John Boston replied to the topic 'Rpi DIY mount stepper control upgrade?' in the forum. yesterday

Wofi, I looked at some of the online resources on the Austrian Precision Mount. If your friend has any more details about the construction of a friction drive, I would be very interested in them. THe sorts of specific questions I have are:

I see references to the need for hardened steel in designs referenced online--did you mean hardened? or is the need for non-hardened stainless steel because of unique friction qualities of the Softer metal yet it retains durability? Or would regular steel or iron work except for rusting? Is a smooth contact area desired free of imperfections and perfect diameter or is a knurled or scored contact area desired? What would be a typical thickness of a wheel to ensure sufficient contact area? Any bearing recommendations? I am thinking of a GEM style mount with a 20KG payload or so stepper and TSC driven.

Sincerely grateful to all


John Boston replied to the topic 'Rpi DIY mount stepper control upgrade?' in the forum. 4 days ago

Has anyone had experience with or considered a friction drive rather than toothed drive? I know it gets good reviews in high end systems but why wouldn't you be able to machine out two diameters and use stepper to work with the resultant ratio? . Some reasons might be problems:

1) The small contact area between metal rollers, while sufficient for low speed tracking performs differently at high speed slewing?
2) The risk of slipping can lead to loss of position and potential collisions
3) Exact specific ratios are easier to achieve by # of teeth rather than carefully machining two diameters to match
4) What is popular and working is tried more often by others hard to get suggestions for machining
5) Possible environmental effects on performance? I don’t know.
Seems a stepper/encoder/controller solution would work great with a friction drive at any size and be in the reach of DIY fabrication of the rollers.

found this link


John Boston replied to the topic 'Rpi DIY mount stepper control upgrade?' in the forum. 6 days ago

Great stuff to listen in on guys! That 350 KG video and the implied near degree per second movement at that weight is awesome to ponder, given the stingy load limits and performance of off the shelf mounts and what they cost to get even decent AP performance.

I have used perhaps a dozen different phidget products in non-astronomical projects so the 1067 "feels" right in addition to liking the usb programmatic control and the safety features. WBIRK I bet there would be general interest for all 1067 users in a well designed heat sink for that board. I am assuming that if the stepper is driving a worm then back EMF and torque holding issues are not the issues they would otherwise be.

I can see some limited advantages in the .9 degree 400 step NEMA 23 motor in an attempt to avoid or limit microstepping, but I would think I would still need a planetary gearing and couldn't go direct at 400 steps even with 360 teeth. Although I can brute force torque, the smoothness I need is only going to come from stepping/planetary ratios (I think). Doesn't the Phidgets 1067 automatically implement stepping through microsteps anyway?

Assuming you wanted to create a mount to drive a 20-30 KG load and didn't mind a slow slew rate, is there any hope for avoiding a planetary ratio in your stepper for RA tracking? Direct drive mounts are such an illusive goal in general, but even direct stepper drive of a 360 tooth 12 inch worm would seem illusive given the desire for arc-seconds smoothness regardless of the motor size or choice. I am going to either do planetary/microstepping or both.

BTW, I have a Phidgets servo motor controller and a nice high torque CR servo with metal gears.. I have a good python program to control rotation and acceleration (use it on a lesser CR servo for focus control) would a high end hobby servo do for mount control I wonder.


John Boston replied to the topic 'Rpi DIY mount stepper control upgrade?' in the forum. 1 week ago

Ray: i am at a conference in Gatlinburg, TN today but I live in Nashville area which is in the path of totality. I am wiling to make an outing in either direction on the path of totality depending on the latest weather forecast 12 hours before the eclipse just to make sure I don't miss it :). There is a true dark sky viewing location I love at the North Carolina/Tennessee border on the cherohala-skyway. that is at 5600 feet and pretty much a maximum duration location. It has the 360 panoramic views and I was hoping it was the sort of location where one might even see the moon's shadow zooming over the landscape..that would be breathtaking.. There is another nearby called Huckleberry Knob and other spots

Cligman's Dome is another 1000 feet higher with a 100 mile view...I'm sure you have read up on what a big event its going to be there. could be a thunderstorm in progress right? It's a daunting task to know how to plan for it.

I suppose I should comment on the stepper info to keep this topical. As I commit some finanical resources to the idea of my own stepper mount control, I am leaning toward some sort of RPI 3 implementation with the phidgets 1067 as these are just products in my comfort zone of previous use. the LX3 I am playing around with does have a wedge already..I was just considering it as a vehicle for learning about mount control. not sure what my mature imaging setup might be. Given Rob's comments about microstepping I was just curious how far a 400 step (.9) with the added torque of the 23 might take someone to be able to avoid using a planetary 15:1 and still move around a good sized load. Clearly microstepping is going to be desirable for low arc-second precision as long as one is clear eyed about the tradeoffs of microstepping. All comments welcome-- I'm just a sponge for now ;)


John Boston replied to the topic 'Rpi DIY mount stepper control upgrade?' in the forum. 1 week ago

Wow, great replies all. I have assumed in general that if I was going to get the torque I needed for a bigger load in the future, some sort of planetary was going to be desirable and that microstepping would be necessary for the smoothness I wanted. What do you think of this motor, and have you seen 400 step motors (.9 degree) with any more torque than this?

I appreciate the strategies for minimizing backlash. Without having a monster worm with greater than 360 teeth how far could this stepper take you torque and smoothness wise? Enjoying dark Smoky Mountain skies visual tonight hope to play with the download over the weekend.


John Boston replied to the topic 'Rpi DIY mount stepper control upgrade?' in the forum. 2 weeks ago

I messaged email for that TSC Raspian RPI3 image thank you! I am attending an out of town conference early next week but I will take a look at it as soon as possible.

Rob I appreciated your comments about sizing and other considerations for steppers. I have a garage sale LX3 8 inch SCT that I have done a full tear down on. I was able to replace a connector and the power supply and restore it to full electronic functionality. l think it is probably worth keeping it intact as is, given that even old hand controller still works, but I thought while having it torn down might allow me to play with a stepper and see how RPI tracking might work. I suspect something in the NEMA-17 15:1 as recommended might handle the load just fine properly balanced but if I were investing already in a geared stepper maybe a 23 would be good for other experimentation.THe phidgets board I want to have anyway has isolation and safety features.

After attempting to image on ALT/AZ on a wedge for abit I am at that point many people arrive where they feel they want to drop the money for an ATLAS or CGEM or such more robust mount. I frankly would rather use that investment as an opportunity to fashion a custom mount at my fixed dark sky location. Portability is not an issue. I would love to build something hardware wise simiar to this using rpi stepper control.

I have access to a motivated and talented machinst who owns a professional shop with astronomy interest but no experience in mount design. Have any of you seen a ATM mount design you love that would support payload similar to the ATLAS or CGEM mounts that I could use as a good starting point to specify my own design? I liked the demo of the TSC GUI and the fact it still operated with Kstars etc.


John Boston replied to the topic 'Rpi DIY mount stepper control upgrade?' in the forum. 2 weeks ago

Sorry for the delay in my response. Thank you both for your helpful replies. Wolfi, I would love an SD card image to experiment with-- are you speaking of an SD image suitable for Raspberry Pi 3 Hardware? I need to order the appropriate stepper and the phidgets controller board.. A recommendation for a good stepper motor choice would be helpful as well as any sourcing recommendation for a planetary gear. I would just love to be pointed in the right direction sourcing wise. I am stuck with a 180 tooth gear RA only drive for now but i am looking for additional Worm drives to play with. Blueshawk thanks for the Gear ratio info and I'll peek at your solution as well.


John Boston replied to the topic 'Rpi DIY mount stepper control upgrade?' in the forum. 3 weeks ago

What is the current state of your 2 motor stepper control library-- seems an issue with the latest commit?

I am interested in using the phidgets 1067 boards to control two stepping motors for RA and DEC control. I have used phidgets quite a bit for varios projects including the 1061 servo motor controller and prefer to work in python just because I am more familiar. Unfortunately, I only have 180 tooth worm drive in an old Meade LX3 to work with for my experiment. However, I have disassembled and the condition of the drive and worm is excellent and was well machined at the time.

I was thinking of swapping the 1/8 rpm motor with a Stepper and giving it a try to see what kind of results I might get For deep sky tracking, this drive would need to advance 1 tooth every 480 seconds with 2.5 steps per second without microstepping (based on 1.8 degree step angle?) Obviously, I am a complete newb to this but very attracted to the idea of stepper control. The 1067 micro stepping of 16 (while coarse by professional standards) would give me 40 steps per second theoretical? which would seem to limit vibration. Can you recommend a specific NEMA motor and a barebones strategy for a newbie approaching this task (assuming to start...DEC LOCK, one 1067 phidges controller and a raspberry pi 3 or windows machine available?? Thank you for any information.


John Boston replied to the topic 'localhost support in Windows KStars for' in the forum. 9 months ago

Sorry don't know how to change that cryptic topic name....


John Boston created a new topic ' localhost support in Windows KStars for' in the forum. 9 months ago

adding indi_fcusb_focuser driver at the linux command line allows me to use the FCUSB Shoestring controller with JMI motofocus focuser. Is there going to be any way to get access to that into the windows version of KSTARS as a local host? The only way i have found to get that driver active is either with a cloudmakers server in MAC or the astroDLSR product or from the command line in linux. I have loaded up the windows KSTAR 2.7 but don't see FCUSB as an option (I wouldn't expect to see it)
Any ideas? Other than running a separate linux indi server and connecting remotely?


John Boston thanked Jasem Mutlaq in topic Voice Control of KSTARS? 10 months ago
John Boston replied to the topic 'Voice Control of KSTARS?' in the forum. 10 months ago

I had not heard of the mycroft project and I am checking that out thanks! I did install the Amazon Alexa US engine yesterday on the raspberry pi using the "SENSORY" and "KITT.AI wakeword processors but this is not a true open source solution and there is no rules engine I can exploit easily. I see the Mycroft AI code is to be released under GPLv3 using the UBUNTU snappy core. Are there KSTARS issues in that distribution?

My shorterm goal is way more pedestrian: Can anyone suggest a way, for example, I could say the word "MOON" and it be inserted into the "find object" filter field of KSTARS ctrl-f menu and advance to the OK button without using the keyboard? I'd like to think there is a way that the "paste text" or some workflow command would work with some dictation product on windows, mac, or Rpi.


Jasem Mutlaq thanked John Boston in topic Voice Control of KSTARS? 10 months ago
John Boston created a new topic ' Voice Control of KSTARS?' in the forum. 10 months ago

I would like to make KSTARS accessible to an astronomer with extremely limited keyboard and mouse skills due to Parkinsons. One approach would be to use scripting and workflows to do automated observing and capture for him. What I was hopeful in addition is that there might be dictation enabled commands that would allow him to navigate some of the common functions of the KSTARS menus that require keyboard/mouse input. KSTARS has many Ctrl-Letter sequences that can be easily captured in the accessibility functionality of the MAC for example. I can say "Hey" then "find" (Ctil-F and the cursor is sitting Where I might like to enter "MOON" but since the KSTARS input field is not text I have not figured out how to dictate instead of typing. Any experience in Mac, Windows, or Linux environments with passing dictation type commands directly into KSTARS as a substitute for keyboard? Im interested in participating in a comprehensive long-term Voice-activated KSTARS strategy, as well as a short-term partial functionality.

Example of Mac voice activated "what's up tonight Menu" command here:


John Boston created a new topic ' Win10 KStars2.6.0 freeze uninstall issue' in the forum. 10 months ago

I installed the beta Kstars for windows on a Windows 10 machine. All was well for the first use. After exit and attempting Kstars the second time, Kstars stopped responding during startup and the screen went white at the "TIPS" display point. Exiting and reloading Kstars repeated the same problem. I did an uninstall through control panel. Re-executing the installer did not have write access to DLL files. Ignoring the multiple errors and continuing the installation (many times) allowed the reinstall to finish and the program loaded successfully. However, once I exited, and attempted to reenter Kstars, the same white out Freeze occured whether I checked to load tips at startup or not.

I will add that It was after creating a shortcut to Kstars on the desktop that this occurred by I tried it afterwards without the shortcut and got the same problem.

Any ideas?


John Boston replied to the topic 'JMI Motofocus using FCUSB on Jessie rpi' in the forum. 12 months ago

This quote from the Shoestring Astronomy page on FCUSB:
"Third-party software that supports the ASCOM Focuser standard will also work with the FCUSB using the FCUSB ASCOM driver. DC focus motors don't provide absolute positioning repeatability like a stepper motor does, but we have tried the FCUSB with third-party autofocusing software and obtained decent results. However, there is no guarantee that this will work for all systems."

1) Peter (or others), from your experience with FCUSB in EKOS, will I have any success at all (even crude success) letting EKOS schedule an unattended observation and capture even a 1/2 decent result? I would consider even moderately focused images of the Moon Jupiter, or M42 a success. Initially, I would just like to be able demonstrate EKOS imaging something without intervention of any sort once scheduled. Is it too much to hope for without investing in a absolute focuser or more sophisticated focuser or some other platform than EKOS?

2) I am currently using python to control a continuous rotation servo which can "serve up" and remove my bahtinov mask on command at the end of my dew shield remotely controlled while I am imaging. Prior to acquiring the jmi focuser I also was successful achieving fine focus using a similar CR servo on the focus knob. Its not a stepper, but I can control extremely slow rotation of the servo and thus the focus knob. If I were to use a homebrew servo focusing solution in leui of the indisupplied drivers and devices, might there way to be a way to insert a scripted routine into the unattended observing plan or alternatively time the observing plan so that such a script had time to execute outside of EKOS? If EKOS was taking a fresh image every 5 minutes, and my routine analyzed the recently acquired image with something like BAHINOV GRABBER and adjusted the focuser prior to the next scheduled image, then when error was acceptable removed the mask for actual imaging. Any thoughts? I'm just hoping as I start to investigate, there's a way to use my crude hardware unattended in some fashion with meaningful results. My project is at and recently my emphasis is an all Indi observing site.

Thanks in advance for any thoughts, and thanks again for helping me over my recent hurdle in understanding.


John Boston replied to the topic 'JMI Motofocus using FCUSB on Jessie rpi' in the forum. 12 months ago

Supplied with the driver name I was able to load indiserver from the command line and operate the focuser. Thank you for your assistance.



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