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My EQ5 Mount Conversion #EQ5 #esp32

Nick Bramhall
 

Hello all. I wanted to post a message to say thank you very much to everyone involved with OnStep and all the supporting materials. There is a wealth of knowledge here that has made my OnStep journey relatively pain free. After a few weekends working on this I'm at the stage where I have a basic system working on a breadboard and thought I would share a few details, although its a pretty standard EQ5 conversion that has been showcased several times before!

  • Mount: Sky-watcher EQ5
  • Microcontroller: ESP32
  • Drivers: Bigtreetech TMC2130 V3.0 SPI
  • Stepper Motors: NEMA 17, 0.9 degree, 2A
  • Pulleys: GT2 60T:15T
  • Motor Mounts: Thingiverse 3D Printed
At the moment I'm using 16 Microsteps on the TMC2130 which gives smooth, quiet operation. Vref is set at around 0.9 for the Dec and 1.1 for the RA axis. Slewing speeds during GoTo are more than acceptable. I realise the motors are a little overrated for the drivers but I had them already and decided to try them out first before buying anything different.

Connectivity is over WiFi using a D1 Mini and/or the USB interface with the ESP32. Everything is powered by a 12V 6A supply.

Wiring was primarily based on Version 2 of the MaxESP as the pinout of the ESP32 module I have seemed to be closer to this than the Version 3 scheme. At this stage I've only implemented the basic features I need, i.e. RA and Dec axis drive plus WiFi connectivity.

RA Axis:

RA Axis Stepper Motor and Belt Drive

Dec Axis:

Dec Axis Stepper Motor and Belt Drive

Breadboard Prototype (from left: Dec axis driver, RA axis driver, status LED, 12V to 5V converter, ESP8266. Above: ESP32 which doesn't fit the breadboard so is wired directly with Dupont cables. Below: motor connections):

OnStep ESP32 Build - Breadboard Prototype

First Light with OnStep (align, GoTo and tracking all tested successfully using the Android controller and Stellarium):

The Leo Triplet

The Leo Triplet, 1st April 2021

  • Canon 6D and Vixen ED80sf Telescope
  • EQ5 Mount with OnStep
  • Unguided
  • 52 x 30s exposures at ISO1600 (26 minutes)
  • Darks, Flats and Biases
  • Captured using AstroDSLR
  • Aligned, stacked and processed using SiriL
I'm very pleased with the result. Sadly my mount has some mechanical issues (a slightly distorted RA worm gear shaft) which I think introduces some periodic error. I generally only keep about 60% of my exposures and am limited to 30 second exposures for the most part. I need to see if I can source a replacement worm shaft or perhaps try autoguiding to see if I can achieve some longer exposure times.

After imaging with the 80mm refractor I changed over to my 200mm reflector and found that the system had no problem swinging this around the sky either. I spent a happy hour or so exploring the Coma-Virgo cluster which has always been my nemesis when star hopping to the various galaxies. GoTo makes finding all these Messiers almost too easy!

Going forward there are a few things to tweak or improve, but mainly it is now a case of getting everything packaged up neatly on a PCB with proper connectors. I have also hooked everything up to a Raspberry Pi running Astroberry so hopefully that will get tested the next time I have the opportunity to do some imaging. Beyond that I might start to think about a focuser, illuminated reticule, limit switches etc etc etc!
Dave Schwartz
 

Fabulous job, congratulations!

On 2021-04-05 12:18 p.m., Nick Bramhall wrote:
Hello all. I wanted to post a message to say thank you very much to everyone involved with OnStep and all the supporting materials. There is a wealth of knowledge here that has made my OnStep journey relatively pain free. After a few weekends working on this I'm at the stage where I have a basic system working on a breadboard and thought I would share a few details, although its a pretty standard EQ5 conversion that has been showcased several times before!

* Mount: Sky-watcher EQ5
* Microcontroller: ESP32
* Drivers: Bigtreetech TMC2130 V3.0 SPI
* Stepper Motors: NEMA 17, 0.9 degree, 2A
* Pulleys: GT2 60T:15T
* Motor Mounts: Thingiverse 3D Printed
<https://www.thingiverse.com/thing:1833860>

At the moment I'm using 16 Microsteps on the TMC2130 which gives smooth, quiet operation. Vref is set at around 0.9 for the Dec and 1.1 for the RA axis. Slewing speeds during GoTo are more than acceptable. I realise the motors are a little overrated for the drivers but I had them already and decided to try them out first before buying anything different.

Connectivity is over WiFi using a D1 Mini and/or the USB interface with the ESP32. Everything is powered by a 12V 6A supply.

Wiring was primarily based on Version 2 of the MaxESP as the pinout of the ESP32 module I have seemed to be closer to this than the Version 3 scheme. At this stage I've only implemented the basic features I need, i.e. RA and Dec axis drive plus WiFi connectivity.

RA Axis:

RA Axis Stepper Motor and Belt Drive <https://www.flickr.com/photos/black_friction/51002576332/in/album-72157718684738953/>

Dec Axis:

Dec Axis Stepper Motor and Belt Drive <https://www.flickr.com/photos/black_friction/51076667602/in/album-72157718684738953/>

Breadboard Prototype (from left: Dec axis driver, RA axis driver, status LED, 12V to 5V converter, ESP8266. Above: ESP32 which doesn't fit the breadboard so is wired directly with Dupont cables. Below: motor connections):

OnStep ESP32 Build - Breadboard Prototype <https://www.flickr.com/photos/black_friction/51094748229/in/album-72157718684738953/>

First Light with OnStep (align, GoTo and tracking all tested successfully using the Android controller and Stellarium):

The Leo Triplet <https://www.flickr.com/photos/black_friction/51094974555/in/album-72157716021064597/>

*The Leo Triplet, 1st April 2021*

* Canon 6D and Vixen ED80sf Telescope
* EQ5 Mount with OnStep
* Unguided
* 52 x 30s exposures at ISO1600 (26 minutes)
* Darks, Flats and Biases
* Captured using AstroDSLR
* Aligned, stacked and processed using SiriL

I'm very pleased with the result. Sadly my mount has some mechanical issues (a slightly distorted RA worm gear shaft) which I think introduces some periodic error. I generally only keep about 60% of my exposures and am limited to 30 second exposures for the most part. I need to see if I can source a replacement worm shaft or perhaps try autoguiding to see if I can achieve some longer exposure times.

After imaging with the 80mm refractor I changed over to my 200mm reflector and found that the system had no problem swinging this around the sky either. I spent a happy hour or so exploring the Coma-Virgo cluster which has always been my nemesis when star hopping to the various galaxies. GoTo makes finding all these Messiers almost too easy!

Going forward there are a few things to tweak or improve, but mainly it is now a case of getting everything packaged up neatly on a PCB with proper connectors. I have also hooked everything up to a Raspberry Pi running Astroberry so hopefully that will get tested the next time I have the opportunity to do some imaging. Beyond that I might start to think about a focuser, illuminated reticule, limit switches etc etc etc!
Otto
 

Very nice!  The 60/15 pulley combination works very nicely and the EQ5 is a relatively easy mount to modify.  Did you buy the 60T pulleys on AliExpress?  They are impossible to find in the US with the 6mm bore.
Nick Bramhall
 

Thanks Dave and Otto!

Did you buy the 60T pulleys on AliExpress?  They are impossible to find in the US with the 6mm bore.
I have ordered 60T pulleys with 6mm bore from AliExpress but am still awaiting their arrival. The ones I am using at the moment are 6.35mm bore which I got via eBay here in the UK. As you say, 6mm bore does not seem to be available other than from China.
Khalid Baheyeldin
 

Nice conversion, and great results.

Maybe you would consider the CnCv3, which uses an ESP32 as the microcontroller, but ready to go PCBs (with some minor desoldering, but you seem experienced enough to manage that). There is also the MaxESP PCB as well.

Added it to the showcase page.
Dave Schwartz
 

6.35mm = 1/4inch. Gotta love a country that's held onto the old imperial system based on the length of the royal foot or the width of the royal thumb!

On 2021-04-05 2:29 p.m., Nick Bramhall wrote:
Thanks Dave and Otto!

Did you buy the 60T pulleys on AliExpress?  They are impossible to
find in the US with the 6mm bore.

I have ordered 60T pulleys with 6mm bore from AliExpress but am still awaiting their arrival. The ones I am using at the moment are 6.35mm bore which I got via eBay here in the UK. As you say, 6mm bore does not seem to be available other than from China.
Khalid Baheyeldin
 

But but but ... imperial is the official system in Myanmar and Liberia too ...
andrea tasselli
 

Or buy a 8mm bore one and add a 8mm OD 6mm ID bush to go with it. Works like a charm.
Dave Schwartz
 

Civilization (and the metric system) might reach them one day too but I won't be holding my breath.

On 2021-04-05 3:16 p.m., Khalid Baheyeldin wrote:
But but but ... imperial is the official system in Myanmar and Liberia too ...
Ken Hunter
 

Simple matter to place the pully in my bench lathe and open the bore with a 6mm drill...
You supply the pulley and postage and I'll do the job gratis... Ken
Nick Bramhall
 

On Mon, Apr 5, 2021 at 07:40 PM, Khalid Baheyeldin wrote:
Nice conversion, and great results.

Maybe you would consider the CnCv3, which uses an ESP32 as the microcontroller, but ready to go PCBs (with some minor desoldering, but you seem experienced enough to manage that). There is also the MaxESP PCB as well.

Added it to the showcase page.
Thanks Khalid! I have had a look at both the CNCv3 and MaxESP options. Ultimately I think I'll go down the MaxESP route as I aim to add more of the features that it offers. In the meantime I'm enjoying learning a few new skills and have designed a PCB in EasyEDA based on my breadboard implementation which should fit in a spare case I already have available.
George Cushing
 

Same for the 48T pulleys they are either 6.35 (0.25") or 5mm. Fortunately 15/64ths = 0.2307". 6mm is 0.2362", so a 6mm straight flute reamer helps. If your uncle didn't leave you one he borrowed from the armory, about $7.
George Cushing
 

Let's see 5/16 is 0.3125" and 8mm is 0.3187", so 8mm is 0.006" over. To press it into a 5/16" bore I'd have to take it down to 0.3130" max. This why the 2, 5 & 4s get worn off my calculator😨
George Cushing
 

Pretty much everything is manufactured to metric. But you still need two sets of everything. Then you pick up an old Triumph and find you need bloody Whitworth!
Otto
 

On Mon, Apr 5, 2021 at 01:29 PM, Nick Bramhall wrote:
I have ordered 60T pulleys with 6mm bore from AliExpress but am still awaiting their arrival. The ones I am using at the moment are 6.35mm bore which I got via eBay here in the UK. As you say, 6mm bore does not seem to be available other than from China.
I found a set of 60T with 6mm bore from Greece.  Shipping was pretty fast at ~2 weeks, though by the time they arrived, I had found a supply of 60T, 6mm bore but no flanges, here in the US.  Actually, I like the no-flange design as it gave me needed clearance.
https://grobotronics.com/
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