Durst L900 repair (plastic gear)

[pavelkim]

Hello everyone,

I've bought Durst L900 several years ago, but it went with a small defect in the lifting mechanism.
There are a gear in the head and a gear plane (is that a correct term?) on the back of the column. They both got broken teeth.
Decided lately to order duplicates for both parts and put the enlarger back in order.

Well... I can't disassemble the head much enough to take the gear off (;
I've read service manual in French, but didn't find the answer.
Can anyone advise?

Pictures:


Details so far:
1a and 1b — stuck.
7 — no idea what this is, but it doesn't look like a screw.
6 — sits tight, can't take it off.
3 — apparently not a screw.

 

[AgX]

"There are a gear in the head and a gear plane (is that a correct term?"

rack & pinion



"3 — apparently not a screw"

If not a set screw, it likely is a clamping sleeve (DIN 1481) and must be driven out with a bolt (pin punch), which must fit exactly.



"Decided lately to order duplicates for both parts"

Durst no longer offer service or spares for their enlargers.
But maybe these are standard tooths, so that you could exchange them with only hassle being mounting the pinion wheel on the axle. Otherwise mounting a different rack&pinion should basically be no problem, but likely would involve more adapting hassle

 

[jvo]

that is the clearest explanation of a complicated mechanism that i still don't understand! it looks like a wonderful machine!

 

[runswithsizzers]

I am guessing that if you can remove #3 and #7, it may not be necessary to remove #1a or 1b.

Number 3 and 7 may be "roll pins" which are driven into holes drilled through the axle. I can't see well enough to be sure. Roll pins are usually hollow and have a lengthwise seam or split because they are made by rolling a sheet of metal into a tube. As AgX says, they are removed by tapping them out with a pin punch and hammer. The pin punch should be flat on the end and just a bit smaller than the pin. If the #3 and #7 go all the way through the axle, then they are most likely roll pins.

If not roll pins, I would guess cap screws which are removed with an Allen wrench. Look carefully to see if the end of the pin have a shallow, six-sided hole.

If the roll pins / set screws are removed, it may be possible that the axle can just be pulled out of whatever kind of sleeve or bearing is contained in #5. May not need to pull the axle all the way out - just enough for the pinon gear to fall off, and slip on the new gear ... ??

 

[AgX]

Number 3 and 7 may be "roll pins"

Interesting, as we Germans as indicated use the term "clamping sleeve" when communicating in English. And I found this term at US sites too. But the major dealer Mc Master does not even know it.
I foresaw that terminology issue and thus indicated the respective DIN number too.

 

[runswithsizzers]

Interesting, as we Germans as indicated use the term "clamping sleeve" when communicating in English. And I found this term at US sites too. But the major dealer Mc Master does not even know it.
I foresaw that terminology issue and thus indicated the respective DIN number too.

I probably should have checked to see if "roll pins" is commonly used. The term "spring pin" may be more common ?

Working in bicycle shops in the US, we called them roll pins. But any technical field tends to develop it's own terminology. The same tool may be called Channellocks, water pump pliers, arc joint pliers, slip joint pliers, etc. depending on who you are talking to.

I was curious about this "DIN number" - so I Googled it, and I see it is quite useful. But, working the other way (from part to number) - if I have a part, and I know it's name and dimensions - how would I find a DIN number for it?

Of course all of this is useless to the OP if he cannot find the replacement parts he needs. I wonder if 3-D printing might be a reasonable option? I have no idea how practical that technology is right now, but I have seen some amazing parts made by 3-D printers. But, with used enlargers being relatively affordable right now, it would not make sense to spend a lot of money to get a replacement part.

 

[TheMissingLink]

Don't panix, help is near! ;-)

I ordered a gear wheel for my L1200 at durst-pro-usa.com afair correctly some years ago ... It has been rather expensive with $60 or so but has been made from metall...

hth

horst

 

[AgX]

Help has gone...

That US firm, that seemingly took over from Durst quite some spares stock for commercial enlargers, went under and with it seemingly all that stock.


https://www.photrio.com/forum/threads/jens-jensen-of-durst-pro-usa.156924/

 

[Randy Stewart]

Durst Pro USA was based in a small town about 20 miles from me. It dealt only with the 4x5 and larger Durst units. It had an good reputation for years, however reduced business forced it to almost close. As of 6 months ago, it still had a website and a small business location. However the story locally is that the owner is not to be trusted, in that if you send him your gear for repair, you are likely to not get your gear or your advance payment back. As to column track pieces, they are probably the same parts as in my M800 (also M700). Durst made them out of a plastic or nylon, which is now very brittle and prone to chipping, should you happen to find NOS parts.

 

[Oxleyroad]

Do you know someone with a 3d printer?

I purchased one 2 years back and it has saved me so many times by allowing me to model the failed part/s and then print them out for everything from outdoor garden equipemnt to tools in the darkroom. The material used in the 3d printers today can be very strong and meet the purpose of the part when selected and post processed correctly.

 

[AgX]

Durst Pro USA was based in a small town about 20 miles from me. It dealt only with the 4x5 and larger Durst units. It had an good reputation for years, however reduced business forced it to almost close. As of 6 months ago, it still had a website and a small business location. However the story locally is that the owner is not to be trusted, in that if you send him your gear for repair, you are likely to not get your gear or your advance payment back. As to column track pieces, they are probably the same parts as in my M800 (also M700). Durst made them out of a plastic or nylon, which is now very brittle and prone to chipping, should you happen to find NOS parts.

The owner died and the business vanished.

 

[pavelkim]

I am guessing that if you can remove #3 and #7, it may not be necessary to remove #1a or 1b.

Number 3 and 7 may be "roll pins" which are driven into holes drilled through the axle.

"There are a gear in the head and a gear plane (is that a correct term?"
rack & pinion

"3 — apparently not a screw"
If not a set screw, it likely is a clamping sleeve (DIN 1481) and must be driven out with a bolt (pin punch), which must fit exactly.

Hello everyone,
Thank you very much for your answers! Sorry, It has been awhile since my last message.

#3 and #7 are the roll pins indeed.
Tried to take those things out, but no luck. Looks like I need a roll pin removal tool. And a roll pin insertion tool! And a couple of backup roll pins maybe.
So, there is still hope. If no one is going to buy the enlarger as is, I'll make one more attempt to fix it.

I'm still wondering why ~100kg heavy duty device has plastic gears and racks in the lift mechanism. But well..
Once again thanks for your comments, guys!

UPD: part number of that gear is AA19313

 

[AgX]

I never heard of a roll-pin removal tool. As said, use a pin punch just a tiny bit smaller than the casing hole.

However a tool that would avoid sliding laterally off, if the pin sat flush with the casing, would be a punch with a protruding pin that fits into the hole of the roll-pin.

 

[Willy T]

I never heard of a roll-pin removal tool.

Ditto.

I have removed/installed dozens of roll pins with appropriately-sized punches. I have a set of roll pin punches bought very cheaply in the 80s for $5. Amazon lists bunches of them.

 

[pavelkim]

https://ezred.com/wp-content/uploads/2013/10/PPT13_main.jpg

I just googled it, and here it is.
The main concern is that if I use a hammer, something will end up bent or more broken than it is now.

 

[AgX]

First time I see such tool. Looks like a weak version of chain rivet tool. However it got a leading point as I advised above for a specialized punch. And in contrast to a punch it does not yield lateral forces on an axle etc.

 

[pavelkim]

Hello everyone,

I finally got rid of the enlarger. Haven't fixed it, sold as is. Currently have De Vere 504 and Omega B-8 which in pair are seem to be way better option than L900.
Thanks again everybody for the support!