Progession of Crucibles

[Harry]

A lot of pictures in here of my own progression in crucibles both in size and materials. I will also post pictures of my tongs and maybe try and rope someone in to taking a few pouring shots.

This progression will include my starting 4" steel welded crucibles, home made refractory crucibles, clay graphite crucibles and my current SiC.

Will kick off with the clay graphite crucibles, these are the ones BCS sells for $60 that are supposed to be #10 but only hold 7 lbs of metal and supposed to be SiC but are really clay graphite with some sort of SiC wash that cracked and flaked off on first use.

Looks good in the furnace, a little small for this bore but works fine.



Doesnt look so good out of the furnace, this is after maybe 50 pots of metal over 20 or so melts. Retired because it just doesnt feel safe at all.



And here is a closeup showing it was actually glazing over, Anon suggested some kind of flux, probably the coating they put on it as you can tell it only happened on the original surface not on the interior surface where it has spalled off.



And here are the new #10 Starbide SiC crucibles, these are so much larger than the BCS #10 it isnt even funny, they also have very thick walls and bottom, build like a rock and ring quite nicely. One is a little shorter than the other and the short one has some slobbery looking finish to it. The manufacture dates have 4 years between them so I guess QC got better.



This shot shows the nice fit for this furnace, just enough room to comfortably get my tongs in around it and plenty for the oil burner to run.



Last shot for this post, this is during the firing of the the left on in the picture above. Will post some after firing pictures later as it kind of surprised me with its glassy lumpy surface but it has a very nice solid feel to it. Firing went well over 2000 degrees and was held for a a good hour before shutting down and bricking it up. The foreground is some of the molds I had poured using the other BCS crucible I have before earlier in the evening.



I will be adding a lot more pictures to this thread including comparisons of the various crucibles I have made/bought in side by side photos which will show the progression in size that I have gone through as I grew more comfortable handling larger pots.

[Harry]

more pictures...

Two SiC #10 Starbides, the left one has been fired. These weigh about 11.5 lbs ea.



This is the #10 SiC next to the the BCS #10 SiC that is actually clay graphite. You can see the tremendous difference in size the BCS holds 7 lbs full the Starbide is supposed to hold 10 and is probably right on but looks a lot bigger in part dues to the much thicker walls and super thick bottom.



This is my progression beginning with the front left steel pipe crucibles. These I made with heavy wall 4" pipe, round bar lifting lugs, 1/4" plate bottom and a link of chain cut in half for the pouring hook on the bottom. Circa 2008 these were state of the art for me. I made about 5 or 6 of them.

The far left one was my one big meltdown, I still do not know what happened but my suspicion is a thermite reaction with the rust of the crucible lit off the pot of aluminum. That crucible was sitting on an extra heavy duty 3" steel plug which was about five pounds or so of steel. After the blinding purple tinged fire subsided I lifted that piece out and shut it down. At the time I had no bottom on my furnace, just a shell sitting on the dirt so I simply moved it the next day and inspected the carnage. There was no aluminum left of the 3 or 4 lbs that was in the pot, it was gone, burned in the fire. I did find 3 big melted puddle type chunks of steel though, the leftovers of the lower half of the crucible and the plug/plinth.

Front right is my home brew refractory crucible. This has a 5 pound capacity and they really work great but I would not use them much over this size or with iron. For their cost though they are a great way for the beginner to step up from steel crucibles using leftover material from making the furnace. It takes some work making a mold but once you have it you can make as many as you want.

In the rear are the (left) Starbide #10 and (right) BCS clay graphite sold as SiC #10



This last one is my homemade crucible inside of the new SiC.

[davidbraley]

Harry,

Where did you buy your Starbride Crucibles?

David