MIG for Cast Iron + Small Welding Table

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SteveHGraham
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MIG for Cast Iron + Small Welding Table

Post by SteveHGraham » Thu Dec 01, 2016 11:26 am

I saw an interesting video the other day. A guy named Tom Lipton bought a busted-up horizontal boring machine, and it had some broken cast iron parts. He used TIG to put them together. The thing that surprised me was that he didn't have to preheat anything (beyond a slight warm-up) or use welding blankets. He didn't use braze. He used 99% nickel rods.

This surprised me, because I always hear that welding cast iron is nearly impossible, and that you pretty much can't do it on any part where you have to worry about heat traveling to something and melting it.

I have a 2HP motor I bought on Ebay. The Post Office broke a foot off the cast iron base. I can't get anyone to buy it, even at the low price of $50. I considered trying to braze it, but that would mean applying all sorts of heat to the motor casing, and I figured I would destroy something.

I don't have TIG, but I have a 180-amp MIG, and I Googled around and saw that they make MIG wire for cast iron. Also, I've seen that some people weld cast iron using stainless wire.

Here's the question: is there any hope I can get this thing put back together with MIG? I would rather do that than have it sitting here collecting dust. I could use it in a future project, such as a buffer.

Also: I wonder if anyone can give me advice RE a compact welding table. I'm talking really compact, like 12 x 12. Nearly everything I've welded would fit on a small table.

I've had to resort to things like welding on the garage floor or welding on my wooden workbench and trying not to set it on fire. Is there a product out there for small jobs?

I have a 13" South Bend lathe faceplate, and I was thinking I might mount it on a vertical pole. I hate to ruin an unused face plate, but I don't have a lathe that size, and the face plate is just hanging on the wall. I would have to destroy the L00 mounting stuff. I was thinking I could put it on a short post with a gearmotor. and a pedal. I could use a clamping set to hold stuff in place.

Last edited by SteveHGraham on Thu Dec 01, 2016 12:06 pm, edited 1 time in total.
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ctwo
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Re: MIG for Cast Iron + Small Welding Table

Post by ctwo » Thu Dec 01, 2016 11:40 am

Steve, I have a mig welder and I used it once to weld cast iron - a small claw hammer that I broke the head off. You might get away with it if you use a lot of small/quick tack welds and build it up slowly. I would heat the parts and keep them warm. I noticed some of my welds popped when they cooled. The hammer held up for a year. It was a hammer, so it worked pretty well...
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SteveHGraham
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Re: MIG for Cast Iron + Small Welding Table

Post by SteveHGraham » Thu Dec 01, 2016 12:05 pm

I was seriously impressed when I saw what Top Lipton did. If there is a way to avoid all that crap with the blanket and torch, then it opens up a whole new world to people who have to deal with cast iron.
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STRR
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Re: MIG for Cast Iron + Small Welding Table

Post by STRR » Thu Dec 01, 2016 8:42 pm

Well, here's the short answer: There are two ways you can weld cast iron. First, you can heat the entire casting to near 450 degrees, then weld the piece. You have to keep it hot until you're done. Then it needs to cool slowly. Bury it in sand, wrap it with welding blankets, throw it in a good fire and let the fire die slowly and the cast iron cool slowly.

OR, Second, you can prep your part, tack it or clamp it together. Weld about 1 INCH and STOP. Let it cool completely as in cool to the touch throughout the entire casting. THEN weld another 1 INCH and STOP. Preferably spaced away from the first weld. This will reduce the accumulated stress in the cast. Let it cool completely and repeat, and repeat, and repeat. This procedure doesn't allow a massive amount of heat accumulation in the casting and thus there is much less stress in the iron as it cools.

My understanding on filler material. It needs to be stainless or high nickel content. You can weld or you can braze depending on the needed strength. If brazing, brass filler is commonly used. TIG is the preferred method of welding as the focus of the heat is very precise and much more localized.

DISCLAIMER: I can weld, but I'm not a welder and I have done very little TIG work. I have assisted on many cast iron repairs, most of them NOT structural such as the foot on a motor.

BUT, how much do you have to lose? The part is already considered scrap in most cases. If you can repair it and make it work wise for some time, You WIN.

Do some research. Look at the welders on You Tube. Welding Tips and Tricks dot com is a great place to get information, both online and You Tube. ChuckE2009 is a welder but much more down to earth (garage type welder). He has welded cast iron and made it work with regular arc and 7018 rod. NOT PRETTY for sure, but it worked.

Good Luck,
Terry

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SteveHGraham
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Re: MIG for Cast Iron + Small Welding Table

Post by SteveHGraham » Thu Dec 01, 2016 8:52 pm

Thanks. I did try Welding Tips and Tricks, but so far I haven't gotten much of a response.

I agree with you; I should try stainless wire and see what happens. It's not like I'm welding someone's heart and lung machine, so if the welds pop, I can try something else.

I'm going to warm it to about 100 degrees, tack it, and then do a bunch of very short welds. I guess I'll try peening them, too. It could work!
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STRR
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Re: MIG for Cast Iron + Small Welding Table

Post by STRR » Thu Dec 01, 2016 9:02 pm

Steve,

I understand the whole idea about NOT preheating is to prevent large amounts of heat in the metal. Heat = Metal Expansion. Keeping it cool reduces the amount of expansion and thus the amount of contraction. There is the biggest problem. The cast shrinks at one rate when it cools but the weld material shrinks at a different rate as it cools. The different shrink rates cause massive internal stresses and then the cracks happen.

Thus, try to weld very short spans and let all the heat fade out before the next weld.

Good Luck,
Terry

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SteveHGraham
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Re: MIG for Cast Iron + Small Welding Table

Post by SteveHGraham » Thu Dec 01, 2016 9:09 pm

Thanks. I've read about the expansion and preheating stuff. The reason I want to try it with only slight heat is that I read some "expert" claiming this was the way to go when you do it in short bursts. Whether he knows anything or not I do not know. I can't heat the part much because of the proximity to the motor windings.

I read a very interesting post today by some guy claiming to know something about metals, and he said non-magnetic stainless wire was the way to go, for reasons I don't recall. I should try to dig his post up again.
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warmstrong1955
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Re: MIG for Cast Iron + Small Welding Table

Post by warmstrong1955 » Thu Dec 01, 2016 9:09 pm

If you can, get some wire with some nickel in it. makes a big difference.
Stuff I use is called ni55.
Multiple passes are better than single pass in most all cases.
When you start welding, you will see that all looks different, in comparison to welding steel. Takes a bit of gettin' used to, to see the puddle, and what's going on.

A little more preheat than 100F would be better....whatever you can do without melting insulation in the motor....
Motor frames, which I have welded, are forgiving, and ones I have welded are quality castings. Cast iron is hadrly created equal.
Most I have done were Reliance, and GE. Not sure with Wee-Bee-Motors...or what you have.
Peening is also good. Needle scalers are excellent for that. Reheating is good between passes.
Cool slow as you can. Floor dry, heated prior in the oven, is what I use most. Peen as it cools, now & then. It'll stress relieve it as it cools.

Bill
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SteveHGraham
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Re: MIG for Cast Iron + Small Welding Table

Post by SteveHGraham » Fri Dec 02, 2016 12:36 am

This motor is a Mitsubishi. It may be Japanese. It doesn't name a country of origin.

What I read about welding warm cast iron was that it was too hot if you couldn't rest your hand on it. I want to try it that way because, well, I don't have much of a choice.

I do have a couple of needle scalers. I wish I had a piece of scrap cast iron to play with.

I considered trying to put studs in it, but it would be like microsurgery.
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warmstrong1955
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Re: MIG for Cast Iron + Small Welding Table

Post by warmstrong1955 » Fri Dec 02, 2016 8:22 am

Mitsubishi is quality stuff, so I would think it would be an easy one.
Cast iron is highly variable in quality, and some can be quite difficult, if not impossible. Has much to do with carbon content.
I've run across some exhaust manifolds that just kept cracking after cooling, with pre-heating, peening and all. Just when you think you got it, you hear a "TINK". :(
I've always tried to get the temp up to about 400 F. Never heard that 'rest your hand on it ' rule. I have had repairs some crack after welding, which was due to a lack of pre-heat, but not the other way around.

Bill
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SteveM
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Re: MIG for Cast Iron + Small Welding Table

Post by SteveM » Fri Dec 02, 2016 9:50 am

As far as a welding table, find a large faceplate, mount it on a bearing and mount that onto a base. Make some locking mechanism to stop it from rotating.

That will give you a nice, heavy table with lots of clamping slots and the ability to rotate the part while you are working on it.

Adam Booth (Abom79) made one out of a really big faceplate.

Steve

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SteveHGraham
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Re: MIG for Cast Iron + Small Welding Table

Post by SteveHGraham » Fri Dec 02, 2016 9:57 am

I saw his table. I thought it was neat, but I didn't understand why it needed to weigh 400 pounds.

I don't like to cut up my South Bend faceplate, but I suppose I would pay just as much for a different one on Ebay.

I'm thinking I might make a turntable I can mount in my Rockwell Jawhorse. I just have to design it so heat can't travel all the way to the rubber Jawhorse jaws.
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