Showcase: Built With OnStep


Stroblhofwarte
 

Hi, I just finish my project to convert an wonderful old Meade LXD600 mount from an old Autostar based system to an OnStep system with an Teensy3.6 board. The electronic fits into the DEC-housing, build on my own PCB based on the MaxPCB2 schematic. I use two NEMA 14 motors, one of them fits exactly into the RA housing. Both axis are now belt driven. For RA and DEC axis I use the TMC2130 drivers, for the focuser an DRV8825. A detailed description can be found on https://astro.stroblhof-oberrohrbach.de/ (in german only). The mount works incredible smoothly and silent, if PEC is trained and enabled, unguided images with more than 3 min. exposure are possible (I never tested exposures above 3 minutes, my camera is not cooled and the background becomes bright).


Now the DEC housing is full. NEMA 14 motor, 200 steps, 1.5A.


The electronic setup. The front plate is mounted, ready to push it into the DEC housing.


LXD600 with OnStep. USB cable to the astroberry, the WLAN antenna for WiFi handbox access.



Khalid Baheyeldin
 

Thank you for sharing your amazing LXD600 conversion.
I tried using Google Translate, but it does not work for some reason. I can look at the pictures though ... :-)

Good to see that the Online Configuration Generator helped ...

I see that you are using VQUIET, which Howard recommends against for most setups. Consider changing that to just QUIET.

Another thing is that you are using a DRV8825 for the focuser. An LV8729 will be much better and generates less heat.

Looks like this motor is the 200 step NEMA14 that you used. It shows that we don't always need big motors. 
And you are driving it without any reduction: i.e 180:1 worm wheel, and all the other reduction is via the 1/256 of the TMC2130!

Mind boggling ...

For the unguided 3 minute images, does every image come out good? Or only 1 in 3 or so?
Is that with the ETX-70 @ 350mm? If so, then no wonder at that low focal length.

I can do 3 minute unguided on my Vixen SXD at 1310mm focal length.
However, not every image is good. I am using 18:1 gear box. The gear box introduces non periodic error.

With guiding none of the above is an issue.


Stroblhofwarte
 

First I planed to use the DRV8825 and Stepper motors with gear reduction. But the drivers are hot, noisy and the motors get hot as well and there was no room for a motor with gear box in the mount. So I use one for the focuser now. I pretty sure I will replace it with the one you mentioned, the LV8729 later.
The NEMA 14 motor is realy not weak, it's much more stronger than the old servo motors used in the orgiginal LXD600 (same gear boxes are used in the LX200) and it runs much smoother with 1/256 than the old motors. I can compare only with the old Autostar setup, I use this mount since 20 years and never tried another one. And with the Autostar, 20 second exposure was the limit for unguided images. I'm sure it's possible to do longer exposures than 3 minutes, but I did not tried. And yes, its repeatable, this exposure of 3 minutes, it's not sometimes or one of three (It took some time before I realize this, I expected startrails, but there was no startrails!). I'm very curious to try the C9 and how this will behave.
You are right, the ETX-70 is not such a big challange for a OnStep controler and this mount. But for normal usage, the ETX-70 sits on the C9 and guide (this is the plan), but what I want to say, the first use of OnStep was fun for me!


Edrien@...
 

Hi Khalid,
Thanks for the great Onstep software. It helped me thru Covid.
I built a platform designed in Fusion 360 and printed it on a 3d printer. 
I attached my Orion telescope to the mount.
Video: https://www.youtube.com/watch?v=6EIOaBXZfqc&feature=youtu.be
I used the ESP32 processor and it works great. Can find all the stars.
Used the moble app and am looking to build the SHC.
Thanks again and keep up the good work.
Pic of the unit attached.


Khalid Baheyeldin
 

On Tue, Sep 29, 2020 at 06:35 AM, <Edrien@...> wrote:
Hi Khalid,
Thanks for the great Onstep software. It helped me thru Covid.
Thanks should go to Howard Dutton, first and foremost ...

I built a platform designed in Fusion 360 and printed it on a 3d printer. 
I attached my Orion telescope to the mount.
Looks great.

If you want it in the showcase, then please tell us more info: what motors,
what gear reduction, which specific board and drivers, ....etc.


Roman
 

Hi everyone,

this week I started my second OnStep project for my Celestron CG-4 mount and completed the electronic part.

Next week I will finish the holders for the stepper motors.

Here are some pictures and my preliminary configuration:

OnStep MiniPCB 1.27
2x Watterrot TMC2130
Stepper motors 0.9 degrees, 1.7A
Motor belt pulley: 12 teeth, GT2
Worm belt pulley: 48 teeth, GT2

And I engraved the OnStep logo with the lettering into the anodized aluminum case with a LASERMAXX Plott 125 laser cutter.

The mount will be used for astrophotography, but only for my small apochromat (D:72, F:432mm).

Kind regards
Roman


Jamie Flinn
 

No fair – laser cutter …….nice work!!!! 

 

From: main@onstep.groups.io On Behalf Of Roman
Sent: Friday, October 2, 2020 7:53 AM
To: main@onstep.groups.io
Subject: Re: [onstep] Showcase: Built With OnStep

 

Hi everyone,

this week I started my second OnStep project for my Celestron CG-4 mount and completed the electronic part.

Next week I will finish the holders for the stepper motors.

Here are some pictures and my preliminary configuration:

OnStep MiniPCB 1.27
2x Watterrot TMC2130
Stepper motors 0.9 degrees, 1.7A
Motor belt pulley: 12 teeth, GT2
Worm belt pulley: 48 teeth, GT2

And I engraved the OnStep logo with the lettering into the anodized aluminum case with a LASERMAXX Plott 125 laser cutter.

The mount will be used for astrophotography, but only for my small apochromat (D:72, F:432mm).

Kind regards
Roman


Khalid Baheyeldin
 

On Tue, Sep 29, 2020 at 06:35 AM, <Edrien@...> wrote:
Hi Khalid,
Thanks for the great Onstep software. It helped me thru Covid.
Thanks should go to Howard Dutton, first and foremost ...

I built a platform designed in Fusion 360 and printed it on a 3d printer. 
I attached my Orion telescope to the mount.
Looks great.

If you want it in the showcase, then please tell us more info: what motors,
what gear reduction, which specific board and drivers, ....etc.


GuitsBoy
 

Retrofitting an old Meade LXD650 with OnStep.

This is currently a work in progress, but initial tests have been favorable.  I am testing both the ESP32/CNC3 as well as the MKS GEN-L v2.0 board since those were the only two options readily available from amazon.  I am waiting for a proper Wemos R32 board to arrive from aliexpress.

More pictures and details available here:

https://www.cloudynights.com/topic/738036-meade-lxd650-onstep-retrofit/

Thanks, 
-Tony


Khalid Baheyeldin
 

Thanks. I added it to the Showcase.


Bert Kruger
 

My 16” conversion for EAA

I have purchased the 16” Meade Dob (Starfinder?) in 1999 in South Africa but when we moved to Australia there was no room in the container to bring it with in its original (bulky) format.  So I broke it up and just kept the essentials to be used at a later stage for a future project.  I also had a 9.25” Ultima which was de-forked to put on an AVX mount.  The Ultima’s mount is equipped with the well-known Byers precision worm gear and has a good slip clutch.  I initially planned to remove the Byers gear from the Ultima mount to build a lightweight Dobsonian.  However, after a lot of deliberation I decided to follow a completely different route with the conversion.

The project is still a work in progress and as will be evident in many of the photos the job is far from complete. I first wanted to prove to myself that the different approach is workable and I think I have achieved that.  I have been through many iterations and with my crude skills and poor quality tools it is going to take some effort to get it in a much better shape.  The initial aims that I had in mind with this project was to build:

-         a telescope with goto and tracking capability by using Onstep as control system

-         a telescope that would be easy to setup or pack up and take up minimum  storage and transport space

-         a telescope that will be used for EAA purposes only by using a CMOS camera mounted at prime focus position (this means there is no need for a secondary mirror or a secondary cage)

-         a telescope that can easily be moved around (up/down stairs for instance)

-         a telescope without a viewfinder by using plate solving with the goto capability of the mount

-         a telescope with an automated focuser and rotator/de-rotator (so that there is no need to touch the telescope after initial setup and alignment)

The current state of the project is depicted in the first photo.


The conversion entails basically the following:

 

-         The Ultima mount was firstly converted by widening base to accommodate the 16” mirror box (500mm wide) plus two bearings (about 17mm wide).  This was done by inserting four pieces of 50x50x1.6mm (each 106mm long – two each side) between the mount body (central part) and the fork arms.  The original bolts that held the arms against the body were replaced with threaded rods long enough to sandwich the 50x50 extrusions (an extrusion of 60x50 would probably work better but the 50x50 extrusions worked well).  The top of the arms were shortened as well and with a bit of surgery the mirror box with its attached altitude bearings basically lowered into slots and is fixed to the arms by using only two 6mm thumb nuts.  Very easy to remove or assemble I must say. See the second photo that shows the aluminium used to widen the base and space between the forks:


 

-         The Ultima mount that was converted into a goto mount by using the Teensy 3.2 mini PCB V1.2.4 build with TMC2130 drivers for the Alt and Az axes.  I have modified the normal Teensy 3.2 build by adding a focuser driver and a rotator/de-rotator driver. The following  photo shows the board built into the Ultima mount:


o   For the AZ axis a Nema 17, 400 step per rotation stepper motor is used with 32 micro steps, belt reduction of 1.5 plus the Byers worm drive of 359:1 is used (total steps per degree = 19146.7). 

o   For the ALT axis a Nema 17, 200 step per rotation with a 99.05 planetary gearbox and a belt reduction of 338:36 is used (total steps per degree = 16532.8).  For the altitude bearings a “better” quality Lazy Susan bearing was used (with spacers between the ball bearings to prevent the ball bearings from locking up).  These bearings are 200mm in diameter but you can get much larger ones in the same format.  I have used my 3D printer to print 4 sections of a GT2 pulley (to form an outer sleeve) that were screwed onto the outside of the one Lazy Susan bearing.  A 9mm GT2 belt is used from the slip clutch at the bottom to drive the Lazy Susan pulley.  I am very proud of the 3D printed slip clutch that I have designed for this scope – very small with a lot of oomph – Only a half turn is needed to lock it up as well.  The slip clutch attached to the Nema 17 motor and planetary gearbox is shown in the following photo:

 


 

 

Fixed to the mount are two wheels with a telescopic handle that was salvaged from a large toolbox. The draw handle is fixed to the wheel base with swivel brackets so that the handle can be laid flat on the ground when the scope is in use (a slight tripping hazard but because the scope is not used for visual purposes there is minimal movement around the scope once setup is completed).  The handle is fixed to the one side of the mirror box with two 3D printed wing nuts when the telescope is stored or moved around.  When the handles are fixed onto the mirror box it is very easy to move the telescope in its collapsed state or erected state (through doorways or even up and down stairs).  The fact that there is a slip clutch on both axes makes it easy to position the mirror box so that the handle could quickly be secured onto the mirror box to form rigid unit when it is time to pack up and go.  I must still add a third (swivel) wheel to the base so that the scope could be pulled around as well (at this stage I am just using a 2”x3” piece of timber as a leg as a quick and dirty solution).

-         The current mirror box size is 500mmx500mmx260mm high box built with 20mm plywood. It has a fixed lid at the bottom (to give strength to the box).  The bottom lid is only 12mm thick with a 110mm hole in the centre that is closed with a PVC cover when the scope is not in use.  The hole is opened when the fan is switched on (the fan is not connected or used yet).  I will have to rebuild the mirror box because it is not possible to fix or patch it up given its current state (too many holes were drilled in places and later moved as I went along making modifications) and it looks really ugly right now.  An 18 point mirror cell with wiffletree is used underneath the mirror- I may also have to revisit this part of the scope at a later stage.

 


 

-         The folding trellis system makes it possible to collapse the scope into the mirror box without having to take it apart.  It comprises four sections that folds into each other plus the focuser section and the vanes that holds the rotator/de-rotator onto which the camera is mounted.  The trellis system was made with 25.4mmx1.2mm square tubing, 3D printed brackets for the swivel ends and a 10mm x 1.6mm round tubing as cross members between the pivot points (this assist with stiffening up the truss in the vertical direction – especially when everything is tightened up).  Wing nuts (3D printed) are used to tighten up the trellis system.  Three 1mm cables are also used to stabilize the trellis truss.  The steel cables are easily attached or detached at the top end and once they are hook up there is enough support to hold up the camera in the middle and to minimise lateral movement.  I think there would definitely be better systems than what I have used here but for now I am sticking to this system otherwise I may easily end up in a never-ending improvement project – trust me this was not the first version.  In hindsight I think that a single 40x40x2 mm pole with three support cables would have done the job just as well and would have been much easier and simpler solution but then it would not have been collapsible (maybe a single telescopic pole would do it).


 

-         The last part of the trellis comprises the automated focuser (the bottom of the focuser is a 40x40x4 square tubing that was cut into shape.  The top part of the focuser is a 25x20x2.5mm channel extrusion that is used as a slide.  The focuser is driven by a Nema 11 (200 steps) stepper motor (no belt or gear reduction is used).  A 6mm threaded rod attached to the Nema 11 motor drives the focuser block up or down. It should be noted that final collimation (to optically align the camera with the mirror) is done on the focuser unit. The focuser unit can easily be detached from the trellis by undoing four wing nuts.  

 

-         The final component of the scope is the rotator/de-rotator that sits in the position that you would normally expect the secondary mirror.  It is actually smaller than the original secondary mirror of the scope and more or less the same weight (I don’t have an accurate small scale to weight it). The rotator/de-rotator is driven by a small 28BYJ-48 stepper motor with a 90:20 belt reduction.  The 90 tooth GT2 pulley and the housing of the rotator was 3D printed.  The camera is directly screw onto the M42 tube (45mm outer diameter) that is supported in the housing with 2x 58x45x7mm bearings.  More detail about the focuser and rotator/de-rotator can be provided if required.


 

I am not sure what to call this build?  It is definitely an ALTAZ mount but it is not a Newtonian or a Dobsonian anymore.  For now I will just call it my 16” EAA telescope?  At this stage I am using it with an ASI178/224 camera (the last photo of the Trifid Nebula was taken with the ASI224).  Not the right cameras for the job (I know) but I can still see much better and more detail that what I could have by using it as a visual scope.  I am also using these cameras because they are very light at the top end.  I am yet to test it with a cheap 0.5 GSO focal reducer in front of the ASI178 – I think that will give me a fairly wide field.  The last photos show what I could capture with the ASI224 during a very small window of opportunity on the first night out.  Collimation is clearly out and there was drifting but the latter is mainly because of poor alignment and levelling that could be improved.


 

 

 

 

 

 

 

 

 

 


Khalid Baheyeldin
 

That is very unique.
It is now in the Showcase page.


MikeyB
 

Hi Bert,

Very interesting project and lots of original thought. Thanks for posting that.
Can you provide some more details on the 3D printed slip clutch that you designed?

Regards,
Mike


Mike Gore
 


Hi,
  I just realized I posted my retrofit pictures to the main topic instead of the Showcase topic
Adding it here to make to easier for people to find in the future  - sorry

All of the recent OnStep developments have really got me motivated to finish up my LX200 refit.
I have created a new face plate and circuit board holder. My plan is to hand wire the prototype circuit based on the STM32F303 bluepill.
Interestingly the actual v1.7 STM32 PCB could almost fit - just 5mm too long on the narrow axis (facing the camera). My PCB holders use the same width.
After hand wiring I will eventually make a PCB and share it with the group.
I have added a 1.3" OLED display to the face plate for future use , a USB C connector, ST4 interface. Push button with RGB leds.
It been interesting using Fusion 360 and a 3D printer - I have spent quite a bit of time getting up to speed - I managed to get function display holder clips that work.
I plan to use the push button as manual limit and the leds for power and tracking status.
I am very please with the progress and thankful to the Onstep project for my motivation.
My last update was over a year ago when I finished to motor mounts.
I have been testing the motors and drive system with an actual V1.7 STM32 PCB with an STM32F303 instead of the STM32F103 - same pinout
-- 
# Home: Mike Gore
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Bert Kruger
 

Hi Mike


The following Sketchup drawing shows the different components of the slip clutch.  The pulley sizes can be changed depending on the drive ratios that you want to achieve.  
Please note that these type of clutches are available if you search for it – I was just not prepared to pay a ridiculous price for it – hence I have made my own.

I designed the GT2 pulleys by using tools available on OPENSCAD.  I normally copy the STL file to Sketchup (which I know well), modify it there and export an STL file again for 3D printing.  The clutch pulley in the drawing below needs to be screwed onto the Outer Shell of the clutch.  You can also strengthen the Outer Shell with 4 small screws or bolts (use the small holes for that purpose).  That would prevent the outer shell from shearing when the forces are applied.  At this stage I am not using it as such but have been able to drive the scope without any problem (so far).  I must however still buy long enough bolts/screws and fit them because this is definitely a weak area.  

If you use more Inner/Outer Disks more force will be transferred to the Outer Shell and ultimately the Clutch Pulley (Which means the footprint can be small).  I have only used three of each and they are only 2mm thick.  It is VERY important for a very tight fit of the Inner Disks over the Nuts and likewise for the Outer Disk’s octagon shape to fit very tightly into the Outer Shell of the clutch.  This is to rule out any play or backlash.  I had to print a couple of sizes to ensure a tight fit because the dimensions of the 3D printed version is almost never exactly the same as the drawing measurement.  Also note that in my application the Clutch Pulley buts up against the inner bearing part of the KP08 pillow block.

The clutch that I have used for this scope is very small (if you compare it to the size of the Nema 17 motor).  That is because I had limited space in the area where it had to fit in.  You can increase the sizes of the Inner/Outer Disks and the Outer Shell (to increase the area onto which pressure will be exerted).  It is also important to slightly sand the flat surfaces of Inner/Outer disks - this will prevent slippage.

The drawing below shows my current configuration.  However it is possible to re-configure the layout of the different components - it all depends on what you require in your specific application.  If have printed the components by just using ABS with 70% print density.  In my case I have also just used an 8mm threaded rod and not a rod with a shaft as shown in the drawing. If you can get an 8mm shaft and tap the thread onto the one end it will probably be the best solution.

Hope the above and the drawing makes sense but let me know.



--
Bert


MikeyB
 

Bert,
Thank you for the detailed description and diagram. It's an interesting design and a good solution to the problem of a simple adjustable clutch.
Same basic principle as a multi plate motorcycle clutch, although these use springs to apply pressure rather than a nut, and backlash is not such an issue.
Regards,
Mike


Leo Barnard
 

Khalid,
The attached image is of my 12-inch SCT (Meade optics) in a tensegrity frame on an Ioptron IEQ30  pro mount driven by my first OnStep STM32 board with SHC. I am currently using the scope and the goto's have been great.  Thanks to you, George, Howard and the whole onStep group for inspiring me to resurrect this mount after the original electronics failed.


Khalid Baheyeldin
 

Can you please tell us more?
What drivers?
What microstepping?
What motors?

Also, not OnStep specific,but interesting to many here: details on the tensegrity frame.


Leo Barnard
 

Khalid,
The current drivers are LV8729's but I started with 4998's.  Next iteration is going to be with the THB6128's as used in the original Ioptron electronics.
Thie drivers are set currently for 128 microsteps but 32, 64 both work. Just rougher slews.  The motors are the original Ioptron NEMA-11 steppers (JKong Motor JK28H528-0804).
I should note for you that the mount is an original Ioptron IEQ30 which I upgraded three years ago to the IEQ30Pro using the Ioptron upgrade kit.  This entailed replacing the original analog motors and controller boards with these current steppers and new driver boards.  Unfortunately, the supercaps that Ioptron chose for the backup power failed and destroyed the vias in the upgrade PCB's so the mount electronics failed last year.
I've spent a year trying to get anyone at Ioptron to acknowledge the problem ... No Joy.
The OnStep project has saved a mechanically sound mount which carries the 12" easily.
Through Asttromart I was able to acquire the 12" optics about 11 years ago and built the frame myself using 80/20 aluminum extrusions and accessories.  Full OTA weight is about 24 lbs, down from the original Meade OTA weight of 57.5 lbs.  The frame design is a variation of "String Telescope" for which Google has many examples.

Regards,
Leo
P.s. I send some more Pics when the Wx clears. Lb.


On Nov 15, 2020, at 3:05 PM, Khalid Baheyeldin <kbahey@...> wrote:

Can you please tell us more?
What drivers?
What microstepping?
What motors?

Also, not OnStep specific,but interesting to many here: details on the tensegrity frame.


Khalid Baheyeldin
 

Thanks
It is now in the showcase.

Some comments below:

On Sun, Nov 15, 2020 at 06:54 PM, Leo Barnard wrote:
The current drivers are LV8729's but I started with 4998's.  Next iteration is going to be with the THB6128's as used in the original Ioptron electronics.
The LV8729 are very accurate. So why change to something else, where it would not give much of an advantage?

Thie drivers are set currently for 128 microsteps but 32, 64 both work. Just rougher slews.  
You mean less noise at 128 than 32? If so, I agree.
But if you mean more accurate, I don't know if the difference would be so marked as to see in slewing.

The motors are the original Ioptron NEMA-11 steppers (JKong Motor JK28H528-0804).
Are these geared, or you used pulleys?

Nice to see NEMA11 motors carrying a 12" SCT (though its weight cut down by the new frame).