Scraping Question

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benster

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I recently acquired an Atlas 10 with a 54" bed. It has wear along the first foot or so of the ways. In order to scrape the whole bed back together would I require a straightedge that's around 54" long? Would a surface plate that long work if I scraped both sides in simultaneously?

Just pondering how I would go about doing it. This would be something to work up to as I don't have much scraping experience and the couple of grinding shops I've contacted haven't gotten back to me about surface grinding the bed.
 
unless you know how to scrape i would not attempt it. Have it ground
 
It is possible to scrape in a surface with a straightedge or surface plate shorter than the surface. That said, t'aint easy. That is for advanced scrapers with lots of experience. It is not at all for someone just starting out in scraping. Even just scraping in a lathe with all the correct tools and a mentor is a major project and difficult work for a beginner, and a patient mindset is required as well. Scraping with a shorter reference surface than the work surface requires careful observation and understanding in interpreting the patterns. It would not be done in two sections, but rather in overlapping
sections.

How much wear is present in the ways?

Edit: The reference surface should actually be somewhat longer than the ways to be correct, so the work will have full contact while sliding against the reference surface.
 
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Get a big plate, verify flatness somehow, then scrape.
 
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Kernbigo said:
unless you know how to scrape i would not attempt it have it ground
Click to expand...

Why would you not have it ground?

Bob Korves said:
It is possible to scrape in a surface with a straightedge or surface plate shorter than the surface. That said, t'aint easy. That is for advanced scrapers with lots of experience. It is not at all for someone just starting out in scraping. Even just scraping in a lathe with all the correct tools and a mentor is a major project and difficult work for a beginner, and a patient mindset is required as well. Scraping with a shorter reference surface than the work surface requires careful observation and understanding in interpreting the patterns. It would not be done in two sections, but rather in overlapping
sections.

How much wear is present in the ways?

Edit: The reference surface should actually be somewhat longer than the ways to be correct, so the work will have full contact while sliding against the reference surface.
Click to expand...

There's several scratches and knicks present as expected in a 50 year old lathe, mostly along the first foot. I haven't measured the wear but when I adjust the carriage to slide smoothly near the spindle its tight about a foot away.

I'll take a look at that book, looks like it'll answer a lot of questions.
 
I use to have a atlas 54"and i don't think that is you problem. First stone or file the nicks, get rid of them. You have a hold down plate in the back side of your cross slide, adjust the bolts in the section the is tight, and i believe if i remember write there is also a flat gib there, adjust that also. I have scraped for 25 years and think for sure if you attempt that it will be a dis tater, more than likely it don't need it.
 
benster said:
Why would you not have it ground?



There's several scratches and knicks present as expected in a 50 year old lathe, mostly along the first foot. I haven't measured the wear but when I adjust the carriage to slide smoothly near the spindle its tight about a foot away.

I'll take a look at that book, looks like it'll answer a lot of questions.
Click to expand...
If you read Kernbigo's quote carefully he was recommending you have it ground, just left out some punctuation. That requires a complete teardown, transportation both ways, and is pricey.

Lathes can have quite a bit of wear without affecting the accuracy substantially, and the wear can also be compensated for. You can stone off the high parts of the dings and scratches, and the low parts do not hurt anything. I do understand pride of ownership, but another way of looking at it is honest wear from decades of use -- provenance and patina. In the end it is your lathe and you should do with it what makes you happy.
 
If you are making parts for NASA, then get a +$30K lathe. If not, then I would enjoy just having a lathe and living with its little quirks. The challenge is in you, not the lathe, to make good parts with what you have. It can be done. Many many folks on the HM are making excellent quality items on old and tired machines. A lot of it is in the skill and finesse of the operator.
 
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