Pics of a stop outside the crucible OCD? Looks like a bar in the mifco pics, but they are crap quality photos so I can't see properly.
I placed my stop on the small tongs so they can be adjusted accordingly depending on the size of the Heated crucible being used. The stop never enters the furnace. When I get around to making some tongs for the A12 the stop will basically be placed the same, (outside of furnace) although the design will be the same as Jason built. I have the mind set of, If it doesn't need to get stuck into the furnace then why do it?
Seeing that, it occurs to me that you could even put that stop up above the pivot if you wanted to. The rein that's made of a piece of bedframe angle on mine acts as a stop, it comes into contact with the other (square tubing) rein and won't close any farther. Pic of tongs closed (pre-addition of the reinforcing ribs on the sides shown above): open: Not adjustable, but I built it to fit the crucible. If the crucible gets bigger when it's hot, it hasn't even been enough to stop me from closing my tongs on it. If it did, I just would close the tongs until it had a good grip and try not to force it any tighter I guess. Could this be one of those things that is really only an issue with larger crucibles? This stuff is built for my #12, and I've never had to squeeze hard to get the reins all the way closed. Anyhow, while I'm at it, and since there is no pouring shank thread, here are some closer-up pix of my pouring shank. The larger piece of square tube that fits around the long 1" pipe handle is 2 pieces of that same bedframe angle welded together; the ring is a piece of an old temporary spare tire wheel whose car is long dead and buried. Jeff
I like the articulating action of Jeffs mad max creation. If you can figure out how to turn the articulation 90 degrees, it would double as a pouring tool too. Less screwing with a pot of metal, the lower the risk of something happening. Instead of the single gripper on each side at 3&9 it could have a pair at 8&10 and say 2&4 on a single shaft from the tool. This way you could pour at the 3&9 position and keep the same articulation of the gripper... Everyone thoroughly confused now? If I could EASILY chop about 6 inches off the height of my furnace, I'd do it in a heartbeat. Mine is too tall and my wheels aren't helping. I will admit, I am a bit nervous picking up a 10 full of bronze as I haven't done it yet. This is one of those things, that if you haven't done it yet......
Ya know........ The 2 things that will ensure your success in handling a 10 full of molten bronze is: 1) Eat your wheaties and 2) Stop pulling on your pud prior to melting and casting. Follow these 2 suggestions and you’ll have no issues.
I just put my limiter on the handles. I'd didn't really think much about it. It just seemed like the right place to put it.
It seems like the placement of that stop would be prone to creep, but maybe not. I generally seen them on the handles so there is not much moment acting on the bolt. You can put a lot of pressure on the bolt at that position. I used two bolts but should have used a single bolt. And I made my tongs excessively wide, but they work ok since my furnace is on the large size. Three contact points will just act as heat sinks and cool the crucible, so not necessary. .
I could easily add another nut stopper arrangement on the other side of the handle.... Not a bad idea atall...
I am doing the "gripper" using a photo of the A10 crucible as reference, turning it into an accurate outline, then modelling accurately in Solidworks for a close support but not applying any pressure on the crucible itself. Still missing a support from each finger, extending to the front. Hunting for SS flat bar tomorrow
Stainless steel? Now you are just showing off. I like that gripper style. If the rest of the tool would allow it, it would be bad ass if you could simply swap out grippers to suit the crucible size. The would eliminate the plethora of tools I have now. FWIW, that gripper needs to only TIP ONE DIRECTION assuming the sides are directly opposite of each other. Maybe a tab or tang on the main frame keeps that from happening. I don't remember at the moment.
What is the purpose of the top two blades? The bottom 2 will hold the weight of the crucible under the bulge but the top two seem useless? What thickness steel are you using for the main curved part that the blades are welded to?
The two top tabs may be a problem. I have found that no two crucibles have exactly the same dimensions, even when they are the same size and from the same manufacturer (Morgan). So I install the top two tabs on the sides of the vertical members, about 90% of the way up the side of the crucible. If you are making a lift/pour combo unit, I guess you may need the retaining tabs, but again I found out the hard way that a fixed retainer tab does not necessarily work, when my #10 full of very hot iron fell out of the pouring shank in mid-pour (I had some nasty burns on the hands from that incident). No two crucibles grip in exactly the same place, even when they are the same size and from the same manufacturer. I use a swivel retainer now that swings down from the top and holds the crucible down regardless of exactly where the bottom grips contact the crucible.
The top tabs are to prevent the crucible moving vertically during pouring. As hinted by Jason, I could fabricobble a different set of grippers for each crucible, if necessary. The tabs are not very well modeled at the moment, as they will be formed from bent stainless flat bar, hence they will have a radius.
Not sure how thick you plan to make the SS bars for your A10. But I found that flat 1/4 by 1.5 steel bar was not nearly stiff enough for an A20. However adding a 3/4 x 1/4 vertical rib so that the net cross section was a “T” rather than a simple flat bar increased the stiffness dramatically so that arrangement was more than adequate. Adding cleats also improved the reliability of the grip since I found straight uncleated tongs allowed an unsettling amount of vertical pivoting/rocking not related to flexing. That pivoting probably will be prevented by the top tabs.
I would mount the top tabs so they don't contact the top edge of the crucible unless the crucible actually starts to come out. An occasional contact with them would be less detrimental to the top rim of the crucible than having them continually rubbing and bumping the rim.
I used 1/4" thick steel with a 1/2" V shaped piece of metal to strengthen the spine. This is too thick to fit into my furnace comfortably so I will need to redo it. You pour with your lifting tongs? Hmm. I made a separate pouring shank for the crucible.
Negativ3, To allow the vertical rib to follow the contour of the curved flatbar, I simply used my thin cutoff wheel on my angle grinder to make cuts 3/4 of the way through the rib spacing them evenly about 3/4” apart. Then just use a few clamps to hold it onto the flat and tack it in place positioning the uncut side of the rib out and the side where the cuts originate against the flat. If the curve is too acute in some areasy, the kerfs may need to be closer spaced or widened as the kerf will close before the rib bends enough to follow the flat. Finally fill in the kerfs and weld the fillet between the rib and flat. Does provide excellent stiffness and does not look horrible if the kerfs are evenly spaced and are of about equal depths.
