Building a New Lathe

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tom osselton:
Nice

Neubert1975:
nice work :thumbup:

tom osselton:
Looks good.

vtsteam:
Thanks Tom, and Neubert. :beer: No photos today because I spent the day removing all of the components on the headstock end of the lathe. I had noticed that the wooden wedge was able to move the faceplate a tiny bit, and I wanted to find out why. The problem turned out to be the method of headstock fixing I had used. I had made an internal clamp bolted to a plate below the ways.

If you recall, the headstock had been made to slide along the ways while boring. This required a slight amount of clearance between the bottom face of the headstock, and the retaining plate screwed to the bottom. Placing a clamp on the inside of the headstock did not eliminate this clearance, because it pinched the way strips, but had no physical connection to the headstock other than the bottom plate. It prevented fore and aft movement, but, didn't fully eliminate the clearance. It was also originally just a temporary fixing, but I had in the years since forgotten about it. :wack:

So now I'm going to file down the lands for the bottom plate, which will remove the clearance and pinch the headstock directly to the ways. And also I'm thinking about adding redundant bolts through the ways themselves and into the headstock. We'll see what kind of wrench access I have for doing this, because there's a horizontal shears support in the area.

Anyway it's probably about time to check the lathe throughout for tolerances, and make adjustments if needed. Also the carriage halfnut has occasionally popped out of engagement, and I want to adjust the detent and spring, as well as alignment with the leadscrew. Nothing fun made today, but I'll feel good after making sure the headstock mounting is solid and the lathe is fully operational, checked and aligned.

vtsteam:
Working on the headstock attachment, I noticed that the black paint was chipping off the corners on the carriage. I'd used sprayed Krylon, a thin lacquer type, and probably should have brushed on a true oil base enamel, like Rust-oleum. I gave a little scratch with a fingernail, and the thin paint flaked off, as if I'd used a scraper. Zinc alloys are also known to be somewhat resistant to conventional coatings. Oh, well might as well take it all off before re-painting. :dremel:

A few minutes work with a hand wire brush, and a blunt screwdriver completely cleaned the paint off the carriage. Underneath was the slightly dulled finish of the zinc as milled -- not unlike hard anodized aluminum, just a little bluer in color. I actually thought it looked better than it did painted, so I've decided to just leave it that way.

Interestingly, all of the unprotected zinc castings I've done for the lathe, all 2 to 5 years old, look completely clean and corrosion free, and look the same as the carriage does now. In the same time period I've had most ferrous lathe parts (and those on other machinery and tools) rust during off usage. There is a lot of damp in this concrete tiny shop and big swings in temperature.

So despite a few early and admittedly well-meant warnings that zinc castings in a new lathe might corrode or suffer serious electrolysis issues, experience shows that the opposite is true: they are unaffected. On the other hand, the traditional lathe building metals used have suffered the usual condensation and damp problems. Since zinc alloy has stronger physical properties than cast iron (or mild steel) it was actually advantageous in this application -- at least from my point of view.

Here is the carriage with the paint scratched off. The shiny upper T bars never had paint on them, and have been in the same shop, on the lathe for 2 years. The lower part of the carriage was painted. The apron is aluminum, and also wasn't painted. I think it all looks better without paint now than it did new. (Oh, also, the newly calibrated dial is in place on the carriage screw).:med:

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