Eric Brown created a new topic ' Scheduler question' in the forum. 2 days ago

Is it possible to have the scheduler configured to interrupt a sequence when a higher priority sequence becomes runnable? For example, if my primary target isn't visible until a certain time / elevation, I typically want to image something else before then, but as soon as possible I want to start on the primary target. If I set the primary sequence to a priority of 20 and the filler sequence as a priority of 10, the scheduler shows that it will run the filler sequence to completion before starting the higher priority sequence. I have to decrease the number of images to get the primary job to start as soon as it meets the criteria to start (at least I have to do this according to the sequence info in the list for start times).

Read More...

Eric Brown created a new topic ' Polar Alignment question' in the forum. 2 days ago

Is there any way to control the slew speed used by the polar alignment process between images? It seems to want to use the "Find" speed for me which is set to quite slow in my mount. Regular gotos use the max speed, and it seems like the PA process should use the same. This seems to be new behavior, though its possible a firmware update to my mount has changed the default Find speed.

And is it possible to control what the mount does after the PA is finished? It seems to want to try to park the scope when done. But typically I'll want to run the process multiple times as I get the alignment dialed in. Ideally it would return to the starting position.

On a related note, is there any predictable way to automatically slew the mount to what it thinks is due north with the RA axis straight up? That's the position that I want to start my polar alignments from as there are obstructions that prevent it from working if I start too far from that.

Read More...

Its not needed, but it might provide some additional resolution, though it remains to be seen whether the mechanics of the RedCat or my seeing conditions lend themselves to improvement.

Read More...

Thanks for the advice everybody. Full Field mode worked *great* last night! It was bang on and worked the first time. Linear worked just the way that I would expect it to. I even tried polynomial mode and it picked the same focus point as Linear, though it didn't seem like it took enough data points to come to that conclusion. I'll have to play around with it more before I put my trust in it.

Woot! I'm really happy with how things are working. I'll still probably switch to the 5:1 stepper at some point, but I'm not in a hurry.

Read More...

The focused worked much better last night. I now get the expected V / curve during auto focus. I could repeatably move focus away from the focus point and back to the same step number and things were in sharp focus. I still need to tune the parameters for the auto focus algorithm itself. It was never able get it to automatically choose the focus point (though I was able to choose it myself based on the data from the auto focus process). I’m using the linear focus algorithm. Once it finishes the first pass, it then appears to try to take multiple readings at the same steps right around the focus point. However my seeing must be varying enough that it couldn’t get consistent enough readings without moving the focuser and would eventually error out. I adjusted the tolerance % without success, though I’m not sure that’s the right parameter. I didn’t spend a lot of time as I wanted to get started imaging, so I just chose the best focus point and moved on.

Read More...

kross wrote:

esb wrote: And a problem like this wouldn't be complete without a facepalm. I just noticed with the stepper attached to my RedCat, if I ran it from 0 (fully retracted) to nearly max (500) and then back to 0, it kept missing the zero point by a few degrees (it was always short). It turns out the grub/set screw for the pulley attached to the stepper is loose. Double-d'oh! That means I have at least 10+ steps of backlash. I'm guessing it will work much better with a tight pulley.


Consider yourself getting off easy! When I did the Rowan belt mod for my Orion Atlas mount, one of the set screws on a pully deep inside the mount wasn't tight enough. Took me a month to figure out why I was getting such bad backlash in Dec movements! So I had to tear the mount apart to tighten that screw. I put blue Loc-Tite on those screws, just because I was mad at them!


Its especially ironic because the grub screw is one of the first things I advise others to check for many different kinds of 3d printer issues. I need to take my own advice.

Read More...

With my existing stepper, backlash now seems to be around 1 step. I can see clear consistent movement for even a single step and when changing directions at most that first step doesn't show full movement. I can see that with large moves in one direction followed by single step moves in the other. When does darkness get here? I really can't way to try it out again.

Read More...

And a problem like this wouldn't be complete without a facepalm. I just noticed with the stepper attached to my RedCat, if I ran it from 0 (fully retracted) to nearly max (500) and then back to 0, it kept missing the zero point by a few degrees (it was always short). It turns out the grub/set screw for the pulley attached to the stepper is loose. Double-d'oh! That means I have at least 10+ steps of backlash. I'm guessing it will work much better with a tight pulley.

Read More...

kross wrote:

El Corazon wrote: My 2 cents on this is that upon microstepping down to 1/32 and using only one step for each move, the motor does not have enough torque to reliably move that one microstep.


When using the Waveshare INDI driver that I wrote, a single step in the INDI control panel will equate to 32 microsteps at the motor. I always end on a full step boundary. I use microsteps for smoothness and quietness, not for increased resolution. If it were to stop on less than a full step, then the motor would need to have power applied to it constantly to hold that position, thus using more power and causing the motor to get warm (or very hot if you haven't tuned the current limit). But with my approach, that allows me to turn off power to the motor when not actively moving for focus.

So I'm not sure if that is esb's problem of it not always moving the same amount with a single step. Does that also happen if you disconnect the belt, just letting the motor run free? If it works fine when the motor is running free, but misses a step when connected to the belt, then it is most likely a lack of torque. You can try slowing down the motor with the delay settings, since stepper motors lose torque when running faster. You can also try using less microstepping via the DIP switches. You will need to modify the source code to match the micrstepping setting of the DIP switches. Eventually I'll make that a configurable option in the INDI control panel.


Ha... our messages crossed. I think the timing is indeed my problem. With the geared stepper, the inconsistent (even reversed) movement happens under zero load. I think I'm just pulsing the motor too quickly.

Read More...

I'm guessing you're getting about a 10:1 gear ratio since the drive gear on your motor looks to have +/- 11 teeth and I'd estimate that if the gear on the scope was a completely circle, it would have ~100+ teeth. In my case, I have a 6.5:1 ratio (20 teeth on the drive gear and 130 teeth on the scope side). And now I'm adding a stepper with a 5.13:1 gearbox.

I did some additional experiments with the geared stepper and discovered that the problems I was seeing with inconsistent (even backwards) movement went away when I increased the step delay in the WMH driver. I had been using a 40us delay per step, and am now using 100us. I'm guessing it was trying to micro step too quickly. I bet that's the issue I was getting on my regular stepper as well. I'll have to see if it performs better with the higher step delay. I also have the option of turning micro stepping off completely. The only reason it was used in the first place was to smooth out the motion and not to actually increase resolution. But if the stepper loses torque in the process, it might be better to just use the native step size of the motor. The gearing should improve both torque and resolution.

I had been looking for your original CAD files to adapt your gear design to my layout. However I can do that pretty readily in Fusion360 if I need to. I also probably have a Nema bracket around somewhere if I end up trying out your design. I'm still hopeful that I can get the belt driven solution to work.

Read More...

I also meant to ask what gear ratio you are using in your setup.

Read More...

Any chance you have fusion360 versions of your designs? In my case, the focuser is also a mounting base for an arca-swiss quick release plate that I connect a custom set of enclosures for the electronics to. And the base / focuser is all 3d printed, so the base has to be pretty thick to give it the needed strength (using most of the gap between the dovetail and RedCat itself). Part of the reason I wanted to try again with the belt solution is that the product from deepskydad.com claims to successfully use a belt-driven focuser.

Ultimately it does seem like a geared approach is generally better though. One of my goals was to allow the RedCat to be completely retracted when not in use. Given that it needs nearly 180° of rotation to do that, I'd need to mount the stepper above the scope or add a riser of some sort to allow room for the gears underneath the scope. I'll have to do some calculations to see if there might be enough clearance for an appropriately-sized gear between the scope and the dovetail if my mounting base wasn't in the way. I might be able to add a slot with clearance for the gear is that seems feasible. How far does your gear extend out from the surface of the focuser?

I still would like to try my geared stepper, though I'm not sure its actually going to work. When testing with the existing driver doing 32-microsteps and having it step just one step, it doesn't always move forward a consistent amount. I'll have to see if the other stepper I have been using does the same thing. I wonder if there is an issue with the stepper driver or the configuration of the Waveshare stepper hat.

Read More...

In my case I'm actually using the same type of reinforced belts that a 3d printer uses. In thinking about my problem, I think the issue is actually too little torque and not backlash / slop due to the belts. And relatedly it may be due to too little rotation needed by the stepper to make a visible change in focus. I am focusing in 1 step increments (with 32 microsteps enabled). I'm going to try to install the 5.18:1 stepper I bought when I was originally working on this. Unfortunately I just noticed that despite claiming to be "Nema 17", the bolt pattern in the front of the gearbox is *not* a nema 17 pattern. Sigh... I'll have to adjust the design and reprint (which is lengthy as the stepper mount is integrated into the mounting plate which is ~232mm x 70mm x 16mm (it needs to be strong). That one takes a while to print, though I do have a fast profile for a .6mm nozzle dialed in from printing PPE, so it shouldn't take quite as long as it did before.

Read More...

Eric Brown replied to the topic 'Problems with image capture during focusing and polar alignment' in the forum. 4 days ago

To see if there were any other unexpected settings, I diff'ed the settings .xml file vs. the default and noticed that "MonoBin" was set to 0 instead of the default of 1.

Read More...

Eric Brown replied to the topic 'Problems with image capture during focusing and polar alignment' in the forum. 4 days ago

D'oh!



I actually went looking for a control like this last night but missed this one (though to be fair, its at the bottom of the rightmost "Controls" page and starts out as the only line scrolled off of the bottom. I had assumed it would be in Image Settings and Image Info showed 14 bits (though that really is the sensor info I suppose). I had also tried creating a new profile in the hopes that might clear any settings, though I suppose the design is to preserve the individual device settings between profiles. Had I not been so tired I would have thought to just reset the settings (though I'm not clear on the difference between 'Default' and 'Purge' in Options:Configuration). Something must have gone wrong after the upgrade as the default for the format is "Raw 16 Bit" and I did not touch it.

In any case that should resolve the issue I was seeing. Thank you.

Read More...