Disposal Frit Maker

If you are making large quantities of frit, you may want to consider building a mechanical frit grinder from a garbage disposal and a galvanized garbage can.  This set up can process a vast amount of scrap glass into frit rapidly, but there are some pros and cons, and a few tips to make your frit grinding more successful.

  1.  The Frit Maker (aka Chewy)
Frit maker for Recycled Glass

“Chewy” the frit maker

The disposal is mounted in the lid of the garbage can (yes, you do have to cut a hole) using the hardware that comes with the disposal.  Here’s a view of the bottom of the lid:

Frit maker wiringI’m using a heavy duty extension cord for the wiring.  It is grounded to prevent shocks.  If you are not electrically inclined (I’m not either) then it’s a good idea to have an electrician help you with this part.

The broken glass is poured into the top of the disposal, gets whirled and ground by the blades inside and shoots out the hole in the side of the disposal into the galvanized garbage can.  Here’s where the glass comes out:

Frit Maker

Glass Exit on Frit Maker

That seems pretty easy, so, here are the other things to remember:

  •  Glass is abrasive.  Although the disposal parts are galvanized and stainless steel, the glass will wear them out, and will wear the galvanized coating off of the steel.  For example, here are the blades inside the disposal.  See how rounded they are?  And notice the rust, this is where the glass has worn the galvanized coating off of the steel, even in the desert of Utah.
Mechanical Frit Maker

Disposal Blades and a bit of rust

No one wants rust in their frit, so, what to do?  Well, you can easily use the same thing that caused the rust in the first place to clean it off.  Run some waste glass through the machine, it will quickly scour the rust away.  Then, simply discard the rusty frit, and you are ready to go.

  • Glass dust is a terrible thing to be around.  Although you’ll never be able to completely control the glass dust, simply because it’s so fine, and there is an awful lot of it, you can certainly catch a large quantity.  This is the dust catching set up I have on my frit maker:
Frit Maker Dust Control

Dust catching set up for Chewy

There is a vacuum hose that come off of the lid of Chewy, then into the vacuum port of the shop vac (I’m using a Bucket Head Vac).  A HEPA filter in the shop vac is an excellent idea.  There is a second hose coming off the exhaust port of the shop vac and into a bucket of water.  The exhaust from the vacuum bubbles up through the water, catching a lot of dust.  I also float a filter made from an evaporative cooler pad on top of the water so the bubbles don’t just release their dust back into the air.  Here’s the water bucket with the lid off.

Dust trap for frit maker

Water trap for glass dust

You can see it’s quite mucky.  Since this is the last stop for the dust, it doesn’t really matter.  Right now it’s frozen solid, so I can’t make a video for you, maybe in a few months!  When I get an accumulation of dust in the bucket, I let the muck settle, then pour off the clear water, package the muck up in a sealed bag and discard.  Even with the dust trap, you must wear a respirator.

Other things to know:

  • The disposal is operated DRY, if you pour water in it, the glass particles will pack together and instantly shut the whole thing down.  Grinding the glass dry keeps it hopping around in the disposal so it doesn’t jam up the works.
  • The disposal will get HOT, you should run it in short bursts, and give it plenty of time to cool off before the next burst.
  • Usually the sidewalls of the disposal wear out long before the motor.  This causes tiny scraps of plastic to end up in the frit, but they can usually be floated out when you wash the frit.
  • Vacuum out the entire disposal when changing colors.
  • Clean VERY well.  Even with the vacuuming out of the disposal, it’s hard to get every tiny particle, and it would ruin your day to have a whole project ruined by a tiny scrap of the wrong frit.  Better be safe and vacuum just a bit more.
  • There will be bits of steel in your frit, I recommend using a rare earth magnet to remove it.
  • When your disposal is new, it will produce a mix of frit sizes that will tend to be on the fine side.  As the disposal wears, the mix will tend to become larger in size as the blades wear out.
  • Use a Ground Fault Interrupter outlet or inline.


Liability Disclaimer:  This article is for informational and entertainment purposes only, constructing the tools and processing glass is at your own risk!  Be safe!


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