9" Disk Grinder speed?

theWeatherman

theWeatherman

Well-Known Member
So I hace been thinking about making a 9" disk grinder. What type of rpms are appropriate for this?

I have a 1/2 HP 1725rpm motor and a 1/2 HP 3400rpm, that can be used for this.
 
I started with a variable speed & reversible disc grinder and was happy I did!
I think Wayne Coe & Moe the dog that has a Forum here can help you find a controller that might work. I would use the slower one if it has to be single speed.

Laurence

www.rhinoknives.com
 
I have to agree with Laurance. even though I started with a vari speed, I very seldom use mine at over 50%, and fine sanding at slow speeds (20% or lower) to say an 800 grit makes hand sanding SUCH a breeze!

Gpd Bless
Mike
 
What laurence said!

I am 'building'(been few months) one too and going with similar speed. I was told 1700rpm tops is good for it, specially since no heavy grinding is planned (unless you do!) :)
 
I suggest a 1 hp motor 1800 rpm motor. Set the VFD to run the motor at double the rated speed (induction rated motors are designed for this type service). I do run mine at higher speeds but also use the slower speeds.

I also sell the Nielsen Interchangable Disk system. Check out my web site and watch the video there.

Let me know if I can help you.
 
Wayne Coe said:
I suggest a 1 hp motor 1800 rpm motor. Set the VFD to run the motor at double the rated speed (induction rated motors are designed for this type service). I do run mine at higher speeds but also use the slower speeds.

I also sell the Nielsen Interchangable Disk system. Check out my web site and watch the video there.

Let me know if I can help you.
Click to expand...

Wayne, could a motor be used as a single speed disc grinder? I am looking at using it as a disc grinder to make sure my flat grinds are flat. I will have to take a look at the interchangeable disk system. But the VFD is just not going to happen right now.

The other question is then, the flat disc or the 1 degree beveled disc?
 
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The problem is that you need to be able to reverse the motor. Of course you can do that with the proper switch but when I was looking into that the switch was about $80.00 and was a bear to wire up. For all of the benefits you get with a VFD it seems counter productive to spend $80.00 for just a switch. You will find that you will want to grind slower.
When you are grinding blade edge up on one side then switch to the other side of the blade edge up the disk is coming up from below.
But don't let me discourage you. Go ahead and set up a grinder with what you have, then after you have used it some if you decide you want the variable speed and reversing features you can step up then.
 
A reversing variable speed disc grinder is a different tool altogether than a single speed machine without the reversing option. There are so many more things you can do with the former that you can't attempt with the latter. It would be worth the wait to save for the multi use tool.

Fred
 
I'd like to offer a different take on the 1 degree bevel. I had one and hated it. There isn't a flat spot anywhere on it. To use an exaggerration to illustrate my point, imagine trying to flat sand with an abrasive covered, upside down ice cream cone. Of course it isn't that much but its still a 'cone' - albeit a shallow one.

Also, a heavy, well balanced disc is a must. The cheap offshore things should come with a bottle of tylenol and a toupee.
 
The 1 degree bevel disk vs the flat disk is one of the reasons for the Interchangable Disk system plus with multiple disks you can have different grits on different disks.
 
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