View Full Version : Finished my 12" Disc Sander

02-12-2008, 10:49 PM


3/4 HP 3400 rpm motor scavenged from a combo belt/disc sander. Made the rest. The table is mild steel and the tooling slot matches my HF Tool Grinder so I can exchange tooling. I've already used the little miter gage.

Table uses bicycle seat clamps, which work great:


The bracket was rounded on the sander. The 80 grit wheel cuts that aluminum like butter. It took no time at all to round the bracket. I was pushing it hard and couldn't come close to stalling the motor. It's way overbuilt, so it is solid and a pleasure to use.

I think I'm going to like this tool!

I plan to use the rest of the parts from the original sander to make a heavy duty 2x72" belt grinder such as the knife makers like.



PS Full build log on my web site:


Also, thanks to all the others who published sander projects for inspiring me to get this done. You're credited at the end of the build log.

02-12-2008, 11:10 PM
Looks great. Kinda inspires me to get my butt in gear and make the belt grinder I want.

02-12-2008, 11:44 PM
Very nice Bob! In case I missed it.. are those discs the "sticky back" kind?

02-13-2008, 12:06 AM
Looks good!Nice solid design.

In case you have never used the stuff Formax makes an abrasive belt and disc grease stick that is the stuff to prevent abrasive loading and increase life,see here near bottom of the page-

Formax Abrasive Belt Grease Stick

No. 26 prevents clogging-- leaving the abrasive grit free to cut cleanly and
smoothly. No. F-26 is recommended for all belt polishing operations-- on
all metals, plastic and glass.


02-13-2008, 12:17 AM
Torker, yes the discs are "sticky back". I guess that's called Pressure Sensitive Adhesive?

Weird, I had seen those sticks and wondered if they worked well. Guess I'll get a stick and have at it.



02-13-2008, 10:31 AM
Further to what wierd said, any sort of cutting fluid will make aluminum cut much faster and leave a better finish. I use WD40 on my 12 inch horizontal grinder/sander. This is especially important when you have a lot to remove as the aluminum heats up a lot at the interface and becomes soft. Then it starts to gum up the paper and the finish is lousy. Lube stops that.

Has anybody ever seen 12" emery disks instead of aluminum oxide? Emery lasts about three times longer in that service.

02-13-2008, 10:54 AM
Bob, if you want some drawings for the 2x72 let me know. I got them from a guy that built one like the KMG grinder, then posted his drawings on the web.

I have mine started but need to finish it up:


02-13-2008, 11:23 AM
Bob, if you want some drawings for the 2x72 let me know. I got them from a guy that built one like the KMG grinder, then posted his drawings on the web.

I have mine started but need to finish it up:


I would be interested in the drawings if it is ok. I am thinking about how to build a 72 x 2 also. thanks.

02-13-2008, 11:35 AM
Ok, I put the file on my site:


One caution, I seem to remember finding a couple dimension errors that I annotated on my printed drawings but I didn't update the pdf file.


02-13-2008, 11:57 AM
Matt, thanks for the posts.

I probably won't copy the KMG exactly, and will draw my own plans. I do kind of want to set it up so I can use KMG accessories if I want, but that's easy enough--just have to duplicate the arm dimensions.

As I often do, I am collecting a page of notes on these grinders before plunging in. Some of you may find it useful:


Best Regards,

Bob Warfield

02-13-2008, 12:02 PM
Was the belt sander garbage or something? The reason I ask is that I have a combination 6x48 belt and 12" disk sander and find I use the belt regularly and almost never use the disk sander. I think this is in part because the disk is less than perfectly flat, but its also because you really only get to use less than one half of the disk area when sanding. Additionally, the rate of cut is variable across that 6" area....dropping to zero at the middle where the tangential velocity is 0. This doesn't make it a good tool for something you want to touch up but keep square. Moving the work back and forth helps with this, but I still find that the end toward the center is not hit as heavily.

On my long list of projects is to make another long-belt sander to dedicate to metalworking. In the mean time, I do have one of the cheap 1x30 Harbor Freight belt sanders I bought on sale for $29 as I recall. I use it a *lot* as its great for sharpening lathe tools. I bought some good, fine belts (down as fine as 400 grit) from a knife supply place and with them I can put a mirror finish on a lathe tool bit. When you want to just "touch it up" like you would normally do with a stone, just head to the sander and its done in a sec...without drastically changing things like center height as you would with a much coarser grinder. It also works nice for lots of other deburring tasks with say a 240 grit belt.


02-13-2008, 04:19 PM
Put the disk horizontal and run it slow and suddenly a 12 inch sander becomes my most used sander/grinder. It makes it easy to keep things square and it doesn't eat the aluminum so fast that a touchup becomes a coverup job.

Alistair Hosie
02-13-2008, 04:33 PM
BOB I should like to know how much the materials have cost on this as that aluminium looks expensive ?However the whole thing looks great as usual keep up the high standards you always produce .Alistair

Weston Bye
02-13-2008, 04:42 PM
What is the typical RPM for a disk sander? I need to decide which motor to use to build one. Good looking job, Bob.

02-13-2008, 05:00 PM
I think that 3450 rpm is typical, but I also think that slower is better. It won't cut as fast, but that's what they make grinders for. With a 12" disk being several dollars, having one gum up quickly is a downer. If you are building one from scratch, this is your chance to make a slow-speed sander.

I have an old one of the Grizzly combination machines as mentioned. I see they now offer it in a low-speed version (1750 RPM IIRC).

I didn't mean to be disparaging earlier, Bob. You truly did nice work!


02-13-2008, 05:47 PM
Paul, the sander was a "shipping damaged return" I bought off eBay for about $50. I figure the motor was worth nearly that. The 9" disk was cracked, but the belt side worked fine. I plan to use the nice crowned wheels and the special tensioning + tracking fine adjustment hub when I build a KMG clone belt sander. But, I wanted to put a 2.5 HP motor and VFD on the belt, so I relegated this motor to a disc sander.

I like the high speed of this disc sander just fine. It's very easy to use for rounding as I did on the brackets, and it keeps things true. I had used a 20" industrial grinder quite a lot when I was taking community college fab+welding courses and really liked it. It was by far my favorite of the various wheel, belt, and disc grinders they had. It was originally my plan to build a bigger disk, but I got looking at prices for the abrasives and decided 12" was the sweet spot cost-wise. I'm very happy with its capacity given the scale of things I build.

I like the idea of using it to touch up lathe tools. I want to build a set of nicer tooling that will be interchangeable between the disc sander, my HF tool grinder, and eventually my belt grinder. It's already been helpful that the HF mitre fits my table slot. I got a nice deal on a universal vise too:


I'm still thinking about how I want to set up my grinding bench for maximum flexibility with all these different machines and tooling.

For those that want it all, a VFD would be a nice addition to your disc sander project. It would be easy for me to swap out this motor if I ever feel a need. Most of the work was in the table and disc.

Note that if you don't want to make a disc as I did, you can buy nice ones from Beaumont Metal Works and other places. I just wanted the experience of making one. For that matter, you can buy a 12" import disc sander for about $150. I still like mine better because it's built solid and I love the smoothness of the bike clamp and the nice steel table.

Alistair, hard for me to estimate cost of parts, but if I had to guess, it was maybe $100. The motor was cheap if I value the other parts at all. The aluminum is tooling plate bought off eBay for circa $2-$2.50 per lb. The bicycle clamps were $3 apiece plus assorted hardware. The table is a piece of 3/4" hot rolled steel plate, which I usually purchase for circa $1-1.25/lb.

Given that the whole grinder including the motor is maybe 45 lbs, it is solid, but the metal just doesn't add up to that much expense. Also, I used what I had on hand. You wouldn't need that big fat chunk of aluminum I used for the base, that's obviously way overkill and a thinner 1/2" plate would've been fine.



Alistair Hosie
02-13-2008, 06:27 PM
Well done Bob looks far better and more solid than any imports I have seen.I have two workshops one for wood and there I have a wadkin bursgreen 16" disc and 6" by 50 odd" inch belt the bigger sander is so good for woodworking in my metal shop I have a 12 " and a 6" belt too this is ideal for metalworking.kindest regards and keep impressing us with your fine workmanship Alistair

Chris Alton
02-14-2008, 12:43 AM
I built the KMG clone belt grinder form those plans and it worked very well.
This grinder is used every time I am in the shop.
This is me using the grinder.