Showcase: Built with Onstep LX200 Conversion


Dan Walker
 

One for the showcase if it is deemed worthy!

 

Config was a MaxESP v3 with 2 focus motors running an LX200 12’’.

 

Onstep

MaxESP v3

 

Comment

RA / Dec Motors

Nema 17 0.9deg 1.68A

https://www.ebay.co.uk/itm/Nema17-Stepper-Motors-0-9-Step-Angle-1-68A-4-Wires-24mm-L-5mm-D-Flat-Shaft/352991476589?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

 

Focus Motors

Nema 14  0.9deg 0.4A

https://www.omc-stepperonline.com/nema-14-stepper-motor/nema-14-bipolar-0-9deg-11ncm-15-58oz-in-0-4a-10v-35x35x28mm-4-wires.html?mfp=149-step-angle%5B0.9%5D

 

RA Dec Stepper Drivers

TMC 5160

https://www.ebay.co.uk/itm/BIGTREETECH-TMC5160-V1-2-SPI-Stepper-Motor-Driver-High-Power-Mute-Driver-For-SKR/184085606097?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

These have CLK wired to ground

Focus Motor Sepper Drivers

TMC 2208

https://www.ebay.co.uk/itm/BIGTREETECH-TMC2208-V3-0-Stepper-Motor-StepStick-Driver-UART-For-3D-SKR-MKS-GEN/184078152381?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

These required the EN pin to be grounded

Wifi

Wemos D1 mini pro

https://www.ebay.co.uk/itm/WEMOS-D1-mini-Pro-16M-bytes-external-antenna-connector-ESP8266-WIFI-antenna/192353086135?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

D3 pin requires cutting off or T-shaped jumper needs to be set to Wemos.

 

Some Images of how I installed the motors to the lx200 mount and focus motors to the rest of the setup.

 

The whole setup:

 

The RA motor was bolted to the front of the LX200 mount. (not so easy to see!)

 

 

Dec Motor

 

Electronics and focus motors. Electronics was installed in a small project box on one of the fork arms. The stepper motor requires significant counterweights on the opposite fork.

 

The whole setup works very nicely now (except the PEC, which I will fix next summer).

 

Got some first photos a few nights back (weather has been characteristically awful for the UK over the past month!) which I will post when processed.

 

Thanks very much to all those who create this excellent system.

 

Dan

 

Sent from Mail for Windows 10

 


Curly
 

Great job Dan looks very neat. Not sure you need to bother with PEC if your guiding, I hooked it up on my Cge pro and haven’t felt the need to waste valuable sky time recording it. Phd 2 and OnStep’s super accurate tracking negate any need for it. 
Looking forward to seeing your pics.

The weather in the UK has been shocking for a lot longer than a month, I think I’ve only had the observatory open 5 times since I converted my mount in the summer. I’ve got a f11 3910mm focal length image in progress if the clouds/wind and rain ever move on. 

Curly 


On Sun, 15 Nov 2020 at 14:37, Dan Walker via groups.io <yuklop=yahoo.com@groups.io> wrote:

One for the showcase if it is deemed worthy!

 

Config was a MaxESP v3 with 2 focus motors running an LX200 12’’.

 

Onstep

MaxESP v3

 

Comment

RA / Dec Motors

Nema 17 0.9deg 1.68A

https://www.ebay.co.uk/itm/Nema17-Stepper-Motors-0-9-Step-Angle-1-68A-4-Wires-24mm-L-5mm-D-Flat-Shaft/352991476589?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

 

Focus Motors

Nema 14  0.9deg 0.4A

https://www.omc-stepperonline.com/nema-14-stepper-motor/nema-14-bipolar-0-9deg-11ncm-15-58oz-in-0-4a-10v-35x35x28mm-4-wires.html?mfp=149-step-angle%5B0.9%5D

 

RA Dec Stepper Drivers

TMC 5160

https://www.ebay.co.uk/itm/BIGTREETECH-TMC5160-V1-2-SPI-Stepper-Motor-Driver-High-Power-Mute-Driver-For-SKR/184085606097?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

These have CLK wired to ground

Focus Motor Sepper Drivers

TMC 2208

https://www.ebay.co.uk/itm/BIGTREETECH-TMC2208-V3-0-Stepper-Motor-StepStick-Driver-UART-For-3D-SKR-MKS-GEN/184078152381?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

These required the EN pin to be grounded

Wifi

Wemos D1 mini pro

https://www.ebay.co.uk/itm/WEMOS-D1-mini-Pro-16M-bytes-external-antenna-connector-ESP8266-WIFI-antenna/192353086135?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

D3 pin requires cutting off or T-shaped jumper needs to be set to Wemos.

 

Some Images of how I installed the motors to the lx200 mount and focus motors to the rest of the setup.

 

The whole setup:

 

The RA motor was bolted to the front of the LX200 mount. (not so easy to see!)

 

 

Dec Motor

 

Electronics and focus motors. Electronics was installed in a small project box on one of the fork arms. The stepper motor requires significant counterweights on the opposite fork.

 

The whole setup works very nicely now (except the PEC, which I will fix next summer).

 

Got some first photos a few nights back (weather has been characteristically awful for the UK over the past month!) which I will post when processed.

 

Thanks very much to all those who create this excellent system.

 

Dan

 

Sent from Mail for Windows 10

 


Khalid Baheyeldin
 

Thanks for sharing.

Any detailed conversion is worth of the showcase page, since it helps future users.
It is now in that page.


Khalid Baheyeldin
 

On Sun, Nov 15, 2020 at 02:42 PM, Curly wrote:
Not sure you need to bother with PEC if your guiding
That is my experience as well: if you are autoguiding, don't bother with PEC.
I have not connected the PEC sensor for almost a year.

At least try it that way, and see if you have a slow sine wave due to PE, that warrants correcting with PEC.
If your PE is low, I am betting that you don't need PEC at all.


Dan Walker
 

Hi Curly and Khalid,

I am sure you are right. I had the electronics out yesterday and was probing the behaviour of the sensor... then thought, this is silly. I am just as likely to break something as I am to fix it and I'd be gutted! So I put it all back, verified it was OK and I will leave it well alone now.

I am guiding and the guiding seems good. 

Thanks very much,

Dan


On Monday, November 16, 2020, 09:46:30 AM GMT, Daniel Walker <dan@...> wrote:


Hi Curly and Khalid,

I am sure you are right. I had the electronics out yesterday and was probing the behaviour of the sensor... then thought, this is silly. I am just as likely to break something as I am to fix it and I'd be gutted! So I put it all back, verified it was OK and I will leave it well alone now.

I am guiding and the guiding seems good. 

Thanks very much,

Dan

On Sunday, November 15, 2020, 11:18:31 PM GMT, Khalid Baheyeldin <kbahey@...> wrote:


On Sun, Nov 15, 2020 at 02:42 PM, Curly wrote:
Not sure you need to bother with PEC if your guiding
That is my experience as well: if you are autoguiding, don't bother with PEC.
I have not connected the PEC sensor for almost a year.

At least try it that way, and see if you have a slow sine wave due to PE, that warrants correcting with PEC.
If your PE is low, I am betting that you don't need PEC at all.


Egge
 

Hi Dan,

you did a very nice job in converting your LX200 to OnStep. I just bought a very old LX200 with defect electronis and would like to do the same.

May I ask a couple of questions:
where is your MaxESP located?  I is in the the original place, where the meade electronics used to be or is it somewhere outside?

Since you are using a wedge and you mentioned "focuser" I assume that you are also doing astrophotography. Do you get good guiding? If you are using PHD2 - what is the typical RMS-value on pointing (e.g. <1").

Can you recommend this setup (altazimuth mount with wedge and OnStep) compared to an equatorial mount for astrophotography?

How about the additional weight on your telescope - is the mount suitbale to carry it? also with wedge?

Do you have more pictures and or details of your conversion?


George Cushing
 

Very nice! Looks like you have the PCB in the base in place of the old main board?


Dan Walker
 

Hi Egge and Geroge,

The PCB has gone into the project box mounted on the right fork arm (see the last picture in the first post). I wanted and indeed tried to mount it in the base, but it was too tight with the RA motor (which is mounted in the base) and would have involved hacking away too much metal, so it went on the arm. Actually glad its there in the end, as its easier to get out and tinker with.

Guiding is pretty good, certainly good enough to take long exposures through the ES80APO that is piggyback mounted. A 12'' LX200 makes a solid guidescope ;) I think RMS is ~1''. I'm not usr eI have a log file, but I'll check. I have recently taken some images of the crab nebula through the LX200 guided by the APO, and they looked good as they were being taken, but they reside in my backlog of unprocessed data for the time being. Perhaps I'll have a go later, so I can give you an idea of how it comes out.

I don't know about recommend. You need a really solid wedge (I have a homebuilt job that weighs a ton and it was a massive improvement over the commercial Meade wedge I had before). I doubt the mount will be as solid as a more compact GEM though. It does come with other advantages, like easy positioning, no meridian flip, comfortable observing position that makes it worthwhile.

The mount can easily handle the weight. The motors are more than powerful enough. The hard bit is balancing. With a wedge mounted fork mount it is not possible to achieve perfect balance for all areas of the sky. So a compromise is required. That said the motors are so far within their comfort zone a little unbalance doesn't bother them. Might have a detrimental effect on guiding, but haven't seen it. 

The best pics are posted here. Can take more of the externals easy enough and I'll get a couple more of the internals next time I take it off the pier. I hope that isn't soon though, as if its come off, its because there is a problem!

Dan


Dan Walker
 

Hi All,

A couple of shots up under the scope that show how I mounted the RA motor inside the base.


Dan Walker
 

Here are the L frames from crab, just stacked and stretched (no calibration frames).
These are 120s exposures @f/6.3 through the LX200 classic 12'' scope using Atik Horizon 4/3 sensor, and the stars are pretty round over most of the image, so guiding (using 80mm f/4.8 refractor) and tracking is pretty good. You can see the limits of the optical system in the corners, but overall I am very happy with the mount and Onstep allowing this.
Will fully process the image with Ha, RBG etc in due course, but this shows that the venerable old LX200 system and modern electronics is a perfectly capable astrophotography setup!


exebece@...
 

wow. irregular stars in corners are optical artefact so it seems that your setup works really well at mechanical level. Perfect image for me. Since I'm interrested in photometry (not astrophotography) result like this would be very cool for me. I hope my lx200 upgrade will result in comparable stage to yours... All my thumbs up about this! And of course this tiny Crab nebula is also an amazing object to shoot ;) Your step-step-step-son may notice also it's shape changing if you spread your hobby across generations :) Friend of mine is imaging Barnard's star for 30 years now and it's speeeeeeeding in the field...