More problems with Jet GHB 1236 metal lathe

A

akoldnav49

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My cross slide became quite stiff and in looking it over there is a large crack in the saddle (about two inches long). I tried to order a new saddle however Jet doesn't sell one directly. They told me every one is different and they will have to build it individually. The projected cost is unavailable and the finished product will have to be scraped into the bed of the lathe. Looking at approximately six months as well as unknown cost. I am not very happy about all of this because I bought this thing new about 3 years ago so no warranty. I have never scraped anything so I don't know the first thing about it and I am 73 years old so low on energy for such things. Additionally I live in Anchorage Alaska so availability for help and advice is sparce. Be careful where you choose to spend your money because some of these don't have very good customer support.
 
It might not be straightforward, but have you looked into the possibility of repairing your cracked saddle? The result will not be as straight as new, so some scraping may be needed anyway, but it would be the lowest cost option.
 
Agreed, wondering if the crack could be pinned and brazed. Or even drill a series of holes in the crack and inject some type of high-strength epoxy (least chance of warpage)
-M
 
Photos please

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For most modern Jet lathes, this custom fitting is not worth it. You could easily exceed the cost of a better lathe. And you would still have a Jet. Sorry to be negative, but we had two Jet metal lathes at TechShop, and they were pretty sad. They, and the sad Jet mills, helped contribute to the demise of the place because they created a toxic relationship between the staff and the members due to the downtime caused by serious issues. Your experience sounds very familiar.

I would start looking for another lathe, almost anything else, even a Chinese mini-lathe. And, knowing that the saddle is already bad, I would be tempted to make a hack repair. Do you have a welder, by any chance? I would try to do a cold weld method repair. See if the crack can self align by clamping it together. If there is any hope, put a couple of tacks in strategic locations along the crack. See if the cross slide now moves freely. Grind the tacks flush if necessary. Do not run the lathe or put any undue stress on anything, but you can check with an indicator. If everything lines up and moves freely, cover up the ways carefully and vee out the crack with a die grinder, or if you are gutsy, an angle grinder. A die grinder run slow with carbide burrs is preferable since it doesn't make a mess. Cut out short lengths of the crack and weld in short lengths. Do not weld if the metal is hot from the last length. This will take days, if done correctly. Eventually, you will get to your initial tacks. Grind these out (they aren't needed and they cover part of the crack) and weld through. Of course, check all the way as you are doing this to make sure things move freely. I don't know if this will work or not, but I have welded a lot of cast iron, and the cold method works. The only thing I'm not sure of is whether the distortion will pull things out of alignment. Obviously, you can stop mid-way and just pin it. This is one of those things that has to be done slowly.

I would rather have an old American lathe, even a clapped out basket case. If you were closer, I have a couple of spares.
 
I would pre-heat the casting to 200F or a little more, depending on the size of the crack. This is to increase cooling time and reduce warping. I would weld with a fine stick of Stoody Castweld 99 nickel specialty rod. That's a professional solution for cast iron. I love silicon bronze, but that's not machinable to the same extent, and the weld isn't nearly as strong as a nickel infusion.
 
Stitching makes sense, but how does a stich block in the middle of a plane resist lifting when twisted so that minimal shear loads exist? In other words, a keyway on a shaft holds like hell axially, but must be retained by a heavy rimmed bolt to constrain effortless longitudinal translation. If the plane were held in tension, it would be a strong fix, but any torsion will have a component of free motion perpendicular to the plane in which the key is installed. I'm saying that this approach is application sensitive, and is limited by the type of movement the part is expected to endure. Do you buy pre-made keys, or have an EDM or CNC to make them?
 
I was able to take it to a local machine shop today that is going to weld it and then re-grind it to profile and that might be sufficient. I really appreciate all the advice you guys were given because the darn lathes are a pain in the rump when they malfunction.
 
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