Twice over the past week, my G11g has just stopped - not powered off, stopped. Once was during setup while I was trying to slew to a target before my session and last night about four hours into my session. My resolution for the earlier session was a full reboot which fixed the issue and it ran all night. By the time it stopped last night, I was two hours into sleep. ;)

I did not turn the mount off between the previous session (two days ago) and last night's session.

I'm having no *physical* cabling issues (i.e. entanglements causing disconnects) and the mount is still powered up. This morning it just will not respond to commands - I cannot get it to park. I hope it's not because it's about 22 F.

All other commands issued to NINA work fine - I just warmed (heh - at 22 F not much warming I can do) the camera and turned off all the equipment (except the mount which will not respond).?

I'm not sure where to begin looking for issues so I'm asking for a starting point before I turn the mount off to reset it - some logs somewhere... ???

I *know* that's not a lot of information but I'm just not even sure what to ask.

Thanks,
Joel

Even using 0.9.degree (400 step) stepper motors and the maximum possible micro steps a direct drive stepper Losmandy G11 has relatively low resolution. Once you use a.more realistic number of micro steps closer to the guidelines for reliable micro stepping somewhere between 16-32 or maybe 64 obviously resolution goes out the door. Testing steppers online for 3D printers and verified by my own testing has shown that the most reliable microstepping rate range fall between 16-32 and beyond this rate the loss of steps due to tremendously reduced torque as the microstep count goes up becomes noticeable. At least if becomes a serious issue on 3D printers anyway.?

--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astrospheric Weather Forecast - South Pasadena, CA?

I was curious about the CQ350 but went with the EQ8-R Pro. My EQ6-R pro is now my portable mount.?

开云体育

That's what I meant.? The mount was an iOptron GEM45 and it has a 1.5" peak-to-peak oscillation in RA with a period of, if memory serves me right, something like 0.7 second.? (Since a 1.5" p-p sinusoid is only 0.5" RMS, and because the period was too fast for PHD2, it looked like maybe 0.5" of roughness and I still got good guiding.)? The motor may have been underpowered; iOptron sent me a new circuit board with different voltage regulator chips that noticeably ameliorated the problem.

Hi Mike,?

Can you explain what you mean by a "period of a full set of microsteps?" I can see that meaning the period of time it takes the motor to complete a microstepped full step. But in my example the motor is moving?3.23 full teeth a second and clearly not losing a second. Thus you must be speaking of a larger sample size.

Analog Devices' Trimanic division's has extensive efforts to deal with the situation you describe. It would be interesting to see if it shows up in the driver's diagnostic output.

-- 
Michael A. Covington, Ph.D.
Consultant, Covington Innovations, Athens, Georgia, USA 

Michael,

Micro step position does vary but I'm not sure it represents a significant issue; this not accumulating during guiding.? The issue appearing like corrected backlash.? And it cannot accumulate in physical position between motor poles (true steps).

I always felt power consumption and the related issue of producing less torque for the power were my issues.? The benefit of being open loop becomes significant only if the weight and power allow for this.

With torque levels at tracking quite small, as you illustrate here, the variation cannot be large, or it shows up in guiding.? I've never seen anyone ask David Partridge?but the RMP of our motor during tracking must be quite low and the ability of our motor to arrive exactly on count at a moment in time also a variant.? Still there too, all just esoteric when compared to the tracking RMS achieved.? Hence the importance placed on achieving Level 6 functionality.

Doug? ?

On 2023-12-31 18:06, Brendan wrote:

You can increase torque by using a larger to smaller belt hub, which is the same as any large to small gear ratio.
--
Brendan

Yes, but it remains the case that torque is not the same across the entire microstep cycle, leading to slight speeding up and slowing down.? We're not talking about lacking the torque to move the load.

Michael A. Covington, Ph.D.
Consultant, Covington Innovations, Athens, Georgia, USA

You can increase torque by using a larger to smaller belt hub, which is the same as any large to small gear ratio. ?
--
Brendan

Good info Michael.? Thanks for posting.

------------------------
Jim W
Phoenix, AZ. USA

Losmandy G11G w/ L6, NINA 3.0 / ASTAP, ASI2600MC Pro, ASI533MM Pro,?Sky-Watcher Scopes, Canon L Lenses.

On Sun, Dec 31, 2023 at 06:01 AM, @VictoryPete wrote:

What is your primary mount?

Sky-Watcher CQ350.? The G11G is my portable mount.? The CQ350 is setup at my cabin in northern AZ.? I wanted a Mach2 but decided the price was too high.

------------------------
Jim W
Phoenix, AZ. USA

Losmandy G11G w/ L6, NINA 3.0 / ASTAP, ASI2600MC Pro, ASI533MM Pro,?Sky-Watcher Scopes, Canon L Lenses.

Since the conversation has drifted to belt drives in RA, despite the title, I've changed the title.? Let me share what I learned with a mount of another brand.

Microstepped stepper motors do not have equal torque at all microsteps.? As a result, they tend to have a small cyclical error over the period of a full set of microsteps, on the order of a second (too short for PHD2 to pick up). (They get behind during the part of the cycle where the torque is lower, then catch up.)? I was able to see this in planetary videos, and of course it puts a lower limit on your guiding accuracy in deep-sky work.

Better circuit design reduces the problem but does not eliminate it.

That is why I chose a servo-motor Losmandy for my current mount. I haven't upgraded to Gemini Level 6 but am hopeful that it will become even smoother.

Belt drives like everything else have their own issues.?

LOL, so the mount is also bad at selling itself? LOL.

Try offering your "bad" mounts at market prices, not what you imagine you think they are worth during a season when people are likely to buy it. Pull down your for sale posts and put them back up in the spring at a reasonable price and they will sell.?

It doesn't help that you both have posted and complained about how bad your mounts are. Additionally posting they don't work how you think they should work and how you can't figure out how to use them unlike about 99.9% of other Losmandy owners.?

It is strange that you guys just keep on being the victims here, I think you seem to enjoy it.?

--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astrospheric Weather Forecast - South Pasadena, CA?

On Sat, Dec 30, 2023 at 11:51 PM, Jim Waters wrote:

I gave up trying to sell my G11G.? Its my secondary mount now.

------------------------
Jim W
Phoenix, AZ. USA

What is your primary mount?

I gave up trying to sell my G11G.? Its my secondary mount now.

------------------------
Jim W
Phoenix, AZ. USA

Losmandy G11G w/ L6, NINA 3.0 / ASTAP, ASI2600MC Pro, ASI533MM Pro,?Sky-Watcher Scopes, Canon L Lenses.

Since I now have an EQ8-R Pro and the stubborn G11 that doesn't want to sell, and they both easily install on my Primalucelab C120 pier, it is interesting to compare and contrast them. The EQ8R-Pro is super quiet and smooth with the belt driven stepper motor, whereas the G11 is noisy and doesn't seem so smooth. I think the pro and cons with both of these is tied at this point, they just are different for each mount.

On Fri, Dec 29, 2023 at 12:15 PM, @VictoryPete wrote:

What make and model mount is that? Direct drive seems like a good idea.

Pete,

Direct drive using stepper motors are not a great idea. Do the math and watch what happens to your drive line smoothness and controller granularity when you switch to a micro stepping motor while tracking.

The Losmandy GM8 & G11 mounts use a reduction gearbox for a reason. Smoother and finer mount motion.detection and control.

The recent L6 firmware updates had a massive amount of time invested beyond merely updating and bug killing for use with modern imaging applications. The bulk of the time was spent on L6 development to increase control detection granularity and movement to improve tracking smoothness. Once the servo motor PIC chip code was completely rewritten to operate using quadrature detection correctly additional issues required fine tuning the control software to eliminate issues that were not present when not using the very high resolution position data now available to the Gemini 2.?

The amazing thing is it worked and most mounts in good condition and using PHD2 see improved guiding and tracking.?

BTW that is the classic Losmamdy 2-piece worm drive on a G11.?

--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astrospheric Weather Forecast - South Pasadena, CA?

Hi Chip,?
Ok the DEC motor is as quiet as my belt driven eq6-r pro now, thanks for the tip NOT overtighten it!
RA is better, but not as quiet as DEC but, I'll leave it for now think maybe that's just the way it is, plus, those AC units outside in the neighbourhood overpower this RA motor easily :-P

Yue

What make and model mount is that? Direct drive seems like a good idea.

Thanks Chip, I'll give it a try!

George, I don't have an explanation for that either, but the method from that 2nd video did help eliminating the backlash - that is, leave a little space, torque the gear and press the block in the direction as shown in that video, tight the cover, then adjust the spring screw.
Adjust only the spring screw (like in the first video) resulted either no backlash but extremely tight spur gear, or smooth spur gear but also backlash.
P.S. George, actually, I think this is what happened in my case, quote Chip's post: "The most common reported issue is worm bearing block shift."

Yue