To attach the INTVAL 2.0 to a Bolex camera, disable the motor and line up the four standoffs
with the mounting holes on the body of the camera and insert the key into the 1:1 shaft.
This can be done by laying the camera on its side--with the mounting holes facing up--and placing the INTVAL 2.0 on top of the body and making sure the key fits into the slotted 1:1 opening.
If you have never attached anything to the mounts before, you may have to
remove small screws that are in the holes. This opens up the mounting holes for
the screws that will hold the intervalometer in place. There are four standoffs
and screws, but only three need to be attached to maintain the hold required for operation.
The buttons on the case control three variables: direction, speed and delay. The direction of the
camera can be set to ``forwards`` (default) with a quick press, and set to ``backwards`` by holding the
button for more than 1 second.
Similarly, the speed can be set to ``1 second rotation`` (default) with a
quick press and set to ``2 second rotation`` by holding the button for more than 1 second. Remember,
during the 1 or 2 seconds that the shutter is rotating, exposure only occurs for a fraction of that time. How large a fraction depends on the setting of the Rexofader.
Delay refers to the time the intervalometer pauses between frames and only matters when running a sequence. The delay is set to ``42 ms`` by default and will be set to however long you hold it down for; holding the button for``10 seconds`` will set the delay between each frame to ``10 seconds``. Pressing the button quickly will reset the timer to the default ``42 ms``.
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All parts of the INTVAL 2.0 are reproducible via 3D printing, laser cutting or are purchasable (example links are to Amazon or [Adafruit](http://adafruit.com)) for a total build cost of ~$50. The files in this repository consist of .SCAD, .STL, .DXF and .INO files. The .SCAD files contain all the elements needed to generate the physical body of the intervalometer with .DXF files for
laser cutting and .STL files for 3D printing. The .INO file contains the source code for the Arduino sketch that powers the INTVAL 2.0.
#### A. 3D Printing
The most time-consuming part of this build *should* be 3D printing the parts for the INTVAL 2.0. Depending on the size of your printing bed it is most likely possible to print all parts in one convenient plate. As will be addressed later, the laser-cuttable elements can also be 3D printed if you lack access to a laser cutter.
In the ``/dist`` directory of the repo, you will find all of the .STL files needed to build the intervalometer. If needed, the .SCAD file can be used to generate additional .STL models, or it can be modified to produce unique parts to your own specifications.
The most delicate and integral piece to be fabricated on a 3D printer is the ``motor_key``, which interfaces the intervalometer to the 1:1 shaft of the Bolex. This part should be printed as close to solid as your printer allows or you should look at a third-party printing service to have it made from stronger materials than the typical PLA or ABS used by most home printers. That said, I have used an ABS-printed motor key extensively with no issues thus far.
#### B. Laser Cutting
The INTVAL 2.0 has a flat panel on which all parts and electronics are mounted. For this reason, and to reduce production time, a laser cutting component has been added. See the much earlier--and now deprecated--attempt to have an entirely printable model in the original [INTVAL](https://github.com/sixteenmillimeter/INTVAL) (or [INTVAL Next](http://www.thingiverse.com/thing:151944) as I had taken to calling it on [Thingiverse](http://thingiverse.com)). Printing the flat base of this version took upwards of 3 hours on my modest printer, and with the accessibility of laser cutters at hacker/maker spaces becoming more common I decided this was feasible to include in my design.
Important to note: **A laser cutter is not required to make this intervalometer.** If you have access to a 3D printer, it's very possible to use the .SCAD files to generate .STLs of the files designated for cutting. Make sure that they are all set to 3.175mm thickness as the design requires 1/8" materials for assembly. A clever person could even improve the design to remove the need for bolts to attach the ``motor_mount_bottom`` and ``electronics_mount`` pieces when making a 3D printed version.
Another note: When cutting the base of the intervalometer, named the ``panel_laser`` there is a circular cut for a skateboard wheel bearing to be inserted. These are made with slightly different tolerances, so do some tests before you cut your final panel. When properly scaled, the bearing should fit snugly so that it can be glued to the panel. The positioning of the bearing is vital to the functionality, so it's best to test the bearing fit using the ``bearing_calibrate`` module and then edit the size of the bearing by changing the ``fuzz`` variable of the ``bearing_laser`` module. Export a new .DXF of the ``intval_panel_laser`` module by using the ``projection()`` function and cut that.
##### Materials
Early prototypes for the INTVAL 2.0 were made with 1/8" acrylic. I was very hopeful that I would be able to make a visually clear product where all of the electronics would be visible. Cool, right? This, unfortunately, was not to be. The forces applied to the prototypes during casual use would cause the acrylic to crack or shatter quite easily. I'm not saying it's not possible, but just that it is a less-than-ideal material for this project.
Here's what I would suggest, in order (all should be cut from 1/8" sheets):
1. Craft plywood - Cheap, flexible and effective. I cut this, add custom designs, stain and coat in polyurethane. Yet to have any issues with it.
2. Delrin (acetal homopolymer) - Too rich for my blood, but should perform better than acrylic. Will probably look pretty cool.
3. Acrylic - Good for prototyping, but may crack under pressure. Make parts to spare if you go down this path.
#### C. Hardware
I would like to further reduce the amount of non-fabricated parts required for this build in future revisions, but here we are. I've run a few spreadsheet models and have the cost-per-unit down to ~$50, but this fails to account for shipping, misprints and a whole host of associated costs, including build time. Needless to say, I don't see a profitable enterprise being build on the production of 16mm intervalometers, which is why I am creating this in the open for others to build and improve upon.
Links below are to Amazon for accessibility and [Adafruit](http://adafruit.com) where possible, but feel free source compatible or equivalent materials from companies that align to your personal ethics. Sourcing from AliExpress can bring the cost-per-unit down dramatically, if you are building these as part of a workshop or class.
The meat of this project are the L298N Dual H-Bridge and the Arduino Trinket 5V. The 3D models are designed for the 60RPM motor listed below, but the design can easily be adapted to other motors. I'm trying out other motors in a few different forks of this project.
1. (1x) Arduino Trinket Pro 5V - [[Adafruit](https://www.adafruit.com/products/2000)] [[Amazon](http://www.amazon.com/gp/product/B0131VM9I0/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=B0131VM9I0&linkCode=as2&tag=sixteentools-20&linkId=PK57RTRI2YRJVT2E)]
2. (1x) Nextrox Mini 12V DC 60 RPM High Torque Gear Box Electric Motor - [[Amazon](http://www.amazon.com/gp/product/B00BX54O8A/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B00BX54O8A&linkCode=as2&tag=sixteentools-20&linkId=DFU3L54JZ3KQJMPU)]
3. (1x) L298N Motor Drive Controller Board Module Dual H Bridge DC Stepper For Arduino - [[Amazon](http://www.amazon.com/gp/product/B014KMHSW6/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B014KMHSW6&linkCode=as2&tag=sixteentools-20&linkId=QZUX2HKYZAL23WGD)]
4. (1x) DC 3 Terminals PCB Mount 2.1x5.5mm Jacks Connectors Socket (5 Pcs) - [[Amazon](http://www.amazon.com/gp/product/B00CQMGWIO/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B00CQMGWIO&linkCode=as2&tag=sixteentools-20&linkId=KMF43HLB5IS2CIFO)]
Additionally you'll need wire and solder of your choosing.
#### D. Assembly
Assembling the INTVAL 2.0 can be done in an hour or so, much quicker if practiced. As mentioned, the largest amount of time should be in fabricating the parts or acquiring electronics/parts. There are 2 things I don't like about this design that I'll be addressing in subsequent builds: complexity of the electronics and crowding inside the case.
##### Mounting the electronics
The L298N is attached to the panel via the three M2 bolts. The space cut in the panel where the fourth would go is to prevent the Bolex's handle from rubbing against the panel. At this point I usually flash the Arduino Trinket Pro with the latest firmware, as in the ["Programming"](#Programming) section, prior to soldering and mounting. It can be done after, though, and can be reprogrammed after it is built.
##### Mounting the motor's base and microswitch
Modify the microswitch as shown in the photos. At this point, I usually solder leads onto the two tabs as shown to save a cramped soldering job later. Insert the microswitch into the ``motor_mount_bottom`` and line the piece up with the 6 holes cut in the panel according to the pictures and rendering. It then gets attached to the panel with 4 of the M5 bolts and attached on the bottom with the corresponding M5 nuts.
##### Mounting the motor
The motor should fit snugly into the ``motor_mount`` piece and can be attached with 2 screws that usually accompany the motor (when bought from Amazon). At this point, I usually solder 2 leads onto the top of the motor and cap it so that the fragile tabs wont break off. I use red and black wires so that I can easily switch their position in the L298N if the intervalometer is functioning backwards.
##### Attach buttons
Three of the buttons are attached to the corresponding holes in the panel. When cutting them, I will add an etched-in label for each specifying (left to right) that they control ``direction``, ``speed``, and ``delay``.
##### Building the plunger
To trigger the intervalometer and to start/stop sequences, the INTVAL 2.0 uses a simple switch that I found is handily made from cheap audio parts. In a pinch, this switch can be hard-wired into the design, but for the safety of the electronics inside I decided on using a 3.5mm socket and 3.5mm cable with a simple momentary button closing the circuit. For this, I buy a 6' cable and cut it in two.
