Disassembling Voigtlander Apo-Skopar process barrel lens

[Nodda Duma]

A photographer sent me a Voigtlander Apo-Skopar 45cm f/9 process lens that needs balsam separation repaired.

Rear group unscrews just fine, but I cannot get the front group disassembled. Does anybody have experience with this lens and knows where exactly the front group unscrews? I *think* it is the very front, in front of the threads as shown, but no matter what I try it --heat/cold, heat on the barrel / freeze the front, PB Blaster, etc. etc. it does not come undone.

Anybody have experience disassembling one of these? There was a series of them, different focal lengths.

here's a pic of the stubborn lens.

[Jim C.]

I have no experience with this particular lens but you may want to look for tiny jam screws that may have been painted over.
Another thought is that the glamour ring is what holds the front group in.

[LabRat]

Patience, some times it takes weeks...

It will let go about the time you give up...

Steve K

[paulbarden]

Have you tried running a bit of acetone into the threads? I've found lenses that have had the front ring locked with some kind of lacquer.

[J. Patric Dahlen]

Maybe the name ring isn't meant to be unscrewed? The lens group might have been installed from the back and then crimped in place.

Arne Cröll has written about Voigtländer lenses and maybe he could help?

[Tracy Storer]

Looks like the front cell shoulld unscrew like most lenses do, assuming there are no set screws holding it in place. Opposing strap wrenches work great, but sometimes you need to get some penetrating oil into the threads, and I have had it take several days. If a few days of oil doesn't do it, sometimes there is paint or lacquer in the threads which can be loosened with a little acetone carefully applied with a syringe or needle tipped bottle.
They can be very stubborn.

[J. Patric Dahlen]

This is my Rietzschel Linear 4,5/105 with balsam problems. The thread on the front can't be for the "retaining ring" since it's too short. And the lens group is crimped in place in the back. So there is no way to have this lens group re-cemented without cutting the mount and machining a new one. I hope this isn't the case with the Apo-Skopar.

[Nodda Duma]

I’ve dealt with crimping before. Slow and steady works.

I’ve tried strap wrench, there’s not enough “meat” to grab on to. PB blaster’s been stewing for a few days.

I think I’ll make a wood clamp for my bench vise to really grab onto the cell, then try unscrewing the body with strap wrench.

[Tin Can]

Strap wrench bend and crush oil filters

I suggest hole saw to cut a close fitting wood hole in 1/2 making a rubber grip

I have used air hammer on filters

[Tracy Storer]

I've done this a couple times too, plywood clamp for the lens cell and plywood clamped down to the bridgeport, strap wrench on the barrel. Works !

I’ve dealt with crimping before. Slow and steady works.

I’ve tried strap wrench, there’s not enough “meat” to grab on to. PB blaster’s been stewing for a few days.

I think I’ll make a wood clamp for my bench vise to really grab onto the cell, then try unscrewing the body with strap wrench.