Crucible tongs for side-access furnace

I didn't like the flat handles so I used 1/2" bar. I may have relieved the front to allow passing the crucible but I always go in low and close before I lift so there is no crushing force. I have used them for 25 plus years with both aluminum and cast iron.

 

Thanks for the feedback @ESC those pics are really helpful as well. I have yet to look, but I think the only thing keeping me back from using my scrap 1/2" square tube is, it's covered in nasty paint. So this weekend might be me gloved up over a tarp smearing paint-remover around (and then likely more mill-scale cleaning) Ahh, the sacrifices we must make to get some solid welding-time in

 

Spent an hour or two cleaning/grinding paint and mill-scale off a pair of scrap 1/2" x 3/32" square tube I found. They're just shy of 4' long, so they'll be perfect partial-replacements for the 1"x3/16" material that's too flexible. Then I got the tongs into my vice with a billion clamps and worked on fixing the head-angle, along with fussing/fiddelling the crucible fit. Now the crucible rides a bit higher up in the grippers when fully closed.



I think I'll cut the "old" handles about 6" away from the pivot, that'll give me plenty of meat to weld on the new 1/2" round-bar handles. It'll also be enough space to add a heat-shield. For that, I'm thinking I'll use a piece of sheet-metal that overlaps in the middle, so there's coverage when the tongs are open.

Thanks again for all the suggestions guys.

 

"Ya only got but one pair of eyes"
-AvE

IIRC, those come with an aluminized head-cover also. PERFECT for scaring the crap out of the neighbors! Or you could DIY something similar.

 

I was at the recycle shop on Wednesday and they had a pallet of those scuba diving helmets: fibreglass, full face perspex dome like a modern version of a diving suit helmet.

 

Correction: I'm an oaf! It's 3/4" square tube that I have, not 1/2", so it's perfect!

I couldn't find my paint stripper and didn't feel like driving to the store. So I spent a few hours grinding nasty brown paint off the square tubing. The good news is this old bed-frame tubing is the good 'ole stuff, no scabs and (surprisingly) no mill-scale. Just paint

I cut the old handles down 7" from the pivot, and after a bunch of three-handed acrobatics managed to get the new handles tacked on. You can see in the pic, the 1-2° upward bend Gingery recommends for the gripping head.

 

Since the only thing holding the tong-halves together is the rivet, and the handles are really long levers, I wanted to add a feature that makes the handles connect and lock together. This both puts less stress on the rivet, and should improves the ergonomics while pouring. So I tacked up some locking-tabs with heavy chamfers, and at a slight outward angle so they can't get hung up if the handles aren't perfectly lined up when closing.



I also cut, shaped and bent up a top-hook, to stop the crucible accidentally falling out while pouring. Didn't get to welding it on yet.

 

Good point, thanks! In fact, that makes me think I should probably make the hook a bit taller. In other words, so it clears the crucible top when the grabbers are at the lowest (grabbing) position (relative to the crucible).

I remember your old thread building that huge shank. It's got a wheel in the middle for leverage & transport doesn't it? It looks like it's painted? How on earth does/what paint withstands that kind of heat?

 

Nice!

Not a lot of progress since last weekend, I only managed to weld on the "accident-catch" this week.



Not the prettiest weld, but I managed three (small) overlapping passes, so I think she'll hold Orrr...there's always the grinder

Secretly, I've been holding off on welding b/c I bought myself a pre-birthday present: A water-cooled TIG setup The complicating factor is the cooler is 220v and I ain't got a place to plug it in. I think I can jimmy together a pigtail box from hardware store parts, that should do for now. Long-term I've got parts on order to wire the thing into my welder so I never forget to turn the cooler on

 

Got the new water-cooler hooked up and running just in time for a welding micro-marathon. Started with some little 1"-square end-caps for the handles.



Welded out the handle locking-tabs.



Then took an hour to grind and flap-disk down all the sharp edges and rust in preparation for paint. I'm just painting the handles, and I decided not to add a heat-shield initially. After my first melt I should know if I really need one. If so, that section will be bare-steel so I can easily weld or rivet one on.

 

Spent about 3-4 hours with an orbital sander and 20 discs (they don't last long) taking all surfaces down to 50-grit. Basically "dull" and evenly scratched all over. Then with some 100-grit wet/dry, I sanded/polished the section between the handles and the grippers (where the rivet will go). That section and the grippers aren't getting painted. I'm told a smooth/polished surface will prevent rust to a certain extent, though I'll also keep it oiled. The mill-scale and oxides will protect the grippers. Of course it's hard to see all the detail in the photo but you get the idea.



The next day it took me about an hour to thoroughly de-wax, de-grease, and give everything a through acetone rub-down. I masked off the gripper and pivot sections, stuck the two open-ends of the tubes together over a piece of round bar, and balanced the whole 10' thing between two roller-stands. Applied three coats of primer and paint, using some leftover 500° engine enamel rattle-cans I had from painting my furnace.


I'll probably let it sit like that for about a week, given how slowly enamel paint is want to dry/cure. The final step is of course to fix the handles together using the rivet I headed earlier.

 

Made some time this weekend to finish up the tongs. I was procrastinating because of what was required to fixture them up for riveting. Had to clear off my whole table and use lots of blocking and clamps so nothing could come loose, while I had a torch in one hand and hammer in the other.


I set the rivet with a 3-lb hammer, then peened over the edges with a wee-little hand-hammer. BTW, that's a square of 3/4" thick steel under the rivet, it kind of looks like wood in the pic

Unclamped everything, then re-heated the rivet glowing-red and worked the handles back/forth to free them up. Let it cool a bit then gave everything a healthy coating of oil.

Here's a final money-shot in their resting (non-lifting) position. The fit is pretty good when lifting and pouring, the handles and head don't flex hardly at all.

If anyone cares to replicate these, I ended up buying way too much material. Here's a more paired down list:

• 3-5 inches of 5" schedule 40 steel pipe.
• 4-ft stick of 1/4" x 1" flat bar.
• 4-ft stick of 3/16" x 1" flat bar.
• Two 4-ft sections of ~1/16" thick 3/4" square tubing
• 2-ft stick of 3/8" or 1/2" flat bar
• Small piece of 3/8" round bar -or- pre-headed rivet stock (roughly 1-1/2" long w/o the heads).