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How bad is this SB 10L bed?

That error depends on the ratio of the width of the ways to the tool height above the ways.

Narrow ways and a tall height (as with many "unmentionable" lathes, makes it much worse. SB as a rule is not too bad.

Scraping the back way to match is not a bad idea. But going to that much work, you may as well make them both good......
 
In addition to the trick that John K mentioned of setting the tool slightly above center for OD or ID turning, if you use an indicator or a DRO on the machine, you can gently "bump" the tool in and out as it travels down the bed. I've done this countless times on heavily worn machines, and can generally hold less than .001" difference down the length of a part pretty easily. A good DRO or indicator will enable . 0001" bumps, which are basically imperceptible. A quick run across the surface with some abrasive paper afterward will make it just about as good as it gets. The trick to this is NOT to attempt use of the handwheel for the bumps. Use a small soft copper or brass block to tap in an appropriate place.

Of course, rebuilding the machine sure makes things less stressful and easier, but sometimes that's just not an option. If it is, I certainly prefer it though, heh. I ran an American lathe for quite a few years that cut in an 'S' curve pattern. I had to bump in AND out, then back in again. That was a bit of a pain, especially as the taper was bad enough that the tool pressure would change in different places on the part down its length, so THAT had to be compensated for also. Good times. However, they actually finally ponied up to regrind the ways and turcite the saddle. Boy was that a pleasure to run afterward after having had to deal with the 'S' curve for so many years.
 
That's interesting, I would not of thought of trying to move it by bumping it, sounds like a good idea. I will give it a try. I have tried a couple of times with the handwheel and had limited success. The special lathe file does work pretty good.
 
Jim rosen suggested continuing my measured data under the head, following is that data, all looks reasonable, the bed is unworn at the ends and most badly worn near the headstock on the front V way, up to 0.025". There is up to 0.005" of wear on the tailstock ways so they would not have been great as a reference surface. This is all measured from the flat surfaces that are between the ways and they were not perfect.

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I looked over a couple of old posts on PM "where are all the metal planers around North America" and "Large capacity grinding company in USA". Initially I was unable to find anyone locally that was interested in machining the bed. I called several grinding shops around the country and got estimates of between $500 and $4500 for the 48" bed not including shipping. Some included scraping, others suggested that scraping is not required on a ground bed.

Thanks to Richard King and Warren Jones I was directed to Rees Acheson in Alstead NH, ([email protected]) he has a planner and is only a 2.5 hr drive away. I am very happy with the job. He planed all the way surfaces on the bed for $250 and provided lots of free advice. The surface finish is exceptional, almost looks like a ground finish to me. It is a way better finish than anything I have been able to obtain with my milling machine. I had never seen a working planer before so I felt like a kid in a candy shop. He removed 0.026" from the ways, he said it was about the worst he had seen on this small of a lathe.The ways are now straight and parallel now so I can use a shorter SE to scrape in the bearing surfaces. After just a couple of passes I think it is looking pretty good.
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Rees also planed the bottom surface of the bed, I scraped in the support pedestals that bolts to the bottom so nothing will get distorted when bolted down.

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I decided I need to prioritize the work some, I want to get the cabinet and larger parts painted before it is too cold in the unheated garage. I removed the underdrive motor to do some welding repair to the cabinet. There were 5 layers I scraped off. The first looks like mill scale, then light green, dark green, yellow and finally grey. Next onto sanding and painting.
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The apron and gearbox need to be rebuilt. Then I can finish scraping the bed and start assembling the lathe in the basement workshop where I can work on it in the winter. The saddle (or carriage) needs to have the V ways machined and have Rulon glued in then scraped for alignment. With a little luck I will be making chips on this machine a year from now LOL.
 
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I used to like it when a customer came back with a part...and a brand new micrometer......and hes "WTF? is happening here.......this shaft is all different sizes"............the boss would measure it ,a bit more force on the mike here and there........and hed say......Ya just dont know how to use a mike properly......its perfect.
 
Ive put the Landis back together again,as I wanted to make some crankpins for a vintage motorbike..........actually ,I have made the pins ,got them hardened and finish ground them..I should have kept the Cincinnatti 12x24 grinder .....but I scrapped it.............scrapped a heap of machines I should have kept .
 








 
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