DIY 8x10 (or larger) Enlarger Chassis

[Ethan]

Made a few more changes. While driving home from work today, I realized that the table never needs to go above ~30 inches, and the lens stage never needs to be more than ~600mm from the negative stage. With that in mind, I split the column into two sections, one for the table, and one for the head and lens stage. Each section has a single motor and lead screw mounted to it, which drive the table on the lower section and the head on the upper section. The head now has a motor attached to it which drives a smaller lead screw for moving the lens stage up and down relative to the head. Three more benefits of this modification are that 1). It will be easier for the arduino controlling the motors to know where each stage is and prevent them from running into each other and causing damage, 2). The column can now be split into two pieces for transport. A ~3ft piece and a ~5ft piece. I did this because a lab in New Zealand contacted me asking if I would consider selling any enlargers, and I realized that even though I don't plan to build many, if someone needs it shipped, freight costs go up a bunch for objects over 8ft, which the previous column was. And finally 3). the top half can be used on its own as a wall mount enlarger.




[Edit: I'm also wondering if I want to make it any taller... the current max height from table to light source is 81.5 inches, and to make a 40x50 print distance of at least 85 inches is needed, and even though I don't anticipate printing that large any time soon, I kinda want to... on the other hand the enlarger is currently 8 feet 3 inches tall, and that's already very tall, and possibly too tall to fit in some spaces. ]

[MartinP]

Made a few more changes. While driving home from work today, I realized that the table never needs to go above ~30 inches, and the lens stage never needs to be more than ~600mm from the negative stage. With that in mind, I split the column into two sections, one for the table, and one for the head and lens stage. Each section has a single motor and lead screw mounted to it, which drive the table on the lower section and the head on the upper section. The head now has a motor attached to it which drives a smaller lead screw for moving the lens stage up and down relative to the head. Three more benefits of this modification are that 1). It will be easier for the arduino controlling the motors to know where each stage is and prevent them from running into each other and causing damage, 2). The column can now be split into two pieces for transport. A ~3ft piece and a ~5ft piece. I did this because a lab in New Zealand contacted me asking if I would consider selling any enlargers, and I realized that even though I don't plan to build many, if someone needs it shipped, freight costs go up a bunch for objects over 8ft, which the previous column was. And finally 3). the top half can be used on its own as a wall mount enlarger.




[Edit: I'm also wondering if I want to make it any taller... the current max height from table to light source is 81.5 inches, and to make a 40x50 print distance of at least 85 inches is needed, and even though I don't anticipate printing that large any time soon, I kinda want to... on the other hand the enlarger is currently 8 feet 3 inches tall, and that's already very tall, and possibly too tall to fit in some spaces. ]

As well as the driving-leadscrews I assume that you have a head counterweight, maybe moving vertically somewhere at the back via wire-rope and a pulley ? And, indeed, a table counterweight too.

[ic-racer]

Ethan will have his own answer, but Durst enlargers of this design do NOT have a counterweight for either the table or head. The drive screw does all the work. Just like a drivescrew jack; no help.

[Ethan]

As well as the driving-leadscrews I assume that you have a head counterweight, maybe moving vertically somewhere at the back via wire-rope and a pulley ? And, indeed, a table counterweight too.

Ic-racer is correct, there aren’t any counterweights. Each stage has rollers which should keep any sideways torque off of the lead screw, so the only force on it will be the downwards force of gravity. LED heads are much less weight compared to traditional as well, so a somewhat large but not giant stepper motor should have enough power to drive the stages up and down

[Drew Bedo]

I haven't read most of these 7pages so this may be redundant.

I recall seeing a video of Ansel Adams working. It showed him using a horizontal enlarger that looked to be based on a view camera. Perhaps an old wooden view camera could be the basis for this project. The issues of illumination and diffusion/condenser etc would be the same, but the basic body of the best would already be there.

Put the thing on a moving carriage or stand and the print size can be as large as your wall space and the length of the room allow.

[Ethan]

I haven't read most of these 7pages so this may be redundant.

I recall seeing a video of Ansel Adams working. It showed him using a horizontal enlarger that looked to be based on a view camera. Perhaps an old wooden view camera could be the basis for this project. The issues of illumination and diffusion/condenser etc would be the same, but the basic body of the best would already be there.

Put the thing on a moving carriage or stand and the print size can be as large as your wall space and the length of the room allow.

That definitely is a great way to get into enlarging 8x10, but I’ve already got a wall mount 8x10 enlarger, and am designing this as an upgrade to that.

On another note, I’ve seen that video as well, but haven’t been able to find it recently. Do you recall which site it is on?

[Ethan]

I think the design is nearly complete, at least the basic parts of it. Now comes the slightly less exciting (to me, anyway) part of figuring out all the details like how cables will be run and where holes will be drilled.

[Ethan]

I just finished modeling screw/bolt holes, and adding other bits and pieces that were missing from the design. I'm using almost all 1/4-20 screws, with the exceptions being mounting bolts for the motors and casters, which are metric. in the CAD model, the screw holes are either 0.25 inches for clearance or 0.201 for tapping. with all the screws and other small bits added to the parts lists, the build is a bit more expensive than I had hoped for / expected, but still below the cost of any other floor standing 8x10 enlarger. With the screw holes modeled, the CAD file is now complete I believe, so I am posting a link to it here if any of you want to download it. The file can be found in this google folder:

https://drive.google.com/drive/folders/1G_CSomiwuKtxWzlYbO0SuIc06Ij5QKUd?usp=sharing


All thats left now is to start building it! If there are any issues I come across while building, I will change the CAD model to fix it and re upload it. I'll also try to make an assembly instructions pdf once I finish it.






[edit: another note about the CAD file, I didn't fully model the power supplies and motor controllers / LED controllers, the power supplies are the green blocks and the controllers are the blue blocks]

[MartinP]

Ic-racer is correct, there aren’t any counterweights. Each stage has rollers which should keep any sideways torque off of the lead screw, so the only force on it will be the downwards force of gravity. LED heads are much less weight compared to traditional as well, so a somewhat large but not giant stepper motor should have enough power to drive the stages up and down

Aha, I missed that there are no huge heavy condenser lenses. Oops. I look forwards to seeing how it turns out

[Ethan]

I didn't get started on the electronics yet, as I decided to re design the light source a bit. My new design uses less expensive and slightly less powerful LEDs, but more of them allow for more even light with a smaller diffusion chamber, which should mean more of the light is projected through the negative and less is lost to reflections inside the head. This is my layout plan for the LEDs, there will be 32 blue 450nm LEDs, 32 green 527nm LEDs, and 31 red 660nm LEDs. I wish there were a green LED closer to 550nm, but as far as I can tell that's a blank spot in the LED range currently. The grey rectangle represents the 9x11 piece of diffusion acrylic which I want even illumination over.