Leica LTM Diff between LTM & R-LTM

Leica M39 screw mount bodies/lenses
Back in the day when we did valve jobs on car engines, we used an abrasive paste to lap the valve to the seat.
If I was committed to using the J8 on the Leica, I would "wear" the threads of the lens, not the Leica flange, using some sort of abrasive paste and an old Russian camera body, I could thread and un-thread the lens, and maybe wear the threads a tiny bit.

I really should sell the Zorki 4 with its J8 and put it toward a suitable Leica lens.
 
davidnewtonguitars said:
Back in the day when we did valve jobs on car engines, we used an abrasive paste to lap the valve to the seat.
If I was committed to using the J8 on the Leica, I would "wear" the threads of the lens, not the Leica flange, using some sort of abrasive paste and an old Russian camera body, I could thread and un-thread the lens, and maybe wear the threads a tiny bit.

I really should sell the Zorki 4 with its J8 and put it toward a suitable Leica lens.
Click to expand...

Valve grinding paste is still available (in the UK). It comes in a little tin with two different grades. Used between a soft alloy lens and a plated brass mount I guess it would take more metal off the lens thread than the mount.

Use sparingly and clean up meticulously!

PS, I haven't done this on a camera but in principle....
 
lukitas said:
Some blueing will show where. Sharpie will do. Paint the thread, screw it in, check where the ink has gone : those are the high spots.
Click to expand...
Thanks for reminding me of a piece of basic engineering that I hadn't thought of in years or possibly decades.

Of course if the thread angle or pitch are different...

Cheers,

R.
 
The focusing mounts on (very) high-end lenses are still hand-lapped; or were a few years ago, when I visited the Leica and Zeiss factories.

Cheers,

R.
 
I have an Austin Seven. All this and more is familiar to me. Yesterday I could be found reaming spring shackle bushes, light relief after the battle of the Contax I shutter roller springs.

Michael
 
Roger Hicks said:
lukitas said:
Some blueing will show where. Sharpie will do. Paint the thread, screw it in, check where the ink has gone : those are the high spots.
Click to expand...

Thanks for reminding me of a piece of basic engineering that I hadn't thought of in years or possibly decades.

Of course if the thread angle or pitch are different...

Cheers,

R.
Click to expand...

Hm, «blueing»* like in dentistry? When the dentist makes a filling, a tad larger than necessary in the end, and the patient has to grind some (blue/violet dyed) paper that shows the dentist where s/he has to remove some abundant substance?

*I'm not sure what the correct teminology is, but I guess the procedure is comparable.
 
radi(c)al_cam said:
Hm, «blueing»* like in dentistry? When the dentist makes a filling, a tad larger than necessary in the end, and the patient has to grind some (blue/violet dyed) paper that shows the dentist where s/he has to remove some abundant substance?

*I'm not sure what the correct teminology is, but I guess the procedure is comparable.
Click to expand...
That's it.

Cheers,

R.
 
radi(c)al_cam said:
Hm, «blueing»* like in dentistry? When the dentist makes a filling, a tad larger than necessary in the end, and the patient has to grind some (blue/violet dyed) paper that shows the dentist where s/he has to remove some abundant substance?

*I'm not sure what the correct teminology is, but I guess the procedure is comparable.
Click to expand...

Hi,

Try carbon paper, if you know what that means; it dates me badly.

Regards, David

PS Thick crud in the threads could be the cause. Run a sharp pin round them...
 
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