This time Success, one smart cookie, I learnt from failure! This time I double reinforced the mold with fiberglass threads (pulled sheet fiberglass mat apart and mixed it with the mud) And I even got a video so the safety officers here can fine me! I think this was the best batch ever, I am over the moon!!
The lifting crucible gripper looks nice, might be worth adding some horizontal curved strips to prevent a really full crucible being top heavy and tumbling out. Also I've personally had a small bit of bronze hit my plastic face shield right over the left eyeball and then disappear instantly from the dust on the plastic flashing off to steam and blowing the bronze back off again. It was caused by not preheating my ingot mould over the furnace to drive off moisture. The plastic was completely undamaged with just a small clean spot in the dust the size of a five cent piece. I can tell you let them cool down a fair bit in the sand from the lack of oxidation, the castings look really nice and clean, no sand burnt into the surface.
The bells look great! Ya didn't show it, but be sure you return that expensive crucible back to the furnace to cool down nice and slow with the lid closed. Helps them last longer.
The logistics of doing the next big bell is already started to sink in, the bell on the left in the picture above weighs 24kgs and the mold was starting to get big and heavy to handle. My next big one to make will go somewhere around 47kg so the mold will be far to big to handle manually, I am going to need more brains than brawn.
The bells look great! Congratulations. Also, your jib crane functioned very smoothly making the hoisting of the crucible from the furnace smooth as silk. Well done. Denis
A tried and true method for casting bells, I don't think we've had anyone here do that before. Please tell us about your methods, materials etc.
Really nice project; you have obviously put a great deal of thought into the process. I am with Mark though, put a face-shield on; they don't cost much compared to face-damage. I had the same thing happen to my face mask as Mark had to his, Cheers Charlie
Ohh bloody no, what have I done wrong. all four are riddled in gas bubbles? they look fine until you take the surface off!
First thoughts were sand inclusions and that is handling procedure fixable. Scanning higher we see porosity. A totally different kettle of fish of course. Something internal going on. Not moisture related as that would be apparent externally. So we have to think of gassy events and temperatures and feed and speed of pour and alloy purity and venting and.... AND, I feel the pain. John
John, I was thinking moisture, I do put pug around the bottom of the core and mantle, and just maybe it was a little damper/wetter than normal. However i have never encounted this problem before. One thing I did change on this batch was the sprue, I made them a little larger as these bells are getting a little bit bigger. I went from 35mm to 40mm diameter sprue. One last thing that did change also was. In the past I was getting a little separation in the loam cope so I did increase the amount of horse hair in the loam. I certainly had no separation of the core in this batch, but is it causing some sort of gassing.
These things can be a bit of a guessing game. How was the inside of the bell for integrity? The main problem you are faced with is sanity. One bad part out of four can be managed mentally but the whole batch? Daunting and haunting. I am no expert on the issue although I have been in the same space and climbed out, but not the next day. Take a different task on for a few days and it is often quite amazing what, sorry but I'm so tempted to say "what bells go off", triggering positive changes to the set up. My best wishes, John.
I just ground away on the inside opposite a very porous outside, and while there is some porosity it is very small and sparse. the surface on the inside is good just like the outside and probably one of the best I have ever done! Yeah I have gone out into the orchard and taking it out on the citrus with pruning!