Closed Loop & Can Bus! Duet3D at Formnext 2023!
ฝัง
- เผยแพร่เมื่อ 3 ธ.ค. 2023
- Tony from Duet3D told me all about how closed loop in motors comes in handy, and shows us a brand new can-bus board for the E3D Revo Roto!
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Joe's speech is absolutely immaculate in his interviews. I mean his knowledge on the subject matter to be able to ask the questions he does to have the interviewee explain the subject to the viewer as if they didn't know anything is simply phenomenal. And the way he's so fluid about the interview is just so professional. Amazing work on the content no matter what interview or video he releases.
Aww thank you so, so much for such kind words. 🥰
Sounds like something that would be useful in a CNC build.
Interesting - never ceases to amaze me how the developments keep coming thick and fast.
CAN should have happened much earlier to be honest. Its been around for eons. And many MCUs even include CAN support out of the box.
Canbus is an awesome solution and really should be adopted as a standard across all home printers. Its cheap, and turns printer wiring into Lego simplicity. I have been using it on my toolhead for just about a year now. I would love to have canbus motors.
Absolutely. But sadly there are still people that prefer their 14 to 25 wire bundles because less setup and no canbus failures. Dude, modern cars without canbus wouldn't exist. Honestly if someone builds a printer from scratch and isn't using a canbus board he is dumb. Not only from a time perspective, but also from a financial perspective. Motion rated wires are actually expensive, locally the meter of 0,25mm2 ptfe insulated wire is 2 euros.
Its worth noting that Duet are using the more advanced version of Canbus that costs money to use. Klipper canbus uses the free version so it doesn't have the same data rate and features. Duet stuff is cool, I like that Beacon style scanner for one, but it costs.
I would love to be able to just run 4 wires to my motors and then the toolhead and then bed scanner. At the moment though my motors are running 48V and I have to canbus to the toolhead board and USB to the Beacon probe. Its not as simple but yeah, way better than wire bundles of 24 or more.
Thanks!
Thank you, this was very interesting.
What was the most interesting thing for you?
I found the brakes in the engine very interesting. People often don't even think about the fact that with larger loads, a brake is of course needed to prevent the print bed from crashing.
6 amps at 48 volts is wild.
Thanks for bringing us this info, Joel! It's always nice to see what will probably eventually make it into the consumer 3D printing market to improve our experiences. High-5!
Informative.
Looked like a CoreXYU set up running the table scan. Glad DC42 is stepping up with closed loop.
Sweet and Interesting!
Nice video. Always interesting. Mahalo for sharing, Joel!
we love to see such cool tech, managing open loop can be annoying sometimes
Oooh I can't wait to get my hands on some of these hehehe
Tony is also a mad lad per Proper Printing’s video lol
I'm excited to get my hands on one of their bed scanners! A beacon probe without the struggle of dealing with Klipper!
i use the mks servo42c controller its realy nice never had a skip and the motor arent heating up.
being able to send performance data back to the mfg reminds me of things I read about during the mainframe days in IT. Where a company would have a contract with IBM, And their mainframe or AS-400 would detect problems with say one of the drives in a storage array, It would tell IBM and next thing one knows the director of IT gets a package from IBM and a phone call to schedule a tech to come out and swap it.
nice =)
What is the blue head at start with Voron logo? I want to print this exact head. Oh, and I need the color too because it's awesome!
The only thing that crosses my mind, other than sheer musculature of these motors, is: how far can we overclock this all and work it into a klipperized machine to make an auto-overclocking benchy buster. I mean, the amount of sensors and compute we work into these machines now with ADXL345 and powerful general purpose CPU's in the loop... could be real cool
First off, I love Duet, but I think that I'll stick with my Teknic servos. Brakes are a great addition to the Z axis, but as for X&Y, meh... However, simply shorting the Z axis leads together when you stop the motor will energize its "internal eddy current brake" (also known as the coil wires :) ).
Getting data back from your drive (servo or otherwise) is usually the bare minimum, however the depth of the data provided is what varies widely. But it's nice that Duet isn't requiring a paid subscription or anything silly like that (looking at you General Electric). And Tony is correct, using the historical data to say when to perform maintenance is very, very nice.
@9:04 you can see the two connectors that Duet provides, the XT30 2+2 (good!) and the RJ11 (imagine screeching record sounds followed by prolific cussing. WTF?). At least it isn't a USB-C connector...
And @9:24 "reduce it down to just four wires". Yeah, like every other Canbus implementation out there. My Qidi's "USB-C" cable is nothing more than a four wire cable inappropriately using USB-C connectors (but it does have the factory "rubber band to hold it all together" upgrade. :) )
And yes Tony, to do wiring properly is difficult, but you can make it much simpler by using the correct damn connectors. Although no one has ever had the plastic clip on a phone jack connector break, am I right? When I was a Controls Engineer for GM, Canbus (in the form of the accursed DeviceNet) connectors (ControlBoss) were our #1 problem with the media. So much so that no new installation is going to ever use DeviceNet again, and finding parts for it is difficult. It had that bad of a reputation.
All that chiding aside, I love both my Qidi and my Duet boards. Excellent hardware on both of them. And I do like the Z probe. Especially the donut board for the probe. :)
What would be a nice addition to your board is a couple of general I/O connections, analog as well as digital, that a user could hook a random device to and the Duet board would parse that data out along with the rest of the devices on the board.
Can see reducing cables being helpful... but
want to get rid of wires?
Go wireless
Run power through the metal x/y axis.
Just ensure the system only powers on when people are not present to avoid accidents... and people inside larger printers when they are running getting smacked by a 300c head at high velocity or melted plastic are not going to end well anyways... so running the power through the x/y rods makes sense.
Home ones can just have enclosure that shuts off when open... just like a microwave.
so if that has a built in accelerometer then it can do input shaping ??
Yes.
Will the microcontrollers on the toolhead board tolerate high chamber temperatures? Some other popular CAN boards will only reliably go up to 85C, which limits printing high performance materials.
I actually asked them at Formnext! The Roto toolboard has a maximum temp rating of 75°C. Although E3D sets the max operational temp of the Revo Roto at 40°C.
I have a silly question regarding CAN. I understand the lack of cables, is better for more reliability. But what about redundancy? Instead of having 1 data cable, have 2. So when 1 fails you get a warning? So the machine can still work if something fails mid print? Probably a little over engineered but something like that I would appreciate. Especially for prints over 24 hours.
I see your point. Duet usually uses an RJ11 cable to wire CAN-FD boards together, so you could use multiple conductors to carry the same signal inside the cable.
Since almost all of the wear-related cable failures are going to be from continuous flexing, there won't normally be shorted cables to worry about. So in theory you should be good in that you won't have your signal clamped down. However, adding a second cable to the mix is just going break at roughly the same moment as the main cable (or before). So you don't gain anything from a second cable. Worse yet, a likely scenario is that your main cable fails on a Monday, and no one is aware of the problem because the backup cable saved the day, and on Tuesday it fails. Not much benefit to that.
Where your efforts should be focused is timely error detection and being able to put the machine into a recoverable hold state until the problem is fixed.
The key is a proper cable that has been designed for continuous flexing. Using a surplus Ethernet cable is not going to hack it. I have surplus DeviceNet "thin" cable which was designed for Canbus (in the form of DeviceNet) from the get-go.
Qidi's "USB-C" cable is effectively a Canbus cable with only four wires (I cut one in half and took a look - it was bad anyhow). So what you've got with it is a four wire cable (yea!), that mostly looks like a Canbus cable (or at least good enough for the distances that we will be going), with completely inappropriate connectors on the ends (WTF?). They are the only ones doing this by a longshot, but all of those designers know better.
Duet is to be applauded for not including that silliness into their design.
Wouldn't it be possible to do closed loop based on back-emf feedback in the motor controller? Then we could also use this tech to make power reqs lower for small and fast consumer printers.
All that tells you is that you skipped steps, not how many.
Great that they are NEW to release close loop steppers. Closed loop steppers have been on the market in hobby CNC for years (servo?)
Closed loop has been around for a while yes. Closed loop steppers are middle ground between actual servo motors and generic steppers. In a nut shell, it tracks the steps and attempts to correct itself when it misses one. Servo motors are still superior, but cost is an issue. In an industrial setting, you rarely see stepper motors used.
Yes but so far from what I can tell all of the closed loop stepper boards are configured to only work with slower speeds (about 1/3rd of the stepper max speed) and so aren't useful for faster printers. In my case running closed loop meant I either had to drop speeds by a half (max of 90mm/s) or the quality was useless because the "error" would increase even with no load or skipping, leading to an oscillating rotation instead of a smooth rotation.
@@SirSpence99 Have you looked into running a printer on clearpath servos? They are incredible motors, but I've never seen one on a printer.
Anyone found closed loop Nema 17 stepper they like? Looking to use for my CNC, only seen Big Tree Tech ones, but mixed reviews 🤷♂️
@@AzaB2C I got the big tree tech ones for my printer. Any speeds above 100mm/s (using voron 2.4 gear ratio, I can't recall what it is but not very large) caused it to be nonfunctional.
From my research they can be reprogrammed with some open source stuff that has way more options but that can be a pain and requires a special module.
Man not having layer shifts would be so nice on my large, long prints.
I wonder if the board on the extruder has any problems with the heat
The steppermotor on the Revo Roto uses 0.45A peak, so no, the driver on the board won't get hot. (The TMC2240 can handle 1A without active cooling)
I can't help but wonder why linear encoders haven't been explored or popularized. Sure, knowing the motor has moved is great. Knowing that the axis has moved would be better.
It is and in CNC they already are, linear glass scales that tell the controller the carriage's position are standard fare in any decent machine, a nice side effect is that these machines never need to home and automatically compensate for wear.
Can someone please explain open and closed loop when it comes to these motors. In automotive aspects it means signal not being read in open and signal being read in closed. Is it the similar concept?
It just means in open loop the driver sends step signals to the motor and if the motor can't perform all those steps then the driver doesn't know about it. For instance if the nozzle hit the print really hard for some reason the stepper motor may just not have the power to move the steps commanded. The motor just loses those steps and continues on. From then on the tool the motor is moving will be in the wrong position.
With closed loop control the driver sends step signals to the motor in the same way but it also has a position sensor on the shaft of the motor sending feedback to the driver. The position sensor allows the driver to always know what the motor is doing in actuality, not just the commands it is being given and to compensate in real time if the motor fails to perform any steps. The driver can send new steps for any that were not executed and ensure the tool is always in the correct position.
So its like just a firehose of instructions pointed at the motor in open loop, vs sending instructions, checking they are done, compensating if needed and moving on to the next. The position feedback closes the control loop.
That's the basics for 3d printers and stepper motors but there are more advanced cases for other systems.
For 3d printers just having the correct sized motors running at a speed they are capable of is really good enough. I haven't had skipped steps on my machines ever unless there was a more serious mechanical problem that closed loop would not solve anyway. For applications with real load on the motors like CNC mills they make far more sense.
I haven't looked at what is available lately but closed loop stepper systems that I have seen all used older, slower and noisier driver chips rather than the popular TMC trinamic drivers that all printers use these days. I don't know why that is the case but its one reason they aren't more common. Duet is no doubt using something much better though.
didn't look him in the eye when shaking his hand
Very interesting...so ....what is the added value for the open source community? Yes value please thank you ;)
What is the name of the toolhead? 0:06
That is a Voron Tridex printer running 2 mini stealthburner orbiter 2.0 toolheads. They appear to be slightly modified versions though. It looks like they just removed the top half of the front cover, maybe to make mounting the toolboards more practical and visible.
If anyone is curious to what I said at 6:46 to my fiancé, it was:
"That's the 3D printing Nerd, btw"
I like Duet3D and this is another good piece of hardware but for me the DWC is the weak point. If you want to build a machine which isn’t a 3D printer you have to use a control panel which is written for a 3D printer or a CNC machine and it’s not easily customised and display compatibility is limited to paneldue which is only for 3d printers and looks like it was developed in the 1990s. If the platform had better control software and gui I’d make all sorts of machines with it.
7:14 That is nice but what i see is a suscription plan to pay. With free data from costumers build a database and sell it back. dont sound fair to me.
servo Motor is way better than close loop
Basically what every cnc does since 20 years...but hopefully cheaper
4:40 than leave the plate fix and move only the headprinter, wasnt hard ehhhh. try to sell problem Duet, no thank you.
I'll be flying the Duet flag after Crimbo, Sick of cheaper stuff ruining my day.
If only it didn't take years for firmware fixes to come.
Hey Joel, bring back the old days when you would just CHILL. 3d print. And make videos. Too much, "oh wow look at this!" Your show has gone from fun family 3d print to news in Silicon Valley button-ups explaining their product, and I thought you were trying to get away from that. None the less love you.