Duet 3 6HC expansion
-
I want to expand my stepper drivers to run at least 2 more extruders, my initial thought was the 3HC as running 2 extra tool boards just for extruders seems over kill along with the extra wiring, however I`ve just found out I maybe able to run a mini 5+ as an expansion board and as its only £4 pounds more with 2 extra drivers it makes more sense! can anybody point me in the direction on how to do this I cant find any specific documents to refer to yet, do I treat it like any other expansion board? and do I need to be on the unstable firmware?
6HC Voron Trident based, 6XD CNC, Mini 5 polar printer
-
@jumpedwithbothfeet most of the issues with the firmware that are currently present will be fixed with the imminent release of 3.4.2RC2.
You use M954 to put the board in expansion mode. Thats all that's needed in the config.g fileOwns various duet boards and is the main wiki maintainer for the Teamgloomy LPC/STM32 port of RRF. Assume I'm running whatever the latest beta/stable build is
-
@jumpedwithbothfeet as @jay_s_uk says you'll need to wait for the next RRF 3.4.2rc release to run the Duet 3 Mini as an expansion board.
Also bear in mind that the stepper drivers on the 3HC can handle 6.3A peak current, compared with about 2A for the drivers on the Duet 3 Mini.
-
@jay_s_uk Thanks for that especially as the Gcode dictionary would of been the last place I would of looked for info!, I gather that it would need to be at the end of the can line as its a main board?
@dc42 normally I would go for the 3HC especially as I'm looking at building a CNC router in the future but £4 extra for 2 drivers is very tempting it`s proving a tricky decision, what would be your choice?
-
@jumpedwithbothfeet which main board do you have?
If it's a Duet 3 Mini then you can get 2 more drivers by adding the 2-driver daughter board, if you have not done so already. If you are already using the daughter board then another Duet 3 Mini seems to be the logical choice, assuming that the additional extruder motors don't need more current that a Duet 3 Mini can handle.
If it's a Duet MB6HC then bear in mind that the 6HC and 3HC can both handle 32V VIN (or a little more with care) whereas the Duet 3 Mini is limited to 25V. If you run into a speed limit caused by too much motor back emf, then increasing the supply voltage will help. Also, depending on the current needed by the extruder motors, the Duet 3 Mini may need fan cooling, whereas a 3HC running at the same motor current will not. Therefore I suggest the 3HC, unless you think you may need more than one additional stepper motor in future, or you want the flexibility of being able to move the Duet 3 Mini "expansion" board into a new printer in future.
Duet WiFi hardware designer and firmware engineer
Please do not ask me for Duet support via PM or email, use the forum
http://www.escher3d.com, https://miscsolutions.wordpress.com -
@dc42 I have the 6HC running on 24v, I don't need the extra drivers at the moment but I like to try and future proof myself as much as possible, in which case the points you made about the 3HC are ones I hadn't considered so thankyou for pointing them out, and I could always add another 3HC if I need more drivers later
-
@jumpedwithbothfeet said in Duet 3 6HC expansion:
and I could always add another 3HC if I need more drivers later
You can indeed. I am one the people testing a 6HC as an expansion board and on my machine, I have 6HC as a main board (board 0), a 3HC as an "intermediate" expansion board (board 1) and a further 6HC as an expansion board at the other end of the CAN "chain" (board 2).
-
Just a quick update if anyone stumbles across this thread - I've just completed my first successful print with a 6HC as an expansion board. The printer has XY and Z motors on a 3HC expansion board, U and V motors on a 6HC main board, and 6 extruders connected to a 6HC as an expansion board. The end stops for X U and Z are connected to the 6HC expansion board and these will stop the corresponding motors connected to other boards with no noticeable latency. The two hot end heaters and their corresponding thermistors are connected to the 6HC expansion board which all work as they should. The hot end liquid coolant pump is connected to the 6HC main board but works thermostatically with the sensor that is connected to the 6HC expansion board. So everything appears to be communicating with everything else as it should. This latest firmware update had to be done via Bossa/USB but from now on, all future firmware updates should work over CAN.
In summary, this being the first use of a 6HC as an expansion board "in anger", some glitches and issues were to be expected but these have all now been resolved (at least for my particular machine). I will continue to monitor and report back anything to the Duet guys.
