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Post by DirtCleaner on Nov 22, 2013 20:40:20 GMT -5
A few weeks ago I picked up this grinder from Haleysdream and finally got it mounted to a bench and a motor attached. I got is spinning and am wondering about the rpms. I don't know how may it is turning but hopefully the short video will play. Any thoughts?
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Post by DirtCleaner on Nov 22, 2013 20:41:11 GMT -5
Looks like the bottom pic is a link to the Photobucket video.
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Post by Drummond Island Rocks on Nov 22, 2013 20:52:35 GMT -5
I have the same grinder set up. I have bought and sold three of them and they were always supplied with a 3-step pulley mounted to the grinder and mine even has another 3-step pulley on the motor side the motor and to adjust speed even more. I just recently posted about mine and you can see the pulley in my photos. I only use mine for cleaning up the backs of my cabs now but its a great flat lap. I'll check what speed mine is set to and get back to you. forum.rocktumblinghobby.com/thread/60844/pimped-flat-lapChuck
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Post by Drummond Island Rocks on Nov 22, 2013 21:17:34 GMT -5
I just checked mine and its set on the center of each 3-step pulley so that makes it 1725 rpm at the spindle. This speed has worked great for me for grinding but you could adjust speeds for polishing with pads.
chuck
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Post by DirtCleaner on Nov 22, 2013 21:52:58 GMT -5
The motor is a single pulley (small diameter) and the grinder is currently on the middle pulley. Nice shop Chuck.
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QuailRiver
fully equipped rock polisher
Member since May 2008
Posts: 1,640
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Post by QuailRiver on Nov 22, 2013 21:56:39 GMT -5
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Post by Drummond Island Rocks on Nov 22, 2013 21:59:06 GMT -5
I assume your motor is the typical 1725 rpm which means right now your grinder spindle speed is less then 1725. Type in pulley calculator in google and there are a bunch of sites that let you enter your pulley diameters and then give you your final rpm but as an example if your motor pulley is 1" and your grinder pulley is 2" then your spindle speed is cut in half.
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Post by DirtCleaner on Nov 22, 2013 23:23:28 GMT -5
I'll get to the formula/math in a bit. But I tried the easy RPM method and counted the rotations for 1 second and multiplied X60. It came to 1680 RPM.
(Date plate reads 1724, 1/4 hp and both pulleys are 3" so 1725 is what the grinder is turning at.)
So the question still stands…Is there an optimal speed for the grinder? I could go to either the 2" or the 4" pulley on the grinder. Other than that I would have to change the pulley on the motor.
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Post by Rockoonz on Nov 23, 2013 0:22:11 GMT -5
My Covington flat lap (FS BTW ) and my Graves Mk1 facetor both have a 1.5" pulley on the motor and a 6" pulley on the lap with a 1725 RPM motor, so it's 431 RPM by the calculator. I think I could go a little faster with them, but 1725 seems like the centrifical force would spin the water right off the disc and wear out the laps quickly. I may switch out the motor pulley on the facetor to 2" to bring it to 575 RPM but no faster. The variable speed ac/dc drive flat laps like Ameritool run like 500-3400 RPM so maybe faster is OK. For opal triplets and intarsia I prefer a little slower. Lee
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