View Full Version : Built myself a 12" disc sander from a furnace motor and shop scraps. (video)

Art Mulder
01-05-2015, 3:25 PM
Video Link Is At The Bottom:

So one of my Christmas projects was to build myself a 12” disc sander. I’ve been wanting to do so for a while. This is kind of an experiment, due to the motor.

I’ve had this motor for a few years. I salvaged it from a furnace — the motor was only a couple years old, so I kept it. The problem is that it is only a 1/3HP motor.

As I looked around various websites and forums and so on, I found several examples of people making 12" disc sanders. But in all of that searching, I only found one person who had uses a 1/3HP motor. All the other DIY disc sander projects that I found were built using 1HP motors.

But in the end, I decided to just go ahead and give it a try. I had nothing to lose, as I was not going to go out and buy a motor or parts. As well, I thought it would be a fun exercise.

http://i.imgur.com/iHG1MBZ.jpg (http://imgur.com/iHG1MBZ)

My motor came with a split pulley -- the pulley was made up of two parts that screwed together so that you could adjust it for wider or narrower belts. I took it completely apart and reversed the one side, which gave me a flat surface to mount to a mounting block.

Before going further, I then temporarily wired up a cord and tested the motor. The motor ran smooth and quiet. More importantly, the mounting block did not wobble at all.

http://i.imgur.com/lwi1yzA.jpg (http://imgur.com/lwi1yzA)

So I moved on and made a 12” disc out of 3/4” Baltic Birch Plywood.

I fastened it to the mounting plate and the motor nearly threw itself off the bench when I turned it on. It was a little off center, which I fixed, but that did not help.

(Later on I’ve found that plywood can really vary in density. I expected better of Baltic birch.)

http://i.imgur.com/9b02E1o.jpg (http://imgur.com/9b02E1o)

So I next built a 12” disc out of some MDF shelving that was absolutely flat, and it ran much better/smoother.

http://i.imgur.com/z4dH82r.jpg (http://imgur.com/z4dH82r)

I then built a rough platform for the motor to elevate it, some legs, and then I wanted to build a dust shroud (also a safety shroud) that went over and behind the disc. This required that I dust off my highschool math+geometry to figure out the angle to rip pieces at to put them on the arch.

I didn’t get it totally perfect — there were gaps on the inside — but I filled those with epoxy and they’re hidden anyways…

http://i.imgur.com/n6PvuJU.jpg (http://imgur.com/n6PvuJU)

I built a basic sanding plaform. Since this is still a bit of an experiment, I just made a fixed non-tiliting platform.

http://i.imgur.com/KepQGDh.jpg (http://imgur.com/KepQGDh)

I closed in the bottom and back, and added a hole for my shop vac to do dust collection.

http://i.imgur.com/I0hRmVq.jpg (http://imgur.com/I0hRmVq)

And wired up a switch.

One thing of note is that this motor is reversible. I am tempted to add another switch so that I can reverse direction. That may be more effort than it is worth. Though I did see one comment online from someone who claimed that his sandpaper lasted longer by being able to spin either way.

http://i.imgur.com/CxjVF13.jpg (http://imgur.com/CxjVF13)

And here it is in action. It’s not 100% flat, but close, and it does seem to remove stock quickly and without burning. (I mounted a 60 grit paper)

Ask me again in a month or two. I plan to report back on how well it has been performing. The dust collection, simple as it was to set up, seems to be nearly 100%, which is great.

http://i.imgur.com/yx4nEK3.jpg (http://imgur.com/yx4nEK3)

I’m very happy with how it turned out. It went together pretty quickly, and I’ve got a functional disc sander. And best of all it cost me all of $5 plus tax, and that was for the sanding disc. Everything else was shop scraps.

There are a few more photos and details on my website, if you’re interested.
Or you can watch me build it on youtube.


Leigh Betsch
01-05-2015, 10:56 PM
Cool. Gotta like shop made machines.

David Falkner
01-08-2015, 9:13 AM
Nice build, well done! If I didn't already have a DeWALT 10" I would build one like yours because there have been many times when the 10" wasn't quite big enough. And that reversible motor can come in handy. There have also been many times when I needed to sand something close to a corner and my only option, that I chose not to do btw, was to sand on the other side, the side going up. Being able to sand on both sides of the wheel would really be useful.

John McClanahan
01-11-2015, 2:03 PM
Nice setup. Most disk sanders have a bigger motor, but you will get a feel for how hard to press into the sanding disk. The split pulley is for adjusting the air output of the blower.


george wilson
01-14-2015, 11:01 AM
You can use the soles of old sneakers to clean your disc. That saves the expense of buying those rather expensive bars of rubber that are made for the purpose. But,they wear out,of course.

Ron Rutter
02-04-2015, 2:56 AM
You can use the soles of old sneakers to clean your disc. That saves the expense of buying those rather expensive bars of rubber that are made for the purpose. But,they wear out,of course.
PLASTIC grocery bags work very well too. All bunched up!