Scraping Question

Ya'll make some excellent points. I'll run it for another year or so and see how I feel then.

chips&more said:
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.
Click to expand...

Part of the problem is I design parts frequently at work that are spec'd within half a thou at 62 surface finish... Frustrating to get home and not be able to hold 2 thou!

ericc said:
Does it cut near the headstock? Or is it too loose?
Click to expand...

It cuts well near the headstock when I adjust the gibs for this area. If I move it farther out it becomes stiff and I worry I'm wearing out the feedscrew/gears excessively.
 
As far as scraping lathes go, the Atlas is probably one of the easier ones, given that it is flat bed. You will need a straightedge, preferable one longer than the bed, as you will need to scrape the bottom of the ways as well. One option is to watch Ebay, you will occasionaly see Atlas lathe beds on there for sale from people parting out lathes. It's kind of buying a pig in a poke, as you don't know if it will be worn out as well. Given that Atlas/Craftsman lathes were mostly purchsed by hobbyists who don't use a lathe like an industrial user would, I suspect you are much more likely to find a good lathe bed than a bad one, so the chance may be worth taking if you can find one close and for a low enough price. It does require patients, though, as it can take some time for the right deal to come up.
 
I've had Don's grinding service surface grind my mill table several years ago to remove all of the idiot marks. Cost me about $200 bucks. They may, may not touch a lathe bed, I don't know. Besides SG the top, both of the outside faces of the bed will have to be touched up too. They probably have the most wear of any of the surfaces. You might even ask around for a shop that has a fairly large CNC mill sitting idle. One that can handle around 60" x-travel. There's a lot of idle machinery in the Houston area right now, you should be able to get a bargain on machining! Be amaze how nice a job they can do on a nice CNC mill.
 
You would also need an inside 90 gauge, to keep the sides of the bed on the inside and outside of each flat way 90 degrees when scraping, there is a bearing surface under the flat as well, for the carriage, you have to measure everything and determine where the wear is, the top of the wide way or under, the outside bearing away from the operator is probably worn..... I own a 12 inch and have looked it over thinking about scraping it

Think about the tool pressure, and what forces it's causing, that's more than likely gonna be how the wear shows up
 
After using the lathe for a couple months I've been able to get a better feel for it and have mostly eliminated any of the ill effects the wear has caused, either through adjustment or locking gibs whenever possible.

I did contact several grinding shops in Houston, I either got no reply or no quotes. You think more places would be itching for work with oil the way it is right now...
 
Most of the old lathes were not ground, they were planed. While not cheap, if you get someone who knows how to get everything setup, it would make the lathe like new. Tim
 
Scraping old cast can be difficult even if she is a high quality casting.
I don't know why, but it seems to get more difficult with age. I'm referring to the metal, and not the discomfort your shoulders may experience after hours of scraping.
You might elect to have the bed "stress relieved" before scraping.
Additionally, some beds are "flame hardened". I don't know about Atlas.

Daryl
MN
 
I've heard of a guy scraping an atlas, they aren't hardened, pretty soft, they ding easily
 
I have recently acquired a South Bend 9c from eBay for truly crazy bargain price. Everything covered in clean oil, and it looks like it has been somewhat cared for - I mean, not abandoned rusty state like we see in some of those "before" pictures.
Even so, there has to be at least a clean-up, and checking out which bits might need fixing or replacing.
This leads to my questions..
Suppose there is enough wear to warrant re-grind, or scraping of the ways. This must surely mean that some parts in the apron would be affected.
Is it that the rack gear needs adjusting with shims?
What happens about the lead screw position? It can't really go anywhere, so what gets modified?
Is it that if any grinding/scraping is contemplated, it cannot be minor, being as it needs to remove at least the thickness of a shim (if that is what is used)?

I don't really know how a professional re-grind operation gets the new surfaces stay in line with the spindle, but I imagine the way is to line up with the unworn regions at the ends, where the original decorative flaking can still be seen.
 
If you know how much is taken off both the bed and the bottom of the saddle then depending on how the drive is (power cross feed or no?) then you could take that amount off the top of the apron and the lead screw should allign with the half nut. If you have power cross feed, then thing would get a bit more complicated, as raising the apron would effect gear meshing for the power cross feed. This will give you a bit to think about. Maybe a pro will come on here and let you know what they do in this situation. You might consider getting the book Machine Tool Reconditioning by Connelley, as it goes into a lot of detail on alignment.
 
You must log in or register to reply here.
Back
Top