3D printed 8x10 film holder

[jimskelton]

I've been on a roll designing film holders for 4x5 and 5x7 that can be 3d printed. I think the most difficult challenge is what I refer to as the pressure plate, which puts pressure onto the dark slide at the opening. The difficulty is making a design where you can install felt at the opening for a light seal, then installing the "pressure plate" over it to hold the dark slide against the light seal. I ended up designing a cap which slips onto the end and over the felt and that seems to work well with 4x5 and even 5x7.

Which brings me to 8x10. Using the dimensions from https://lf.animaux.de/filmholders , I designed an 8x10 holder with the same end cap as the 4x5 and 5x7 holders. Because 8x10 holders are quite large (296mm on end), and most 3d printers don't print that large, I cut the main body into two and put a tongue and groove into the body to help make it stronger, as well as an overlap on the side to help seal out light. If you orient the holder at 45 degrees on the 3d printer plate, it should fit within a 220mm square build area (Ender3 V3). I've printed film holder rails in the past at 45 degrees and the extrusions are smooth so it works fine (I still use 5x7 holders printed this way).

I would recommend printing as strong as possible: 4-5 walls and 100% infill. My slicer says it will take 450g of filament! So estimated cost of around $10. Even on my bambu printer, it estimated 14 hours, so I haven't printed it yet. If anyone wants to try, it's on thingiverse: https://www.thingiverse.com/thing:6289831

[Kiwi7475]

Looks interesting; what are you doing for the dark slide?

[Graham Patterson]

You must be printing vertically - there's no way to do those slots with supports using a filament printer. Since there is no end flap, what is the clearance at the end of the film for extracting it? There are no finger recesses.

It looks like the notch code will have to be at the light trap end to be readable by touch (sometimes it is necessary to check what is in a holder 8-) ).

The dark slide material will be the make/break issue. I don't see the 4x5/5x7 holders under your ID on Thingiverse, so I don't know what you are using.

It would have to be split in to three sections to fit my printer 200mm build height. I think the results might be better printing three short sections plus cap rather than going right up to the maximum. Tall and narrow parts magnify any issues with alignment and clearance.

The cap approach seems an interesting alternative to the finger springs used in commercial holders. Is there a risk that the felt will catch when the dark slide is reinserted?

[ic-racer]

I was going to order to have some of these printed in black resin by JLC 3D. I got nice results from them in the past.
I can't figure out what is going on with the pricing. Is there something in the larger part's file that makes it $227, whereas the smaller part is only a dollar? It is not like it is 200 times bigger.

[jimskelton]

So yes, they are designed to print vertically. I'm not sure what you mean by finger recess...

Yeah, dark slides are tricky. I haven't printed one of these yet, so I'm note sure what I would use for a dark slide, though I do have a stiff vinyl folio cover that might work. Or, a piece of tin or 1.5m aluminum.

That's a good point as far as splitting the print. Maybe I'll make a couple of versions--one split in half so it'll only have to print 150mm high, and another that'll print 100mm sections.

And so far the felt hasn't caught, but thanks for pointing out that potential problem. I'll fillet the surface where the felt is at the opening so there's a gentle transition between the felt and dark slide. I just saw someone's idea of using repelling magnets and a light trap to push against the dark slide so am thinking about how to improve this, but I'd like to keep it simple but effective.

The 4x5 and 5x7 holders on thingiverse are nonstandard. The 4x5 ones are smaller to fit in the profile of Polaroid cameras (so the back doesn't stick out of the sides of the camera), and the 5x7 was made for a home made camera. Both are more narrow than a standard holder.

[jimskelton]

Wow! that's pretty expensive. It does take almost 1/2Kg of filament, and it ties up a printer for a long time. I was thinking this could be economical, but $227 could go toward a few used 8x10 film holders!

I was going to order to have some of these printed in black resin by JLC 3D. I got nice results from them in the past.
I can't figure out what is going on with the pricing. Is there something in the larger part's file that makes it $227, whereas the smaller part is only a dollar? It is not like it is 200 times bigger.

[jimskelton]

I would use either tin or aluminum, or thicker folio vinyl if you can find it.

Looks interesting; what are you doing for the dark slide?

[Graham Patterson]

The cut outs are needed to get your fingers under the film to ease it out. The Fidelity ones have them under the flaps.

Zebra wet plates v2 put in a finger notch to get the plates out. The seem to have a source of carbon fiber sheet for dark slides. A quick look at retail suggests the 9x13 (roughly) size needed for a dark slide is rare.

I looked at doing 8x10 holders a while back, but concentrated on using finger springs in the light traps and doing the sides and ends separately. Dropping the flaps is interesting, but I wonder how much curve is required to load the film without them.

I think the concept is sound, I just ask about some practical issues. Look for the Zebra wet plate video on YouTube. It might be interesting.

(I’m on an iPad tonight - have to be brief)

[jimskelton]

This isn't a plate holder--but getting the film out is an issue. I normally use a plastic spatula like tool to ease the film up so I can grab it, but I'll look at those finger notches--sounds like a great idea.

And the 8x10 holders I've done in the past were build non-standard out of wood using separate sides and ends. I'm thinking of separating out the sides/ends because they are the most critical thing to get right. The body of the film holder can be made out of whatever material is the right width/strength and doesn't need to be printed (that probably alone needs 250 grams or so of filament).

I don't know anything about wet plate, but in looking at zebra (or Robert Beiber's at https://www.printables.com/model/239...late-holder-v4) I really like the design, especially the repelling magnets used for the light trap!

The cut outs are needed to get your fingers under the film to ease it out. The Fidelity ones have them under the flaps.

Zebra wet plates v2 put in a finger notch to get the plates out. The seem to have a source of carbon fiber sheet for dark slides. A quick look at retail suggests the 9x13 (roughly) size needed for a dark slide is rare.

I looked at doing 8x10 holders a while back, but concentrated on using finger springs in the light traps and doing the sides and ends separately. Dropping the flaps is interesting, but I wonder how much curve is required to load the film without them.

I think the concept is sound, I just ask about some practical issues. Look for the Zebra wet plate video on YouTube. It might be interesting.

(I’m on an iPad tonight - have to be brief)

[malexand]

Here's my version of 3-D plate holder - this a 5x7 I designed and printed this summer. I based it off my 1903 wooden holders. Parts are printed to mimic the slotted wood, including joinery that creates light tight glue joints. I use garolite for the septum, currently using existing 5x7 filmholder darkslides, but I have garolite waiting to be cut for future holders. The light trap is a strip of black velvet ribbon glued to a strip of aluminum, glued into the printed slots. All glued with CA or 'super-glue'
I printed up a dozen and have used them quite a bit - I don't baby them. Took them camping.. Even the grey proto-types I made have proved light-tight. If my life were more organized I might get it posted to Thigaverse someday...