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View Full Version : Making pulleys for a tool post grinder



gdm62
04-29-2004, 09:13 PM
I got a south Bend heavy 10 that I'm making a tool post grinder for. How does a person turn the convex on a pulley so he can run a flat belt. I want to make my own pulleys but don't know how to do this on the lathe.
Thanks
Gary

bernie
04-29-2004, 10:24 PM
Why not use a V belt?

Forrest Addy
04-29-2004, 10:42 PM
The feature is called a "crown".

set your compound to 3 degrees out of parallel to the spindle axis. Skim a 3 degree shallow bevel for 1/3 the width of the pulley on each end reversing the compound angle from the second bevel. File the cusps to a flat having a 2 degree bevel. You should have 5 equal width bands with a wider margin on each edge. This process is called "faceting" - making a smooth curve from a series of straight lined cuts.

Blend the pulley crown into a smooth curve.

Evan
04-29-2004, 11:34 PM
Not really worth the effort IMO. They have cheep 8" drill presses on sale this week at Canadian Tire for $25 US. 1/4hp motor and a pair of step pulleys with belt and lots of spare bits for other projects.

G.A. Ewen
04-29-2004, 11:53 PM
Evan, would you mind posting a photo of yours again, I can't find it.

Evan
04-30-2004, 01:31 AM
George,

Here, but my server seems to be down or my ADSL is out. May not be available until Friday

http://bbs.homeshopmachinist.net//Forum1/HTML/004762.html

[This message has been edited by Evan (edited 04-30-2004).]

J Tiers
04-30-2004, 09:02 AM
Depending on the speed, any step pulley commercially available may be totally unsuitable.

My little Dumore runs the wheel at a choice of about 10,000 rpm or 16,000 rpm. At those speeds, step pulleys will be too big, too inherently unbalanced, and naturally, made for v-belts. Those are also probably unsuited to the application just as a class of belt.

It uses flat belts, and carefully balanced pulleys. If the pulleys vibrate, this will telegraph through into the finish.

If you have a big machine and will run the wheels at a reasonable grinder speed, that may not apply. Flat belts do seem to have been the preference for grinders, however.

gdm62
04-30-2004, 11:50 AM
Thanks all for the reply.

Bernie, V belts cause more drag and viberation then flat belts. The set in the belt causes thing to jump when it comes around to that set.

Thanks Forrest. That should get me started. I know I could buy some pulleys but what fun would that be.

Evan, I have seen your pictures of your drill post grinder. Nice! I do this stuff as a hobbie and my needs for one are small. I don't care how long it takes to make one. I just like making things. The price for one of those drills would be worth it just for the motor.

Fred Prestridge
04-30-2004, 01:20 PM
There was atwo part article in HSM starting in the Jan-Feb issue 1999. It included how to crown the pulleys and a couple of sources for the flat belts.