Designing and 3D printing an slotted Graflex film holder

[Ramiro Elena]

It has been several months that I have unsuccessfully tried to find slotted 4x5 Graflex film holders for the RB. Until it hit me I could probably copy one in a simple 3D design software. After all it doesn't seem there are very many parts.

The printing could go two ways. One could be making it in wood with an X-carve type of machine. The other would be using a 3D printer for which the more appropriate material should be used (I am thinking light safe).

Any ideas to which would work best? I would have to dig into figuring out the 3D software first.
As for the patent, once designed, could the template be shared for free without incurring in illegalities?

Good day!

[Pere Casals]

It has been several months that I have unsuccessfully tried to find slotted 4x5 Graflex film holders for the RB. Until it hit me I could probably copy one in a simple 3D design software. After all it doesn't seem there are very many parts.

The printing could go two ways. One could be making it in wood with an X-carve type of machine. The other would be using a 3D printer for which the more appropriate material should be used (I am thinking light safe).

Any ideas to which would work best? I would have to dig into figuring out the 3D software first.
As for the patent, once designed, could the template be shared for free without incurring in illegalities?

Good day!

Hola Ramiro,

Let me point the 3 options I use for similar applications, (including the DP holders I've in course) :

1) Print in it black ABS, if you have your own printer think that ABS is a bit tricky to print with, you need a hot bed and adjusting well temperatures. Remember to adjust scale, in the slicer software (Cura...) remember to scale up the object size because the hot part (240ºC) suffers some 1% contraction when it colds, so you have to measure a test print to adjust the right scale.

I the UPC there is a proficient printing service at good price.


2) Rather than printing the part you can print a mold of the part in Polyethylene, then you spray in an anti-adherent, and you fill it with a technical resin (polyester, polyurethane...), I've been buying here (formx) http://formx.es/contacto.php (bcn) and to Feroca (Mad), in the resin you can mix black dye and cut fiberglass, resulting a reinforced plastic. You can also put metal inserts in the mold (perforated platings...) before dumping the resin to get top notch technical parts. This is a good choice if you are to make a number of copies, with the right resin-catalyzer you can demold the parts in 10min, and reuse the mold.

3) For parts that can be hard to demold because geometry, you can print the part itself and then making a silicon mold that you will fill with the technical resin+catalyzer.


Working with molds also allows you to polish the surfaces for a nice finishing, but ABS prints are also quite strong, for holders think that later inserting a metalic plating to work as septum is a good idea, this will correct any bend in the part that resulted from thermal contraction.

Feel free to PM me in any doubt if I can help

Salutacions

[Ramiro Elena]

Hola Pere,
I think I am leaning more towards wood carving with a CNC machine. As you say, 3D printing will probably give more professional results but it might also be more complicated and expensive.
I am trying to measure the holder and figure out the least amount of parts needed. I see a central core measuring 121x169x6mm + two frames on each side that attach to the central core + the two bottom flaps attached to the holder with black tape. The remaining parts would be the two dark slides.
There's film I need to process still inside the one film holder I have, so I'll need to figure out how the film rests inside the holder still.

I don't know much about 3D printing, hopefully, the sketch I make can be used to 3D print too.

[Pere Casals]

About price, ABS filament it can be 16€ for 1Kg, then you need a printer, today a good enough Prusa i3, ABS capable, it can be found 166€ (see Anet A8, amazon, ). Single problem with a 3D printer is having to spend some 20h learning to obtain decent prints.

Anyway wood is an exellent material, but with wood you also need to select well the raw material, if not wood may bend with humidity changes.

In my design of a DP holder I've replaced the two bottom flaps by a 3rd dark slide, just an idea:





For your design, rather than milling from a solid block you can mill the profiles, like this:



And then making a frame with 4 profiles. ...and inserting an alluminium plating (septum) in the central groove, that plating should ensure flatness...

If you mill the profiles you don't need a CNC machine, it can be done with any brico machine able to make slots.

Also there is no need you mill it from wood, you can take a block of plastic, I'd recommend POM type (Acetal , https://en.wikipedia.org/wiki/Polyoxymethylene), it is easy to mill and a very good material. (I buy POM bars at BRONCESVAL S.L. Broncesval Catalunya, Pol. Ind. Molí dén Xec Can Barneda, 5 (Junto Baricentro), 08291, Ripollet Tel. 93 565 10 70).

If instead milling it, if you want a custom plastic profile you can order it here: Masanes Servindustria C/ A 13-15 Moli dels Frares, 08620 Sant Vicenç dels Horts Teléfono: 936 72 48 18

You just give them a drawing of the profile, say the material and how many meters, in 3 days you'll have it, made with tight tolerance...

[Ramiro Elena]

Thank you Pere, lots of very good information. I had no idea 3D printers were that cheap. I might have to reconsider that option. The question is if ABS is light safe.
Also, POM sounds a lot easier than wood for cutting and routing. I might go several ways with this...
I don't know anything about 3D software so I guess I'll spend some time trying to figure this out.
Nice to have someone near with so much good information

[Pere Casals]

Thank you Pere, lots of very good information. I had no idea 3D printers were that cheap. I might have to reconsider that option. The question is if ABS is light safe.
Also, POM sounds a lot easier than wood for cutting and routing. I might go several ways with this...
I don't know anything about 3D software so I guess I'll spend some time trying to figure this out.
Nice to have someone near with so much good information

Yes, ABS is light safe if it's black, I made a Sinar lensboard to CAMBO receptacle adapter in ABS, it's opaque and it takes a 2kg Symmar 360 convertible, and a lensboard for a LOMO O-2 600mm, it works perfect.

[el french]

I use Fusion 360 for 3d modeling. It can create either gcode for CNC machining or stl files for 3d printing. The price is reasonable (free) Do you have any specs for the film holder?

[Ramiro Elena]

I'll give that a look el french, thanks!
Here's what I have so far. Still figuring out how to continue with the design. This is just a sketch I made for Pere. The idea is to use old bag magazine septums attached to the central piece (green).


Graflex-RB-Film-Holder-measurements2 by Ramiro Elena, on Flickr


Graflex-RB-Film-Holder-measurements3 by Ramiro Elena, on Flickr