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Material and Thickness selection of 3D Print Super 8 Developing tank

CrazyCockatoo

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Sep 5, 2024
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74
Location
Sydney, Australia
Format
35mm
Hi guys,

I plan to 3D print a super 8 developing tank to process tri-x reversal at home, and I need some advice on which material to use. My choice is https://www.printables.com/model/1414937-super-8-8mm-16mm-film-development-tank-and-spiral

I have black PLA and PETG-HF on hand. Black, white and transparent (PETG) . Currently I plan to print the reel with clear petg so it would allow easier fogging during reversal. But not sure should I use PLA or PETG for the tank and center core, I know ABS would be better option but my printer can't print it. Anyone have ideas on which one to choose?

Thanks for your reply in advance
 
I've used both PLA and PETG in standard b&w and c41 processes without issue. I haven't tested either with bleaches. Keep in mind that 3D printed parts are generally not watertight and can get some chemistry inside them. Printing with 100% infill or sealing the parts after printing are about the only ways to avoid that.
 
Agreed. I've used plain PLA for non standard reels without issue, however 100% watertightness for a tank etc. is a whole other matter. I haven't had any real problems with PLA on self-watering planter pots and trays using the recommended settings, however plain cold water won't test a print like warm dev or bleach.

Don't be shy on infill, you'll probably need to experiment with other settings (wall thickness, flow rate) or consider coating the inside of the tank with some kind of sealing product. Good luck with it... I'm actually working through a spiral reel design to fit in a Jobo 2830 tank. Would love to be able to dev and scan my own Super 8 at home without selling an organ every time ;-)
 

I plan to use 100% Infill for the tank to block light, so it won't be an issue. I do BW reversal which is at 20 celcius so it should last without any problems.

Will Bleach corrode or dissolve pla or petg？

for watertight at the lid I think the tank is designed that you turn the handle on top to agitate rather than inversion or roll so not really important.

I'll use .4mm nozzle for tank and .2mm nozzle for the reel in order to prevent scratches
 
CrazyCockatoo said:
Will Bleach corrode or dissolve pla or petg？
Click to expand...

I recently printed a 110 reel in PLA+ and it's survived two C41 processes thus far. Not sure how it'll go long term, but as I wash the snot out of all my equipment with hot water to limit issues with chem residue messing with my overpriced German plasticware, so that can't hurt.
 
PLA will be attacked by water over time. But a developing tank and reels do not actually spend that many hours wet over their lifetime. Given the choice, PETG would be better in terms water resistance. I use PETG and ABS for things I expect to get wet. PLA has one characteristic in its favour - it is the most rigid of the common filaments, though that should not be critical in this case. PETG is slightly flexible by comparison.

If you are using the common 0.4mm nozzle, then I'd suggest looking at a minimum of three walls (1.2mm) of black filament, and four walls (1.6mm) if the design permits. The same applies to top and bottom layers, scaled,, where you will probably be in the 0.2mm layer range. Be careful if your design features walls that curve onto tops as the radial thickness can turn out to be less than the XYZ axis thickness. Make sure your print speed and extruding temperature permit good layer adhesion to avoid voids and porosity.

When I used to do transparency processing I used to transfer the reels to a white bowl with water at process temperature in order to blast them with light, and I turned the reels over half way through. Transparent filament rarely prints really transparent, but it will pass more light than white.

There are some newer PLA (+ or Pro) versions from some manufacturers that are supposed to have better heat and moisture resistance.
 
grahamp said:
PLA will be attacked by water over time. [snip]
Click to expand...

Maybe eSUN PLA+ is premium stuff, but I have probably half a dozen self-watering pots approaching 2 years old that have always had some amount of water in them, and no leaks or decay yet.

One planter has been moved outside to save the plant (damn cat) so I'm curious how much the UV exposure will affect it.
 
benderscameracorner said:
Maybe eSUN PLA+ is premium stuff, but I have probably half a dozen self-watering pots approaching 2 years old that have always had some amount of water in them, and no leaks or decay yet.
Click to expand...
PLA+ has additives to make it less hygroscopic which should help with stability, and the breakdown process is already slow at room temperature
 
I would also like to know this as well, I have a 70mm processing tank I would like to make. Designing these things is not an easy task…
 

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I think I would print the reels with 0.2mm with 100% infill, while the tank body will use 0.4mm nozzle with 2mm wall, to make it more secure maybe.

I have an exposed kodachrome film coming in a camera I've bought before, I've done a snip test and results looks fine. Maybe I'll use it as a test and see if there's any issues, so if anything went wrong it won't ruin my important films
 
grahamp said:
There are some newer PLA (+ or Pro) versions from some manufacturers that are supposed to have better heat and moisture resistance.
Click to expand...

thinkbrown said:
PLA+ has additives to make it less hygroscopic which should help with stability, and the breakdown process is already slow at room temperature
Click to expand...
Mine is Bambu lab pla basic, but I've ordered PETG HF and transparent (clear) PETG for the reels, should arrive today
 
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