Moving the total steps per revolution doesn't equal an actual revolution
Version 2 of the myFocuser Project
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Got my solderless build working last night, first with the 14hm11-0404s and now with the 17hs13-0404s-pg27 and I can get both to move and reduced noise/heat by turning down the drv8825 current pot, but noticed that the number of full steps documented for the stepper won't actually turn the stepper a whole revolution. I left it current turned all the way down because if I turn it up too far the stepper hums and gets pretty warm. Went back through the docs - is there a step I missed somewhere in terms of setup or is the myFocuserProL app the only place needed to enter in the important numbers?
Also, I like the weight of the 14hm11 but did notice that the torque is pretty low, just a little bit of resistance made it skip steps, so decided to bump it up to the nema17 pg27. Anything else besides gearing that I should be doing to help with the nema14 torque?
Many thanks!
MR
https://www.dropbox.com/s/ks3cwabbg2cxcou/Stepper%20Motor%20Issues-01.mp4?dl=0
What I like to do is manually adjust by using slow speed over a long move, back off the pot till it stops, then gradually very very slowly turn pot till motor moves. Then I put thumb/finger on stepper shaft to try and stop it turning. If I can stop it I turn up the pot a little more till no steps are lost.
27:1 (26.85:1) Planetary Bipolar Nema17 Stepper Motor
0.067 degrees per step - gives 5370 steps per revolution
What I do is use focuser presets - set preset 0 to say 5000 and preset 1 to 10370 then use the presets to determine if it moves one full rotation.
Thanks for the help! I checked resistance of the stepper and looks to be around 30 ohms just like in the video, The one thing I didn't do when I switched over to the pg27 stepper was change the microstepping dip switches on the drv breakout board (since I'm doing a solderless build). Once I switched back to whole steps it works perfectly!
For the Nema14 stepper, should I use whole steps on the breakout board and control microstepping on the windows app, or should I always make sure those two things are the same?
May that help with the limited torque I was getting from the Nema14?
For the solderless version, the dip switches set the step mode. Even if you set the step mode to something else in the app, it cannot overwrite that. But for clarity,
1. set the step mode on the board
2. use the same step mode in the app /ascom driver
The NEMA14 has more torque than the 28BYJ-48 but will not lift anywhere near what the geared PG27 can do. People often under estimate how much torque is actually needed.
Got everything working great and have a nice printed case for all the solderless components! The only thing I noticed was that with the coils on or off there is a decent amount of play in the focuser before it starts moving. I just realized last night that I had the original myfocuserpro build on there instead of myfocuserpro2, so will try flashing that and adding some backlash compensation. It looks to be somewhere around 500 steps on the pg27 stepper - is that normal/to be expected?
From my own experience 500 steps backlash for a PG27 is huge. My own PG27 is around 22 steps backlash. I assume you are using direct drive to the single focuer knob [not the dual speed knob].
Correct - I went back and looked at it again and I noticed that the flexible coupler grub screw that holds the stepper axle was allowing some play. I re-tightened it pretty snugly and now there isn't any 'slop' in the rotation anymore. Will try it out again this weekend but hopefully that's all it was!
So I was finally able to push the myfocuserpro2 firmware and install the Windows program after uninstalling the previous Windows program and ASCOM driver. When I attempt to move the stepper I get no movement and the logs look like this:
=START=========================================================
9/23/2020 11:15:58 PM: movefocusercmd: Serial Port is Open
9/23/2020 11:15:58 PM: movefocusercmd: ConnectedState is true
9/23/2020 11:15:58 PM: movefocusercmd: Check if TC is ON
9/23/2020 11:15:58 PM: movefocusercmd: TC is OFF, so move is permitted
9/23/2020 11:15:58 PM: movefocusercmd: Check if focuser is moving
9/23/2020 11:15:58 PM: movefocusercmd: response = I0#
9/23/2020 11:15:58 PM: movefocusercmd: ismoving is false, now Get Position
9/23/2020 11:15:58 PM: movefocusercmd: response = P0#
9/23/2020 11:15:58 PM: movefocusercmd: Moving to = 500
9/23/2020 11:15:59 PM: movefocusercmd: Check if focuser is moving
9/23/2020 11:15:59 PM: movefocusercmd: response = I0#
9/23/2020 11:15:59 PM: movefocusercmd: Focuser has stopped
9/23/2020 11:15:59 PM: movefocusercmd: Get Position
9/23/2020 11:15:59 PM: movefocusercmd: response = P0#
9/23/2020 11:15:59 PM: movefocusercmd: Move completed
9/23/2020 11:15:59 PM: movefocusercmd: =END===========================================================
Is there any additional configuration required when using the v2 vs v1 firmware?
Thanks!
Mathew
I thought you had it working?
V2 is here
https://sourceforge.net/projects/arduinoascomfocuserpro2diy/
To use V2, you have to
1. Download the windows app from this project
2. Download the ascom driver from this project
3. Download the firmware from this project
4. Reprogram the controller with the v299 firmware
5. Install the windows and ascom software from 1 and 2 above
With 12V on the controller turned on and also connected via USB
Start the windows app
Set logging on Extra Settings/Log File/Enabled
Set the comport and baudspeed [9600]
Connect to the focuser
1. Are the values updated in Windows? Yes or NO
2. If NO, then post the logfile created by the windows app
3. If YES, attempt to move the motor by clicking +500
4. If the motor does not move, then post the logfile created by the windows app
You cannot mix and match v1 with v2. It is all v2 or all v1.
Anything else besides gearing that I should be doing to help with the nema14 torque?
I normally adjust the pot manually. Skipping when applying pressure to the stepper shaft means the current could be too low and it needs to be increased ever so slightly, I normally set it to move like 10,000 steps on slow speed, then as the motor is moving hold the stepper shaft and very very slowly adjust the pot from not moving to moving with out missing a step. The adjust of the pot is very delicate and minute adjustments are required.
Can you please get my email address on gmail from either the PDF. And email me your firmware file you used to program the controller.
Regards
Robert