Scraping Of Old Lathe Ways

[4GSR]

I think a lot of flaking is done for the sole intention of making a less than proper job look better, to pretty it up. Of course, some flaking is desired for oil retention, so I am certainly not saying that flaking is a scam, far from it...

Yes, it makes a worn bed way look good from a machinery dealer back in the days. When I say worn, some of the lathes I recall seeing were in the 18-36" swing variety, had anywhere from none to as much as .030". Yes, it wasn't a scam to say, but you had to pay attention to what you were deciding to buy. Most of them, you could tell they were worn and usually the dealer would say it had wear. Wouldn't tell you how much, you had to decide on that. Not to bring ethnic groups into the picture, the saying back then was most machine tool dealers were run by Jews. No offence to them, just a old saying I remember hearing from those around me back them. Ken

 

[Glenn Brooks]

Iam very curious about this. With modern cnc grinding technology able to hold less than .0005" flatness (in some cases I've been told grinding can hold .0003" consistently) along the ways and the mating surfaces of apron, cross slide and and tail stock, How is the way oil able to provide the necessary lubrication film necessary to mitigate wear? if the clearance is less than the molecular size of the oil film , the oil will be continually squeegeed off the surface by the passage of the closely fitting saddle...

Glenn

 

[Bob Korves]

Remember that we are talking about more than just the grinder when a lathe bed is ground. This is the same lathe bed that we bend and twist just by tweaking the feet a bit. The setup of the lathe bed in the grinder is critical to the final results, and there is no doubt lots more room for error there than in the grinder. A shop that grinds lathe beds on a regular basis and takes pride in their work will likely have all the kinks worked out for getting repeatable good results pretty much every time, regardless whether using a CNC or manual grinder. A guy who just bought a machine, old school and well worn CNC or clapped out manual machine, and just got it set up yesterday, and who never tried to grind a lathe bed before, might have some real issues, at least for a while. It is always the talented and interested machinist, working with machines and tools he knows, and carefully attending to all the details, who 'magically' always turns out good work, even when using worn out machines...

Hand scraped machine reconditioning has exactly the same issues, just different tools and techniques...

 

[samthedog]

I have attended a scraping course with Richard King and know the basics but it's a steep learning curve that requires a great deal of time to perfect. I have a Biax and all the hand tools but what I don't have is the time. People can wax lyrical about accuracy but the truth of the matter is that unless you are running a temperature controlled shop with headstock oil radiators, have your measuring tools calibrated annualy and have the machine levelled on a vibration isolated slab you won't notice a thousandth here or there.

I have a friend in Australia who does machining and welding and is the handiest guy I know and when asked to what accuracy he can make a part, he say, "accurate enough that a man on a galloping horse would approve it". He uses clapped out machines and turns out beautiful work. He would approve this article:

http://www.mermac.com/klunker2.html

Paul.

 

[4GSR]

Iam very curious about this. With modern cnc grinding technology able to hold less than .0005" flatness (in some cases I've been told grinding can hold .0003" consistently) along the ways and the mating surfaces of apron, cross slide and and tail stock, How is the way oil able to provide the necessary lubrication film necessary to mitigate wear? if the clearance is less than the molecular size of the oil film , the oil will be continually squeegeed off the surface by the passage of the closely fitting saddle...

Glenn

Glen,

With all of this technology available, you still have to scrape in the mating components for perfect alignment. But you run non-metallic materials against ground surfaces which have low anti-friction values that don't require as much lubrication as cast iron against cast iron requires. You also build in oil passages in these scraped in surfaces for lubrication. You do flaking on the internal, non-exposed, slide surfaces along with proper scraping to provide "pockets" for oil retention. Then last, cut oil grooves in the surfaces to get oil to these pockets. Lubrication is generally provided by some kind of pressurized system or a cycling system that provides lubricant in so many "cc" of oil per minute/hour.

For the home shop environment, this means basically the same thing, but re-thinking how to provide lubrication to these areas needing lubrication. If you want to spend a few dollars, probably close to $300, you can install a cycling system on a lathe or mill. Would it be worth it? Sure, only if you use the equipment daily and maintain it. These automatic systems will go thru a lot of oil in a days time if you are not careful in fine tuning the metering units as well as the lubrication unit itself. You can also install a hand operated unit, which I recommend, that allow you to decide when to give it a "shot" of lubricant. Last, you can install Gits style oil cups and fill with oil frequently.

You can put all the precision you want into a way system, but if you don't provide lubrication for it, it will be worn out in no time!

Ken

 

[Rustrp]

Not to bring ethnic groups into the picture, the saying back then was most machine tool dealers were run by Jews. No offence to them

But you did, and you did. If you think it might offend, and I'm not sure why your comment wouldn't, then simply put, don't say it. Your profile shows that you are a Staff Member and a Global Moderator, and I think the world expects more from those in a position to lead and direct.

This isn't a kneejerk reaction to your comment. I slept on it and still today no one has addressed it. Making bigoted stereotypical comments on a Hobby-Machinist site is inappropriate. Actually, it's inappropriate anywhere, and a disclaimer or apology in advance doesn't make it justifiable.

 

[samthedog]

But you did, and you did. If you think it might offend, and I'm not sure why your comment wouldn't, then simply put, don't say it. Your profile shows that you are a Staff Member and a Global Moderator, and I think the world expects more from those in a position to lead and direct.

This isn't a kneejerk reaction to your comment. I slept on it and still today no one has addressed it. Making bigoted stereotypical comments on a Hobby-Machinist site is inappropriate. Actually, it's inappropriate anywhere, and a disclaimer or apology in advance doesn't make it justifiable.

Meh, I have Jewish blood from both sides of the family and I take no offence. Ken was recalling what he was told, he didn't say he thought that himself, and even if he did, so what? Now.... who wants to buy my reconditioned Southbend? You can tell it's good because I flaked the bed

Things are only offensive if we choose to take offence.

 

[graham-xrf]

Hi Folks
This seems the right place to ask a newbie-type question about the "downstream consequences" of scraping the ways when restoring a lathe.

(In context - this would apply to South Bend(s) 9C and 9A, one each, both currently pretty much covered in oil and wrapped over in old sheets, stashed in anticipation of a future adventure with them).

Suppose one has taken the plunge into the whole business of stripdown, cleaning, measuring, and done a good job to end up with parallel ways with surfaces scraped to print OK on a reference straight edge. Include the saddle (carriage?) and all that goes with it.

In all this, metal was removed. Everything is (a bit) lower than it used to be! How does all this affect the connection to the leadscrew?
Is there ever work to be done within the apron to "shift things" to compensate for the metal removal?

I have been reading all the great threads, and looking at the pictures of the lovely restored machines, but so far, I have not seen any much explanation of what is done to put it together again, all aligned and mated together. The position of the SB leadscrew does not seem very "adjustable".

Is it perhaps that the amount of wear correction is generally too small to matter to the mechanism in the apron?