Tuesday, June 28, 2016

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

6 comments:

  1. it looks remarkably like the Olympus 45mm

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  2. screwing, schmowing...I used JB Weld with great success. If I mess up or change my mind later a bit of heat gun action makes it soft enough for disassembly and removal. I have even done it on plastic bodied lenses (Pentax-110) and while machining and screws are way more elegant, the results are the same: lens focuses 100%
    I do prefer to make my own extension tubes/adapters for most lenses even if one is available commercially as dimensions are often wrong on the commercial ones anyway.

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    1. Epoxy is also my preferred method but I want to try something new. Tried I did and I completely ruined the parts I made for the Cintagon. Back to the drawing board.

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    2. Epoxy is also my preferred method but I want to try something new. Tried I did and I completely ruined the parts I made for the Cintagon. Back to the drawing board.

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    3. bummer, I like the way you machined that piece. Did the drilling not align?

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    4. @gnarlydog: I simply do not have the right tools to drill and tap holes. It's far harder than I imagined.

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