Subject: Re: Machine Tool Reconditioning

From: [email-masked] (Orest I Koroluk)
Date: Fri, 26 Jan 1996 14:10:26 -0500

In article <[email-masked]>, [email-masked]
(Roger Mawby) wrote:

>  Anyway, I am interested in re-building the lathe and intend to
> re-scrape the ways using the methods set out in the book "Machine Tool
> Reconditioning".
> I assume it to be the same book referred to in these articles (mine is
> authored by Edward F.Connelly).
> I have quite severe wear on the rear inverted V-way around the middle
> of the bed, in the region where the saddle spends most of its time!. 
> Have you reconditioned any lathe ways yourself ? and/or what do you
> believe would be a practical amount to scrape off in preference to say
> having the slideways ground? . I have made some measurements and
> believe I would need to take the ways down at least 0.020" - Is this a
> practical to scrape this amount ? 
> 
>                                         Roger

IMHO (OK, not really that humble) 0.020" is a tremendous amount to remove
by scraping, especially as it has to be done over the remainder of the bed
that is not worn. Although I have not scraped any machine tools I have
tried the technique on some odd pieces of cast iron to test the waters. I
have made three granite surface plates by generating them from first
principles and can tell you that I was glad that they were pretty flat to
start with. At first progress comes quickly, but nothing teaches you
patience like lapping 60 lb chunks of granite together, for hours and
hours.

To get a good start I would look at getting the bed planed or milled
first, then fine tune it by scraping.

Orest

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From: [email-masked] (Paolo Zini)
Date: 26 Jan 1996 10:27:02 GMT

In article <[email-masked]>, [email-masked] (Jonathan M. Elson) says:
>
>Roger Mawby ([email-masked]) wrote:
>: [email-masked] (Jonathan M. Elson) wrote:

I am restoring one Myford lathe, severely worn, I have posted several
question in this newsgroup and I have received a lot of usefull info and
suggestion. 
Between all I have found the book (In England) and spare parts from Myford tanks to the
help from the newsgroup.
Tank to all.
I write again on this subject because I am working on the late and I am
interested on all the problems.

>
>: >I just got my copy.  It only took about 2 weeks!  The book is well worth it
><snip>
>
.......SNIP......
>
>Yes, that is the author.  It is the 19th printing of the 1955 issue,
>although someone inserted two cartoons from 1967 or so at the end of
>two chapters.
>
>: I have quite severe wear on the rear inverted V-way around the middle

REAR? strange! I have not observed this in my first replay...
In my Myford the FRONT way was severely worn, not the rear.

>: of the bed, in the region where the saddle spends most of its time!. 
>: Have you reconditioned any lathe ways yourself ? and/or what do you
>: believe would be a practical amount to scrape off in preference to say
>: having the slideways ground? . I have made some measurements and
>: believe I would need to take the ways down at least 0.020" - Is this a
>: practical to scrape this amount ? 
>
>No, you'd die of old age before you got rid of 20 thousandths!  A new

I have removed at least 0.01 from the side of the bed ways and 0.02" from the 
saddle and I survived.....

>bed is designed to be scraped .001 to .003, according to Mr. Connelly.
>He does mention scraping as much as .015 to correct wear and errors, but
>this is with power scraping machines.  The bad news is, he says NEVER grind
>the bed!  After grinding, you get a glazed surface that is IMPOSSIBLE to
>scrape!  Hmm, that is pretty interesting - I SURE didn't know that.

The book says hard to scrape the first time, says that a ground surface do not
retain oil, not impossible...

>So, the best advice is to find a large horizontal mill, and have the ways
>milled.  I think there might be some way to use fixtures and a dremel-type
>hand grinder with cylindrical carbide cutters (rotary files) to use the
>good part of the bed as a guide to cutting down the high parts.  Peruse

This seems to me really dangerous... The scraper work is checked at each pass
this can be checked only at the end.

>the book and see if you get any ideas.  But perhaps a long guide which
>slides down an unworn facet of the top of the bed (or maybe the bottom)

If the lathe is worn, where you find a unworn FLAT scraped surface? The
factory do not scrape FLAT useless surfaces.

>and carries the dremel or air-powered die grinder could be used to accurately
>remove the high parts.  Your .020" seems incredible!  Was someone using a
>tool-post grinder daily on this lathe for years?  I have a 10" Atlas, a

This is the true point .020" (about 0.5 mm if I am right) is not incredible
(I have seen one lathe, still working, worn for 1 mm) but is really impressive.
Check the saddle, may be that, due to the wear, it sit down on the wrong place;
I have seen also this on my Myford.

>cheap lathe with just a flat bed (no Vees), built in the early 1940's,
>used plenty, and I just miked the bed (from the bottom guide surface to
>the top) and it varied .001" at most from the center to either end!
>That to me indicates .001" wear in the worst spot!  I was actually amazed!
>I believe the front-back wear is less.  As best as I can tell, this lathe was
>NEVER scraped at the factory, just ground on a special bed grinder and left
>that way.

I have done the same on Myford, and I have obtained one final error of the top
surface of ways of about 0.02 mm ( about 0.001" ).....

>One advantage of a well designed Vee-way bed lathe is that the Vees are
>supposed to wear approximately evenly, so that the front-back position of
>the carriage (the most important) does not vary.  An up/down error is much
>less important, because the sine of small angles is very close to 0.
>If the vees are worn so badly that the carriage sets down on the flat parts

If the bed is worn the carriage V-ways are worn of a larger amount, this is the
first place to check.

>of the bed, however, then there is no simple fix.  The bed or carriage needs
>repair.  relieving the place on the carriage that touches flat on the bed is
>the first step.

There is a dirty trick: scrape the V ways of the carriage rougly flat, cut two
strip  of brass, silver  solder the strip under the V-ways of the carriage and scrape
and scrape the bras flat...... IS REALLY A DIRTY TRICK
>
>Anyway, the book tells how to measure these errors with simple tools 
>(although some of those precision levels and straight edges are quite
>expensive).  If you want to get down to details, I have never done scraping
>before, either, but I HAVE done a great deal of simpler maintenance on my
>poor, abused Atlas.  (That abuse was BEFORE I got it.)  But I would certainly
>be glad to discuss methods in the book, and how you might accomplish them
>with somewhat less fancy tools than Mr. Connelly assumes you have.

I have been forced to build the straight edge from scratch.....
The difference is the tool, i started using one scraper built from a file and the
work was slow and hard, finally I have invested 60 $$$$$ on one carbide blade scraper
and it makes the difference.

>                                                Jon

Paolo

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From: wayne weedon <[email-masked]>
Date: Sun, 28 Jan 96 17:11:39 GMT

In article <[email-masked]>
           [email-masked] "Roger Mawby" writes:

> I am a UK Model Engineer currently building a 3 1/2" (Scale 3/4" to
> 1ft) 0-6-0 tank engine on a faily worn out Boxford lathe, which I
> believe is very similar to a Southbend.

 I don't know where you are, but if you are in the South you might like to
consider Machine Tool Services in Poole.  They specialise remachining
machine tools from the smallest lathe to full size industrial units.

 A friend has just had his Brigdeport turret mill reground and hand scraped
and it was a very nice job.

                        Wayne...

-- 
wayne weedon

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From: [email-masked] (Jonathan M. Elson)
Date: 29 Jan 1996 06:28:36 GMT

wayne weedon ([email-masked]) wrote:
: In article <[email-masked]>
:            [email-masked] "Roger Mawby" writes:

:  I don't know where you are, but if you are in the South you might like to
: consider Machine Tool Services in Poole.  They specialise remachining
: machine tools from the smallest lathe to full size industrial units.

:  A friend has just had his Brigdeport turret mill reground and hand scraped
: and it was a very nice job.

Gee, I'd like to know what they charged for regrinding and scraping that
Bridgeport.  I've got one, too, and although it really seems to be fine, it
would give me a data point on what this kind of work costs.  Actually,
doing an Atlas lathe is a much smaller job, partly because the main ways
are all right angles, no Vees.