At what point is a lathe bed too far gone?

Here is a video showing the movement of the front v way from the tailstock end to the headstock end. This is using the tailstock as a sled with an indicator on it - apparently that is in nice shape still.


I also measured a bunch of other things and the read bed thickness varies about .005" in the bad section.

I have not disassembled the carriage yet to see how it is but I believe it is far more worn even than the bed - without any shims in the rack the pinion gear does not engage it at all!

Anyone here vote for trying extreme measures to save this thing since it is worn out anyway? I saw this video & was intrigued since the tailstock as a sled does seem to be in good shape as far as I can tell. I ran it along various surfaces and there are some where it does not deflect at all.


As for the carriage, currently thinking about a build up of either Turcite or cast iron strips epoxied in place then machined back out til its in usable condition.
 
I wish I were closer. I couldn't see in your video what you were attached to and what you were indicating on. It does make a difference.

I would like to take this offline, as it created a huge spitting match about how you measure ways for wear. I have been taught a way that is reliable, but I'm tired of defending it. Please PM me if you want to go down that road.
[edit] I have now viewed the video (my browser needed updating). What you measure is just as important as how you measure.
 
Using the tailstock as a sled can tell you something or nearly nothing, depending on how it was done. It is not the best method for measuring ways for wear. Using worn ways to test for worn ways is fraught with potential problems.
 
I wish I were closer. I couldn't see in your video what you were attached to and what you were indicating on. It does make a difference.

I would like to take this offline, as it created a huge spitting match about how you measure ways for wear. I have been taught a way that is reliable, but I'm tired of defending it. Please PM me if you want to go down that road.

Sounds good, thank you.

Sorry for the video, I realized after I uploaded it that there is no perspective.

So my lathe is setup in this way: (see attached illustration for more detail)

There is a front V way
Then a flat
Then the gap between the rails
Then a smaller V way
Then a flat

The front V way is used *only* by the carriage/saddle
The front flat is used by the tailstock, and the head stock
The rear V way locates the head stock and the tailstock
The rear flat is used only by the carriage/saddle

The gap does not locate anything & is used only for clamps (tailstock, steady rest)

bedway-illustration.png
 
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There are tons (literally) of big lathes out there going for very little money as we in North America de-industrialize. You can likely find something for $1k or less. I have seen some big name brand lathes go for half that, but they were large. So if your shop is in a garage at ground level it is a no brainer. If you have to lug it into the basement it probably won't work. So for the price of regrinding you can get another lathe that has years left on it (if you chose carefully). Don't buy something that you have not inspected. Messing with something that is that worn will bring only frustration where as getting a large, rigid machine that has been well maintained will bring you nothing but joy.
 
A good, reconditioned old lathe is worth 3 times what a new chicom lathe is worth IMHO, I have a rockwell that had the bed worn .008, I contacted Dick Treimstra and he didnt have one but the guy in Vermont did. So now I have had a bed that is worn .0008 sitting next to the lathe for the last 3 years. I started scraping in the saddle, but life has gotten in the way. Someday I will get it finished. That amount of wear can be fixed, good machines are hard to come by in the southwest...so if you have lots of options, then go with a new one. Good luck Tim
 
It all depends on what it is, how much it is worn, and what else is out there available to you and how much time and confidence you have in your sklls. Anything with 8 thou of bed wear is going to have a LOT of wear everywhere else too. So a rebuild (a real one, not the fancy paint jobs you see on youtube) will be a hell of a lot of work. But if it is a monarch 10ee or a hardinge it might be worth it and you will learn a ton in the process. Or if you enjoy that sort of thing and wantto learn scraping then have at it. Even if you have the be ground there will still be other parts to scrape. So it does all depend on your situation. There is no single righ answer for everyone.
 
At one shop I used a SB 9A with more wear to produce accurate parts. We mapped the ways and made allowances for wear. On small parts, it worked very well.
 
At one shop I used a SB 9A with more wear to produce accurate parts. We mapped the wauys and made allowances for wear. On small parts, it worked very well.

Dabbler . I am staring at a SB 10 heavy right now . The ways are badly badly worn . They used this thing for polishing aluminum rollers and never got the grit off the bed . I got it free . I could care less how it cuts myself , as I may use it for small change parts only , but you think the thing could be ground and scraped reasonably well ?
 
If it is *really* bad, you need to take it to someone with a surface grinder and straighten it first. Scraping can do a small amount, but if it is that bad, you might need to have it done mechanically.

Fortunately you have an Iron bed, which is not induction hardened. Makes the job go faster.

Up here, ginding the 2 Vs and both flatways on a 60" bed is about 2K$ CDN - single provider has a monopoly. It does take about 2 days of time, with setups and proper measuring - so I guess it is close to fair.

BTW - sblack has it right. Even if it is SG, it will need to be scraped to provide oil paths and hold the oil. See "Moore Pattern Scraping on Youtube. An old lathe isn't worth a professional rebuild unless it's a Monarch or Hardinge (again thanls sblack!).
 
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