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Question Toolhead connection: Canbus, HartK PCB or other alternatives? What to go for?

Andreas

Andreas

Active member
Printer Model
V2.4R2
Extruder Type
Clockwork 2
Cooling Type
Stealthburner
Cheerio everyone, I'm just building my first 2.4(R2) and the toolhead has so many options that I need some help. After way too many hours of reading about different alternatives I finally decided to go for SB, CW2, Tap and a Rapido hotend. I'm pretty confident this will serve my needs.

However, the electrical connection is still sth I didnt really dive into. I know I could use a HartK PCB or Canbus.

But, what is the pro and con of each solution, and is there even more I didnt consider?

Happy to hear your opinions!
 
Andreas said:
I know I could use a HartK PCB or Canbus.
Click to expand...
Or no additional solution. You can crimp molex connectors to the wires from the toolhead and bring wires through the cable chain, and make the connection at the toolhead without any PCB or added hardware. This is all going to be hidden behind the cover anyway. This is the stock config, works fine, is the cheapest, still allow for easy replacement of components.

HartK PCB is a neat design but fall into the "nice to have" category to me.

Canbus allows for way less wires (only 4), potentially allowing to get rid of the cable chains and use an umbilical solution which will make the gantry much lighter.
 
Well I should have mentioned that I own a V0 and I didnt like how I did it there: just having cables from toolhead to the board.

Also, what about the voltage; Is there anything specific I need to take care of when using the canbus solution?
 
When bulding my V2.4, I went straight to the Hartk board. I liked the cleanliness of the build - you have just one connector and the board firmly screwed to the toolhead. No fiddling with multiple connectors and guessing which one is which. But then I started having issues with my wiring. My wires started breaking inside the cable chains and after a while I got absolutely mad about it. So I ordered EBB36 and converted to CANbus. If I ever build another Voron I would go straight with CANbus. The wiring is super easy and clean.
 
If you are going for a stealthburner - SB2040 CANbus all the way. I personally, will never build another printer without a CAN toolhead board. The SB2040 is basically the CAN version of the 2-board HartK, so you can use it with a full-stock stealthburner. It's $20 and the rpi2040 now also supports CANboot so updates are easy. The only potential downside compared to other CAN boards (like say a Huvud - that I also have but swapped out) is if you're going for super high temps, the rpi2040 isn't really designed for more than 85C.

I know I'm biased, but I always had bad experiences with the microfits (I can crimp JSTs but for the life of me struggle with the microfits) and between bad crimps or pins coming loose between thermal cycles - I lost hours of time pulling off my cover, trying to find the problem, recrimping, all without messing something else up and having to start all over again. Eventually (after a year or so) all that fiddling caused my loom to start developing breaks.

Since switching to CAN (and boards that primarily use JST) - I simply don't need to worry about my toolhead electronics.

Fairly sure all the weight saved by having all that wire out of my gantry also helped improve my print quality.
 
Sounds interesting, thanks for sharing your experiences
tillin9 said:
... and the rpi2040 now also supports CANboot so updates are easy. The only potential downside compared to other CAN boards (like say a Huvud - that I also have but swapped out) is if you're going for super high temps, the rpi2040 isn't really designed for more than 85C...
Click to expand...
Why do I need the rpi2040, what is it for? Does it replace the U2C?
 
The rpi2040 is the micro in the sb2040 toolhead board (as opposed to an STM micro in most other boards, e,g, STM32F103 on the Huvud).

You still need a CANbus host controller like the U2C. I run a CANtact in one V2 and switched to running CAN bridge on my other (Octopus Pro).
 
i love the 2 pc hartk pcb, but CAN is awesome. 4 wires coming out of the toolhead for everything. I'm using the Mellow FLY-SB2040v1. currently, I'm testing it without a UTOC but direct to the octopus pro.
 
I'd really like to go for Canbus now; I'm still confused what I actually need to buy to get it running.

Is it only the two things?
  • BTT EBB36 or sth similar like Mellow Fly
  • A U2C Interface
 
Watching this very closely @Andreas . Your specifications in your first post in this thread is exactly what I was planning on doing, along with the Rapidio head. I am getting close to this point in my build, so hurry up and get a BOM for me! LOL (just kidding)
As far as cost, we are spending a fair amount on this build anyhow, so an extra $100 or whatever to get a CANBUS solution is perfectly acceptable to me.
 
I dont think its that expensive, and if it really works without any major issues to set up you might be saving some time for wiring. Although it'll also take some time to dive into the topic deep enough to get it running. If youre going for the same setup you might want to invest a bit in a trianglelab or original bondtech bmg extruder kit
 
I switched over to a CAN-bus setup on mine, I regret not doing so earlier. Really simplifies things IMO. Go umbilical at the same time and you'll have a really clean setup
 
Yes - to go CANbus you need:

1) A CAN toolhead board - e.g. a Mellow SB2040, Huvud, EBB42/36 etc.
2) A CAN bus adapter which can take many forms:
  • A USB -> CAN adaptber (U2C, UCAN, CANtact) - Buy whichever one is available and cheapest. I have expensive CANtacts since I purchased these before lower cost USB options existed.
  • A waveshare (Pi hat) - I would not recommend for new builds, the CAN bus it provides is slower and while probably won't cause an issue for a single toolhead, can have limitations if you want to do more complex things later.
  • A controller board with Klipper configured to run in CAN bridge mode. (Basically, you need an Octopus or Octopus Pro - I am not aware of other boards that offer this)
You need to get a CANbus on the Linux computer that runs Klipper and then use that new CAN port to connect the toolhead board.

I ran a Raspberry Pi4, Octopus Pro, CANtact, and Huvud in my new V2 before changing to Pi4, Octopus Pro (Bridge Mode), and SB2040.
I am running a Pi4, 2 SKR1.4 Turbos, CANtact, and SB2040 in V2.1438.

This isn't the most beginner-friendly tutorial - but it shows all the pieces and how to setup a SB2040:

Here's Eddie showing a Waveshare and a Huvud:
 
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I'm about to start a build and I'm asking many of the same questions as you @Andreas. Definitely going StealthBurner with TAP and CW2.
Other parts of the forum warn away from the SB2040 (see this doc) and so I'm finding the conflicting advice confusing. Likely just going to go for the toolhead board, get everything working well and put in canbus once things are a little clearer. But canbus is attractive and so would love to be convinced there aren't the problems I'm hearing about...
 
SimplifiedLife said:
I'm about to start a build and I'm asking many of the same questions as you @Andreas. Definitely going StealthBurner with TAP and CW2.
Other parts of the forum warn away from the SB2040 (see this doc) and so I'm finding the conflicting advice confusing. Likely just going to go for the toolhead board, get everything working well and put in canbus once things are a little clearer. But canbus is attractive and so would love to be convinced there aren't the problems I'm hearing about...
Click to expand...

I won't let this user's bad experience with the SB0240 discourage you. Putting in a tool head board and making a cable only to go CAN later is a fair bit lot of work that can be avoided. Let me respond point by point:

1) Seeming not to understand AGND. To support multiple (5V and 24V) voltages for the fans, the switching is done at the ground. Red wire - proper voltage for the fan (24V for stock), Black wire - AGND.

2) HV end-stop really needs a pull-up ^ in the Klipper config. This is a real issue. I didn't have it with my first board but did run into it with my other two. Asked in the Mellow section of the discord and was informed a few minutes later what I needed to do. I do wish they updated the documentation to make it clear if your HV end-stop doesn't trigger (and maybe even if it does), to put the pull-up in the config. Seems the author never got to the bottom of it and rigged up something more complicated causing the next issue. I kind of cared because inductive probes work better at higher voltage. Mine did work at 5V, so before I knew what to do, I used the other plug but lost some working distance. If you are going Klicky/ TAP this is a complete non-issue - use the dedicated 5V end-stop plug.

3) Temperature issues 1 - the author seems to have had issues with the board voltage due to using the HV end-stop source and 5V end-stop sink. This one is mainly self-inflicted.

4) Heatsink - I did not use the included heatsink, it is not necessary. If you want to, I will concede that depending on how you mount it and what you are looking to sink, what was provided might not work.

5) Temperature issues 2 - I have noticed the temps displayed from the rpi2040's internal thermistor and the onboard chamber thermistor trend a little high. They read ~30 degrees C when no heaters powered on with my nozzle and bed at room temp around 23 degrees C. They actually never get to the 85 degrees C the rpi2040 is speced for, but do wish they were more accurate. The author never seemed to test these readings with another thermometer and then seemingly got frustrated with cooling mods.

6) HV end-stop squishing wires - Not sure if the author installed the board correctly. On my 3 stealthburners, it's a little tight - i.e. annoying if you want to remove the HV probe without first unscrewing the board, but it definitely fits. Given how much trouble I had with my probe coming loose with microfits, I tend to personally like it being a tad snug.
 
I see some people take the OTUC board out and just connect the CAN board to the Ethernet port on an Octopus? It's hard for me to tell what is the best practice or method here.
 
NoGuru said:
I see some people take the OTUC board out and just connect the CAN board to the Ethernet port on an Octopus? It's hard for me to tell what is the best practice or method here.
Click to expand...

Basically putting the Octopus in bridge mode (Klipper firmware options) uses the USB composite feature to expose two devices - a serial port for "normal" mainboard communication to control the steppers and peripherals and a CAN adapter. The STMs in the Octopus boards are fairly beefy (i.e. when running Marlin or RepRap firmware they have to do all the processing) so while doing this does technically add overhead, it doesn't matter.

If you have an Octopus and are willing to try bridge mode - it does work - I use it in one printer. It is a less tried and true config, so fewer guides, and you may get stuck with some edge cases or early adopter problems. One I can recall is, for example, CAN boot via USB (for easier firmware updates) didn't work initially in bridge mode.

If you don't have an Octopus but already have a working printer - I definitely don't suggest getting an Octopus and going through the hassle of reconfiguring solely for CAN integration as USB adapters are fairly low-cost now and work just as well. My older V2 started with two SKRs, so I just added a USB adapter.
 
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