Anybody wants a stepper motor analyzer?
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@zapta said in Anybody wants a stepper motor analyzer?:
@ccs86, very interesting. Those PA 'pulses' is not how I imagined PA.
It explains the extreme noises I got at the time when I tried high PA values with a 600mm bowden printer. The stepper was so erratic that I had to install it on RC rubber dumpers. Eventually I switched to a direct drive and the problem solved.
I wonder if PA has one 'natural' profile or if different firmware developers come with different profiles. There are many degrees of freedom in shaping the profile which we reduce to a single number.
I have found that the current PA implementation is not useful at all on my bowden printer, and I think it's about as well-tuned as a bowden gets. I have a few thoughts on why it is missing the mark that I posted here:
https://forum.duet3d.com/topic/17752/pressure-advance-discussion-for-future-development
There are certainly different ways to implement PA, but the same basic principle is a the base: increasing volumetric extrusion rate, requires increased nozzle pressure (filament drive force). The filament drive system acts like a spring, so you can increase pressure/force with an increased spring preload (being a certain number of steps "ahead").
Klipper has a PA "smoothing" algorithm that I think would be really helpful in calming down the extruder motion. But I think bowden machines need more,
On the steps chart, you can think of the green line here as PA=0. The orange area is the steps boost for 20mm/s, and the red area the additional steps for 80 mm/s
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Hi Zapta - nice work with the Stepper analyzer.
I would like to buy one - do you send to Denmark? And what will it cost?
many greetings
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Hi @webhunter, build 30 units and gave to people here at cost. Currently I don't plan to build additional ones but all the files are in public domain and anybody is invited to build, including commercially.
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@webhunter You can certainly get your own pcb (note, not assembled with components) from a place like JLCPCB or OshPark and build it yourself, or source assembled units from JLCPCB using the source files.
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@webhunter, I used the files here to order the boards from JLCPCB with SMD service.
https://github.com/zapta/simple_stepper_motor_analyzer/tree/main/kicad/JLCPCB
It includes only the components they support which means that some parts you will need to order and solder yourself (the two current sensors, the two connectors, the Raspberry Pico module, and then you will need to attach and connect the TFT module). Make sure to get the exact TFT module for compatibility with the hardware and firmware.
Of course you can get bare boards and solder everything yourself but it depends on your SMD soldering skills. The TFT connectors have 0.5mm pitch and it's easy to bridge adjacent pins (and it's possible to fix if you or JLCPCB happened to bridge them).
Let me know if you have further questions.
Edit:
- When ordering from JLCPCB with SMD service, they will fix the orientation of a few components. That's normal since they assume different footprints.
- PCBWAY may provide a more complete service (with current sensors and Pico board soldered) but ordering SMD service from them is slightly more involved.
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@zapta one Idea would be to integrate the RP2040 directly. Will Look Into that Option If i have any time
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Hello everyone.
Just a quick update. I finally got time to build a couple of the analyzers. I will go in tonight and do some testing. Once I'm done I will have a couple available. Send me a message and let me know if you're interested.
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@pcr, yes, using rp2040 directly would be a good move forward, considering that JLCP now carries it as a standard SMD service part.
Dustin Watts, the designer of ESP32 Tochdown (which which I copied the form factor and TFT model) mentioned recently doing something similar to his product and may have schematics to share (he is available on his Discord channel and is very open source friendly).
https://www.tindie.com/products/dustinwattsnl/esp32-touchdown/
Another good move would be to switch to a current sensor that JLCPCB carries (I found an allegro +/-5A with 5V supply and lower bandwidth one that may fit with some adaptations). Or, placing the SMD service order with PCBWAY which has access to more parts (Dustin Watt order from them and they also sponsor his YT channel)
@Th0mpy , that's awesome.
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I have some sensors from the legacy one left. So i will build some of the pico ones.
Anyone wants one in europe
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I'm working on battery powered one. Consumtion is 220mAh so around 2H autonomy. Charge and use as the same time when USB plugged. Small Housing redesign, 1mm thicker.
Still waiting sensors from china (hard to find them in europe!) -
The current sensors that used to cost $1.39 each are now $6.12, from the same vendor, due to the global semiconductor shortage.
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A side note, if you want to make a stepper extension cable or need for any other reason connectors that mate with the Duet's 4 pin kk connectors, these DigiKey part numbers seems to fit
WM13471-ND ; housing
WM2330CT-ND ; pins
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@zapta
The current sensors are £3.35 each, if you buy ten, from the same supplier via this site:
https://gbr.grandado.com/products/10pcs-lot-acs70331eolctr-2p5b3-acs70331-a70331-70331-sop-8-ic-chip-original?gclid=Cj0KCQjwtrSLBhCLARIsACh6Rmi87C-4ieahOuPrFe5HqIFy459C3PG6qSX53DwHaApaXtR0o5t1YjEaAsZZEALw_wcB&variant=UHJvZHVjdFZhcmlhbnQ6MjUzMzY3MTI3I've just ordered five PCBs and ten sensors; I'll probably build two units myself so if anyone in the UK wants a board or sensors (at cost) let me know.
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@rjenkinsgb, that looks as a good price considering the current shortage.
Please be aware that there are fake allegro ICs on the market. If you buy through Aliexpress they will give you a refund if you got faked. The signs of faked current sensors are
- Pins 1,2 are not shorted.
- Pins 2,4 are not shorted.
- The face is sanded (below the new marking) and the pin 1 dimple is shallow or non visible.
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@th0mpy definitely interested.
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Someone have 2X spares ACS70331 to sell in europe ?, can't find them. Thanks
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Well, JLC are on excellent form as usual - the five PCBs arrived yesterday.
The current sensors have been despatched, but I don't have a delivery date yet.
I will post an update when they arrive.
