Shim stock is great for estimating the amount of wear when you are inspecting the machine and trying to get your game plan together. The problem with trying to use it to build up a worn surface, is that the surfaces didn't wear evenly.
Of course not. On the machines in question, the wear on the softer CI of the underside of the saddle is several times as severe as that on the ways.
And that is the general case. In the "real world" it is less on a 12 X 20 10EE because the saddle and its "wings" are actually a skosh longer than the 20" worth of traverse.
Look at a(ny) longer-bed lathe.. the ways are far longer than even a wide carriege. That unfavorable ratio puts more wear onto the carriage underide even IF it was as hard as the ways. And it
is not.
Worse? Look at an El Cheapo Asian hobby-grade lathe such as a "Precision Matthews" that is trying to maximize traverse within an overall length and keep the weight down..AND has its HS, TS, and toolpost "jacked up" in the sand. Their carriages are very SHORT or "narrow". The lesser bearing surface, lesser "lever arm" narrow carriages want to "tip" left or right far more as they work under load. So their "rocking horse" curve of wear gets "worser sooner". Very VERY "sooner" if ever they were to attempt "industrial grade" working.
If you pin or glue shim stock to these curved surfaces you now have regained the lost height, but the fit still sucks.
Surely it would. IF you just laid a single thickness flat to the curve as worn, yes.
Just don't do that. You do not have to.
One can "shim the shim" in steps. The "center" is meant to not bear the same in any case. Scraperater folk relieve it a skosh when working directly to CI when new.
So there are SIX wear surfaces in effect.
- Left, right, (relieved center between) on the flat is two.
- Left-right, (relieved center between) on
each face of the inverted Vee is four more.
Soo.. one may apply a filler/bonding plastic BETWEEN the bronze wear strip and the CI underside of the saddle.
Nice if it is milled flat first. But it need not be.
IF... the Bronze wear strip is formed flat and compliant to the ways - it is now as if it
was the way. Same plane.
Fill between the Bronze and the worn CI? That corrects the variance in the gap.
Just with a plastic cheaper and more easily had, easier to work with than Moglice.
Because it does NOT have to also BE the "wear strip" at all.
Call that "division of labour". The Bronze takes the wear. The adhesive/filler adjusts the gap. Pre-milling now optional.
We get to use these machines by keeping the cost and time within the bounds of what we can afford. Not what we only WISH we could afford.
Building 80 years worth of goodness back into an 80 year old machine may give the MACHINE 80 years. Or 800 years, given it is no longer in 3 shift War work.
But I have only 20 years. At best. So why would I?
If I were running a revenue business and
really needed "as new"?
I'd buy new.
And go like the very hammers of Hell itself to TRY to wear it out in FIVE years. Or less.
So it had made a nice profit ...as well as the price of an even BETTER replacement. That's how you build wealth.
And reduce the risk involved with the "as"(s) part of not-really-new!
Some OTHER part of that old machine with "as new" ways can bust your as(s)-pirations in a New York MINUTE!
We need to strike a more reasonable risk/reward balance than investing multiple thousands of dollars in scraping classes, months if not years of our lives doing scrapimg.. only to cry as $1,000 to $3,000 worth of new spindle bearings call for THEIR share of economic
ransom.
Can't have everything. Not "all the time", anyway. It all has a price of time, money, or both!
BTW: "Brass" has no place here. Bronze is
not interchangeable with Brass- nor the reverse - just because neither one is Iron.