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Thread: Measuring old lens threads

  1. #11

    Join Date
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    Re: Measuring old lens threads

    Great. Thanks all. Yes SRB are still going but I have a machinist in Scotland who can do the work but its a ferry and 2 1/2 hours away down winding roads and the ferry is, how can I pt it, errr, unreliable at present. I may get there but may not be able to get back. So I'll have a good read and see what I can sort out. Thanks everyone.

  2. #12
    (Shrek)
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    Re: Measuring old lens threads

    As someone who routinely cuts flange threads on a lathe, don't get overly complicated here. You're not talking about tolerances in the thousandths to make a flange, you need the approximate thread pitch and a rough idea of the diameter, and you just keep cutting till it fits. I don't spend more than 2 or 3 minutes measuring anything. Whitworth or modern threads? Who cares, so long as the flange fits snug and doesn't let any light through. Yes I have machined other things to much higher tolerances, it's just that that's a complete waste of time for a basic lens flange.

  3. #13

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    Re: Measuring old lens threads

    Quote Originally Posted by Jody_S View Post
    ..... you just keep cutting till it fits
    Which means shipping the lens .....

  4. #14
    (Shrek)
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    Re: Measuring old lens threads

    Quote Originally Posted by pgk View Post
    Which means shipping the lens .....
    With antique lenses, this is the only way to be sure. Note that only the barrel needs to be shipped. There is simply too much variation in hand-cut threads, barrels that may be out of true from being knocked, threads damaged from being forced or hit, etc. If you're talking about a Betax #4 or something, the threading is known and a flange can be purchased that will fit all Betax #4s.

  5. #15
    Tin Can's Avatar
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    Dec 2011
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    Re: Measuring old lens threads

    I bought my 900 Jena from Thailand or...?

    I asked the seller to get a flange made where he was

    I knew it would be cheaper
    Tin Can

  6. #16

    Join Date
    Dec 2012
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    Re: Measuring old lens threads

    Quote Originally Posted by Tin Can View Post
    There is a guy making flanges

    I recently bought one of his standards

    I think he is in Portugal, wonderful work

    The name may/will come to me
    Randy are you thinking of Jose at Custom Photo Tools?

    Great work as you say, he made me a flange for an Ilex #5, and a 2" Whitworth to Ilex #5 adapter so I can use my TTH RVP (and other TTH barrel lenses) with the shutter.

    Both made in brass and they were a perfect fit without sending the items to him.

    I'm not affiliated in any way, just a very happy customer.

  7. #17

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    Dec 2012
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    Re: Measuring old lens threads

    Quote Originally Posted by pgk View Post
    ... Fortunately the lenses that I have are all from one maker and are certainly all Whitworth profile threads ...
    I'm doubtless stating the obvious here but if they are Whitworth threads do they comply with the RPS standards? For instance TTH standard lens ranges use flanges of 1, 1, 1, 2, 2, 2, 2, 3, 3, 4, 4, 5 and 6, with 24 TPI up to 3, and above that 12 TPI.

    The top (and bottom) 6th of the Whitworth thread height is rounded over, and obviously there has to be a difference ('tolerance' I believe) between the male and female threads - could these factors be making your measurements look wrong?

    I would think that even with wear on the overall diameter as long as the thread walls are in good condition and are mating properly you will get a good fit. At least Whitworth is a clearly defined statndard.

    Machinists have data tables of the correct tolerances to apply for a male or female thread - I only had to say that my RVP had a 2" thread for Jose to make the adapter the right size and fit.

    Good luck anyway!

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