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View Full Version : re-surfacing ways - grinding vs scraping vs $$



Scottike
08-21-2011, 01:39 PM
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
08-21-2011, 02:05 PM
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
08-21-2011, 02:17 PM
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
08-21-2011, 02:21 PM
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
08-21-2011, 02:25 PM
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
08-21-2011, 02:29 PM
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
08-21-2011, 03:05 PM
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
08-21-2011, 03:32 PM
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
08-21-2011, 03:33 PM
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
08-21-2011, 04:03 PM
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.

Robin R
08-21-2011, 04:30 PM
I would think it makes a big difference to the viability of the project where the nearest machine rebuilder is, shipping the lathe to Texas would increase the cost considerably. If you could find an outfit within reasonable driving distance, you could save a lot of cash and have the opportunity to watch the process.

Something else worth considering, would be to attend a scraping class like the one lazlo went to. It would make it much easier for you to accurately asses the real condition of your lathe and might even give you enough skills to do the scraping part of the rebuild yourself.

lynnl
08-21-2011, 04:49 PM
Just as a ballpark guess, how much wear should one estimate as having taken place, when the original frosting/scraping marks just barely cease to be visible?

beckley23
08-21-2011, 04:54 PM
Lazlo-Had time on my hands and didn't need the machine, why spend the money?

Anyway, here's one of the lathes they're talking about.
http://www.practicalmachinist.com/vb/monarch-lathes/wreck-update-146913/
Harry

Scottike
08-21-2011, 04:57 PM
Yes Robin, I agree, I think a scraping class would have to be in order for me before I would begin a project like this. And a lot of practice on other smaller projects first.

DFMiller
08-21-2011, 07:34 PM
Scott,
Have you done a survey on the machine to assess how bad it is?
This is described in Connelly's book, Machine Tool Reconditionin
http://www.machinetoolpublications.com/

There is no doubt that Forrest has a better version in his head and its a pleasure to hear him recite his wisdom in person.
I had the pleasure of attending his scraping course last year. It was in Seattle. With any luck he will run another course soon.

Sounds like an interesting project.
Dave

Scottike
08-21-2011, 09:58 PM
Beckley23, You do amazing work! I just read a goodly portion of the thread you suggested,( I had to stop, but intend to coninue later) and my hat is off to you. You displayed lot of patience, fortitude, and perserverence in addition to skill with that Monarch. I look forward to reading it through to the end and seeing the finished product of your labors.
I am finding it to be a goldmine of information for scraping and rebuilding a lathe.
DFMiller - I've only done a very cursery check on the front V way and found .0035 difference on the back side and .002 on the front measured from just in front of the ts to just behind the saddle, with the saddle moved as close to the hs as I could get it and the chuck removed.
so more investigation is needed, but that will have to wait 'till I can clear the decks a little bit.
Added Connelly's book to my reading list.
Any a class or lecture by Forrest would definitely be well worth attending.

EVguru
08-22-2011, 05:29 AM
I had a 48" by 12" mill reground here in the UK.

Top of the knee, saddle and table.

Including Turciting (actually Rulon) and scraping back to alignment, the cost was 700 (about US$1150).

J Tiers
08-22-2011, 09:30 AM
I'm not entirely sure I would bother for 0.002 to 0.0035 wear.

Unless the lever arm is causing the tool to move a lot due to a varying difference between front and back ways, your total error is going to be small.

Your choice, of course, but most folks are on board with re-grinding when the wear is more like 0.020, not 0.002.

Scottike
08-22-2011, 11:52 AM
J Tiers, I agree that the amount of wear does not appear to be a great amount, but that was only a cursury examination of just one v way from right to left. I feel that it's enough to warrant a closer, more detailed exam of all the ways, with the level checked and saddle removed, if for no other reason than to be able to keep an eye on it down the road.
As I said earlier, the lathe can still hold a tolerance, it's just beginning to show it's age a bit. I hate it when things come up behind me and bite me in the butt!
Currently I'm going through the gearbox and replacing some bushings, a couple of worn gears and shafts and generally bringing it back up to snuff. When that's done the apron and Reeves drive will be next, I'll be taking a closer look at all of the ways at that time, unless I get hung up waiting on parts.
I guess that's what started this whole thing - the amount wear I found in the gearbox is making me wonder about everything else.

Mark Hockett
08-22-2011, 04:44 PM
Scottike
If you do decide to rebuild the lathe you are fairly close to a very good machine tool re-builder that can handle the bed resurface. The company is Lindmark Machine Works in Seattle,
http://www.lindmarkmachineworks.com/id28.htm

Scottike
08-22-2011, 05:52 PM
Thanks Mark - Added them to my favorites list. It's nice to know there's a place close by with those capabilities. I wasn't sure what kind of resources we had around here for that kind of work.
edit: That's some nice looking work on your site.