Good morning!

I know that this has been discussed several times already. I started this thread to collect the available closed loop options for the Duet3.

I have two custom large format printers in the making. One with a build volume of 1000x1000x1000mm for printing architecture models and one with 500x500x1000mm for printing speaker enclosures. With a Build volume this large speed and reliability are essential. Therefore, a closed-loop motion system is a "must have" for my clients.

For the Duet3 I have found the following options:

1. Duet3 + Duet3 Expansion 1XD + external closed loop stepper drivers that accept step/dir signals

2. @dc42 I am aware that there is a closed-loop extension board in the making for the Duet3. Is there already a rough estimate on the release date or beta test?

3. Is there an alternative "of the shelve" closed loop solution available that support the CAN FD protocol?

Cheers,
Max

And with this start Gcode for PrusaSlicer the correct heightmap is loaded according to the temperature of the printbed.

{if first_layer_bed_temperature[0] <=40}
G29 S1 P"heightmap_roomtemp.csv"
{elsif first_layer_bed_temperature[0] <=70}
G29 S1 P"heightmap_60°.csv"
{elsif first_layer_bed_temperature[0] <=90}
G29 S1 P"heightmap_80°.csv"
{elsif first_layer_bed_temperature[0] <=110}
G29 S1 P"heightmap_100°.csv"
{endif}

Thanks everyone for your ideas and feedback. This is by far more elegant than my original idea.

@bearer @Phaedrux

I have solved the issue by installing the unstable version (DSF Version: 2.1.3) of Duet Software Framework on Raspberry Pi. and also reverting back to RC11

The guide links to the stable version of the DSF and latest version of the reprap firmware which, at least in my case is not compatible and will lead to the "DCS is unavailable" Error.

cheers Max

@Phaedrux Thank you!
After trying about a dozen different tutorials on how to install and configure motion I found one that worked for me.

Motion setup tutorial

Cheers
Max

I have been using compressed air for hotend and part cooling with great success for over a year now and would like to propose the implementation of means to control things like RC-Servos or Stepper motors or even proportional valves with M106.

Removing fans from the print head comes with a number of advantages like:

• reduced bulk

• reduced mass

• reduced wiring

• reduced noise (My airpump provides more than enaugh pressure/airflow for two hotends incl. part cooling for each hotend and is far quiter than any of my previous fan setups.)

• no breakdowns due to broken or clogged fans
  (Vibrations during printing decreases the fans lifespan and they tend to suck in small parts of filament and get blocked)

• far better cooling since cold air from the outside is used instead of hot air rising from the heated bed. -> Cooling performance is independent of the temperature inside the printer.

Further more, the M106 command could be used to open/close ventilation flaps in order to control the temperature in printer enclosures like suggested by @achrn here.

This feature has been requested in different forms a couple of times by now by different users. I have tried everything from rc-servos to proportional valves with limited success due to firmware restrictions See the thread here . Most of the proposed solutions were based on a demon.g doing some kind of conversion. But since RRF version 3.3 the demon.g is only called every 10 seconds, the delay is just to long for responsive cooling.

One suggestion I found very interesting was to call a macro instead of the fan definition in config.g when the g.code contains a M106 command.

-Max

@lirwin17 Wonderful, thanks a lot for your effort and support!

@t3p3tony said in Duet3D 1HCL - Closed Loop Controller Beta test:

Can I just double check you mean 36000mm/s and not either 3600mm/s or 36000mm/m ?36000mm/s would be a "F" parameter of F2160000

Sry rookie mistake! I did indeed mean mm/min and not mm/s

@dc42 I had the same problems described by @TypQxQ after upgrading from RC3.2 to RC3.3.
The new binaries fixed the issue.

Cheers
Max

@mikedc

Hey, thank you very much for sharing this. I will give it a try!

-Max

Short update:

I am on my third print with the closed loop drivers and so far they are working quite well. The axes are sticking to their position very well. I really have to apply a lot of force to push them off course, and they will snap right back.

I am printing with up to 300mm/s and was able to increase my acceleration and jerk significantly. On the downside I had to limit my max. speeds to 20000mm/min or 300mm/s.

@lirwin17 I have two motors on my Y axis. They are both wired to one 1HCL board, but only one has an encoder. It calibrates fine, and I did not spot a significant problem during printing. Only the recorded graphs were of no use on this axis (at least for me). Maybe something to keep in mind for future development.(especially for autotuning. )

Furthermore, I have the impression that the drivers run in full step without any microstepping as soon as I switch to closed loop. It sounds very much like my very first printer. The prints also show a strong stepping pattern.

Cheers Max

@dc42 Okay, thank you for clearing this up for me.

Please excuse me for reheating this topic! I have the chance to get my hands on 3 PD2-C4118L1804-E-08 Closed loop stepper motors with integrated CAN-Open controllers.

Do you think it would be worth a try? I can send them back within 60days free of charge...

Cheers
Max

Okay, I have to revise my previous statement about the max. achievable speeds:

In fact my open loop travel speed is set to 600 mm/s (36000 mm/min or 900 RPM) and this already includes a 25% safety margin.

I just did some speed testing on my printer. I achieved speeds up to 1500 mm/s (2250 RPM) on a single axis without problems. I did not test the performance with multiple axis moving with other stuff like CoreXY interpolation and Z height adjustment going on. But it is an indicator of what the motor/driver is capable of in open loop.

In closed loop mode, my motor sound is kind of "wobbly", like it is slightly accelerating and decelerating on every turn. The "wobbly" sound becomes more noticeable with increasing speed. The Motor loses its position when the speed is over 400 mm/s (600 RPM).

Right now my setup is slower in closed loop than in open loop

-Max

@lirwin17 said in Duet3D 1HCL - Closed Loop Controller Beta test:

Thanks for pointing this out! It would be useful if I could gauge just how much of an issue this is. Would the current top speed be an issue for you? Or is it just a nice-to-have? If anyone else would have issues with this limitation, please do say

For me, the whole point of switching to closed loop was to increase speed and reliability. In open loop my printer starts skipping steps at around 900 RPM (36000mm/min). During printing, I limit the travel speed to 24000 mm/s just to be on the safe side. So if it can reliably run at 900 RPM in closed loop, it would be okay for me. Everything more than that would be a nice to have.

@lirwin17 Wonderful, thanks a lot for your effort and support!

@t3p3tony said in Duet3D 1HCL - Closed Loop Controller Beta test:

Can I just double check you mean 36000mm/s and not either 3600mm/s or 36000mm/m ?36000mm/s would be a "F" parameter of F2160000

Sry rookie mistake! I did indeed mean mm/min and not mm/s

@lirwin17 said in Duet3D 1HCL - Closed Loop Controller Beta test:

This graph looks good
Step phase basically means the current rotational position of the motor (step phase = current step position * 90 mod 360). As the motor rotates 4 steps, I would expect to see the graph you give - it increases by 360 degrees, but rolls over once due to that mod 360.
The main point about step phase is that it roughly follows desired step phase - which it does

Aaaah okay, that makes sense

I just installed the latest firmware. The D an I parameter plots are now much more comparable to the one's in the manual, and changes in the parameters can now be seen in the plot. BTW, I often get some parameters as this zigzag lines...

R75 I0 D0.26

R75 I2000 D0.26

One more Thing:
EDIT: (I wrote mm/s instead of mm/min. Absolute no go, especially if you call yourself an engineer ) Thank's @T3P3Tony for pointing that out!

I noticed that when I put the motor in closed loop mode the maximum achievable speed is reduced to about 22000mm/min. In open loop mode I run at 36000mm/min easily.

@alankilian Thank's I will have a look!

Cheers,
Max

@maxgyver

Okay, this is what I have tried so far:

• Quadruple checked my wiring, tried different encoder cables (long, short, with and without shielding/grounding.)
• Confirmed the CCP/PPR by turning the shaft by hand (motor disconnected) and checking the position results with M122 B50
• Disconnected all other CAN-Boards from the printer
• Disabled Input shaping
• Tried with a second 1HCL board
• Tested with a different motor

The Step Phase and desired step phase plot is still all over the place.

I have tried tuning the motor. But I get stuck at the derivative value that does not really influence the graph.

R70 I0 D0

R70 I0 D0.3

@lirwin17 said in Duet3D 1HCL - Closed Loop Controller Beta test:

Is it passing tuning now?

Yes, it is passing the tuning. Sometimes tuning reports "incorrect polarity of the driver" first and then passes on the second try.

Is your motor current set to the maximum for your motor? If not, try increasing it and see if it brings the step phase/desired step phase closer together.

Changing the current doesn't make much of a difference.

Cheers
Max

@t3p3tony Okay, this is the data chart with the N-pin disconnected