[How do I?] "map" The Errors On A Older Lathe?

jjtgrinder

JJTGRINDER
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I am at the point that I want to "MAP OUT" all the wear so I can determine where the problems are. I feel like that is the best first step. Then I can determine how to correct them, and so forth.

I have been "slogging" thru the "Machine Tool Reconditioning" by Connolly and the articles that Micheal Ward wrote in the "Home Shop Machinist" magazine. I am at a point that making measurements would be informative for determining the next action.

I read that there may be a method that allows using lasers to make the measurements.

True or rubbish? Any ideas or help would be greatly appreciated.
 
When I look at a machine tool such as a lathe, there are three areas i look at.
1) wear on the ways
2) mechanical things like the apron, headstoock and such,
3) Electrical

Wear on the ways.
How worn are the bed ways? With a little experience, you can make a determination of the degree of wear. Is it not too bad? Is it worn to the extent that it shows ridges and obvious areas that are worn? Compare the worn areas with that is not worn. And this is something that can be done without a need of an straight edge. Straight edge can be used later for fine tuning how much wear there actually is.
Next move to the cross slide ways. Again what degree of wear does it have. Is the cross slide loose in the middle and tight on the ends?

Once these things have been done then you can work on how to fix these things. OR not to fix them. Do you scrape and re-fit slides? or do you send it out and have the bed re-ground? If you have a decent Bridgeport size mill, some of the repairs can be done right there in your own shop.

This is just a start. It goes on and on.

BTW- I just bought a 14 x 40" Rockwell lathe just like the one in your avatar.
 
As Connelly pointed out many times in his tome, Machine Tool Reconditioning, you need to look carefully at the guiding ways of machines for the least worn areas to find the original surface planes and then scrape "straight down."

You will need a decent straightedge as long as the ways are to map out the wear properly, and a scraped precision straightedge(s) to scrape them. For instance, after looking carefully at the ways, use the unworn ways along the headstock and the relatively unworn ways at the tailstock end to reach an estimate of the original surface plane in those sections alone. Then lay the straightedge on the ways and check the gap all along the bed. Typically you will find the most wear near the chuck and in the first couple feet from the chuck toward the tailstock. The straightedge and feeler gauges can give you a good idea of the wear that exists. When you go to recondition them, please read and understand Connelly carefully and well. Starting with the wrong parts first and using poor choices of which ways to do first will cause much extra work, perhaps enough to scrap the lathe before it is done. Understand his methods. It makes sense when you truly understand what you are trying to achieve and how it relates to successive parts of the machine. Scraping is slow work at best, and you need all the help you can get. I am sorry, I know nothing about using lasers and do not trust me using the concept because of it. It is not rocket science, they could do fine work in the mid to late 1800's with the tools they had then, why not today?

Tell us about the machine...
 
Thank you for the replies. I am still trying to finish reading the book by Connelly. I thought I would begin trying to identify all the problem areas while I'm still reading the book.
My lathe is also a Rockwell Delta 14 x 40. Most of the wear is in the carriage ways near the chuck. The lathe cuts a taper when you chuck a round bar and make a light cut. The taper is smallest near the chuck.


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Maybe just live with it. Use the lathe as it is. Wear conditions can be foreseen and then planned around. Something broken or missing on the lathe, maybe not so and must be fixed. My lathe has a few tenth’s taper in it when turning round. I live with it. Most of the time it means nothing in my projects. If it does, then I know it’s coming and work it out. If this is your hobby lathe and not building stuff for NASA. Maybe just live with it…Good Luck, Dave
 
Understood, chips.


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When you say "it gets smaller at the chuck end" How much are talking about?

Typically with a worn bed, the taper is usually big at the chuck end and small toward the tailstock.
 
When you say "it gets smaller at the chuck end" How much are talking about?

Typically with a worn bed, the taper is usually big at the chuck end and small toward the tailstock.
Ken,
I would have to make a cut and make some measurements to give you solid figures. Do not remember the differences. Like .002 in 4" if I recall.
 
Ken,
I would have to make a cut and make some measurements to give you solid figures. Do not remember the differences. Like .002 in 4" if I recall.

If you are only getting that much in 4", that is pretty darn good in my book. My best lathe is lucky to get that in 2" on a good day!
 
if the ways on the bed of a Rockwell are worn, you can scrape in the carriage but the bed will need to be planed not scraped. Many of the Rockwell lathes have hardened ways and scraping is not practical for them. I have the 11 Rockwell, you can see pics of how I measured my ways by doing a search and you can see my king way tool, I also have been accumulating different indicators in the .0005 to the .0001 range. Someday I may actually have my lathe back together.
 
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