hp needed for a disk grinder?

tmickley · Jul 18, 2002

How much hp will I need for a disk grinder using one of rob frinks 9" disks? Anyone gotta source for one?
thanks for any help..

Sylvester · Jul 18, 2002

Noting less then a 1hp but a 1 1/2 to 2hp
would be better, but thats just my $.02

peter nap · Jul 18, 2002

I agree but I also feel that more power is almost always better. I have a 2.5 on one of mine. It's slow but doesn't burn blades during finish work.

rfrink · Jul 19, 2002

Yikes!

I was thinking 1/2 to 1 hp until I saw Sylvester and Peter's post.

So it makes me ask,...what do you think you'll use it for. Will you be squaring up bolsters, slabs, light deburring and leveling....

...Or will you be grinding blade bevels, hogging, profiling steel and other gross material removal like you do with your 2X72?

I just got my Peter Atwood video where I saw his nifty set-up with a 9" disk. I'm thinking that it is a small motor..1/3...1/2 hp..(But don't know for sure)? He runs it very slow, for delicate work. It is pulley driven.

Maybe Peter will jump in and describe his set-up with the specs.

ragnoor · Jul 19, 2002

Wondering about this also, why the need for so much power? I have 3 disc grinders, that I use everyday. There is a 10" 1/2 HP 1720 rpm, that is used for flatening and tapering tangs. Have 2 others that are 9" vari-speed and reversing, used mostly for grinding blades, 3/4 and 1 HP. There are 4 more smaller ones, I use for general chores. Have not ever bogged any of these grinders down, but have not tried to. I always try to let the grit do the work and not force anything.
Ken (wwjd)

tmickley · Jul 19, 2002

Originally posted by rfrink
I was thinking 1/2 to 1 hp until I saw Sylvester and Peter's post.
So it makes me ask,...what do you think you'll use it for. Will you be squaring up bolsters, slabs, light deburring and leveling....
...Or will you be grinding blade bevels, hogging, profiling steel and other gross material removal like you do with your 2X72?

All of that but probably squaring things up most of all. I was thinking 3/4hp would be enough since it would only be driving the disk but I wasn't sure so I thought I'd ask. Since I'd like it be variable speed (and reversable would be a nice gee whiz to boot)it looks like I'll have to go higher than 3/4hp.

Any other input would be appreciated.

BTW Rob, I'll be getting a disk from you when I get a motor and know the armature size.

Don Cowles · Jul 19, 2002

Just my opinion, but I think 3/4 HP is plenty. I use two disc grinders equipped with them.

Sylvester · Jul 19, 2002

Hey if Don saids a 3/4hp will do then
thats good enough for me because Don`s the
Man

I said what I did because each time
I used what I thought was enough hp. I wished
I had more

rfrink · Jul 19, 2002

Yep! Too much is always better than not enough!

My shop motto: "when in doubt, double it!.... then if it looks about right.... double it again and you're getting close."

Take Care,
Rob

Mike Hull · Jul 19, 2002

Had me wondering too. I have two disc grinders with 1HP AC motors. They came off belt grinders converted to VS, and I consider them more power than I actually need.

Plain ol Bill · Jul 19, 2002

I'll jump on the band wagon too then. For a disc grinder I think 3/4 - 1 HP is plenty. Now when you go to a belt grinder (2 X 72) then we are talking a minimum of 2 and preferably 3 HP or more IMHO.