Minolta Rokkor-QF 40mm f1.8 Conversion Part Deux

I first converted this lens with filter ring and glue, as I wrote in this post with more pictures here.  It was a relatively easy conversion so I decided to redo it with the lathe, to hopefully make it look and work better.

Most of the conversion work was already done so this second conversion was pretty quick. I just needed to machine the spacer with the required thickness for infinity focus, drill and tap holes on the lens board and the newly machined spacer to attach them together, and then do the same for the E-Mount adapter, which was original a Rollei to E-Mount adapter with a missing lens release pin, and I decided to to use it as the mount.

The part at the right is the spacer I machined.  The left part goes inside the spacer.

I am quite happy with this particular conversion.  The lens fit together very well with no play and wiggles, except at the mount if you really twist it hard.  I did messed up the spacing of the mount and it's not perfectly centered, and this has the effect of off-setting the aperture index mark slightly.  Not a big deal but I could have done much better.  When I get more adapters, I will redo it, or, my next exercise, make my own E-Mount!  Another small problem is the focusing is not as smooth as I would like, probably because the focus guide hole is a bit tight.  Hopefully I can tweak it and make it feel a bit smoother.

Home made drill bit sleeve for the collet.

For this project, I used the milling attachment that came as part of my lathe.  It was used to mill the path for the focus guide to go through, and also used to hold the parts for drilling, as I don't have a drill press.  There is also a set of collets that came with my lathe but none fit the tiny drill bits, so I made a sleeve from the shaft of a Dremel bit.  A hole was drilled with the same drill bit that this sleeve will hold.  Once the hole was drilled, I cut a slit on one side of the shaft, thinking that should be good enough and it should give and clam on the drill bit when put on the collet.  But because it was made of hard steel, the sleeve didn't clam on the drill bit at all, so I had to cut more slits on the other side and is now working like a charm.

All done.  Looks pretty good, eh?  You can see the aperture index mark is off to one side.

This has been a good exercise for me.  This gives me more confidence that I could do more complex conversions later on.  Below are pictures I took after the new conversion, with the Sony A7.

My First [Simple] Lathe Project

Yesterday I finally found some space to setup the lathe.  Unfortunately I have no metal rounds to practice with, so I used a projection lens I bought from the camera show couple weeks ago as the practice piece and first project.  Yes, I know.  I am trying to walk before I learn how to crawl, but hey, I have many hours of YouTube experience under my belt.  That's got to be good enough to get started, right?

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 bad ugly.  For one thing, the tool bits were all dull, and I think the speed I was using was a bit too slow.  I am not sure what kind of metal the lens barrel was made of, but it was not aluminium or brass. In the end, I removed the large, smooth grooves on the lens, but left behind tiny and sharp grooves.  It looks nothing like the smooth finish I see on YouTube!

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

A New Adventure Begins

Yesterday, with my wife's encouragement, I purchased a used Taig Micro Lathe II.  This was not my original plan at all, even though I wanted a Taig.

Originally I planned to buy the Taig Micro Lathe with the most basic setup, and gradually add new accessories as needed.  In fact, I already bought the AC motor, as well as a variable speed DC motor that I took out from a treadmill, and was ready to order the Taig when I found this used one in the local buy & sell, with many accessories, including both a 3-jaw and 4-jaw chuck, milling attachment with optional vice, set of collets, a few tool posts and some tool bits already included in my wish list, for hundreds of dollars less than new.  The only thing I was hoping to have included were some end-mill cutters, but that's not a big deal.

The whole setup is very small.  All fits on a small table and does not take up a lot of space.

I am really excited.  It has been my dream to own a machine that I can actually use to make stuff, instead of most tools that I use to fix stuff.  Now all I need is to find a place to buy some metal stock so that I can start learning.  It will probably take me months to get reasonably good at this but I have so many broken/badly converted lenses that I can practice with :)

On with the new adventure!  I will keep everyone posted on the progress with (hopefully) regular blog updates.

Taig Micro Lathe II