This is my attempt to re-engineer my old 6x12 rollfilm back into a scalable and adaptable design for large format cameras (4x5", 5x7", maybe 8x10"). _
As a starting point - here's my old 6x12 TinkerCAD-design: https://www.thingiverse.com/thing:2894651
- of course a 3d printable and usable rollfilm back.
- different formats possible with type 120 rollfilm - from 6x6 up to 6x24 (depending on the targeted camera format)
- The design should be scalable for being used with 4x5", 5x7" or even 8x10" large format cameras by just changing a handful of variables. I am not targeting medium format cameras/platforms like Mamiya RB/RZ, Bronica EC/GS/SQ/ETR, Hasselblad, Kiev88, Horseman 6x9, Graflex 2x3, Fuji GX or any other format smaller than 4x5". It may be possible to scale down and fit the design to some 6x9/2x3" platforms, but I won't make any changes just for scaling down.
- Improving my OpenSCAD skills. Learning to use it efficiently. Learning to do good parametric development/design.
- Learning git/github and sharing my code with other people
- Checking out the limits of home 3D printing with a very limited set of available tools
- modular+parametric design
- all parts must be either 3D-printable or easily available via Amazon, eBay, Aliexpress or Temu.
- no special tools required besides a decent 3D printer and some common tools like little files, screwdrivers, sanding paper, cutter, scissors, ...
- no exotic third party parts/components
- form follows function
- KISS
- keeping the basic concepts of my old 6x12 back
- no explicit pressure plate
- film "rollers" are fixed because it's easier to keep the measures/tolerances
- parts for the base plate won't be glued (except dark slide light seal) ==> dovetails
- film "roller"/re-director will be integrated and printed
- less "cubical" design than first version; maybe even flat enough to slide the back under the ground glass
- using the excellent BOSL2 library https://github.com/revarbat/BOSL2/wiki
- no "extension" over the targeted platform and thus avoiding to move the film plane back (and using spacers or dedicated ground glassses): max format for 4x5" will be 6x12, max format for 5x7" will be 6x17
- looks like it will be a bit more re-engineering than just "porting" my old design to OpenSCAD. After having a look at some other (commercial) roll film backs like the Super Rollex or the Toyo family, I will also use some inspirations from there.
- I always wanted to ge rid of the screws for locking cover and baseplate together, so I am now locking cover, baseplate_top and baseplate_bottom via dovetails.
- currently missing / not yet (re-) designed:
- advancing lever ==> I am currently evaluating different ratchet mechanisms/designs
- spool holders ==> will be quite simple parts
- film counter ==> for the first version I will stick to the "spy window"
- light seal for the baseplate bottom, but this is just a simple cubical to be glued into the base plate
- STLs. I didn't print any parts yet and it will probably take one or two itereations for all the tolerances to match.
- printable parts are almost complete
- avancing lever is derived from a little ratchet tool
- film insert and cover got a counter window
- film insert is prepared for a unrolling preventer (to be made of spring steel wire)
- I am progressing with winders and spool holders
- now it's time for lots of test printing.
- first test prints of the back plate revealed some small glitches (already fixed).
- first complete prototype will hopefully available by the upcoming weekend...
- meanwhile I printed all major parts.
- the parts are fitting together, but showed the need for minor fixes/improvements (mostly printing related)
- next iteration is leaving "mockup" stage and should be able to perform the basic mechanical functions (film loading, film advancing, disassembling without tools)
- clearance for the film spool inside the film insert was too tight (already fixed)
- replaced some cube() objects with cuboid() from the BOSL2 library to round some edges (already done)
- test with printed dark slide instead of sheet metal (cutting a raft from one of the prints), added file for printed dark slide
- printing related optimizations
- some minor parts are still missing: back plate light seal, winder blade, knob for film spool missing, lid for film counter window
Some very kind people asked me about the possibility to show their appreciation by donating to me.
If you really felt somehow obliged to do so, then you should use https://paypal.me/EdgarKech :-) . But I am also happy if you post pictures of your build to https://www.facebook.com/groups/3dprinting.and.analog.photography/