller than 2L. Where should I look?
And if I can't go smaller, how come?
Brad Smallridge
Reply to
Brad Smallridge
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I tried that. Even on my 10EE it was a chatter box. Just too much cutting surface area. I made a 40 degree point HSS form tool. Ruff out pulley with cutoff blade, cut left side, move carriage, cut right side. This was for a six groove sheave and it only took and hour.
Reply to
Karl Townsend
Metric v-belts as small as 5mm wide are available, though not widely.
If you need a reinforced belt, look at poly-vee belts...
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For very light duty, an unreinforced round urethane belt may work for you, for example:
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Reply to
Ned Simmons
Brad, First, be certain of your dimensions, please reference the machinery handbook. In that you will find that the "V" angles are slightly different for each belt size. They may look the same, but they are not. Second, yes, you can plunge cut the groove in a single operation, but the blank must be really securely chucked and supported with the tailstock, the machine should be at least 8 tons in mass and have a 10-15 hp motor. You need a seriously stout machine to cut an "A" size pulley. Without that the chatter will make the task impossible. I have a 18 x 54 Lodge & Shipley in pristine condition. It weighs 6 tons, has a 15 hp motor and I don't do it. When making one off pulleys, I use a parting tool and blow the center out to depth, then I use a specially ground tool to shape the sides, but I only do that on the L & S. On smaller machines, the first step is the same then I turn the compound to the correct angle and machine each side seperately. Steve
Reply to
Steve Lusardi
I ground a narrow bit to approximately the correct angle on both sides (like an Acme threading tool) and rough out the groove by wiggling it from side to side while slowly advancing. The angled sides are short and not ground to cut well, so they serve as stops. The chip is small enough that a large spoked pulley pressed onto a mandrel doesn't slip. Then I finish the sides to the proper angles with the compound. Jim Wilkins
Reply to
Jim Wilkins
Ditto. The tool I use is made from O1 and has a 40 degree end and a 30 degree end. Small diameter pulleys need significantly less than 40 degrees due to distortion of the belt section. Once most of the meat is removed with a parting tool, the flanks can be cut one at a time quite smoothly.
The other thing to do is to put the pulley blank on an arbour between centres. That way it can be attacked with more clearance at the headstock end if the topslide is cranked over.
Mark Rand RTFM
Reply to
Mark Rand
If you had turned the pulley on a mandrel between centers for left side clearance for the compound, life might have been easier. We turn a lot of V belt pulleys for class 8 trucks using a carbide parting tool but that is on a cnc lathe where things are a bit different than an engine lathe using a compound.
Reply to
I just grind mine from large HSS bits, like 5/8" , and use an existing pulley as a gage. I've turned cast iron, steel, and aluminum pulleys no troubles on my 16" Southbend, with an aloris toolpost. Use a parting tool to hog out the middle first. If you do get chatter marks, just consider that extra grip for the belt :^)
Reply to
You didn't say what material you used. When I made a 4-step sheave I started by drilling/reaming the hole, then I used a mandrel and did every other operation on the one setup. I remember grinding a tool with a long angled tip but I'm positive I used the swiveled compound to feed it along the edge rather than plunging it all at once - this on a 9" South Bend, not a rigid lathe. Of course, rough out the slots with a parting tool, get most of the material out of there. I made mine out of aluminum - it's held up fine for about seven years now, no signs of slackening. I've seen guys glue up circles of hardwood and turn those into sheaves too. Steel would be real hard on a little lathe.
Reply to
Grant Erwin

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