Pulley Ratio question

[noodle23]

I got my motor today. Its a 1/2hp @ 1725rpms motor. i was wondering what the best ratio of pulleys would be to run a monster mill. I was think 8:1 but what do you think?

By the way i assume the following math tell me if im wrong.
12" pulley mill and a 1.5" pulley on the motor equals an 8:1 ratio

thanks guys

 

[weirdboy]

Well, your math isn't wrong. 215 RPMs seems like a good match to me.

 

[kevmo]

From the website:

The best speed to run all of the drill driven mills at is around 150-250 rpms

And this:

Most AC motors run at the slowest speed of 1725RPMs. This means that you need to reduce the speed by a minimum factor of 10. So you will need a mill pulley that is 10 times the diameter of the pulley on the motor to get down to 172.5 RPMs assuming your motor runs 1725 RPMs... Look for a small pulley with a diameter of 1.5" or less, and a large pulley to mount on the mill of at least 10" with 12-14" being preferable. Worth noting is that usually the pulleys will have different pitch diameters depending upon the width of belt you use. If you use a narrower belt, it will ride lower down in the pulley groove, and effectively reduce the diameter of the pulley.

 

[noodle23]

Thank you both. Sorry Kevmo i just over looked that. Cheers

 

[outside92129]

Here's a good site for pulley/sheave calculations:
Pulley And Belt Information Calculator

8:1 would work well. You would need a 15" sheave to achieve 10:1, they start getting expensive real quick at the larger sizes.

I have a spare/new 1.5" sheave if you're interested.

 

[noodle23]

Here's a good site for pulley/sheave calculations:
Pulley And Belt Information Calculator

8:1 would work well. You would need a 15" sheave to achieve 10:1, they start getting expensive real quick at the larger sizes.

I have a spare/new 1.5" sheave if you're interested.

what is the bore size of the 1.5"? and how much do you want for it?

 

[outside92129]

1/2" bore. $4 delivered? I think i can cram it into something and ship it 1st class mail. I bought the wrong thing and just want it out of the house (seems wasteful to just throw away something brand new).