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DIY new mount for novoflex pistol grip follow focus (A)?
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PostPosted: Sat Jan 07, 2017 5:02 pm    Post subject: DIY new mount for novoflex pistol grip follow focus (A)? Reply with quote

This is the mount end of my early version novoflex:



The silver collar holds the mount on. The mount rotates from landscape to portrait, you can see the ball bearing that clicks. The mount is 2 piece, three small M2 bolts secure it, when these are loosened or removed the 2 halves unscrew. The thread is M42x0.5 (measured ID of female end = 42.3mm, OD of male = 41.9mm using cheap vernier calliper which may not be very accurate).
So my plan is to use an old M39 t-mount:



Cut off the circumference with the grub screws A leaving flat surface B on which cheap M42 adapters for PK, sony A etc can be attached. The nub of it is adapting the M39 screw to M42x0.5, so that this can be screwed in. I was thinking of filling the gap with steel epoxy putty, using WD40 to prevent that sticking to the M42 thread so it will unscrew. But a bit of a rim on the LH side of the middle piece means that won't be so easy to do. Any ideas - is an adaptive piece M42x.0.5 to M39 an off the shelf thing from an engineering works? Is that something a 3D printer could do?


PostPosted: Mon Jan 09, 2017 3:30 pm    Post subject: Reply with quote

Well I consulted the local engineering shop about a M39 to M42x0.5 adapter (like the M39-M42 adapters sold on eg ebay for 99p). They can do it, but it was going to cost well north of a hundred quid - "lot of work in those fine threads!"

So think again....


PostPosted: Mon Jan 09, 2017 3:57 pm    Post subject: Reply with quote

marcusBMG wrote:
Well I consulted the local engineering shop about a M39 to M42x0.5 adapter (like the M39-M42 adapters sold on eg ebay for 99p). They can do it, but it was going to cost well north of a hundred quid - "lot of work in those fine threads!"

So think again....


Are you sure about the thread pitch? It's very unusual.
In photography M42x1 & M42x0.75 are both common, and annoyingly both just called M42 by Chinese adapter sellers
(In normal engineering thread pitches at 42mm seem to be wider with 1.5 to 5 being available according to my searches.)

Rather than spending a significant amount having a thread machined (not a lot of work but may need a die they don't have) how about simply gluing an adapter to the thread with hot melt glue or the less reversible epoxy? You can probably use one of those 99p e-bay adapters if you remove some of the threads to leave it as a snug fit.


PostPosted: Tue Jan 10, 2017 2:51 pm    Post subject: Reply with quote

DConvert wrote:
Are you sure about the thread pitch? It's very unusual.In photography M42x1 & M42x0.75 are both common, and annoyingly both just called M42 by Chinese adapter sellers
(In normal engineering thread pitches at 42mm seem to be wider with 1.5 to 5 being available according to my searches.)


Absolutely - confirmed by the engineering shop.

Quote:
Rather than spending a significant amount having a thread machined (not a lot of work but may need a die they don't have) how about simply gluing an adapter to the thread with hot melt glue or the less reversible epoxy? You can probably use one of those 99p e-bay adapters if you remove some of the threads to leave it as a snug fit.


M42x1 male is actually a loose fit in the M42x0.5.
What I have done is use the inner collar from a t-mount as a mould. I "tacked" it in place with a few blobs of standard quick epoxy, centering by eye. The gap between this and the M39 of the t-mount was filled with steel epoxy putty, pressed firmly into place to eliminate bubbles and gaps. First try it stuck too well to the collar. Second try I used 3-in-one oil instead of wd40 on the collar to stop it sticking and let it cure a bit longer. Eased off the tacking blobs with a modelling knife and then it took a pipe wrench to ease the collar loose but this worked. The thread created engaged surprisingly well in the mount end - snug and a reasonable bite. So IMO this is a viable way to proceed.
However I have now sold the PIGRIFF-A so it's a bit apropos...




PostPosted: Tue Jan 10, 2017 3:58 pm    Post subject: Reply with quote

marcusBMG wrote:
M42x1 male is actually a loose fit in the M42x0.5.
What I have done is use the inner collar from a t-mount as a mould. I "tacked" it in place with a few blobs of standard quick epoxy, centering by eye. The gap between this and the M39 of the t-mount was filled with steel epoxy putty, pressed firmly into place to eliminate bubbles and gaps. First try it stuck too well to the collar. Second try I used 3-in-one oil instead of wd40 on the collar to stop it sticking and let it cure a bit longer. Eased off the tacking blobs with a modelling knife and then it took a pipe wrench to ease the collar loose but this worked. The thread created engaged surprisingly well in the mount end - snug and a reasonable bite. So IMO this is a viable way to proceed.


Glad to hear it worked.
I've got a number of lenses wanting adapting to common threads. I might just try a turn of PTFE thread tape on the fitting before gluing together. Should make unscrewing fairly trivial, and I have a ready supply of it Smile
The steel epoxy does sound like a better long term solution than hot melt glue.