Duet3D 1HCL - Closed Loop Controller Beta test

A Former User

@samlogan87
what is the benefit of 48 volt?

cheers
richard

samlogan87

@gruna-studio you are able to run it much faster

A Former User

@samlogan87
really? the motors can drive faster?

since two years I´m working with 3d printers and duet and I never heard about it. haha

Is there a good summary from Duet?

Today is "1HCL-Monday". !!!!

cheers richard

dc42

@gruna-studio driving stepper motors at the desired current depends on having enough driver supply voltage to overcome the back EMF of the motors, which increases with speed. It's especially important with high inductance and high current motors. You can estimate the voltage needed using the calculator at https://www.reprapfirmware.org/emf.html.

A Former User

@dc42
ok thanks a lot!

A Former User

@dc42
any good news?

samlogan87

@gruna-studio i know. I am hanging out for them. I have money burning a hole in my pocket

A Former User

@dc42
Hey any good news?
Cheers
Richard

T3P3Tony

@gruna-studio yes! finally over the bottle neck. drop me a line tony@duet3d.com as you have been waiting a while so we may be able to supply directly from next week (before we can get any to our resellers). also @samlogan87

Note support for these is still experimental in RRF 3.4

A Former User

@t3p3tony

yeeeeah!
thanks a lot.

So there is the first question.
Is there any experience with specific encoders I could use?

Is this an actual information?

If there is no picture yet, I can provide you some good ones and other documentations.

Thanks a lot
Richard

samlogan87

@T3P3Tony awesome. Sent you an email regarding getting some boards

T3P3Tony

@gruna-studio the SPI connected encoders are not yet fully supported. we have done some limited testing but for now I recommend using quadrature encoders.

dc42

@gruna-studio the encoders we have had most success with are the 1000 PPR (4000 CPR) ones built-into some 1.8deg stepper motors. There are some examples at https://www.omc-stepperonline.com/closed-loop-stepper-motor/.

A Former User

@dc42

OK... nice to know. Can´t wait to install it.

My X-axis works with an double shaft nema 17 who has belts on both ends. So I can´t ( at the moment) install the a new motor. How about the encoder of stepper online. I guess they´re quiet similar to the build in encoder.. or am I completly wrong?
May it´s a cheaper solution to upgrade specific axis.

https://www.omc-stepperonline.com/encoder/

This encoder would fit nicely in my system but I`m not sure if this is working in the same way as the built in encoder of stepper online nemas.

cheers Richard

https://www.omc-stepperonline.com/download/HKT30-32.pdf

alankilian

@gruna-studio Can you find some place that verifies you can get a 4,000 counts-per-revolution encoder? I looked at their web page and data sheet and I don't get a solid feeling that's true, but it might be true.

I see CPR and LinesPerRev/PulsesPerRev (LPR/PPR) used incorrectly all the time.

If you can only get a 1000 CPR encoder that's going to be too low a resolution to get you good performance. If the data sheet says CPR but they really mean LPR than it's OK, but without buying and testing one you won't know.

A Former User

@alankilian https://www.rls.si/eng/products/rotary-magnetic-encoders

But I´m no really sure with the configurations there.
Share it if you do one if you want.

I think they have all we need in future.

Concerning the stepper online encoder. I think I´ll ask them and let you know.

Cheers
Richard

dc42

@alankilian a 1000 PPR (pulses-per-rev) quadrature encoder provides 4000 CPR (counts per rev, better called transitions per rev). The EXP1HCL board uses all 4000 transitions. The 4 transitions that occur in the time of 1 pulse probably won't be as evenly spaced as the pulses, but using them still provides a benefit over using just the pulse count.

@gruna-studio if the encoder spec is 1000 PPR (not 1000 CPR) then the resolution should be OK. We've only tried one system using a separate encoder (not from stepperonline) and we've had poor results; but that may be caused by something else on that machine. If you do use a separate encoder, you need to make sure there is no added backlash in the encoder caused by it being separate from the motor. So the mounting of the encoder on the shaft and the encoder body on the motor need to be rigid. As long as the EXP1HCL is in beta test and not a fully released product, we'd rather you use stepper motors with integrated encoders, so that we can be fairly sure that any issues you report are not caused by poor coupling of the motor to the encoder.

A Former User

This post is deleted!

A Former User

@dc42
I just got my boards! thanks a lot to providing me in this early stage.
I saw there are some changes to the version 0.3. Is there already a wiring diagramm?
cheers
Richard

dc42

@gruna-studio latest EXP1HCL documentation is at https://docs.duet3d.com/en/Duet3D_hardware/Duet_3_family/Duet_3_Expansion_1HCL.