Fix Wobble on Disc Sander

Back in 2014 i build a 12" disc sander using an old furnace blower motor.  I used melamine for the 12" disc and built the frame out of 2x4's.  It wasn't perfect but it's worked fine for years.  The biggest issue was that the disc wasn't perfectly balanced and it wobbled.

Fix Disc Sander Wobble 


And here's the original video from when i built the sander.

Disc Sander - Make DIY Build


The problem occurred when i made the steel mounting flange between the motor and the disc.  I welded a large washer to a steel pulley.  Somehow during the welding it shifted and wasn't perfectly 90 degrees.  So when i say it wasn't balanced what i really mean is that it wasn't perpendicular to the motor and that caused the wobble.
weld pulley flange, 90 degrees, belt disc sander

It looked ok, but not balanced and at 90 degrees.
mount disc to sander, metal pulley, electric motor

Parts to attach flange to disc.
how to fix wobble in sander, disc, disk

Lots of people complained that it was dangerous...they were probably right.  They said that the unbalance would wear out the bearing and cause the disc to break apart.
diy disc sander, make, build

So 3 years later i decided to try and fix it.

I started by spinning the disc by hand and marking the parts of the flange that high and low (1,2,3,4).  Then i loosened the 4 bolts that held the disc in place and shimmed the low area with some paper shims.
how to shim, shim disc, disk, sander, belt

I then shimmed it on the 2-3 side, with trial and error, until the wobble was virtually gone.
fix unbalanced disc, mower, blade, sander, shim, how to

It took a lot of trial and error to finally get it right, i ended up having to put several shims at different angles to get the balance correct.  But i finally got it so that it was almost perfectly perpendicular to the motor and the table.
build tool, disc sander, easy, cheap

Had i known it would have only taken a few minutes i would have done this years ago.
how to build a sander

The next thing that needs to be done is to add a guard/shroud over the disc.  That would block any debris that may get clogged and shoot up into the air.  Or if the disc breaks apart it would keep it from flying in every direction.
easy to build disc sander, shim 12" wheel

Definitely safer now than it was before.
fix an unbalanced disc sander

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