# Repairing Cracked Cast Iron Atlas 10F bench



## rfdes (Mar 24, 2013)

Hi -
During my paint prepping for my 10F lathe, I was degreasing the cast iron legs for the
lathe stand and noticed a 1.5" crack in one of the legs.  Don't know if it has been that
way for the last 50yrs or so but want to attempt to fix it.  I have no access to welding but
I hear that you need to know what you are doing to weld cast iron.  I've seen others report
success in using JB weld to repair engine blocks, etc.  Does this seem viable for this application?
Any suggestions?

Thanks-
Jim


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## iron man (Mar 24, 2013)

JB weld is over PR'd glue that is no better than any epoxy it has a tensile stregth of about 3200 PSI regular solder is 25000 and I would not solder it!!! JB weld use to advertise with the help of Paul Harvey you could weld trailer hitches with JB weld and I saw one come in the shop that someone tried it. The trailer broke loose and hit a car head on..   

 I have welded mountains of cast iron with a product called cast weld GP from stoody corp. any welding supply can get it or has it. grind out the crack and weld it up while it is cooling just peen it with a sharp chipping hammer to expand the weld while it is cooling and dont try to fill the crack all at once keep it cool and take your time you will be fine.


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## Uncle Buck (Mar 24, 2013)

I think a cast repair like this is fairly easy these days. The challenging cast iron repairs years ago and even now are exhaust manifolds I suspect.


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## george wilson (Mar 24, 2013)

JB weld will not do. You need to braze the caster iron back together. The cracks are ground into bevels,pre heated and brazed to fill up the bevels. Someone who knows how to do this can make the joint about as strong as ever.


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## Tony Wells (Mar 25, 2013)

If I was not comfortable doing the repair myself, I'd seek out a automotive head repair service. They properly weld cracked cast all the time, and this would be easy for them. There are several in your area according to a quick Google search.


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## iron man (Mar 26, 2013)

I never tried chronotron but I really liked the cast weld GP it was a nickel alloy with a powder iron center core and you dont have to preheat the cast and that can be a benifit I have also welded engine blocks with this stuff and what is nice about it is it is very machinable. as a precaution I always peened the weld after running a short path this stops the weld from shrinking and cracking I never had it fail on any kind of cast including exhaust manifolds. But it would be interesting to try other products.. Ray


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## Restorer (Apr 5, 2013)

Reparing Cast Iron is very difficult.  I have used the following methods with success but if you rush or skip a step the results will be very poor.

A) Thourly clean and degrease the part, at least 1/3 of the part length.  Wire wheel first and evaporating solvents.

B) Locate the end of the crack, drill a hole through the part.  This will stop the crack from continuing.

C) On the non visible side of the part, grind and vee the crack out more than 1/2 way through the thickness with a disk grinder.

D) Select the repair method that is available to you locally, 1) Welding or 2) Brazing.

E) The next operations are critical!  With an Oxy-Acetylene tourch heat a wide area around the crack with the immediate area near the crack at RED heat.   This will burn out any remaining oils and organic contamination.

F) If brazing, apply flux to the vee and melt in the flux coated brazing rod, starting from the hole and proceeding to the edge of the part.
When finished continue to heat the area in general gradyally backing the tourch away to allow the iron to cool slowly. (20 minutes minimum)

G) If welding, use Nickel rod and a back step method as follows:  Look at the drilled hole and move toward the edge of the part about 3/4 inch.  Strike the arc their and weld back to the hole.  Chip the slag, wire brush, apply tourch heat for a minute or so continuing to peen the weld bead with the chipping hammer while heating the surrounding area.

H) Locate the previous start end of the weld bead and go another 3/4 inch past twards the part edge, strike an arc an weld back to the end of the first arc.  Again chip the slag, wire brush, apply tourch heat for a minute or so continuing to peen the weld bead with the chipping hammer while heating the surrounding area.

I) Repeat step H, untill the crack is repaired to the edge.  

J) Continue applying heat around the weld area for several minutes (20 minimum), gradually moving the tourch back away from the part to reduce temperature very slowley.  Alow to cool to room temperature very slowly with no breezes in the area.

K) Wire brush, use an automitive filler to level any defects.  Sand, prime and paint to complete the repair.


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## iron man (Apr 5, 2013)

Restorer said:


> Reparing Cast Iron is very difficult. I have used the following methods with success but if you rush or skip a step the results will be very poor.
> 
> A) Thourly clean and degrease the part, at least 1/3 of the part length. Wire wheel first and evaporating solvents.
> 
> ...



I hate to sound cranky about this procedure but this was exactly how I was taught to repair cast iron and doing it this way made it extreemly difficult and the results where about 50/50 on failer, so I set out to try other methods and after I got done I found that welding cast iron was as easy as welding steel. Drilling the hole at the end of the crack never solved a thing that is a left over idea from WW2 aircraft windshield repairs and I never saw any advantage at all. Then heating up the cast iron hot if not red hot in one area just cause's it to split more and usually past the hole you just drilled.

The method I used Never failed me even on items that other shops had repaired and failed which made matters worse. I started using utectics welding rod but found that the Cast Weld GP to be more forgiving and cheaper I would grind out the crack and start at the end of the crack and work out. I always welded a 1/2 to 3/4 of an inch and then with a needle scaler on an air chisel I peened the weld till it was cool enough to lay your hand on. I kept doing this until I was at the start of the crack, the reason cast iron cracks is because the weld shrinks and pulls,, the peening action expands the weld causing no stress on the cast so it has a chance to re-crack. Keeping the heat low also prevents the cast from expanding and causing the crack to (run). I did this for 25yrs and never found a casting I could not repair except if the cast iron was burned out like a burned out manifold or something exposed to high heat which would turn it into carbon.. Ray


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