GNAL stands for Gnal's Not A Lomo because it isn't.
While inspired by a certain motion picture development tank the goal of this project is to create a free, open-source, modification-friendly processing system for small format movie film with the added constraint that it be 3D printable or otherwise able to be fabricated on a small scale.
All source code and STL files for printing will be made available in this repository.
Building this project in a scripting language serves two purposes: it uses only free and open-source software to generate the GNAL processing spirals and it future-proofs the design by preserving its dimensions in human-readable text format.
Even if OpenSCAD were to disappear tomorrow (and we sincerely hope it doesn't) it would still be possible to recreate the GNAL models in another CAD program just by reading the code and reproducing the measurements.
Please read through this README for information about materials, printers and troubleshooting your prints. Check out the [development notes](docs/) if you want to modify this project.
* [aniwaa.com Search: Printers with print bed > 225mm x 225mm](https://www.aniwaa.com/comparison/3d-printers/?sort=price&order=asc&filter_search&filter_price_minimum&filter_price_maximum&filter_build_size_width=225&filter_build_size_height=225&filter_build_size_depth)
* [aniwaa.com Search: Printers with print bed > 300mm x 300mm](https://www.aniwaa.com/comparison/3d-printers/?filter_search&filter_price_minimum&filter_price_maximum&filter_build_size_width=300&filter_build_size_height=300&filter_build_size_depth)
There are people printing spirals in sections on smaller printers, but that is not a *recommended* use of these files as it requires extreme precision to reconstruct the parts into a reel that will load without problems.
Another thing to consider is the longevity of the bond made by the adhesive you choose.
Don't let that stop you, though. A multi-part printed reel is just not a priority for *this* particular project.
An enterprising spirit might notice the `gnal_50ft_spiral_quarter()` and `gnal_100ft_spiral_quarter()` modules in the V3 OpenSCAD scripts and begin to wonder what is possible.
[PETG](https://en.wikipedia.org/wiki/Polyethylene_terephthalate#Copolymers) is currently the recommended plastic for printing the GNAL.
Since this is a piece of darkroom processing equipment its exposure to water and photochemistry is inevitable and should be considered primarily.
PETG (Polyethylene terephthalate glycol) is PET--which is a plastic that's typically encountered in plastic bottles and food containers--in a copolymer with glycol.
Various manufacturers have published [safety data sheets](http://www.ilpi.com/msds/) for PETG filament.
The only warning about reactivity I have discovered states that a condition to avoid is "strong oxidizing agents" which may include reversal bleaches that are comprised of strong acids.
This is not a scientific evaluation and may stand to be corrected.
[ABS](https://en.wikipedia.org/wiki/Acrylonitrile_butadiene_styrene) is a viable option but has a greater tendency to warp on larger prints without proper temperature control around the print bed.
Since this model needs to be perfectly flat across the bottom of the reel, this is not ideal and will make for a challenging print.
ABS is a plastic commonly used in injection molding and is also generally non-reactive with photochemistry.
[PLA](https://en.wikipedia.org/wiki/Polylactic_acid) is not recommended but this doesn't mean you can't get an acceptable result with it.
The lack of endorsement comes from mostly anecdotal experience witnessing the wear and tear caused by exposure to water on PLA prints.
Biodegradable and porous, PLA will wear down in the weakest parts first and on this model that would be the spiral.
If you do not need your processing equipment to last a long time, you may find it acceptable.
PLA stands for polylactic acid and is likely the most reactive material to use with photochemistry where it is vital to maintain pH for consistent results.
The first thing to consider when your prints are coming out warped off the print bed is whether or not your **material** is appropriate for this model.
Check the [material](#material) section of this README for more information, but there's a chance if you are using PLA or ABS that large flat prints of this size are warping due to limitations with the material you are using. PETG has proven to warp far less in my own anecdotal experience and is the recommended material for this project.
The thermal properties of the material you're printing with are what causes warping, so check if your printer is being set to the recommended **temperatures** on both the bed and extruder for the material and printer you are using.
Warping occurs consistently when a section of a part cools too quickly and contracts while the rest of it is still being printed.
Mitigate this by using an enclosure on your open-frame printer or by printing in a space with low air movement but still with appropriate ventilation for the material you use.
The **slicer** you use and the **settings** in its configuration will make a lot of difference in how your print comes out.
During the development of this project [Cura](https://ultimaker.com/software/ultimaker-cura) is the slicer used most for test prints, however you might find that different software works best with your machine.
The settings are important to test before you commit to a complete print of the spiral part.
This is a fraction of the overall settings that Cura has, but they note some of the key features that were changed from the default profile for PETG and my printer.
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The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Product.
THE PRODUCT IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE PRODUCT OR THE USE OR OTHER DEALINGS IN THE PRODUCT.
