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terraPin Box Turtle 4X5 Pinhole Camera

by schlem, published

terraPin Box Turtle 4X5 Pinhole Camera by schlem Apr 1, 2017

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Tinkercad

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Thing Statistics

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Summary

One Sheet; One Shot!

The terraPin Box Turtle is designed for 4X5 sheet film or photographic paper and consists of only four 3Dprinted parts. The front and back halves slide together to sandwich a sheet of film 75 mm (or 35mm) from the pinhole. The shutter is designed around four (4) rare earth magnets, 8mm x 3mm, that hold the shutter in place and work as pivot points when snapping the shutter open or closed. Behind the shutter, the pinhole is mounted with a locking cam-clamp.

All photos by Moni Smith using either Fujifilm Neopan Acros 100 B&W film, or Kodak Ektar color negative film.

Expanded information and instructions coming soon!

Box Turtle 75
focal length 75 mm
pinhole 0.30 mm diameter
f/256

Box Turtle 35
focal length 35mm
pinhole 0.20 mm diameter
f/215 (nominal)

Photos are of early prototype, STLs differ in detail.

NOTES

  • Added 35mm wide angle version
  • Revised shutter and pinhole_clamp to work with both 75 and 35mm versions
  • Added some light-trapping to front of camera, to minimize light leaks from box joint.
  • Added small indexing pips to hold pinhole_clamp in position w/o glue

ATTENTION
This work is licensed under the Creative Commons - Attribution - Non-Commercial license. This license applies only to the files and documents available for download from the Thing Files section of this Thing.
All other related content (photographs, videos, and verbiage such as contained in "Description" or "Instructions" ) are excluded from this license, with all rights reserved, unless specifically available for download This notice constitutes a clarification, not a change, to licensing for this design.

Print Settings

Printer Brand:

LulzBot

Printer:

TAZ 4

Rafts:

No

Supports:

No

Resolution:

0.25 mm / layer as printed

Infill:

20-50% for strength


Notes:

Print this tool to MAKE SURE YOUR FILAMENT IS OPAQUE!

Post-Printing

ASSEMBLY

  • four (4) rare earth magnets, 8mm x 3mm
  • pinhole 0.30 mm diameter for 75mm Box Turtle; 0.20 mm for 35mm version
  • 1/4-20 flanged nut for tripod nut
  • epoxy for mounting magnets and tripod nut
  • Super Glue or other Cyanoacrylate glue for mounting pinhole and locking pinhole_clamp
  • Magic Marker / Sharpie for blackening backside of pinhole, magnets in body
  • flat black paint for reducing reflections if your filament is shiny. Cheap insurance.
  • razor

Use a razor to shave off any ridges from tape on the hot bed. Especially around the pinhole/shutter area. You want the shutter to sit absolutely flat on the front of the camera.

The location of the magnets should be obvious. Orient them the same at both ends, so that it doesn't matter if the shutter blade is upside-down or rightside-up.

The "pinhole_clamp" is a clever bit of snap-fit joinery that twists into position to hold the pinhole against the back of the front half. Carefully secure the pinhole on the clamp with some Super Glue. The clamp will only go on one way. It rotates counter-clockwise to lock. Two tiny nubbins stand proud to lock the clamp in position. You should be able to pop it free if you want to monkey with your aperture. See photo.

The fit of the two halves is snug, Open and close the sliding joint slowly to avoid damaging your pinhole. It will work looser with a little use.

After adding the light trapping around the lip of the front, the two halves will only slide together properly in one configuration. The tripod nut on the bottom of the BACK will be opposite the thing:2206746 lettering on the top of the FRONT. These surface features can be discerned by touch in a changing bag.

How I Designed This

Simple tools work great!

I designed this camera to be used for generations. I could have made it much flimsier, but I believe that tools need to be robust and durable. It should withstand a fall to the floor and other hazards. I designed it 100% in Tinkercad. Took me a couple hours total design time with a few revisions. Try it, if you haven't!

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hi, where i can find the pinhole piece to mount inside the box? thanks!!!

Hi

That part is included in the SHUTTER_PLATE. It rotates into position and locks. You will need your pinhole completely fastened to the twist-in part, Otherwise, it may wrinkle. I use a tiny bead of super glue.

hi, thanks for the reply, i mean this piece in the photo. sorry for my bad english ;(

Sorry for the misunderstanding. These two cameras are designed around pinhole diameters (0.20 / 0.30 mm) that are readily available on the Internet from manufacturers who make laser-cut pinhole apertures. However, you'll pay a lot of money for that precision. Luckily, it's really not that critical for success. I make all of my own pinholes (and I make a LOT), using THIS METHOD. If you have a micrometer or digital caliper, you can easily make an accurate pinhole.

A couple tips:
I use brass shim stock, available at any good hardware store, but a soda can works fine. Don't forget to blacken the back side of the pinhole!
"Beading needles" come in very fine sizes, and are great for making pinholes. Use a "pin vise", locking pliers, or a pencil eraser to hold the needle.
I have found that finest wet/dry sandpaper gives the best results for polishing the tiny burr off the back of the metal. I use at least 1200 grit sandpaper. 600 grit, for instance, tends to tear the delicate edges of the pinhole.
In the end, if you find you aren't getting accurate exposures, you can adjust your exposure time, but the cameras are designed to allow for easy pinhole replacement.

I hope that helps! Let me know if you have any more questions!
Todd

Tank you very much Todd, you are super!
I will print and try to make my own pinhole.
i will update you ;)

Print the 35mm front yesterday ( 13 hours on Zortrax M200 + Z Ultra Black ), just a small warping on the large plate on one side ( between raft and piece ), not a big issue ...

The back is printing right now ( 10 hours 30, same printer ), put some adhesive spray before to prevent warp but still a bit warping on the large plate, similar place between raft and plate, maybe not a big issue at the end if the "box" is correct, I still waiting ...

I keep update !

Update:

The back is now finish, even with adhesive spray the warping is more marked on one corner (2mm). The front and the back fit correctly together and more easily with a light sandig on the corner, not a big issue like I said, just aesthetic, a very usable item, size of a small book.

I printing a new one for fun with a rest of Z-Ultra ABS, a pocket one ( scale 1:2, 62.5mm X 75mm x 35mm ) with some improvement ... pictures soon !

How's the pics coming?

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