Question on belt sanders for tool grinding

DHarris

DHarris

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I'm a newbie to the hobby machine world and trying to get some items / tools in order to start playing with a small Sherline lathe & mill that I inherited from my father when he passed away. Now that I'm retired, I am making the time to start to play with these for use in some of my other hobbies. With that said, I have a 1 inch belt sander that I've "beefed" up a little so I can use it for grinding HSS tools for the lathe. Right now it's a 1750 rpm motor but has a reducing belt drive (motor pulley is ~2 1/2" and drive wheel is ~1"). I've ordered a pair of step pulleys (2 - 3 - 4) so I can select from ~ 875 rpm - 3500 rpm for the drive wheel. Belt is 42" version.

So my questions;
1) what speeds do you all use for grinding HSS tooling
2) what grits do you use for grinding
3) what types of belts do you use (Aluminum oxide or ?)

Thanks in advance for any / all inputs

Dave Harris
 
Hi Dave. I'll give you the first response. I use a Sears 1/2HP 2 X 42 belt sander.
1. My sander is direct drive, so 3450 rpm is all I have right now. This is fine for shaping/hogging but a slower belt speed would be better for finishing.

2. I use 24 grit AO belts to shape tools, 80 grit to remove the coarse belt marks, then diamond stones to hone. I have belts from 24 - 600 grit. That 24 grit belt works well for me when shaping tool bits. It cuts fast and cool compared to my bench grinder.

3. Aluminum Oxide is the most reasonable in cost and they work fine for HSS and cobalt tooling. The tricks are to have a platen that does not flex - not even a little bit - and use stick wax lube when you grind tools. Ideally, you want to have a Pyroceram platen liner so the platen remains flat for a long time.
 
I rough HSS tools on a grinder and then finish the angles with 100 grit on a grizzly 4x36 belt sander. If I need perfect angles like a threading tool I use a miter gauge and 100 grit on a 12 inch disc sander.
 
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