Immediately, I found many problems. The carriage had quite a bit of play. A quick consultation with the Taig Micro Lathe guide fixed it by adjusting the gib screws. Then the 3-Jaw chuck is grossly out of true. It's so bad you can see the wobble and it would be impossible to turn anything like this until I find a way to true it. The 3-Jaw chuck is supposed to be self centring, as all the jaws move at the same time when you tighten/loosen it, but it's not doing a good job at it. Luckily, there is the 4-Jaw chuck that was included with the lathe, but that brought up another problem. The 4-Jaw chuck's jaws are independent. You can tighten each of the 4 jaws individually. But, in order to make the work piece perfectly centred, one needs a dial gauge, which I have, but I don't have the base to set it. So in the end, I just did many trial and error tightening and retightening until it was visually running true. This is a laborious and imprecise process without the dial gauge.
Finished - I will not show you the 100% crop of the turned area. It just looks disgusting.
I removed the lens elements from the lens; they came off easily by unscrewing the front and rear groups. This is part of the reason I wanted to use this lens. The lens barrel was then mounted on the 4-Jaw chuck with as true as I could visually tell, and started turning. I just wanted to remove the grooves on the lens so that it would have a smooth surface, and it would also provide a stop for the step-up ring that I would use to mount it to the focus helicoid. This turned out really
Angenieux 70mm f1.5 Projection Lens on the helicoid
Next I wanted to bore the hole larger on the 30-52mm step-up ring, just large enough to slip on the lens barrel. This part was done relatively painlessly. The aluminium of the step-up ring was much easier to work with.
So, in a way, it was a success, only because I was able to use the lens and I didn't have to go nuts trying to find a ring that fits the lens barrel and trying to glue it so that it's parallel to the mount.
What did I learn from the first lesson in using a metal lathe? It's kind of fun, but what overwhelmed me was the sheer amount of metal shavings from such a small and simple project. A Shopvac is a must. To make the lathe run smoothly and efficiently, it needs to be optimally conditioned: true chucks, sharp bits, right kind of bits, right accessories and most of all, the skills to make it sing. I will keep doing simple projects until I am comfortable to convert a real lens.
Daisies - Angenieux 70mm f1.5 Projection Lens & Sony A7