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Repair crack in Shape-rite crank link (was Opinions on how to repair)

Adam Selene

Plastic
Joined
Mar 31, 2019
I have been reviewing my options to repair this piece. It is part of a cast iron rocker arm to a Shape-rite shaper. I have never welded and dont have a welder so that is out. Other options include jb weld, brazing and pinning such as with the lock-n-stitch products. Anything I am missing? how would you guys go about this?

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I'd also vee it and braze it. If you have a lathe turn a carbon plug for the hole before you braze it. The plug will keep the braze from getting into the bore and it will not stick to the carbon.
 
I'd also vee it and braze it. If you have a lathe turn a carbon plug for the hole before you braze it. The plug will keep the braze from getting into the bore and it will not stick to the carbon.

As in carbon welding plate? where would I get carbon?

Looks like brazing method is most popular. I have considered just making one from steel and it may come to that if i botch this up (i will take dimensions before I attempt anything). Everything I have read implies that cast iron is sensitive to heating and sudden cooling. Thinking through how I would do this, I would have to braze one side, flip it and braze the other side as the crack runs on both sides of the set screw. That reheating wouldn't be a concern would it?

That set screw is not critical. I can move it even to the other ear that is not cracked. Is there nothing that could be used in the bore to keep the halves together?
Thanks for the thoughts on this.
 
In regards to heat: I've had decent luck brazing cast iron with a decent sized rose-bud rather than a small tip. If the material can take the heat, don't be afraid to heat up a large portion of the part rather than just a little bitty spot. From my experience, that's where cracking really becomes an issue, not so much with how much heat is there but with how evenly it is dispersed and how quickly it dissipates. The heat will help clean the break and let the filler rod really soak into it rather than just adding a ball on the surface. However at this point the other risk is actually melting the iron but as long as you only get it hot enough for the filler to soak in then move on, you should be safe. The complexity of the part will also play into how stable it cools, but that part looks simple enough to just leave it out in the open to cool.

We have a box of Lye in the welding area just for cooling welded parts. If it's something we're concerned about cracking, we'll pack it in there and it will still be too hot to touch 12 hours later.
 
I had a problem getting the braze to wet out on CI repair, I found going over it with a needle gun after veeing out made the difference between success and utter failure, sposed to break up the graphite, or something like that.

Cheers
D
 
I had a problem getting the braze to wet out on CI repair, I found going over it with a needle gun after veeing out made the difference between success and utter failure, sposed to break up the graphite, or something like that.

Cheers
D

Interesting thought that one. I have done a lot of cast iron brazing. I can see how your remedy would work and why. The graphite in cast iron "smears" as it is ground away. You're establishing "bare iron" by doing the needling.

Joe in NH
 
Adam,

Quite a while back I purchased a Shape-Rite from another PM member who happened to be local (I live in a machinery desert). Mine appears to have been used in production, was crashed sometime in its life, and has a brazed tool head slide repair that seems quite strong.

Parts for these are pure unobtainum, BUT, at the moment eBay seller "kwktools" (no affiliation with me) has several Shape-Rite parts listed (door, ram clamp handle, saddle). I purchased a ram stroke pointer from him (mine had the tip broken off) and the transaction went smooth, meaning reasonable price, shipping was fast and the item was as described.

This particular part isn't listed, but I think it would be worth your time to contact him through eBay and ask if he has the rocker arm. From what I can tell, he is parting out a Model B.

Here's a link to his currently listed items:
https://www.ebay.com/sch/kwktools/m...hRsAAOSwjthcWlBF&rt=nc&_trksid=p2047675.l2562

By the way, do you have the later "Model B", or, like mine, the earlier "HY DUTY". Both are 8" stroke.

Good Luck,

Tenaya
 
Interesting thought that one. I have done a lot of cast iron brazing. I can see how your remedy would work and why. The graphite in cast iron "smears" as it is ground away. You're establishing "bare iron" by doing the needling.

Joe in NH

Thought I was going mad at one point, was sent some info that suggested shot blasting, I figured the needle gun wasnt a mile away from that so gave it a go, thankfully it worked.
Heres the trip.
 








 
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