knife grinders

J

jraney

Joined
Aug 6, 2010
Messages
77
just wondering if you can have to many rpm's? i found a cheap belt sander online that runs around 3400rpm, is this too fast ?
 
RPM is only proportionally relevant to the speed of the belt. The speed you need to think about is Feet Per Minute of belt speed. You figure that out with the formula below.

(Pi * Dia) * RPM = SFM (Surface Feet per Minute)

(3.1416 * diameter of drive wheel) * 3400 = Feet Per Minute of belt

Now that being said. I will not comment on the preferred belt speeds. I will leave that to some of the more experienced users.
 
Like Carl said, the more relevant issue is going to be the size of the drive wheel. That being said, if it's something like a 2x42 craftsman, chances are it's going to be "kinda fast" in my opinion. Plenty of makers use these grinders with great success however, but it does take a lighter touch when using finer grits, as these speeds tend to heat things up pretty quickly.
 
that was my concern, i did not want to heat the metal to much. i know that going cheap is not the best way but i have other priorities and this is just a hobby, but on the other hand i would like to save myself alot of frustration and time. the only knife i have made or started on i done with 1 file and there has got to be a better way.if i were to buy this cheap belt grinder could it be possible to change the wheels to make it slower or faster.maybe rotate them ? anyhow i think i will try to get this thing and if it works for me then great if not maybe i can use it for a design model. i do have a 1/3 hp motor which i think is small but it was free so i might as well use it for something. thanks for the info.
 
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