dc42 what would be the difference between defining them as axis and extruder ? Don't they both react the same ?

Somehow I figured out I need M584 for what I want to do, but

My machine will have 2 steppers on Y axis, 1 on Z and 1 on X.

Can I somehow easily configure the duet so that my first Y stepper runs on the Y-driver and then the second Y stepper runs completely parallel in movement, but driven by the E1 driver?

M584 X0 Y1:5 Z2

But what with extruder 1 then which is probaly assigned by default to E1 ? Or should I use then

M584 X0 Y1:5 Z2 E7

My ultimate goes is this setup

X axis on X driver
Y axis on Y and E1 driver (2 motors with each a driver)
Z axis on Z driver
NO extruder needed, but I want 1 virtual axis (It might be E0 or E1) which sends its step and dir signals to the expansion header where I can grab them. They will NOT drive a stepper but give signals to some other piece of electronics.

I think I found one who will even go faster. he has a little higher inductance, but half the holding torque.

I can move my axis perfectly fine with only 0.2A on the current motors which are rated at 1.5 , so I require very little force.
Chances are big that this motor will have enough juice to move the axis and will also be able to go faster in the end because if reasonably low inductance EMF, but due to the lower holding torque also more margin in the EMF due to rotation of the motor
https://www.omc-stepperonli
ne.com/hybrid-stepper-motor/dual-shaft-nema-17-bipolar-1-8deg-22ncm-31oz-in-1-33a-2-8v-42x33mm-4-wires.html

I wonder what the back EMF due to rotation is based on. For this last motor that seems so be the limiting factor and not the inductance. It seems like it is related to the Rated holding torque so I guess thats as good as it will get for that motor (if 28 mm/s is the calculated limit, then maybe 25mm/s would be a safe limit and that is a very acceptable speed for what I want to build

If I plug this one in the calculator (and I enter 2500mA rated and 1500mA given current @ 24vDC, then this motor should theoretically give me 28mm/s before things go red

The current motor is a kysan 1124090 with 4,8mH inductance and 2,8 ohm resistance

I can reach around 13mms on my leadscrew with 24vDC and I can even achieve this while powering the motor with only 0.2A while the motor is rated at max 1.5A

So the motor is too powerfull for what needed.

I tried the EMF calculator (didn't even know this existed) and found out that lower phase inductance can lead to higher speeds.

I cannot us other leadscrews because I bought second hand THK KR20 rails which are ultra high precision screws at quite high price

So I have to stick with them and I have to find motors with lower inductance if I want higher topspeeds. I'd like to be able to reach 20mm/s if possible because the printer I'll make for this won't go faster than that.

Anyway, The motor I'll need probably can we nema 17, but also nema 14 or even 11 since I am perfectly able to run it at 24V 0.2A currently, so there is margin.

Any idea where I could find motors specificly suited for higher speeds and having lower inductance ? I have 1 goldenmotor nema11 here (model 28HD1411-02) and that motor should have 4,8ohm resistance and 2,8mH inductance, so this one should go faster.

Any tip/shints are welcome

I tried that EMF calculator and indeed I see that when I go past 15mm/s (which is 3200steps per mm) then I and get red numbers

It also looks like microstepping has nothing to do with it and also that running the motor at 1A lets me achieve higher speeds than running is at 0.5A (under the condition that the motor can produce enough torque of course)

So now what ? Any suggestions for quality motors which have lower inductance and could give me higher speeds ?

Inductance is 4.8mH± 20%
Supplyvoltage is 24vDC
Wiring is factory wiring and I tried 4 identical motors which makes me think they won't be all faulty

Any idea ?

Hi,

I keep getting this error/warning

Warning: motor phase B may be disconnected reported by driver(s) 0

I have atached a nema17 stepper motor and configured it to have

M92 X3200.00 Y200.00 Z200.00 E420.00      ; set steps per mm
M350 X2 Y16 Z16 E16 I0                 ; configure microstepping with interpolation
M566 X50.00 Y900.00 Z12.00 E120.00     ; set maximum instantaneous speed changes (mm/min)
M203 X6000.00 Y6000.00 Z180.00 E1200.00 ; set maximum speeds (mm/min)
M201 X20.00 Y500.00 Z20.00 E250.00     ; set accelerations (mm/s^2)

Only X motor is connected. The motor is rated for max 1.5A and I tested with all kind of settings between 1 and 1.5

This motor is driving a leadscrew with 1mm pitch
So I define it as 3200 steps per mm (based on the default 16x microstepping on duet) and then reconfigure for x2 halfstepping without interpolation (It does the same if I choose x16 I1 however

As soon as I let my motor reach 900rpm . (resulting in 15mm/s speed on my leadscrew) I start getting these warnings.
I can however go a lot higher than 900rpm on the motor and it doesn't stall, but what are these warnings and what should I do with them ?

Are they any indication of step loss? Or is this some kind of bug ?

Kind regards,
Bart

@dc42 said in Getting the digital step/dir signals on stepper X,Y, Z:

command in config.g to assign both an internal driver and a driver on t

ok thank you.

You say drive up to 12 steppers of which 9 can be axes. Out of curiousity, but what are the other 3 then ?

Hi,

I would like to use a duet 2 wifi for making a extremely precise (but ultraslow ) laser resin printer.

The XY stage will be dome with THK linear rails using ballscrew with 1mm pitch and Z axis too.

X, Y, Z is all very easy to setup because in that case it is just acting like a cartesian printer.

I would however like to be able to sense the signals for step/dir on the X axis.
Allow me to explain. The controller on the board sends step and dir signals to the trinamic drivers and those make sure the motor works.

But is there a place where I can actually connecta dupont connector and read the real step/dir signal which will probably be 5/3.3vDC ?

I searched on the 50 pin expansion connector, but there I think only the signals for the EXTRA duex channels can be found ?

Also, it might seem a stupid question, but I'll ask it anyway.

Is the Duet 2 wifi capable of driving 5 steppers totally independent of eachother with each their own accelerations etc..... .

I bought some 24V fans. Like you said this is most probably the best way to do it anyway.

Regarding optical endstops. I was hoping I could use endstops like these http://www.ebay.com/itm/Optical-Endstop-Switch-RepRap-Mendel-Prusa-RAMPS-v1-4-For-3D-Printer-arduino-WC-/221488349461?hash=item3391bc0115:g:h1YAAOSwTuJYrUyC

They are made to work on ramps, but there is no specification about what voltage they will use.

The DUET (ethernet) will be driven with 24VDC, but does this have implications for the endstops ? Or are these driven at another voltage anyway ?

I read that they would work on 3,3V, so if I try my endstop with GND to GND, VCC to a 3,3 voltage supply and then measure the signal, if it works (reacts) then it should work with duet ?

Kind regards,

Bart

Because the fans I'd like to buy are not available in 24VDC version . (at least not easily available in my shop)

Maybe just a small follow up question, but the 2 PWM fans will actually run on the same PWM speed. Couldn't I then just wire them in series on a 24VDC output of the duet ethernet ?

For the permanently on hotend fan I could do with direct wiring and let that one just pass the duet (give it a small PSU on its own)

Hi there.

I would like to feed my stepper motors with 24V , but my hotend fan (permanent on) and part cooling fans (pwm) are all 12VDC

I will have 1 hotend fan and 2 PWM part cooling fans.

Is this possible somehow on duet ? Can the fans run on another voltage than the steppers or do I need to do strange tricks there?

For info: The cartridge heater in the hotend is also 24VDC

I searched on google and found multiple posts where it is mentioned that duet has dual power supply possibility and than duet switches to ground etc, but I didn't really find a page with the info about it. For example some basic connection diagram or whatever.

So I do want to connect :

1. All stepper motors on 24V

2. All fans (1 always on and 2 pwm) on 12V . (but these 2 pwm fans may run in parallel)

3. Heated bed will be 230vAC through a SSR

4. Heater cartridge is 24V

5. I don't know if my endstops (optical) can run on 24VDC

Kind regards,
Bart

Hi there,

On the documentation I found the following information about the mounting of the duet wifi and the duex expansion

"The Duex5/2 is designed to be mounted back-to-back with the Duet WiFi using long M4 screws and spacers"

What does that mean BACK to BACK ?

Anyone have a photograph which shows what that means ?

Kind regards,

Bart

We might be able to buy 0,25 or 0,15mm custom diamond, but what I actually meant was that pushing filament through a 0,15mm nozzle through bowden…. is probably not going to work at all.

Thanks Ian.

By the way, I am drooooooling when looking at your video's with the diamond hotend.
I do have an E3D Kraken here, but I'm affraid that a bowden setup is certainly not going to let me use 0,25 or 0,15mm nozzles without troubles.

So in first instance I'll design for single and dual titan aero direct drive, but since my carriages will be cnc milled out or alu and delrin, I will provide easy mounting options to exchange the printing head without having to retighten the belt system.

I'm currently busy designing the important pieces in fusion 360. I don't know if I'll model everything in fusion because I think that might be a loss of time and a lot of mechanical thinkwork is easily solvable in 2D too (like seeing how far a carriage has travel and where nozzles will be when carriages are at their end.

I'll certainly keep posting and the intend is to go for a duet as driving board. Most possibly NOT a duet wifi as my main alu frame is 45x45mm alu and from experience with my lasercutter (which has built in computer too) inside those faraday cages you don't get a lot of signal . So I might go for the ethernet version

Well I'm certainly not doing "reprap" thinking, thats a fact. I don't even think e3d would advise anyone to put a 0,15mm nozzle on a machine based on printed parts.

I allready made an all metal machine, which was a 1600x1200x800 cnc 80W co2 laser cutter. It uses the same principle and achieves quite good speeds and precision. It is simple cartesian and not corexy, so there is a lot more mass on the X gantry.

I'll try it anyway with the nema23 0,45° steppers . If it doesn't give nice results, the swapping to nema17 is maybe 15 minutes of work, because in a coreXY setup motors are easily switched.

I do understand what all of you above are saying, so it is not that I want to pretend I know better. I don't know better for sure, but I have already experience with these motors and will give them a try. If they don't give me enough speed, then they are easily swappable for another motor.

Ian, it will not be ballscrews anymore. I will indeed also use the T8 screws with a 2mm pitch, 2mm lead and anti backlash nuts + linear guides to protect against bed movement (rotation/wobble,…)

I wanted to use ballscrews, but they were "chinese" quality and didn't get past quality checking (hey, what would you do if you discovered that 1 1204 ballscrew wasn't even 12mm, but 11,6mm wide. I would call it rubish)

I throwed the 3 ballscrews in the trash

I don't really understand why my setup might be not accurate enough ? Can you elaborate a little more on that ?

Only thing I can see is that my machine might not be able to achieve super speeds. That is something I do certainly agree with.

But what would not be accurate on an all metal machine with THK linear slides (these babies cost a couple of $100's a piece) + a 325x325x8mm alu bed leveled on 3 leadscrews with 3 extra lineair guiderails for making it even more rigid + all other parts will be precision milled in Delrin or Aluminium?

I also did some calculations based on the formula's and this is what I calculated.

My motor is

800 steps per revolution or 0.45° per step with accuracy of 1 arc minute (as far as I know only 1 manufacturer in the world makes these: Lin Engineering)
U = 24V
R = 1.2Ohm per phase
I = 3 Amps
Inductance = 1.2mH/Phase
Inertia 2.1oz/in

This looks like very low resistance and inductance if you ask me? These motors are highly specialized stuff costing around $250 a piece. (and yes I bought these but they are currently mounted on my self made laser cutter so I already have them + the laser could work as well with my other regular nema23 motors and then use these on my 3dprinter)

Calculations:

Time to fully energize coil = 3 x 1.2 / (24 - 0.5 x 3 x 1.2) = 0.162ms
Max speed (20steps per mm) -> 1000 / (20 x 0.162) = 308 mm/s

308 mm/s = 6160steps per second , so in 16x microstepping thats 98560steps or 98,560kHz (perfectly possible on duet)

Am I missing something?
Am I calculating something wrong DC42 ? You seem to be very knowledged about these kinds of calculations and I just THINK that I used the formula's correctly.
These