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.

Update on the Progress of the Lathe Project

I have been quite busy with other stuff lately so I haven't really spent as much time as I would have liked on learning to use the lathe.  But, so far, I have done a few small projects, mostly with positive results.  Now that I know what the lathe can do for me, it would be hard to live without one.  It is, of course, not without lots of frustration.  The learning curve is steep, especially since I had no prior experience with a lathe.  Below is a very condensed summary:

• The 1/4 horsepower motor is not powerful enough to do quick, smooth deep cuts.  It often stalls when making what I consider reasonable thickness of cuts.  Boring a larger hole or making a parting cut could take a long time and this simply drives me crazy.  I have to remind myself that the Taig Micro Lathe was designed to make small parts and I need to be patient.

• The lack of thread cutting capability as a default feature on this lathe is now a small annoyance.  I actually have a need to cut threads, and it's more often than I originally thought I would need.  Outfitting the Taig Micro Lathe II with thread cutting feature would mean an expensive upgrade (for me).

• The small size of the lathe is one of the best features.  It sits on a small desk with space to spare.  That, alas, is something of an Achilles heel.  This means working with anything larger 3 inches in diameter is difficult.  Also see point #1.

• It's hard to describe the feeling when a project is completed.  It's a feeling that should be experienced.  A sense of purpose, accomplishment, and the whole process was therapeutic. 

So far, I have used the lathe to help convert a few lenses to work on Sony E-Mount, from very simple turning of the lens barrel to actually making parts.  The pictures below shows few of the lenses I have done.  One thing I have learned, is that drilling and tapping small holes and making them aligned perfectly is no easy task without proper tools.

Three Amigos - Konica 45mm f1.8, Argus Cintagon II 48mm f2, and Minolta Rokkor-PF 45mm f2.  The Konica and Minolta lenses share the same 12-17mm focus helicoid for focus.  Both uses an M42 mount I savaged from old lenses to mount to the helicoid.  If I could cut threads, I would have no need to use old parts, because eventually, I will run out of them.  The Cintagon II modification is only partially successful.  It works, but not well.  You can see extra holes on the part that I made.  Those are mistakes :) I think I will get rid of its original focus mechanism and use a helicoid for focus instead, or converted to L39 or M mount.

In all, I really enjoy using the lathe to make lenses work better on my camera.  Hopefully my skills on using it will improve and the conversions will look and work better in the future.

Bokeh - Minolta Rokkor-PF 45mm f2 (from the AL rangefinder) & Sony A7.

First "Real" Lathe Project - Argus Cintagon II 48mm f2

My buddy Cliff got me some aluminium rounds and now I can actually do some "real" lathe project :)

The aluminium rounds came in 12-inch lengths.  I really should have them cut into 2 inch pieces, because cutting a 2.5" diameter round took almost 20 minutes with a hack saw by hand.  I originally thought that I would cut each piece to the lengths I want, so I won't waste any materials as they are quite expensive, but that does not seem like a great idea now.  In any case, the very first lens I want to make usable on my A7 is the Argus Cintagon 48mm f2 lens that came from a Argus rangefinder.

The reason I choose this lens is because it's the easiest one to do.  All it needs is a proper length of tube between a mount and the lens.  I thought it would be a piece of cake.  I just needed to bore out the piece, drill and tap the screw holes and it's done.  What could be simpler?

The pieces - Left: thin mount, middle: tube I worked on, left: the lens 

Well, it's not really hard, but it has taken far longer than I thought.  As my first time turning and facing a piece of solid metal, there were (and still are) lots of things to learn.  What tool bits to use, truing the work piece, etc.  While boring out the required space to fit the lens, the weakness of a micro lathe is quite apparent.  There is simply not much power/torque for deep cuts/turns.  Everything must be done slowly, even on soft metal like aluminium.

I am happy to say, the piece is is almost done, except I need to drill, and tap the screw holes for the tube on the side, and the mount at the back, and there is only one problem.  I don't have any small tap tools, drill bits, and a drill stand.  This whole business of lens conversion takes so many other tools and accessories that I didn't think of at first.  In any case, I ordered a Flexshaft for my Dremel 4000 from Amazon, and it came in a couple of days.  I am going to mount it on the cross-slide, somehow, and drill the holes on the side with the tube/lens mounted on the lathe chuck.  For the mount, the holes need to be drilled on the back, I think I will mount the Flexshaft on the tail-stock and hold the mount/tube with the chuck.  For all this to work, I have to make a mounting jig for the Flexshaft and secure it on the cross-slide and tail-stock.

All fitted together.  Still need to be screwed together.

It's almost impossible to buy a set of micro tap and tiny screws locally at reasonable prices, if you could find them at all.  I order a thousand pieces of M2 (two millimeter x 5mm) screws, a set of small drill bits and a set of 10 micro taps with size from M1 to M3.5, with handle for about $40 from AliExpress. The only problem is, shipping usually takes at least a month, and on top of that, Canada Post is likely going on strike next week and who know for how long.  In the mean time, I have an urge just glue this thing together until all the parts arrive :)

It's very gratifying to see all the pieces fit together and I am very glad I bought the lathe.  I think I am going to enjoy this.

Argus Cintagon II 48mm f2 Sample

First Lathe Lesson - Centering the Work Piece

I want to share my experience with anyone who is considering or starting to play with a metal lathe, and will post whatever I consider useful.

I wrote last time about the very bad run out of the 3-Jaw chuck.  Did some more research and found that there isn't too much can be done about the chuck itself, other than buying a high quality one with high precision.  But that is just one of the factors that affect the precise centering of the work piece.  A 4-Jaw chuck is still a little better, but it takes much longer to get everything true.  I have a dial gauge with a magnetic base on order and should be here soon.  In the mean time, I learned that using a ball bearing can make the work piece on a 3-Jaw chuck run much more true than without.

Got a broken bicycle bottom bracket that has a ball bearing still on, and it broke at the perfect place.  I really don't need to modify it, except to thread a screw on it, and then clamp it on a tool post, like this:

Work piece centering tool using a ball bearing from a broken bicycle bottom bracket.

To use it, mount the work piece just tight enough that it won't come off when the lathe is turned on.  Run the lathe in slow speed, and gradually a advance the ball bearing until the bearing start to turn.  The work piece should now run true enough to start turning.  I don't have the dial gauge yet to check the run out, but to my eye, it was light years better than when I was turning the Angenieux 70mm f1.5 projection lens.

All these changing of tool posts and change the belt position for different speed of the lathe is quite tedious.  All the more motivation to convert this lathe to use a variable speed DC motor, and buy a quick change tool post.

Water Quality Sampler Post - Zeiss Opton Tessar 75mm f3.5 & 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