grinder speed

[dudeinthehut]

Hello all,

Just wondering what a good speed is for a belt grinder with a smooth rubber contact wheel.

Is 3300sfm too fast for final grinding and polishing of heat treated blades? What if I rig up a water cooling system for the belt?

I guess I just want to know what is the ideal speed so I'll know how far off I am, and therefore, how careful I should be when polishing.

Thanks.
Andy :confused:

[Ray Rogers]

What is ideal for one person will not necessarily be ideal for another. The popularity of variable speed grinders helps to support this opinion. Around 3300 sfm is about the top speed of most grinders. You will find that people with variable speed grinders like to slow down as they go to finer and finer grits. I run mine at half speed or a little less with 400 grit and full speed at 60 grit. Cooling with water should help but it can be pretty messy and it won't give you the extra control you would have from being able to slow down. For polishing, slower is better in most cases ,,,,,

[cactusforge]

What Ray said except that I run the Burr King at over 5000fpm for profiling and the rough grinding on forgings that have been heat treated. Before I tried this I asked Tur-Grit about it as I did not know how much speed the belts would take. Thy informed me that the belts would be safe at that speed and more. I get a lot better performance this way. Gib

[SteveA]

Just finished my homebuilt. Three speed using pulleys 3600, 1800, 900. Picked the top speed by hearing what guys used at the blade symposium the two years before I started construction. On the other hand, Pop at Pop's Knives and Supplies recommended much faster - I think like 6000, but not sure of that, to get the best out of the ceramic belts that he was suggesting IF I had the grinder speed to take advantage of it. But by that time I already had the parts that would determine the speed gathered up, so 3600 is my top speed. Haven't had a chance to actually make a blade with it yet, and won't till end of April, but just from picking up the first piece of scrap steel at hand when the grinder was ready, I'm pleased with the way it cuts...

Another engineering consideration is that faster is always harder on something. What got me is that a 4" wheel is 1 fpm per rpm. Smaller wheels turn faster for the same fpm. Since I'm set up primarily for flat grinding (right now that's all I'm set for - platten and slack), I have one 2" wheel, and to go a lot faster, those little bearings would be getting into router-like speeds. Made me just a little nervous, and I decided not to go there. But there are lots of people here with a lot more experience than I have...

Steve

[dudeinthehut]

Thanks a ton guys.

I was teetering between a good deal on a 3300sfm/1750rpm machine with a 6" smooth wheel and constant speed or a pricier unit with an 8" serrated wheel and the ability to be run by my variable speed grinder. Both have decent plattens.

I'll let you know which way I go.

Andy