Durst L1200 Magnification Grip Slips

[Sevo]

Cor, the disc ( E ) with the rubber ring looks severely worn to the point of seeing the reinforcing cords in the rubber.
Is there something inside that may be scraping against the rubber on ( E ) ?
For something like that to wear down to the point of seeing the reinforcement doesn't make sense to me on an enlarger.

That is no sign of wear, the cords get exposed as the rubber sheet is cut into discs. If there should be wear, it will not be on the edges (which don't touch anything) but on the surfaces (this is a friction disc). In my experience, there is no wear proper, but the surfaces harden until the friction drive slips - so far I managed to cure that on mine by sanding down the rubber disk. If that should eventually wear it down, it should not be that hard to find a suitable rubber sheet to cut a replacement from.

[ic-racer]

That is no sign of wear, the cords get exposed as the rubber sheet is cut into discs. If there should be wear, it will not be on the edges (which don't touch anything) but on the surfaces (this is a friction disc). In my experience, there is no wear proper, but the surfaces harden until the friction drive slips - so far I managed to cure that on mine by sanding down the rubber disk. If that should eventually wear it down, it should not be that hard to find a suitable rubber sheet to cut a replacement from.

I replaced a similar slipper clutch on take-up spool of my Bolex movie projector with rubberized cork and it works well.

Also, the more I look at the pictures, it looks like the two adjustment screws are to adjust the friction on the mechanism.

[Cor]

Thank you guys for the feedback so far !

I am not worried at all about the teflon gear and the rack and pinion (?) rails it grabs, they look still perfect.

IC-Racer, I indeed think I'll first gently try to adjust those 2 screws.

Sevo: if adjusting those screws does not work, I will give your approach a try. Is the disassemble as straight forward as it looks ? I guess I will first secure the head with a large belt to the base board so it it will not "jump" up.

Thanks again,

Best,

Cor

[Cor]

Ok,

Updating an older post of mine; I tried to clean rubber friction disc "D" by sparsely spraying some pure ethanol over it, and use tissue paper to clean it. Now the grip "A" works again, so it drives through C, D and E the fine focus again, but now I have the opposite problem: the grip B does not dislodge the friction disc any more, guess the ethanol made some gooey matter on the surface of the rubber disc.

So if I raise or lower the head the whole mechanism (A/B connected to C/D) spins/runs.

Am I right in assuming that this does not matter too much since the white (telflon) cog wheel and rack and pinion rails (right of E) are always engaged anyway. The dislodge grip B is there only to move the head up and down faster and smoother ?

best,

Cor

Hi,

I have this 20+ years old Durst L1200 Laborator (condensor version) which has been working flawlessly. Recently I noticed a small problem with the hand grips you use to raise and lower the head:

Seen from the back: Grip A is for the fine adjustment, B dislodges and is used to move smoothly over larger distances:

Attachment 127961

The problem that grip A does not function any more, ie the head does not move when turned.

A closer look reveals this:

Attachment 127962

So Grip A drives chain C and a metal disc, which has a black disc (of rubber or ? material) attached to it, which is supposed to take a long metal disc E which drives the Teflon gear for the fine adjustment.

As I judge is :this black material is worn, become smooth, and does not "pick" up the metal disc E by friction any more (I assume that a clutch works along these lines, not to well versed in mechanics).

Is this the cause, and is it repairable (with not too much effort and difficulties) ?

thanks and best,

Cor

[kngkc]

Hi, recently I was given a L1200, my issue is the handle B does not lock the enlarger head to the column. The counterweight pulls the enlarger head all the way to the top. Does anyone has a solution please. Thanks