Flat way repair

So I found this sort of rig on YouTube, and Gabe it a try. I’m making a lot of assumptions here in considering these numbers. I don’t have a tenths indicator because I dropped and broke it. Anyways I’m assuming the bed is as level as possible, and the thousandths indicator would be sufficient. After all, this bed is trashed right? I was thinking I’d get .008-.015 readings. Well assuming again that my setups are rigid, the worst wear I could find was .004” drop from the headstock area, and about 12” forward of that. This isn’t the whole bed ways area, but just the visible wear from the saddle. Parallelism I’m having trouble quantifying...like say from back of rear way to front of front way. But that doesn’t seem insurmountable. Once again, I don’t know what I’m talking about, so that statement is probably not useful.

2B2CDB12-7527-48ED-A608-5D60E822CD73.jpeg

6F491C2C-2915-4C9C-91E5-DD34F72A028D.jpeg
 
Your test setup is not ideal, it follows the low spots, tending to average them out. Still, that is not too bad of a reading. The real question is, what are you going to do with it? If you have to buy major parts to complete the lathe, it will be cheaper and much easier to just buy a lathe in decent condition.
 
Well I thought there must be something wrong with my test set up. Maybe setting up and carefully leveling the bed to a surface plate, and then sliding the indicator base on the granite with the indicator tip on the ways?

What will I do with it. Well I don’t know. Probably nothing, other than using it as a learning tool. I’ll keep my eye out for another basket case. They’re out there. This is the 54” bed, which would be handy maybe. But mainly this is about learning something. I’m open to whatever lessons come out of it. I’ve got a pretty tight grip on my wallet, so there won’t be any rush to buy all the parts back. Here’s a novel idea: I buy the castings, which sell for peanuts, and start working on making all the innards. I feel like I remember reading you can get part drawings from Clausing. Anyways that’d keep me busy for awhile. There’s a lot going on in that apron. I’m pretty sure there’s nothing in there that’s precision ground. How’s that for an exercise in futility? Lol
 
Think about the "sled" with the indicator measuring out in front of it. On any evenly curved surface, curved upward or downward, it will show zero deviation. On any dead straight and parallel surface, it will also show no deviation. On an unevenly worn surface, the needle will move up and down, but what exactly is it telling you? Which is going relatively up or down? The indicator or the sled? How do you keep track of the cumulative errors? A nice, perfectly flat cast iron straightedge can be compared with the ways to find the high and low spots. The right tool for the right job...
 
Well I thought there must be something wrong with my test set up. Maybe setting up and carefully leveling the bed to a surface plate, and then sliding the indicator base on the granite with the indicator tip on the ways?
...

Use a straightedge and feeler gauges to identify low spots. Lee Valley offers some reasonably priced straight edges in various lengths that will give you a fairly accurate test.

http://www.leevalley.com/en/wood/page.aspx?p=56676&cat=1,240,45313,56676

BTW, Lee Valley also sells Starrett straightedges. These are more spendy but made to higher tolerance.

http://www.leevalley.com/en/wood/page.aspx?p=71658&cat=1,43513,51657

Craig
 
So with a 123 block, and feeler gauges, there’s no spot in the entirety of the ways that will accept a .0015” feeler. I can imagine that using a straight edge spanning both ways could show a different result. So I will see about borrowing a precision level from work. Thank you gentlemen.
 
You can also check using a precision parallel or straight edge that is 12" long or longer and using a light behind. If an incandescent light is seen between the way and the straight edge, and is orange, you have a thou or more at that point. As the light becomes bluer, you have a smaller gap, and when it winks out entirely, you have less than 3 tenths. When it is orange, you can measure with a feeler gauge...
 
A 123 block is not long enough to test anything with feeler gages, If you find problems with it, you can probably see the problems without it.
 
So with a 123 block, and feeler gauges, there’s no spot in the entirety of the ways that will accept a .0015” feeler. I can imagine that using a straight edge spanning both ways could show a different result. So I will see about borrowing a precision level from work. Thank you gentlemen.
A precision level and a straightedge are not the same thing. Ideally, you want a quality straightedge that is as long (or longer) than the bed. Remove the tailstock, carriage and headstock. Normally, there will be virtually no wear under the headstock and very little at the far end of the ways where the tailstock normally sits. Thus the straightedge from one end to the other will help you find the areas of maximum wear. Normally a short distance in from of the chuck is the lowest but it depends how your machine was used. The outside edges of the bed guide the carriage and could also have wear. Same for the inside edges of the bed as they guide the tailstock. Even the undersides of the bed could have wear although you may want to just check for variations in thickness with a micrometer.

Craig
 
Well thanks guys. But we've already reached the point of financial sensitivity. If I need a precision straight edge longer than 54" to properly evaluate the machine, then I'm done evaluating. I'll do the micrometer checks to see what sort of variations in thickness the bearing points have, just for curiosity's sake, and put the headstock back on, find a nice lighted spot in the barn for it, and use it for making file handles. I'll save myself a hundred dollars if I make a hundred of them.

Honestly, I'm not sure I'm giving up yet. But I'm not buying a one time use item to find out if something I decided was junk a long time ago, actually is junk. lol
 
Back
Top