homemade ceramic crucibles update

[xlchainsaw]

after i completed my new furnace i needed crucibles...i bought one new....it was made of clay and graphite about the size of a decent coffee mug!!! it cost me $90 au.. whilst i was waiting for it....(it took about 3 months to arrive) i made my own
these are fire clay based.

i made a mold...... this took nearly a week full time!!! i cast a solid block of aluminium!!! 6 inch square and eight inches high!! then i cast a mounting block for the inside.....i was guided by dave gingerys book on crucible making

these crucibles stood up to two brass melts a peice!! not bad!!! but???

i started to add powdered graphite from crushed gouging rods into the mix.

some brass castings from the crucibles

now these have been lasting for five brass melts a peice..

when they crack!!!!!!!! i grind them up add some more fireclay and some more graphite...

repress into crucibles once again.....the mold allows me to press up a crucible in just ten minutes!!!

i became very hard pressed for time and didnt have time to remake them and i had 65 garden taps to melt!!!!!!

so i christened my new crucible....so far its with stood 10 fireings of brass but its going thin on one side.....it might last another 5 to ten melts of brass???? i will let you know.

 

[tel]

Are you firing those crucibles before use, or using them raw?
I got the Gingery book on crucible making and made the mould from concret and the inner former from laminated and heavily polyurethaned MDF, got fireclay, grog, and the other stuff on hand, but haven't made use of it yet.

 

[xlchainsaw]

no i dont bother to fire them. i thoughly dry them in the oven up to 250 deg c. then straight into the furnance...i figure as they arent hard to make ....quanity over quality was better . its easy enough at the best of times to break them bought or homemade.