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The Eddgwick arrived!

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awemawson:
Steve, if the bed is a double inverted V, often there are relatively unworn ways - usually a flat and a V - that the tailstock bears on - these can at a push be used to grind the worn ways.

If you look at the first picture Matthew posted in this thread, where some reamers are laying across the bed, you can see the two pairs of 'V and flat' - one for the carriage which will be the worn pair, and one for the tailstock that should barely be touched.

Turcite is mainly used to build up under the carriage and / or cross slide, to bring them back up to original height so that shafts and lead screws still keep their original relationships. Although some machines do have ways entirely made of Turcite it's not usual to do this as a repair.

mattinker:
Steve,

Thank you for your thoughts and the http://www.eztram.com/helpfulhints_results.asp?Hints_ID=13 I don't think your being defeatist, I think it's important to know how to go about compensating.
 I haven't actually tried the lathe yet so I don't know what I'm up against. The wear is visible without even touching, which is why I'm a bit apprehensive! There are unworn machined surfaces along the sides and the top of the bed that would make good guide surfaces for a grinding carriage. The "moglice" option I think is out for me because of the length of the bed, I may be able to use it on the cross slide, but I'm not sure that I'll need to.

I'm in the thought phase, I suspect that it would be a huge scraping task, I have to admit, I like the idea of making a grinding carriage we'll see about the reality!

I see Andrew has answered while I was typing. The rear "V" way looks to be in much better shape than the front. There are also the sides and the two places on the top that look good like nicely machined faces. Once I've got the carriage back together I'll know more!

Regards, Matthew 

 

vtsteam:
So for a DIY grinding jig you could maybe use the tailstock (if beefy enough) as a sort of mount for a grinder. The tailstock would have to be fastened down to allow sliding without vertical play (depends on the fixing method).

I don't know how the headstock is attached to the bed. On a smaller lathe like the ones I own the headstock rides on top of the ways, though bolted down. If removed (and removable) the ways could conceivably be ground throughout, and the headstock scraped to lower to equal the removed material of the ways, bringing it into proper height with the tailstock.

If not removable, I guess the Turcite would be needed on the tailstock. Or maybe if the tialstock has a removable shoe (as mine does on the Craftsman and new lathe)  a new shoe could be cast thicker to compensate. I do wonder about the carriage -- how important is it that it remain the same height if the ways are scraped? I do think the vees for the tialstock would need to clear in it, but that isn't bearing fit, just a clearance fit and so probably fairly easy to do.

vtsteam:
Actually, re. above, if the headstock set on the ways and was removable, whether it needed to be scraped to equal the drop in the ways would depend on what it bears. The tailstock part of the ways would remain at original height. The carriage portion would be the lowered part.

Likewise the tailstock might not need Turciting/shoe thickening, and maybe the opposite - scraping. It all depends on whether the headstock center height moves down with the grinding process or remains where it is in relation to the tailstock (and how it moves after the operation). Complicated to describe in words, but probably quick to see on the actual lathe.

hanermo:
I believe several peeople have successfully ground lathe beds with all sorts of cartridges and carriages, from a router motor onwards.
Several threads, even video on youtube.

The only question is what is your reference plane, and how do you effect movement.

I, myself, would use linear rails, and a temporary carriage mounted on them.
I import and sell linear rails, so I have them in stock - this does have an effect.

I originally made a temp carriage to grind the ways on my very large shop built cnc mill.
It ran on a large glass table, and the grinder was a std double end grinder from the home store.
Worked fine.

This time, I have just fit the linear rails to large tool steel flats directly as first step.
The flats are first smoothed with a large belt sander.

And no, it wont dig in, because the flats are very large in comparison to material removal rate of a sander.
Even using a top end industrial hand sander (Festo, 1400 W), 50 mm tool steel flats, 2.4 m long, 20 mm thick.
45 grit belts.
35 mm linear guides bolted onto the 50 mm wide flats. The edges got rounded a bit, by 1-2 mm. Doesnt matter at all, as the edges are not used.
The assy runs smoothly, and one end of back side has a bit of twist.
This is very clearly felt by moving the back carriage by hand as it gets stiff.
I will qualify the error a bit with a few DTIs, and then later smooth or shim the underlying part as needed.

Moral of story:
Its doable, and not all that hard.

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