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Brick Molds

A project log for RepKiln

A small and inexpensive kiln for melting metals and firing clay

matt-mosesMatt Moses 05/23/2017 at 07:242 Comments

To review the big idea:

  1. Make clay out of dirt
  2. Make bricks out of clay
  3. Make kiln out of bricks
  4. Make stuff out of kiln

This project log deals with step 2, making bricks out of clay. There are a lot of great videos on youtube of people making bricks by hand. Here are a few that I drew inspiration from:

I built three brick molds so far before getting one that even kind of works.

Brick Mold Version 1

The first version is shown in the image below. This is a two part mold. The dowels and angle brackets are attached to the base plate, while the frame lifts off. The idea is that you fill it from the top, flip it over, remove the back plate, and then lift up the frame. The problem was that the bricks did not release cleanly during this process, and the result was just multiple blobs of gooey clay stuck hither and yon. It was a mess.

Brick Mold Version 2

I had high hopes for this version, but it didn't work either. The metal angle brackets on the large plate made it difficult to slide the plate off the bricks. Trying to lift the large plate off didn't work either, because the bricks would tear into pieces and portions of brick would stay stuck to the plate.

Brick Mold Version 3

The third version simplifies the design and has space for only one brick. The back plate (the thing with the holes in it) is completely smooth so it can be slid off the bricks, instead of lifted. There are two extra pegs on the pegboard to perform alignment. The frame is one piece, but it has a slight draft angle built in to aid with removing the bricks.

Wedges drawn on the blocks show the acute angles of the bevels, for creating the draft angle in the frame when assembled.

It is important to have the pegs aligned as accurately as possible. The pegs were cut square with a chop saw and then drilled with a lathe to get the holes on center.

Discussions

will.stevens wrote 05/28/2017 at 06:02 point

Thinking about cake-baking analogies, I wonder whethera covering of oil, or a sprinkling of finely powdered dirt on the sides of the mold help with brick removal.

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Matt Moses wrote 05/29/2017 at 21:37 point

I've seen videos where the mud is rolled in a powder before being thrown
into the mold. I could try it. The stickiness seems to be quite
dependent on the recipe, too. I may not be using the best mix. I should
probably try some systematic experiments with different proportions of
sand, perlite, clay, and water to see what works best.

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