re-surfacing ways - grinding vs scraping vs $$

[Scottike]

OK, I just gotta ask -
Just how expensive would it be to have the ways and saddle on my 10x36 lathe reground? Would I need to have the headstock & tailstock done as well to realign everything?
Would a person be looking at scraping afterwards? Or would scraping alone get it there, presuming the condition of the ways isn't too bad.
I'm not looking to try and make a super precision machine, just bring it back to OEM.
I don't know that much about grinding or scraping, but I figure this is the one machine they'll have pry my fingers from when I go to that big machine shop in the sky.

[SGW]

I can't comment on cost, but I'm pretty sure you would need to re-fit the headstock, carriage, and tailstock after grinding the ways.

If the grinding shop knows its business, scraping may not be necessary. Scraping might be the easiest way to re-fit the headstock, carriage, and tailstock though.


Or, in theory at least you could forgo the grinding and do it all by scraping, but it would be a heck of a lot of work to scrape all the lathe ways to-form and parallel for 36 inches each.

[Mcgyver]

I've been quoted 200-300 per foot, so say a 1000 -1200 to grind that lathe. That's the grinding only, not everything that follows. There's some great content here and on PM explaining it in detail

I can't comment on cost, but I'm pretty sure you would need to re-fit the headstock, carriage, and tailstock after grinding the ways.

If the grinding shop knows its business, scraping may not be necessary. Scraping might be the easiest way to re-fit the headstock, carriage, and tailstock though.
.

generally they have to be scraped to the freshly ground bed. While each of the flat surfaces comprising the V's and flat will be flat, parallel etc to a high degree of accuracy, the angle of the V is not guaranteed to be the same neither is the height of the V's apex to the flat. On quality lathes, when made, they scrape these to the bed.

You also have to plan for the height change - leadscrew etc won't be in the same position to the apron. Or use moglice/turcite to raise the level.

Then there's the cross feed and compound.

Its a lot of work. As much work for a best of class lathe or the budget lathe. I'd give some consideration as to what lathe you want to do this to....the process is inherently accurate - its not like you grind/scrape a beater to a .001 and a 10ee to .0001"....this process will make a lathe like new (assuming gears and bearings were properly bathed in oil and are in good shape). but its only worth doing to certain lathes imo.

Otoh you can do the entire process by hand (no grinding)

[Scottike]

Thanks SGW,
At this point, I figure that even if it costs as much as a new, comparable, import lathe, it's still worth the cost to rebuild what I've got - as long as the castings are solid, all else can be rebuilt.

Good input there Mcgyver,
I was trying to think through what all would be affected, leadscrew and rack would be about it. no problem with the qc gearbox, enough adjustment there. And of course the cs and cf would need work too.
Your right about a lot of work, but like you say, it would be a new machine when done.
Is a Rockwell 10" worth it? It's no beater, and can still hold a tolerance, but she's starting to show her age. It's time to start thinking abut a plan.

[lazlo]

A bunch of guys on PM have had their lathe beds ground at Commerce grinding in Dallas. It runs around $1,000 for 36 - 40" ways. They charge around $100/hour including setup. The setup being the majority of the cost.

Yes, you'll have to Turcite and scrape the saddle to match, or the halfnuts won't line up.

[lazlo]

Otoh you can do the entire process by hand (no grinding)

Well, not if they're hardened ways, which most industrial lathes are.

Harry Beckley is the only person I've ever seen attempt to scrape hardened ways, and he used a Biax with carbide blades. I asked Rich King about that, and he was amazed that someone would subject themselves to that punishment

[Scottike]

No, they're not hardened ways, if they were, I probably wouldn't be having to ask about this now, but then again, it makes the work easier that they're not. guess that's a double edged sword?
edit: Lazlo, If I adjust the height of the leadscrew and rack, wouldn't the saddle & apron be fine then? Even though they were scraped /reground?

[lazlo]

Lazlo, If I adjust the height of the leadscrew and rack, wouldn't the saddle & apron be fine then? Even though they were scraped /reground?

But then you'd have to relocate the gearbox too?
Most people just glue-in a piece of Turcite (Rulon, Garlock) that's roughly the same thickness as was ground off the bed. That keeps everything else in alignment.

We glued and scraped a faux Turcite way in Rich King's class, and it was a lot easier than I expected.

[rkepler]

No, they're not hardened ways, if they were, I probably wouldn't be having to ask about this now, but then again, it makes the work easier that they're not. guess that's a double edged sword?

Even hardened ways wear. My 10EE had something like .007" on the bed and .012" on the leading edge of the saddle.

edit: Lazlo, If I adjust the height of the leadscrew and rack, wouldn't the saddle & apron be fine then? Even though they were scraped /reground?

Since you have to scrape the saddle back in anyway and put something in for that it's less work to simply build it back up to the original height than to scrape it in at the lower height and then adjust the gearbox, apron and mounting points at the tail end to the new saddle height. Using Turcite or Moglice lets you put things back and with a better way material (assuming that your lathe has a decent lubrication system that will maintain it).

[Scottike]

The gearbox mounts to the support for leadscrew, so adjusting the height of the leadscrew would also raise/lower the gearbox. Backlash between the gearbox and fwd/rev tumbler is adjusted by rotating the box on the mounting boss, and the fwd/rev tumbler can be adjusted to control the backlash between it and the spindle gear. Of course that all goes out the window if too much meat is removed from the ways headstock etc.
edit: It's beginning to sound like a plan a,b, & c better be ready.