Setup 6 external drives from 50 pin header
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so to answer your question – you can't bypass drivers 0-4, those are built into the duet but they can be re-purposed , you can however use the dir/enable/step pins from the expansion header, and the CONN_LCD adapter to connect to your external high current/voltage stepper drivers. There are a total of 7 drivers you can add that way -- I suggest to utilize as much of the onboard drivers as you can -- you can remap them to do other things where you don't need as much current/voltage. I also suggest adding a 24v power supply and power Duet using 24v instead of 12v.
So you would simply remap X driver to be driver 5 -- and plug your external driver into the expansion 50 pin header as documented in the wiring diagram https://duet3d.com/wiki/Duet_WiFi_and_Ethernet_wiring_diagrams – look for E2 --> E3, E4 and so on, that's your drive 5,6,7,8,9
the CONN_LCD as David linked to earlier that's drive 10,11
If 7 drivers is enough, you won't need to use the onboard drivers at all -- otherwise you can map drivers 0-4 to be your extruders possibly?
M584 X5 Y6 Z2 E0:1One thing to note, configuration is not pin based, it's drive based
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FYI, the build plate my printer uses is about 20lbs – factoring in the frame, heat spreader, borosilicate glass, PEI etc -- and I put a 30 lb dumbbell on it -- and had no problem moving it -- (up and down only though) -- I have 2 Nema 23s, rated at 2.8a running on onboard drivers at 24v 2.4a. Steppers are not even hot or struggling -- 20 lbs is not much for a slow moving build plate to move up/down. Normally in a 3D printing scenario you wouldn't want to move a heavy bed along more than 1 axis. 7800 rpm for rapids is not crazy fast, as many 3D printers move 12000-18000 or faster on rapid moves, you should be OK in terms of functionality.
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Thanks for the explanation. However, IMO using high torque Nema 23 motors for the extruder drivers is huge overkill, even if you do have an objection to using geared extruders. High torque Nema 17 motors are adequate for ungeared extruder drives. Even if you want to use Nema 23 extruder drivers, the motor speed of an ungeared extruder is so low that it only needs a low voltage to drive them. You could use 2.8A Nema 23 motors driven from the Duet powered from 24V, and that would still give you far more torque and maximum extruder speed than you need.
Excess extruder torque is a bad thing. If the nozzle becomes temporarily obstructed, you want the torque to be low enough that the extruder drive skips steps. That way, when the obstruction is removed, extrusion will resume. If the torque is too great, then when the nozzle is obstructed the extruder drive will grind the filament up instead, and there will be no trip to resume extrusion.
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I'll add my twopence worth. My build plate weighs in at around 8 kg (17.7 lbs) and is driven in Z via 3 lead screws and single 59N.cm Nema 17 at 1800 mA. With my 3 colour hot end and passively driven extruders the mass in Y was a tad over 3Kg driven via two of the same Nema 17s but note that 45 degree infill uses only one motor. This arrangement was capable printing at up to 300mm/sec speed (acceleration set to 660 mm/sec^2). So I'd say that running pairs of Nema 23s at 24V is overkill but hey it's not my money.
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Absolutely agree with David.
You can use nema 17 stepper with a quality bondech bmg extruder – yes it's geared (but only 3-1), but it grips the filament from both sides and is more than capable of pushing plastic through, at very high flow rates, it's also light and is made very well.If you have the expansion board you'd need to not connect those pins (step/enable/dir) for E2-E6 to the expansion board, so a custom ribbon cable is likely needed) -- you'd also likely should not setup M906 for those drives either -- as they should not have any current associated with them.
So if you use M584 to remap X to 5
then by my understanding M906 should not contain a reference to X since it's now external, so there is no need to set it's current to anything. (David correct me if I'm wrong on that) -
I'll add my twopence worth. My build plate weighs in at around 8 kg (17.7 lbs) and is driven in Z via 3 lead screws and single 59N.cm Nema 17 at 1800 mA. With my 3 colour hot end and passively driven extruders the mass in Y was a tad over 3Kg driven via two of the same Nema 17s but note that 45 degree infill uses only one motor. This arrangement was capable printing at up to 300mm/sec speed (acceleration set to 660 mm/sec^2). So I'd say that running pairs of Nema 23s at 24V is overkill but hey it's not my money.
Price difference for the pair of nema 23s – 2 lead screw setup was like $20 -- just an extra stepper and using a nema 23 vs a nema 17 and some synchronization mechanism -- my argument was that a 20lb bed can be moved by a lot less than 5a worth of high torque nema 23 steppers -- clearly your point is that it can be moved by even less than what I built. So I think we're in agreement that Duet has more than enough oomph to move a 20lb bed adequately.
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ok so if correct me if I wrong,
x,y are on lcd connector z e0, e1, e2 and on breakout header board. so the m584 should look like this. m584 x10 y11 z5 e0:6 e1:9 e2:8
this is how I have them arranged. not sure how the line should be written entirely.
And is that all that is needed to have them run?
do the end stops have to be moved to match the drive connection location, because each connection provides then with the drive pins. Im using the reprap/ramps to switches. I know the wiring is reversed on these.A bit different M584 X10 Y11 Z5 E6:9:8
PS you should not skip numbers – you skipped 7 -- you can omit 9 I think
Make sure the end stops stay on X Y Z respectively, that was a bit confusing for me -- drives move, end stops don't -
Just to add, this thread is more about helping with setup, then trying to prove my mechanical issues. I use it for milling as well. …................................
Fair enough. It's just that the Duet board is designed primarily with 3d printers in mind. Although I am a huge fan of Duet electronics and firmware, I have to say that for your particular application, this may not be the best board to use. You will be paying for a lot of hardware and feature that you can't/won't be able to use. Why pay for 5 expensive driver chips that would be redundant?
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A solution would be to build a board with only the core of the Duet, without any drivers/Fet/etc, and use all your external stuffs.
There are maybe dev boards with the same chip? You may have to remap a few pins in the code for SD card, ethernet or so, but it shouldn't be too complicated.
My 0,02€…
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I skipped 7 because it doesn't support an endstop. all the other connections on the expension breakout board are connected to the arm populated by end stops for extruders. my purpose is filment run out sensors. simply roller lever style limit switches limit switches used as endstops for the filment tripped when it runs out. nc wired. m581 (1) triggers pause.g with m582 setup in startup sting. drive 7 doesnt have an end stop listed where in connects to the 50 pin header on the breakout board, as per build 11
everything has an end-stop look for pin marked E4-stop on the 50 pin header, it's also on the duex5, but I think you're confusing yourself doing that. Keep in mind though that the end stop for extruder 0 and 1 are on the duet.
End stops don't follow drivers – so remapping the driver for e0 to driver 7 8 9 whatever still leaves the endstop on the duet -- E0 end stop -- there is no purpose to remap end stops -- they're just switches.What steppers are you using for extruders?
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@fma:
A solution would be to build a board with only the core of the Duet, without any drivers/Fet/etc, and use all your external stuffs.
There are maybe dev boards with the same chip? You may have to remap a few pins in the code for SD card, ethernet or so, but it shouldn't be too complicated.
My 0,02€…
Sounds like he has the hardware, no need to build custom boards. I would have recommended he get a DueX2 since he doesn't need the extra drivers and sounds like he only needs at most 4 extruder mosfets, unless I miscounted – and is not using the onboard drivers for hardly anything, but DueX5 works fine, just means bypassing some pins and spending more -- plus more people are using the core of Duet for other purposes since the platform is excellent, and this just shows the flexibility of what can be done.
