Firebrick Mold

thingiverse

Warning! This uses high voltages and high temperatures and can be very dangerous. You make and use at your own risk! Homemade firebrick recipe: 4 parts Pearlite 2 parts Type S Mortar 1.25 parts Water I used a yellow plastic cup to measure and it this recipe makes one brick 13cm x 6 cm x 26 cm. Why S Type mortar? Because it has cement and sand already in it (you don't have to buy each separately) and it only cost me about $6 for a 60lb bag of it. I bought two of the small $5 bags of Pearlite from Lowes. So 8 firebricks cost about $16 and there's over half the bag of Type S Mortar left over. Let the bricks dry for over a week. Yes, a week. The bricks will be fragile. You can flatten them by rubbing them on your driveway or sidewalk to remove high points. You can cut the brick with a sawsall or sheetrock saw (for mitering). Then you'll want to warm the brick to about 180F (90C) for an hour or two to expel any remaining water before getting it any hotter or steam could build up inside and cause it to pop into pieces or worse explode. I used 2500w Kanthal wire. I cut it in half and stretched it by putting an Allen wrench in it and turning it to separate. I then only used about 85% of that piece and the rest as clips pushed into the fire brick to hold it in place. https://smile.amazon.com/gp/product/B07CKPW6JQ/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1 After using the kiln, the bricks will be sort of sintered so if you tap on the bricks they will sound more like ceramic than clay. https://www.youtube.com/watch?v=rFgBjgDpqFE I used superglue to glue the box and channel parts together. Glue then tape then lay flat and then let it fuse for about 15 to 30 minutes. I then covered the inside of the box with 2 inch shipping tape so that it would be smooth for when lifting up. (I used ABS so you may want to test this gluing method if this works for PLA or PETG but it probably should). I used this video to get the brick size but ended up using a different brick recipe than they used after watching a few more videos: https://www.youtube.com/watch?v=2Gs6z--gMQk So... $10 Pearlite $6 Type S Mortar $6 for Kanthal wire $3.50 for terminal block $0 power cord I had --- About $25 for the kiln not counting the PID controller & SSR. You could probably get a PID controller & SSR on AliExpress for about $15. You could probably get a K-Type Thermocouple on AliExpress for about $5. There's YouTube vids on how to wire a pid controller, ssr, and thermocouple. So, about $50 total give or take? After making and testing the kiln, if I were to do it again, I'd want to make it bigger inside (like 10 cubic inch inside). Currently, the kiln is about 6 cubic inches inside, which is small. The maximum for a 110v kiln is about 1 cubic foot before it gets too hard to heat it with a 110v element. The thickness of the brick seems OK and holds up well. To do make the kiln bigger, the bricks could be stood upright rather than laid on their side for the sides to make the kiln taller (10 inches tall inside). An extra panel could just be printed and glued to make a longer box for the bottom and top. So adding an extra panel and gluing that in would be a long enough brick. It would add about 4 inches to would make a 10 cubic inch inside kiln which would be more like it. Anyway, the current sized kiln works but if I were to do it again, I'd make it just a few inches bigger inside.