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I'm new to this forum and want to say thanks for the resource and thanks in advance for your help!
Do carbonized rods work well? Do the deteriorate quickly? Do they leave a round hole?
Let me explain my situation. I have 32 "egged out" 5/8" holes in a 3/16" x 2 1/2" strap. I need the holes round again and replacing the strap is not really an option because of the rest of the frame it is a part of. I have brochure advertising carbonized rods that you insert into the hole, weld around the stick filling the gaps, remove the stick, and you have a round hole again. This would be an easy and acceptable fix for my application, but does it work?
03-06-2004, 03:36 PM
Well, welcome to the ZOO, and now that the brochure has served the purpose of enlightening you to a process you didn't know about, toss it in the trash. Of late, there has been a major hustle by vendors to sell very overpriced carbon inserts for welding up holes.
Carbon is unique as the only element that does not grow when heated, carbon shrinks. A decent welding supplier will have a stock of carbon rod in various diameters that can be used as a hole filler you can weld up to.
There is a little learning to this, and it really isn't a friendly process if you are filling a hole in thick material with stick, because of slag. With MIG process the carbon inserts work very well.
After the weld has cooled you just shatter the carbon out of the hole.
You can also machine carbon rod if you need to fill a broken out threaded hole, and screw the carbon into place. After the weld is cold, you will need to retap the hole because the carbon shrinks, and the resulting hole will be undersized.
03-06-2004, 05:42 PM
Welcome to the forum Okie. That is a process that I didn't know about. Franz, would the carbon be for a carbon arc torch?
I will call a welding supplier Monday. So I guess using my wire welder would be the easiest and probably most consistent or would there be a specific stick that would better serve my purpose. Thanks again!
03-06-2004, 06:26 PM
WELL . . . . Ya' learn something new every day !
I never heard of, (or thought of) that ...but it sure sounds like it would work ! :cool:
03-06-2004, 06:40 PM
Oakie, use your MIG machine. Cored wire and or stick both present a problem because the flux buildup can't be removed if you need to weld multiple passes. It's next to impossible to chip slag without breaking the carbon.
Carbon becomes very brittle after you weld next to it, and will often fracture during the welding itself.
Yes, you can use the same carbon rods that are used in a carbon arc torch.
The trick is to make a carbon fillment that occupys the space you don't want to fill with weld metal. Just sticking a carbon rod in the hole and holding it there will work, but you waste a lot of carbon that way.
In the case of a strap where you are filling holes, backing the strap up with a copper bar and using a carbon button might be the best way to procede.
You can also use carbon filments with O/A welding.
I recall an oldtimer telling me to insert a piece of copper tubing and weld up to the tubing...the weld won't stick to copper. Franz,(not that I'm calling you an old, of cource) ever heard of this?
03-06-2004, 06:49 PM
Sounds to me like that would melt the copper....?
03-06-2004, 06:54 PM
Carbon works MUCH better than copper, and believe this Old Fart, you can stick copper to steel when you really don't want to.
Copper backing plates work well and generally don't get stuck cause the mass of the backing plate is sufficient to chill the weld pool immediately adjacent to the copper plate.
Copper rods will work, but are EXPENSIVE and a pain in the a$$ to knock out.
Referr back to the original statement of the unique property of carbon relative to heat. Copper grows, and you'd have an oversized hole, carbon shrinks.
Another interesting property of Carbon is that it has lower electrical resistance when compressed.
03-06-2004, 07:14 PM
If your local welding shop doesn't stock carbon rods, and you don't want to call Ted or Dave at Mahany Welding, 585-271-0870,
here's a source. http://www.crloo.com/Products/Hand_Tools___Supplies/Hand_Tools_2/hand_tools_2.html
03-08-2004, 03:10 PM
Wow, this is very interesting. Franz is a wealth of experience. Thank you.
Question, when you say to use a carbon rod, are we talking about the same rods that we have for CAC? And are we helped or hindered by the Cu or Al coating on these rods? For bigger holes, like the 5/8" mentioned earlier, I'm assuming it must be something different than a CAC rod, though.
03-08-2004, 04:53 PM
Mac, carbon rod is pretty much carbon rod, and for this purpose the copper coating ain't necessary, and might be a pain in the as$.
The URL I posted sells up to 1" rod, and I'm sure there are other sources as well. I've used elevator contacts machined to size on bigger holes, and they worked well.
When I get into the supply house, I'll ask who manufactures the rod they sell, they stock it up to 1" diameter, and 12" long.
BTW Mac, nice picture of you working on the dam.
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