Making a replica of Durst RCP 20

[arturo_rs]

Hello everyone, I need your help.


I’m planning to build a functional replica of a Durst RCP20.


The starting point, I want to reproduce the gears that drive the rollers, since this seems to be the most complex part.


Based on the photos I have, I can identify at least four different types of gears (possibly five or six), but I’m missing key dimensions to move forward.


Also, I would need:

• The outer diameter of the gears
• The number of teeth

If anyone has access to a machine and could take these measurements, or provide any additional technical information, it would be extremely helpful.


Any advice or insights are also very welcome.


Thank you.

I am going to print with a 3d printer. The material of the gears will be PETG.

I also have the other materials planned.

 

[arturo_rs]

The rollers will be made of stainless steel 304 or 316, also acrylic tube and FKM or PTFE in contact with the chemicals.

 

[koraks]

Why would you want to replicate it exactly? Do you have a donor machine to use as a basis, is that it?

What are you going to use for the rollers?

Perhaps somewhere over the weekend I can send you the numbers you're looking for.

 

[arturo_rs]

Why would you want to replicate it exactly? Do you have a donor machine to use as a basis, is that it?

What are you going to use for the rollers?

Perhaps somewhere over the weekend I can send you the numbers you're looking for.

I’m tired of developing RA-4 paper using my Jobo tank—sheet by sheet. I’ve been thinking about starting this project for a long time, but I never quite committed to it.


A few months ago I saw that a fellow forum member, @elgatosuizo, was making a replica of the Durst Printo, and that got me interested.


I don’t have anything yet—just photos and videos taken from different angles that I found online. From my point of view, it’s simpler than the Printo.


The first hurdle is the gears—their dimensions.


I’m planning to use PETG for the gears. Although it has decent chemical resistance, I know I’ll eventually have to replace them. That’s not an issue.


Then there are the rollers. They’re built in layers:

1. Base – A 6 to 10 mm rod made of 316 stainless steel
2. Intermediate – An acrylic tube to increase the diameter, bonded to the metal rod with epoxy
3. Outer layer (in contact with the chemicals) – Latex rubber becomes sticky over time. I’m considering NBR, EPDM, or PTFE tubing—the last one is the most chemically resistant

I should be able to reach a final diameter of 16 to 20 mm.


After that, I’ll move on to the bushings and the springs that apply pressure to the rollers

 

[arturo_rs]

Perhaps somewhere over the weekend I can send you the numbers you're looking for.

The more data and measurements, the better. Thank you

 

[koraks]

Honestly, if you're starting from scratch, I'd not try to replicate an RCP20. Where will you get the housing? The shape of the baths is essential to its 'fuel economy' so to speak. That's not something I'd suggest printing, either.

Given the massive amount of time you'll end up spending on this project, I honestly think the most sane approach would be to actively search for an existing machine. They're around; it takes time to find one, but sooner of later you'll likely get lucky.

 

[thinkbrown]

https://www.cameradactyl.com/mastersystem/p/mastersystemprocessor it may be worth consulting some of the development videos Ethan Moses has posted about his modular photo processor. There's a lot of good info there

 

[mshchem]

You need to get a couple 1 gallon SS tanks and print baskets or 8x10 film hangers. Two 8x10 sheets back to in a hanger 3 hangers at a time. Six prints. Develop, stop, blix in 2 minutes wash for a minute or so.
I have a RCP-20, I use it more for black and white snapshot/postcards. It's great for printing smaller prints when you're trying to determine exposures etc.

I always allow for 45 minutes to clean up. You cannot leave chemistry in these overnight

 

[arturo_rs]

Honestly, if you're starting from scratch, I'd not try to replicate an RCP20. Where will you get the housing? The shape of the baths is essential to its 'fuel economy' so to speak. That's not something I'd suggest printing, either.

Given the massive amount of time you'll end up spending on this project, I honestly think the most sane approach would be to actively search for an existing machine. They're around; it takes time to find one, but sooner of later you'll likely get lucky.

Maybe you´re right.

I've been thinking about gears for several weeks now, and that's just the beginning.

 

[arturo_rs]

You cannot leave chemistry in these overnight

I know. When not used it has to be clean

 

[arturo_rs]

I´ve been searching other machines. I found the Colenta. At least the pdf helps.

 

[arturo_rs]

I think I should, using the information provided by photos and videos of other machines, create one from scratch.

I shouldn’t insist on making a replica, but rather something new—modular and as simple as possible.

 

[arturo_rs]

https://www.cameradactyl.com/mastersystem/p/mastersystemprocessor it may be worth consulting some of the development videos Ethan Moses has posted about his modular photo processor. There's a lot of good info there

Yes, I saw that too at the beginning of this.

The video:



I like that it uses helical gears instead of spur gears, the bushings are good too (a plastic piece). The rubber bands are very good and simple solution.

What not liked is the heat shrink tubing. In contact with the chems becomes brittle.

 

[mshchem]

Yes, I saw that too at the beginning of this.

The video:



I like that it uses helical gears instead of spur gears, the bushings are good too (a plastic piece). The rubber bands are very good and simple solution.

What not liked is the heat shrink tubing. In contact with the chems becomes brittle.

Kinda neat, but looks like Legos. Ask oneself, do you want to spend your time building equipment or making prints?
All you really need with RA-4 is a tray and warm chemistry. I use a couple different machines.

Slot processor like a Nova are lovely. Jobo tubes are so expensive anymore. If you had a dozen tubes that would be a way.

 

[thinkbrown]

Kinda neat, but looks like Legos. Ask oneself, do you want to spend your time building equipment or making prints?

Both? I love photography but if I didn't want to tinker I'd just shoot digitally and print on a modern inkjet.

 

[arturo_rs]

Kinda neat, but looks like Legos. Ask oneself, do you want to spend your time building equipment or making prints?
All you really need with RA-4 is a tray and warm chemistry. I use a couple different machines.

Slot processor like a Nova are lovely. Jobo tubes are so expensive anymore. If you had a dozen tubes that would be a way.

I don´t make 2 or 3 prints. I make the full 35mm roll of 36 exp. I have, in 3 weeks 180 photos waiting to be printed (20x30cm) and counting. So, the trays or the Nova are not an option.

I know not everyone has the ambition to create something new. I'm a nonconformist who wants to surpass themselves.

What's available isn't enough for me; I want more.

I've made some other projects, like a darkroom timer. My latest is the second version, a fully equipped 10x10cm box.

So, I want both: making prints and building a machine, and I am gonna make it.

 

[mshchem]

Both? I love photography but if I didn't want to tinker I'd just shoot digitally and print on a modern inkjet.

I love building darkrooms as much as using them.

One thing I thought of. Have you considered a hand crank? Not sure if this would help?

 

[mshchem]

I don´t make 2 or 3 prints. I make the full 35mm roll of 36 exp. I have, in 3 weeks 180 photos waiting to be printed (20x30cm) and counting. So, the trays or the Nova are not an option.

I know not everyone has the ambition to create something new. I'm a nonconformist who wants to surpass themselves.

What's available isn't enough for me; I want more.

I've made some other projects, like a darkroom timer. My latest is the second version, a fully equipped 10x10cm box.

So, I want both: making prints and building a machine.

I have a roll easel I need to get going. Allows you to expose 1 after the next, then feed the strip through your roller transport machine. I just need to get off my duff.

 

[halfaman]

I don´t make 2 or 3 prints. I make the full 35mm roll of 36 exp. I have, in 3 weeks 180 photos waiting to be printed (20x30cm) and counting. So, the trays or the Nova are not an option.

I know not everyone has the ambition to create something new. I'm a nonconformist who wants to surpass themselves.

What's available isn't enough for me; I want more.

I've made some other projects, like a darkroom timer. My latest is the second version, a fully equipped 10x10cm box.

So, I want both: making prints and building a machine, and I am gonna make it.

Probably you already know but I will say it anyway. You can develop more than one sheet per run with the appropiate Jobo tank. You can process two 24x30 cm sheets with the 2850 tank and four sheets per run with the Expert 3063. Both are huge tanks (I have the 2850), you need a Jobo CPA/CPP/ATL to fit them, and the Expert is pricey while not prohibitive. The chemical use per run is the same or less than developing individual sheets with a 2830 tank.

I personally processed two 20x25 cm sheets with the usual 2830 tank for a photo I must print several times and it worked really well.

 

[arturo_rs]

Probably you already know but I will say it anyway. You can develop more than one sheet per run with the appropiate Jobo tank. You can process two 24x30 cm sheets with the 2850 tank and four sheets per run with the Expert 3063. Both are huge tanks (I have the 2850), you need a Jobo CPA/CPP/ATL to fit them, and the Expert is pricey while not prohibitive. The chemical use per run is the same or less than developing individual sheets with a 2830 tank.

I personally processed two 20x25 cm sheets with the usual 2830 tank for a photo I must print several times and it worked really well.

Yes, I know it. Also I build a “thing” using pvc pipe for developing 2 sheets of my jobo (1510+1530+1530) at once.

It’s not enough

 

[koraks]

I shouldn’t insist on making a replica, but rather something new—modular and as simple as possible.

I would follow the same approach, really, if I absolutely had to build something to begin with. Take inspiration of the existing machines out there, then combine concepts into something that suits your particular use case.

But...@mshchem nailed it here:

do you want to spend your time building equipment or making prints?

 

[arturo_rs]

I’m also researching the internal transport rollers of inkjet and laser printers—their parts, components, and how they work.

 

[arturo_rs]

I think that I am gonna post, in this post, information about the parts, how do they work and what are made of, in case it helps anyone.

The external part of some rollers are made of PVA — Polyvinyl Alcohol

AION PVA Sponge Rollers ｜ AION Co.,Ltd.

Utilized for many years in a variety of industries, our PVA sponge rollers are valued for their outstanding moisture-wicking capability and drying performance. In addition to enabling continuous moisture wicking with simple machinery for pressing the sponge rollers against and rotating them...

www.aion-kk.co.jp

 

[mshchem]

I think that I am gonna post, in this post, information about the parts, how do they work? and what are made of, in case it helps anyone.

The external part of some rollers are made of PVA — Polyvinyl Alcohol

AION PVA Sponge Rollers ｜ AION Co.,Ltd.

Utilized for many years in a variety of industries, our PVA sponge rollers are valued for their outstanding moisture-wicking capability and drying performance. In addition to enabling continuous moisture wicking with simple machinery for pressing the sponge rollers against and rotating them...

www.aion-kk.co.jp

View attachment 423915

This is great information. I think the key is finding parts. Try to assemble not fabricate whenever possible.

 

[arturo_rs]

An this document of the Fujimoto CP-31 is
the best I’ve found today.

I recommend you to take a look is your interested what are the parts, even the screws!

1 document in 4 parts.

Also a few photos