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Lathe Bed Re-grinding

santal8

Plastic
Joined
Jun 17, 2008
Location
Terre Haute, In.
As a new member to this forum, I would like to tap into the vast experience of others by asking about lathe bed re-grinding. I will be undertaking my next lathe restoration project soon. It is a 13" South Bend with a 5 foot flame hardened bed manufactured in 1971. Although the condition of the machine is what I will call very good, there is water or moisture related damage on the bed near the headstock, specifically some pitting from rust. I am considering having the bed ground. It appears to me that .005-.010 of material removed would result in a very clean bed. I am asking for recommendations for reliable companies in the midwest that do such work. Also, I am not well informed as to the cost of such work. Any ideas what kind of money this involves? I am in Terre Haute, Indiana Thanks in advance for any advice! Mark
 
I'll be interested to hear the responses too, but based on what I've been told your looking at quite a bit of cash to get the job done. Some of the 10EE guys had their beds reground and I believe there was a place down in Texas (?) that charged 700 bucks to grind the bed. (You had to pay for transportation) But apparently that was the cheapest place anywhere near the midwest and someone was recently quoted 1200 bucks to get it done.

Just use some red scotch bright and shine on the ways a bit. Call any remaining pits "oil retention areas" :D :D
 
Mark,

If the pitting is not raised and mainly cosmetic, I would live with it. A flame-hardened bed likely does not have appreciable wear unless it was used very hard.

Having a bed re-ground will not only diminish the hardened quality of the bed material, it will also cost in the neighborhood of $2000+ for many machines - probably yours too.

If the pitting is a bit raised, consider scraping it or dressing it with a stone, then living with the pitting.

I can't recommend any specific place in your area, but give this serious consideration before dropping $2000+ into a $1500 lathe.
 
Mark,

What are you going to use the lathe for- hobby or business use?

If for business, where the accuracy of your lathe will make money, maybe its worth having the bed ground. If its for your hobby, unless its going to be a museum piece, I would spend the money.

If the machine cuts accurately- even if you use it for a professional machine shop, its not necessary. If you want a museum piece, look for a lathe that has no pitting.

Its like engineering- don't over tolerance the drawings unless you really need it. Over tolerancing makes the parts more expensive and more difficult to make.
 
Its the "Flame Hardened" part that makes it expensive. I had my 9" re-cut on a planer for $500, and a friend of mine had the same company do his 16" SB for $700. But a planer won't do the job on a hardened bed. You are doing the right thing by researching, I found huge price differences between different shops, some were as low as $1000 for grinding some as high a $5000.

To add to the pot a bit more, my lathe had about .010 wear on the ways, but the bed had bowed over the years so even after they had monted the bed as best they could it still took .020" to clean up my ways. They were correct in the work they did, and my lathe all leveld out on its bench does some really fantastic work. So be prepared to have to shim components more than you think. You will have to shim your leadscrew down to realign it with your saddle. Also the Rack gear will need to be shimmed down for proper gear lash. You may want to consider having the same shop the does your bed machine your saddle as well. There is always more wear in the saddle than the bed. I don't know if the saddle is hardened on your lathe, mabey some one else here could comment on that. I did my saddle work myself, its not all that difficult just very time consuming (and exhausting).


I will say this, when its all said and done you will be very glad you did it. A lathe like yours with a reground bed will probably outlast your grandchildren.
 
I think I need to get over my desire for the "museum piece" outcome...When a machine turns out too nice, a guy is afraid to use it....the first scratch hurts the most.....Thanks for the reply!
 
I recently asked Leblond what the cost to regrind ways is. Here's their response:

Ryan,

The estimate price to completely rebuild your 13"X6' South Bend lathe is
$14,000 to $16,000. We do not offer a service just to regrind ways, etc.

The work would be done at LeBlond's rebuild facility which is out of state;
i.e. not in Amelia, Ohio.

Regards,
DeWitt W. Engle
Manager
LeBLOND LTD
3976 Bach Buxton Road
Amelia, Ohio 45102

I thought that was interesting.

Ryan
 
I have purchased SBL repair parts from LeBlond and I am glad South Bend lathes are popular to the extent that repair parts and service are still available, thier service was very good BUT.......I believe that price range is a little out of my reach (understatment). Thanks for sharing that information!
 
Channelling Mr. Rodgers

The estimate price to completely rebuild your 13"X6' South Bend lathe is
$14,000 to $16,000. We do not offer a service just to regrind ways, etc.


Can you say "thieving b******s?" I'll bet you can!
 
I don't know how deep the flame hardening goes on SB beds, but on Monarch beds it's about 1/8", and I would the SB would be comparable; I think you would be safe getting the bed ground with the hardness remaining intact, the price is the decision point.
Commerce Grinding in Dallas quoted me 2000.00 to grind my EE bed which is slightly smaller than the 13" SB bed, Schmeide Grinding in Tulahoma TN was also at 2000.00. The 700.00 price from Commerce, mentioned above, was from a few years ago, the 2000 was from last November. My impression is that it may it may depend on who you talk to at Commerce about the price.
If you are set up for scraping, it is a long, labor intensive job, and yes a hardened bed can be scraped. See the following for what's involved;
http://www.practicalmachinist.com/vb/showthread.php?t=146913
With regard to dropping the gear rack, gear box, etc after grinding, there are a few fillers that can be epoxied, cast, etc, to build up the carriage to original height and eliminate the need for relocations of the aforementioned components. I will eventually get to that point.
Harry
 
In 1993 we rebuilt 6 heavy 10" South Bend lathes, vintage 1957 with soft beds. All were sent to a company in Detroit, Mi. for the bed grinding work which was $600 per bed. Each bed had wear and some dings but nothing excessive. We opted for machining the underside of the saddle when re-assembly took place. As I understand this, there are 2 chioces for fitting machines back together after grinding: 1. shim down gearbox and leadscrew support. 2. machine the underside of the saddle allowing the apron to be higher in the amount ground off the bed. Option 2 carries the risk of the gear on the apron (power cross feed) being engaged too far with the gear (pinnion) on the cross feed screw in the saddle. I remember having that problem on a couple of the 6 we rebuilt. The fix we decided on for that problem (although maybe slightly incorrect) was to remove the spur gear from the apron and using the appropriate gear cutter, machine each tooth deeper. If I remember correctly, this amounted to cutting each tooth about .005 deeper and reducing the outside diameter of the gear as well. I know, this changes each tooth profile but allowed mesh without binding. We did not build up the saddle surfaces with Turcite.....The 6 machines are in a college metals laboratory and although this may be inconsistent with how a "super precise rebuilder" would do things, we felt a good bit of accuracy was restored to these machines and the useful life was extended.....they are still in service by the way.....Thanks again for the helpful feedback!
 
A soft-bed lathe and a hardened-bed lathe are as similar as a grapefruit and a jack hammer.

A hardened lathe bed shouldn't be considered for regrind unless the rust holes are big enough to drop a screw driver through them. Small rust pockets will not affect the accuracy of the machine at all. If there are whiskers projecting above the normal surface, they can be removed without stoning, which could damage the hardened surface.

All of the wear on a hardened lathe is on the bottom of the saddle, and it may be considerable. This is where you should direct your attention. But even saddle wear will seldom affect the accuracy, unless it's so bad that the saddle is unstable.

If you look at the geometry of the system, you'll see that the bed provides a flat reference surface. The saddle supports a single point (the tool) at a particular location relative to that surface. Even if you inclined the saddle at 45 degrees, you wouldn't impair the machine accuracy as long as the saddle position remains unchanged relative to the bed over the full length of travel.

- Leigh
 
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Hard beds wear, take my word for it. If the lubrication is maintained the wear is greatly reduced, my 66 year old 16" lathe is a testament to that, but my 66 year old 12" lathe needed a complete reconditioning job due to lack of lubrication, and they both have hard beds.
Harry
 
I take it you've never closely observed a Hardinge stick bed. (HLV-, -H, HC) Many of them even have plastic under the saddle. The saddles barely wear, but the hardened beds sure do.
My comments are based on working with a machine tool rebuilder for the past twelve years.

You can find exceptions to any statement if you look hard enough. That does not invalidate the statement. It just proves you have nothing better to do with your time.

As to plastic-coated saddles not wearing but wearing the hardened ways below, perhaps your universe follows different laws of physics than ours.

- Leigh
 
Leigh, it is not a physics problem, merely a mechanical one. The "universe" is full of examples of soft materials embedding grit & eroding harder ones. Lathes, often.

Quote: "As to plastic-coated saddles not wearing but wearing the hardened ways below,..."

I would never do it and argued against it, but Mr. Paul Babin who apparently is a recoginized and prolific Hardinge rebuilder claims on another post that it is possible to reuse a saddle after having the worn bed ground, without stripping the factory plastic, as long as the adhesive is not compromised. http://www.practicalmachinist.com/vb/showthread.php?t=159382

What machine tool builder in MD? What part of MD? Define "working with".

Thanks!
smt
 
I don't have to look very hard to find worn hardened lathe beds, they aren't the exception, especially if the lathe has seen any kind of use. My friend bought new lathes for his shop, and every one had a hardened bed, in 10 years they all showed signs of wear, some of them significant.
You can slow the wear factor down with good lubrication practices, but you're not going to stop it.
The 2 lathes I cited above are Monarchs; the 16"CY has about a .004" drop on the outer ways, and in 18 years of using it I've never had a problem holding tight tolerances, the 12"CK was the subject in the article "Reconditioning a Lathe- Revisited" in HSM starting in Sep/Oct '04. The main difference in the condition of the 2 machines was the condition of the apron oil pumps. The CY's was, and still is, working; the CK's self destructed about 30 years ago through lack of maintenance, and nobody paid any attention.
Harry
 








 
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