More Grinder Questions

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unky_gumbi

Joined
Aug 28, 2009
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7,951
It seems there is a lot of grinder talk being thrown around here lately and I have got a lot of information from them, but one thing that seems to come up often is the HP of the motor to run it.
What is the lowest HP rating that would be acceptable for a 2X72 grinder? I am in a bind with my power supply and stuck with 120V. Being that a VFD seems to be the best way to set up a grinder to achieve the belt speeds needed to make a versatile grinder and most 110V VFDs stop at 1hp, is that too low or will it get most jobs done for the hobbyist?

It almost seems that all of these grinder questions should be answered in a sticky
 
You are going to pay for it, but the KBAC-27D is said to be able to run 1.5 HP variable speed on a 15 amp 120volt circuit.

Verify this with Rob or someone else.

There may be others, but it's the only one I have identified to be able to do that.

It is also able to take a 2HP motor should you decide to upgrade later when you have a 220v input for it.
 
FWIW, I have 2 Variable Speed Grinders - and both are 1 HP. The only time they bog down on me is tapering tangs - so I slow down a bit for that. Works fine for me. If I was looking for high speed production, I'd probably want more, but my knife making is about finesse - not power. ;)

Rob!
 
You could make 1HP work, but it will probably bog down on you if you're not careful.

Wide blades with flat grinds and flat platens require the most HP. Smaller blades and hollow grinds don't need as much power because there is less frictional loss when using a wheel. So the knife you're grinding will affect the HP you need. 1HP is more than enough for a small hollow ground folder etc.
 
Well I just scored a 1.5hp 3 phase for $50 so that frees up some money for the better VFD I will probably order the grinder in a box kit in a couple of weeks if I don't get an anvil at the auction next weekend
 
I have two 2"x72" grinders with 1hp motors and they can rip steel off at a pretty good rate if equipped with the right belts and used with the proper techniques. It is possible to bog them down, but as has been noted already this is mostly a problem when doing flat grinds on large surfaces, such as tapering tangs. This is about the only time I grind with heavy pressure, otherwise I find that better control (and less heat build up) is offered by moderate pressure and sharp belts.
 
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