Building a disk grinder

Phil705

Phil705

Basic Member
Joined
Aug 23, 2007
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364
Or is it disc grinder? Anyway, I am trying to see if I can build a disk grinder and trying to save some money over the excellent Beaumont grinder.

I am thinking of a 1hp AC motor with a VFD, then I would buy the disc and mounting plate from Beaumont. Any suggestions on combinations of reversable motors and VFD's (brands and models) that would work?

I am not electrician, but can usually muddle through on basic wiring if the manual half way understandable.

Suggestions appreciated.

Phil 705
Winthrop WA
 
My suggestions:
1) get a motor that is washdown rated or at least dustproof (TEFC, for example)
2) get a dustproof or washdown duty VFD if possible
3) get it with a dedicated speed knob and a dedicated reverse switch
4) carefully consider whether you want a horizontal grinder or a vertical. I decided on horizontal and am very happy with it. Had I not thought it through, I would probably have gone vertical.
 
Count Chocula has a good point about making a disc attachment for your Bader. That would be cool. I've been thinkng about your buffing attachment tooling arm idea, have almost all the parts in hand and will build myself one soon. If it works well, I'll let you know what I used to build it, etc.

When I look around my shop sometimes, it's apparent to me that I have a LOT of motors, each dedicated to a machine. Seems a bit excessive, at least I have my VFD running three of them.

On a more strictly thread related note, as far as a VFD I usually recommend the Teco FM50 series. I think you can get one to run one horse for like $120. I've not seen that they have any extra precautions or problems with running motors rated at less HP than their max capacity. Also, I blew one up and returned it- was pretty honest that it may have been my fault, the techs OK'ed me a new one nevertheless. Since then, they have my undying loyalty. I've heard about more popular and expensive NEMA4 VFDs that are more picky and enjoy less of a reputation for customer support.

A knowledgeable member once stated that cheap VFDs were rated for higher HP than they could really handle, and that the overload protection circuitry was sized smaller than the VFDs are rated. I checked the specs on my "cheap" TECO, and the overload circuits were rated easily high enough to handle overloads for 3hp motor draws. The other guy agreed, was surprised.

Also, I've done stupid things like switching power to a different machine while running, and had apprenti do the same once or twice. Didn't faze my VFD, luckily.

The only caveat is that you'll have to protect the VFD with your own measures. But there are enough here who have done that that you have good examples for options.

Good luck, Phil.
 
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One totally different approach to building a disk grinder would be to get a small wood lathe and use that as your drive system. I have a full size lathe that I use. Mine has a variable speed control, which is nice to have. Also, the lathe platform can be used to build a support for detailed work on small items like guards.

Ken
 

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I have a 2"x72" that runs a 1.5Hp 3Ph motor via a KBAC VFD. I have another motor coming to replace the motor on my disc grinder so it will run off of the same VFD. I already bought the Nielson Disc system. I have yet to install the Nielson Disc as I am waiting to put it on the new motor.
My current disc is a 3/4" Hp reversible TEFC motor and is very nice as is.
I have a disc stand by RW Wilson. I love it. Repeatable adjustments from 90 to 45 degrees. It also swings away easily for freehanding. I'm going to weld a 3"x3" piece of pipe to the front of the stand to allow it to convert to either vertical or horizontal.
AC Richards, Nick Wheeler and Mike Quesenberry are all right, discs get stuff FLAT!
I haven't used one with variable speed but wouldn't use one that wasn't reversible.
 
12345678910 said:
kbac24d is a 1 hp nema 4 vfd

Wayne Coe sells them

If you already have a toolbar type grinder, you could just add a disc attachment.

It's more $, but also consider the Rod Nielsen interchangeable disc system
It lets you quick change discs.
http://www.nielsendesigndiscgrinder.com/Welcome.html
Click to expand...

I've been wanting to add a disc grinder for a while now, but have not yet done so due to space (and financial) limitations. I have a KMG...could you elaborate on how to add a disc attachment to it? This would seem to be a great solution to my problem(s).
 
PIndelicato said:
I've been wanting to add a disc grinder for a while now, but have not yet done so due to space (and financial) limitations. I have a KMG...could you elaborate on how to add a disc attachment to it? This would seem to be a great solution to my problem(s).
Click to expand...



I'd likely put the disc on the right side so the motor is not inthe way as nick mentions.
http://www.bladeforums.com/forums/showthread.php/656948-New-KMG-Attachment
kmg_disc1.jpg





http://www.bladeforums.com/forums/showthread.php/724695-Shop-photos
KMGdisc.jpg
 
I didn't know how to upgrade my disc until now. After the first of the year, the KMG will have yet another use.
 
Something I notice is that all these bearings are standard deep grove radial ball bearings.

There is no thrust bearing component, but we are pressing against the disc.

We do the same when the disc is attached directly to the motor too.

Maybe the pressure is light enough that it just doesn't matter?

A thrust bearing, or perhaps, tapered roller bearing wouldn't hurt.
 
When looking at these pics I thought the same thing as you, Count. It would make sense to have a thrust bearing in this application, unless the forces are really small.
 
get the iron disc from K& G supply... aluminum sucks

disc is about the most valuable thing in the shop... and don't skimp on the hp ... i've got a 3/4 baldor on mine 1700 rpm... don't go with the fast motor... no need for speed but rather torque

G
 
12345678910 said:
I'd likely put the disc on the right side so the motor is not inthe way as nick mentions.
http://www.bladeforums.com/forums/showthread.php/656948-New-KMG-Attachment
kmg_disc1.jpg





http://www.bladeforums.com/forums/showthread.php/724695-Shop-photos
KMGdisc.jpg
Click to expand...

Interesting idea, thank you for posting it. I had thought about getting a longer shaft for the KMG and putting a disk right on the drive wheel, which should be simpler but it would be even further away from the VFD reach-wise and I'm not sure about leaving it on there when it's not being used.
 
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