Small Travel 3D printed OnStep EQ mount for telescope

NOTICE NEW Harmonic drive version is now on HrEM

Sumary

It is new version 3D printed OnStep EQ telescope compact mount for OnStep goto controller, now use 17HS19-1684S-PG100 Nema 17 Stepper Motor with 99.05:1 Planetary Gearbox or 17HS15-1684S-HG100 Nema 17 Stepper Motor with 100:1 High Precision Planetary Gearbox (recommended for astrophotography)

Only RA axis can use for longtime astrophotography (Tracking speed is Sidereal, Lunar, or Solar)

• FreeCAD sources on Github
• RA and DEC PBC design is on EasyEDA
• My OnStep Mini 2.0 box on base MiniPCB2 and Teensy3.2 with drivers TMC2130

for 32 or 128microstep

or

• My OnStep Controller Box for on Arduino Mega2560 board with drivers DRV8825 for 32microstep
• Demo video
• Astrophotography gallery from this mount is here

BOM

16x M3x10mm screws

4x M5x60mm screws

1x M6x400mm threaded rod

10x 2.5x8mm self-tapping screws

20x 2x6mm self-tapping screws

6x M3 nuts

4x M6 nuts

4x M5 wing nuts

For HG100 High Precision Gearbox 8x M4x10mm imbus screw

8x M4 Assortmen

Optional for metal Clamp 2x QR-50 Quick Release Plate Clamp Mount Compatible For Arca SWISS

2x Metal clutch see Metal-clutch.pdf or Aluminum Shaft Coupler Bore Diameter: 5-8mm, DxL: 14x25mm and print key-clutch.stl

Optional for Polar scope holder 1x Skywatcher HM5 Polar Alignment Scope

1x Red Led 3mm

1x 50K Ohm 3296W Trimmer

1x Baterry 3V CR2016 (CR2025, CR2032)

3x M3x10mm screw

3x M3x25mm screw

2x 2.5x8mm self-tapping screws

(use a M3 tap to create a thread for screw)

I recommend using this right angle adapter for the polar viewfinder

Optional for Metal Weight

• DOMYOS CAST IRON WEIGHT TRAINING DISC WEIGHT 28MM 0.5 Kg
• M6 nuts

OnStep config.XXX.h

For 128microstep HG100 100:1 High Precision Planetary Gearbox

// Axis1 is for RA/Az // calculated as : stepper_steps* micro_steps* gear_reduction1* (gear_reduction2/360) // 17HS19-1684S-PG100: 200* 128* 1* 100 / 360 = #define StepsPerDegreeAxis1 7111.1111111

// Axis2 is for Dec/Alt // calculated as : stepper_steps* micro_steps* gear_reduction1* (gear_reduction2/360) // 17HS19-1684S-PG100: 200* 128* 1* 100 / 360 = 7111.1111111 #define StepsPerDegreeAxis2 7111.1111111

// PEC, number of steps for a complete worm rotation (in RA) // calculated as : (StepsPerDegreeAxis1360)/gear_reduction2. // 17HS19-1684S-PG100: (7111.1111111360)/100 = 25600 #define StepsPerWormRotationAxis1 25600L

For 128microstep PG100 99.05:1 Planetary Gearbox

// Axis1 is for RA/Az // calculated as : stepper_steps* micro_steps* gear_reduction1* (gear_reduction2/360) // 17HS19-1684S-PG100: 200* 128* 1* (99+104/2057) / 360 = 7043.59531 #define StepsPerDegreeAxis1 7043.59531

// Axis2 is for Dec/Alt // calculated as : stepper_steps* micro_steps* gear_reduction1* (gear_reduction2/360) // 17HS19-1684S-PG100: 200* 128* 1* (99+104/2057) / 360 = 7043.59531 #define StepsPerDegreeAxis2 7043.59531

// PEC, number of steps for a complete worm rotation (in RA) // calculated as : (StepsPerDegreeAxis1360)/gear_reduction2. // 17HS19-1684S-PG100: (7043.59531360)/(99+104/2057) = 25600 #define StepsPerWormRotationAxis1 25600L

For 32microstep PG100 99.05:1 Planetary Gearbox

// Axis1 is for RA/Az // calculated as : stepper_steps* micro_steps* gear_reduction1* (gear_reduction2/360) // 17HS19-1684S-PG100: 200* 32* 1* (99+104/2057) / 360 = 1760.89883 #define StepsPerDegreeAxis1 1760.89883

// Axis2 is for Dec/Alt // calculated as : stepper_steps* micro_steps* gear_reduction1* (gear_reduction2/360) // 17HS19-1684S-PG100: 200* 32* 1* (99+104/2057) / 360 = 1760.89883 #define StepsPerDegreeAxis2 1760.89883

// PEC, number of steps for a complete worm rotation (in RA) // calculated as : (StepsPerDegreeAxis1360)/gear_reduction2. // 17HS19-1684S-PG100: (1760.89883360)/(99+104/2057) = 6400 #define StepsPerWormRotationAxis1 6400L

NOTE:

• For correct motor direction install JST XH socket for RA axis in PCB with reversed pins:
• RA and DEC Clamp is very critical thing. For print use ABS with 100% infill or create from metal (recommended for heavy telescope).
• Use stones and cement to fill the weights or create from metal.
• Use acetone glue to attach the holders to the metal weights
• Use a tap to create a 1/4"-20 UNC thread in Aluminum Shaft Coupler

Old version:

• 2018
• 2017

Another recommended link:

• OnStep SHC (Smart Hand Controller)
• OnStep ST4 Handheld controller
• OnStep for Sky-Watcher EQ5 mount
• OnStep for SEBEN EQ3 mount
• My DIY Telescope
• Wood tripod upgrade for telescope with Eyepiece plate

Update:

• 2019-01-05 Add RA and DEC PCB Box for new wiring version on MiniPCB2 or MaxPCB2
• 2019-01-20 Add BOM for screws and nust
• 2019-02-04 Add link for new My OnStep Mini 2.0 box
• 2019-05-16 Add support for 17HS15-1684S-HG100 and some metal parts
• 2019-06-25 Add HM5 polar scope holder
• 2019-07-15 Add Metal Weight Holders
• 2019-07-17 Add new DEC_PCB_Box_For_MiniPCB2_V2 better to use with Metall Weight
• 2019-08-16 Add RA_Polar_Finder_Clamp_V2
• 2019-11-30 Add another metal clutch - Auminum Shaft Coupler with printed key

Category: DIY