# Another 2x72 Belt Grinder



## jocat54 (Dec 28, 2018)

I have been slowly getting this together-finally got to the point of assembly to test it out. It didn't blow up or smoke so maybe it will work out okay
Used a 2hp treadmill motor and made the controller using an scr and diode bridge (about $18).
Still need to make a tool rest and electric box for the on/off switch and scr controller and find the room for it


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## Threadkiller (Mar 13, 2019)

nice job! How does the treadmill motor work under load? I assume pretty well, they have to be pretty stout.


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## AGCB97 (Mar 13, 2019)

So what would be the normal SFM speed or range of the belt?


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## Buffalo21 (Mar 13, 2019)

A belt sander/grInder is a great shop asset, I bought a 2” x 48” Jancy RadiusMaster (about 4000 fpm) about 10 yrs ago, it may be the most used tool in the shop.


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## AGCB97 (Mar 13, 2019)

So a 4" drive pulley on a 3450 RPM motor should be just right?
Thanks
Aaron


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## Buffalo21 (Mar 13, 2019)

4 x 3.1416= 12.566”

12.566” x 3450 = 44,610”/min

44,610” / 12” = 3718 fpm

I would not what to be any slower, that speed will remove a lot of metal, the most important choice is going to be belt grit and composition. I have acess to a Burr-King that turns close to 7500 fpm, a speed I find to be too fast, its hard to control, it very easy to remove too much, as it god awful quick. I much prefer a machine in the 3500 to 4500 fpm range.

The best general purpose belt for me is a 2” x 48”, 50 grit, ceramic grit made by Carborundum. It’s coarse enough to remove metal quickly, but still leave a good edge finish. Any thing I tried below 50 grit, left gouges in the metal surface and above 80 grit, worked too slowly.

I was lucky one of the local, specialty steel manufacturers has machines that use my size belts, so I started to use their speed belts, because of the volume they use, the supplier get them to me for about $2/ea..


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