A Welcome Addition to the Shop

The Grant Street Garage has a new toy! It's a metalworking lathe, of the class of lathes usually called "8X". That means that you're supposed to be able to spin something eight inches in diameter, if you're crazy enough. Regular readers of this blog know that I already had a metalworking lathe and also a mill. Indeed, a recent post detailed an upgrade I made to my smaller "7X" lathe. That upgrade helped a bit, but the small lathe was still just too light and non-rigid for serious work.

Then, one of the leaders of our Make717 group, Ben Eisemann, posted this lathe (complete with the rolling tool chest underneath) on our group Facebook page, and also on Craigslist. After discussing it with my metalworking mentor, Phil Oles, I posted "SOLD!" on the Facebook page.

Alas, Ben told me that someone had responded to the Craigslist ad a mere 19 minutes before I posted my message, and it was already sold. Over the next couple of days, I was actually moping around about it - In my mind, I had already moved that lathe into my shop! But then Ben called and said the first buyer had backed out and it was mine if I wanted it. I wanted it!

Many thanks to Ben and to my friend Troy Nace, who helped get the lathe to Grant St. It's heavy, and those strong young men moved it where I never could have. Once it was here, I took a look and did some cleaning and oiling, just trying to see what I had bought. One thing that delighted me was the drill chuck Ben included for the tailstock - it's a really nice one. I mean, as in hundreds of dollars nice!

After cleaning, I decided to make the first test cut. I chucked a piece of 3/4" aluminum rod and took a couple of cuts to true it up. Then, I measured the diameter and got 0.735 inch.  Seven hundred thirty-five thousandths, in case you don't read that sort of number often. I then set the dials to take a cut of 0.002 - two thousandths, or "two thou" if you want to sound machinist-cool. After the cut, I had a tiny step where I stopped - you could barely feel it with your fingernail. It's the faint line about halfway down the shiny part:

So, now for the moment of truth. I measured the cut end and got 0.733 inch - a difference of exactly two thousandths! That's promising!

A few days later, Phil came over to see what I had bought, and to help me align the tailstock. In other tests, I knew it was quite a bit out of alignment, but didn't really understand how to align it. Phil brought these instructions along - click the picture to see the instructions full sized:

The next two and a half hours were a very interesting learning experience for me, in how to measure precisely (Phil had brought his own dial indicator and stand) and in how (and how not) to make precise adjustments. We had some frustrations along the way, but at the end we got this result:

Let me decipher that picture for you: The long shiny part (about 9 inches long) was my final test cut. The marking on the left says "H .736". That means the diameter I measured at the headstock end of the cut was 0.736 inch. The other side says "T .735". So, the difference between the extreme ends of the cut was only 0.001 inch - "one thou." Dividing by 9, that means my error is just over 0.0001 (one ten-thousandth), which machinists read as "one tenth". A tenth of anything bigger than a thousandth is too big for a machinist to care about, so a "tenth" is always 0.0001.

Phil blessed it as a machine capable of doing precision work. Now I have to learn to do precision work! And I'm keeping the little 7X lathe also. In our setup work, I found it very useful to have two lathes, so I could prepare a test piece on the 7X, and then do the detailed work on the new 8X. I mentioned this to Phil, and he said, "That's why I have three!"