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Here is my first upload onto thingyverse…
My printer is an Ender-5.
I always wanted to take images of the night sky and never really liked the “Barn Door” style DIY trackers, I am sure that they work but they are not for me… This leaves me to buy something or create my own, and here is my design. I wanted something 3D printable and smooth, I was always amused by the print in place planetary gear sets and gained some inspiration from them (thing 53451). So I started with Math and trying top figure out a reasonable working motor speed…
The Math:
Earth revolves one time per day, so my output shaft in RPM needs to be:
1RPD=1/24hrs*60min) = 0.000694… RPM
Wow that is tiny… So I’ll need to gear this thing way down. I can do a 5:1 reduction with a planetary design and I figure that I’ll need to stack 6 of them to get the input reasonable.
5x5x5x5x5x5= 15,625:1 gear ratio. OK, Wow again…
So the final math for the motor input is:
(1/(24*60))(5x5x5x5x5x5) = 10.850694 RPM
Well that is doable, not so bad…
Now its time to design, print, and program:
The printouts follow:
Print PETG, 0.4mm nozzle, 0.5mm line width, 0.2mm Layer height
AimingSight x2
DrillAdapterTool x1
DrillAdapterTool2 x1
ElectronicsCase x1
ElectronicsCaseCover x1
HeadCollar x1
HeadMount x1
ModularPlanetaryGear_Body x6
MotorCoupling x1
MotorMount x1
MountSpacer x1
StepperDriverSupport x1
TransmissionPlate x5
Attach TransmissionPlate to planetary gears with M4 screws and 2x plastic washers (see below) on each. Used to engage the next sun gear in the lineup. Tighten each M4 screw through the plate through 2x washers all the way and then back off 1-1.5 turns so that it rotates smoothly (4 screws and 8 washers per gear set, each planet gear has M4 printed threads in them, you will need to do this 6 times). Lube with teflon dry lube (see below) for smooth action.
The DrillAdapterTool and DrillAdapterTool2 are for exercising each gear set after printing with a drill with a 1/4 hex adapter, spin them fast to make them smooth. Lube with teflon dry lube.
Stack 6 gear sets on top of one another, the TransmissionPlate will attach between each set of gears. Use 4x M4 screws on the outside for each set of gears. The holes on the side of each set have preprinted threads. You will need to rotate each set 1/4 turn to line up the holes. The final gearset gets the HeadMount attached, 4 screws, 2 washers per screw, back off 1-1.5 turns per screw.
Install Home Depot 1/4″20×1″ SS screw into the HeadMount to attach the small ballhead from the gorilla pod (see below).
Install the HeadCollar and MountSpacer to the gear set. Print the MountSpacer to compensate thickness of washers on last section it default prints 2mm . I printed mine at 1.6mm (Z=80%) so that the HeadMount does not wobble, adjust accordingly (printed in cura reduced Z in 10% increments). Spray chamfer on head mount so that it moves smoothly without friction. The HeadCollar attaches to the Manfroto Ball head (see below).
Attach the AimingSight x2 to the top of the assembly as far apart as possible. This is used for sighting Polaris by adjusting the lower tripod ball head. Do this before attaching the camera.
The BatteryHolder gets attached to one side through the reverse side of the gear set mounting holes using M4x8 screws. There is a small 3mm hole on the side that gets a M3x8 screw to hold the battery in place.
Make the electronics assembly. Attach the arduino to the Electro cookie with its USB port in line with the edge. strip one end of short USB cable and find the red and black wires, strip and attach to the power rail on the ElectroCookie, do this some way down as you should hot glur the cord to the board for support. Attach the 5V and ground to the arduino. Remove the 4 input pins on the stepper motor driver and install on the reverse side of the driver board. Attach the driver board pins to the ElectroCookie connect the arduino pins 8,9,10,11 to the driver board pins int1,2,3,4. Use the StepperDriverSupport to attach the stepper board (Opposite the pins) to the ElectroCookie. Attach Arduino Pin 4 to optional on off switch or directly to ground (recommended). Attach the driver board power input to the power rail on the ElectroCookie supplying the 5VDC from the battery to the motor.
Install the MotorMount to the gear set. Install the Motor coupling onto one of the 28BYJ-48 motors and attach to the MotorMount with M4x8 screws. Thread USB cable through largest hole in the ElectronicsCaseCover and the motor wire the opposite direction through the same hole. attach motor to driver. install electronics assembly in the Electronics case and install the cover with 2x M3x8 screws. Attach the electronics case to side of gear set opposite the battery with 2x M4x8 screws.
My v1 arduino code attached. Use the CheepStepper library.
I tested this with 2 12hour runs, after each run the battery only discharged by 1/3 and the output rotated 180 degrees. After the 2 runs the output was inline with the starting point.
on a clear moonless night take outside, attach to large tripod, sight Polaris, attach camera and point at the sky.
Thanks, Enjoy!
My shopping list:
https://www.amazon.com/gp/product/B07ZYNWJ1S/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B07KC9C6H5/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B07CJYSL2T/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B076KDFSGT/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B01D4V3UCQ/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B07NRWY7CF/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B00PRY1792/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B06XQMBDMX/ref=ppx_yo_dt_b_asin_title_o04_s01?ie=UTF8&psc=1
I used Ideas from here programing the Arduino:
https://www.youtube.com/watch?v=avrdDZD7qEQ&t=6s
This article was first featured at https://ift.tt/3eRNA93 on May 8, 2020 at 04:24AM by WLT
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