| SatNOGS Rotator v3 | |
|---|---|
| Rotator Information | |
| Type: | Az/El |
| Cost: | ~200 USD |
| Release Information | |
| Status: | Beta |
| Latest Release: | Torx Flathead (v3.0.1) |
| Repository: | [1] |
| Documentation: | [2] |
Contents
Intro
v3 marks a major re-haul of the SatNOGS Rotator design, with learnings from v2 applied. You can see a lot of the thinking and background research that was conducted prior to v3 development in this thread.
Specifications
| SatNOGS v3 Rotator | |
| Plastic Parts | 26 |
| Non Printed Parts approx. | 345 |
| Cost | ~ $220 |
| Controller Electronics | SatNOGS Rotator Controller |
| Type | AZ/EL (possible X/Y) |
| Motors | 2x NEMA 17 Stepper or 2x DC Motors |
| Frame Material | Aluminum T-slot 20x20 |
| Speed (deg/sec) | 6.5 (Stepper motor), 20 (DC motor) |
| Torque (Nm) | ~26 (Stepper motor), ~64 (DC motor) |
| Dimensions (mm) | 306.5x197x142.5 (AZ/EL) |
| Weight (kg) | 6.2 |
| Pro | |
| Con | |
Sourcing
3d Printing at a Fab Lab or your local hackerspace: If you don't have your own 3d printer, then a local Fab Lab or hackerspace may be able to do it for you. Fab Labs and hackerspaces are places that have invested in the machinery and you can take the designs to them. Generally they need .stl files to import into the software that runs the machines, but this should be discussed with the Fab Lab or hackerspace. You then pay for the material, time or a combination of the two for each of the parts or any other agreement in place.
Most people building the rotator have had success builds with simple ABS material for the 3D printing parts.
T Slot - If you don't want to cut the pieces yourself, then you may be able to find a supplier that will do this for you. (Here's one in the United Kingdom.)
Hidden corner connectors - AliExpress gave the cheapest supplier
A good US source is MISUMI-USA; they will also cut to length. MISUMI has several other global locations [3].
Beware, the 20-series T-slot from 80/20 Inc. in the US has slots that are only 5.2mm wide. The hidden corner connectors from e.g. AliExpress will not fit.
Stepper Motors - eBay
Belts - eBay
Fixings / Pipe - eBay
Build Sequence
- Make sure you have all parts
- Follow the instructions for mechanical assembly
- Once mechanical assembly is ready, construct the SatNOGS Rotator Controller and connect it to the assembly.
- You are ready! Proceed with testing.
Worm Gear Box Calculations
- Gear ratio: i12 = 30
- Angle between axis of gears: δ = 90 deg
- Number of threads in worm: If i12 >= 30 then z1 = 1
- Number of teeth in worm wheel: z2 = i12*z1 = 30
- Center distance: initial case a = 45.5 mm
- Worm reference diameter: AGMA d01>= 11.5*(a/25.4)^0.875 = 19.15 mm, so d01 = 19.5mm
- Worm wheel reference: d02 = 2*a - d01 = 71.5 mm
- Axial module: ms = d02/z2 = 2.38 , so ms = 2.5
Recalculate d02, a with new axial module
- d02 = z2*ms = 75mm, a = (d02+d01)/2 = 47.25mm
- Axial pitch: ts = π*ms = 7.854mm
- Reference lead angle: γ0 = atan(d02/(i12*d01)) = 7.3 deg
- Worm tip diameter: dk1 = d01 + 2*hk = 24.5mm
- Worm teeth reference addendum in axial section: hk = hk* *ms = 2.5mm
- Worm tooth reference addendum coefficient: hk* = 1
- Worm root diameter: df1 = d01 - 2*hf = 13.5mm
- Worm tooth reference dedendum: hf = hf* _ms = 1.2_ms = 3mm
- Dedendum coefficient: hf* = 1.2
- Worm length: L = 2.5_ms_sqrt(z2+2) = 35.36mm
- Worm tooth thickness: smx1 = smx1* * ts = 3.927mm
- Tooth thickness coefficient: smx1* = 0.5
- Normal pressure angle: aon = 20 deg
- Worm wheel throat diameter: dk2 = d02+2*hk = 80mm
- Worm wheel root diameter: df2 = d02 - 2*hf = 69mm
- Worm wheel outside diameter: de2 = dk2 + 2*mx = 83.5mm
- Worm wheel tooth external addendum: mx = n*ms, 0.4<=n<=1.5
- Effective worm wheel face width: b2H,max = sqrt((2_a - df2)^2 - (2_a - de2)^2) = 23mm
Test Sequence
Test sequence needed
