Cracked cast iron frame

snipped-for-privacy@gmail.com fired this volley in news: snipped-for-privacy@4ax.com:

Mike, it's a frigging lemon press!

Dump the $20 and find an arbor press for that sort of work. You'll spend more than $20 on time and materials trying to fix it, and it won't last; not under that sort of force. The screw exerts more side-thrust than down force!

Lloyd

Grind the cracks out to a vee , braze with brass . Might not be a bad idea to have it buried in vermiculite and then cover it up to cool slowly when you're done . You'll want to alternate sides , you might even keep it round enough not to bind . Or seize ...

_Braze_ it. Tighten up the crack to a few 1/1000's & let the braze wick in. Take out screw & clean the bore really well. Good as new. Well, almost. Order of magnitude easier than welding.

Bob

+1 on the v-grind, and either braze or TIG, or braze -then- TIG. Heat to red hot first, then weld. It will allow the brass to get all the way through the width of the cracks if you've properly fluxed it.

Otherwise, just look for a beefier press which is made to squeeze metal, not fruit.

Thats a fairly easy repair. Though to be fair..Id consider brazing it before "welding" it. It is cast iron.......

Pull the screw. heat the whole thing up with a rosebud. Warm it fairly slowly until the entire thing is HOT.

Put some braze rod in the crack(s) and let it melt well along with fluxing really really well.

While the braze is still molten (keep heating)...Clamp both halves together with a big ass clamp..

Heat with a rosebud again until the braze melts and both halves close up, then finish with brazing rod along the crack openings.

You may..may at this point..consider V ing the cracks and filling with braze again. But the material is so thick that it may not be needed.

Gently back off the rosebud a little at a time until it starts to cool

Let cool ..if you can stick it in a bag of vermiculite or kitty litter overnight..it would be a good thing and let it cool slowly. Cast iron doesnt like fast cooling..not at all.

Tommorow...put in mill and mill a flat near the vertical center of the threaded section on both sides through the crack..as close to the screw as you can get.

Drill and tap each side for a long socket head capscrew

Install one of each in both sides, pinching the crack together (may not be needed..what say you guys?)

Repaint, reinstall screw, beat oneself in head with cheater pipe until it sinks in that cast iron isnt the same as cast steel.

And the next time you break it..it will bust someplace else and you just repeat the process around and around until you are welding the bolts together..at which point Id go to 6011 for the bolt welds.

Now if it snaps while cooling..paint it again and put a stripe of red paint along both cracks and when dry, put it up on a promenent shelf where you can see it every day. Then put the cheater pipe on the handle for additional refreshment of that memory. And show the grandkids. And the neighbors when they come by.

(G)

Gunner

Gunner Asch fired this volley in news: snipped-for-privacy@4ax.com:

Nobody's even mentioned the grease that's sneaked into that crack while it was growing. Probably damned-near the whole width of it is full of grease.

Good brazing flux? Ehh... probably not...

LLoyd

I'd hope he'd have stripped and degreased the living hell out of the thing before heating to braze, don'tcha know?

I would throw it out and buy or make something else.

i

Heating up with the rosebud properly will likely burn out whatever grease is in there. And I rather suspect the 2 cracks didnt grow until he loaded it with the cheater..so it might be pretty clean.

Shrug

Ah yes, the trophy wall! Most shops have them.

I certainly have one!!

Judging by the "loud crack" sound he referred to, I bet there were no cracks until the final featherweight push on the 12' breaker bar. ;)

The crack's clean and should weld easily, with a bit less strength.

What he needs, though, is a HF 20T air-over-hyd press, huh? That should handle copper tubing pretty well.

Greetings Michael, I have experience with this type of repair that worked well. At wotk someone pounded on the large vise and it broke through the ram that encloses the screw. I was taking a welding class at the time so I brought it into class to fix it. I built an open top "oven" out of firebrick and set the vise part into it. I then heated the veed out part to nearly red heat with a big torch. Using flux and brazing rod I wetted the cast iron vee with the brazing rod. Once I had the surfaces completely wetted I just filled with brazing rod. I did this repair in about 1.5 hours and used a lot of welding gasses. This repair was done over 20 years ago and I still use the vise. Frankly, I did the repair for the experience, your press may not be worth it. It may just crack somewhere else. Eric

I throw stuff out the window above the main workbench. It really sucks when you hear it hit a previous contribution.

I don't know why everybody says to vee the crack. The depth of the vee will be so much less than the frame thickness that it can't be significant. And the braze will wick into the crack without needing a funnel.

The link Ed posted in the "Joining Stainless Wire" thread about silver brazing

had a chart showing joint strength versus joint width. The maximum was for a joint .0015 thick!! That thickness joint had a much higher tensile strength than the silver itself (3X). Joint strength fell off dramatically with increasing thickness. Thus a vee will be much weaker than a close joint.

Bob

I often toss my mistakes into a crucible and try again ...

Bronze brazing (actually, it's brass) is a little different. It has a higher bulk strength and works better in fillets. But it doesn't have the high *joint* strength of silver in close joints.

I saw that graph and I don't doubt it, but it's a little sharper than others I've seen in the past, and the usual recommendation for silver brazing is to have joints of 0.002" or slightly less. That's in close agreement with the graph from H&H, which AWS re-published.

There are silver braze materials (and special bronze brazing alloys) formulated for use in fillets but their ultimate strength isn't quite as high. The maximum joint strength for silver brazing that's usually quoted is 120,000 psi, for close-fitting joints. As you say, that's close to three times the bulk strength of the material.

When you silver-braze wires, and when they're in contact in a parallel joint, enough of the joint is within the high-strength range that the overall joint strength is quite high.

Keep in mind that there's a distinction between silver-brazing that's done like soldering, wherein the braze wicks into a close-fitting joint, and what is sometimes (inaccurately) called "braze-welding," which is mostly a matter of wetting the material on both sides of a joint and building up a fillet. That's how Brit race-car builders made their tubular space frames back in the '50s and '60s. In that case there may be some wicking but you don't count on it.

Too bad Jim Rosen isn't around these days. He's pretty knowledgable about silver-brazing.

Greetings Bob, It is very hard to get brazing to wick into cast iron. Even silver brazing alloys. I thick it is because of all the free carbon (graphite) present at the surface. I have brazed a lot of cast iron and it is always a bit of a chore to get the brazing alloy to wet the cast iron. Brazing rod typically has at least as high tensile strength as cast iron, and typically more, in thick sections. Eric

Wetting is a big issue, and graphite flakes or smeared graphite on the surface is a major cause of trouble.

But it's only one issue of several, when it comes to brazing cast iron. Here's an article from the British journal _Welding and Metal Fabrication_ from 1980 that I remember using as a source for an article I wrote a year or two later:

It covers it well, although it doesn't address repairs. You probably could find an alloy available in the US that has the same properties as the one discussed in the article.

A few notes: This casting is almost certainly gray iron. Where the article discusses nodular iron, that's what we mostly call "ductile iron" in the US.

And, finally, I think this particular job is a waste of time and money, as others have commented. It could be a worthwhile learning experiment, however. But don't count on finding any brazing alloy or flux that could allow the braze to wick into that crack without opening it up first.