6 headed printer

theBohnanza · 18 Dec 2017, 00:35

Hello Guys,
i am currently in the process of planning a printer, which will have up to 6 tool heads with one hotend each. The tool heads are going to picked and parked by the effector.
The Machine is going to be build in Corexy kinematics.

I consider the duet Wifi to be the driving electronics, but i'm not quite sure yet, which features i can achieve with it and which Hardware configuration i'm going to need.

1. I would like to use external Closed Loop drives for X and Y.

2. The Board should handle up to 6 tool heads with 1 hotend and one Extruder each.

3. Each Toolhead is going to have 2 Fans. One cooling the hotend, one cooling the print. It would be nice, if the hotend cooling fans are temperature controlled each, meaning, that only the active hotend Fans are getting cooled. Currently i don't think thats possible with duet 3d stock parts, am i right?

More importantly each Toolhead needs to have it's own part cooling fan. Which shouldn't be a problem, i guess.

Reading other treads here in the Forum, my conclusion is, that i should get the Duet3d Wifi with the Duex5.
I have read, that this configuration is able to drive 2 additional motors via the LCD Port, so i think thats my way to go? Do i loose the ability to connect an LCD here?

Connect the 6 hotends, extruders, and part cooling fans to the corresponing outputs. All the hotend cooling fans have to be powered parallel and handled as one.
That way, i still have 4 Stepper drivers left over, which enable me to drive the Z axis with up to 4 motors.

What do you guys think, am i right?

Well, thats it with my questions for now. Thanks for your time.
I am really curious for your answers.
Cheers, Alex

justine.haupt · 18 Dec 2017, 03:24

Hi Alex, I'm sure others will comment but I'll answer what I can starting from the end.

i should get the Duet3d Wifi with the Duex5.

Yes.

I have read, that this configuration is able to drive 2 additional motors via the LCD Port, so i think thats my way to go? Do i loose the ability to connect an LCD here?

I wasn't aware that it could be configured that way, but not surprised. But I don't see that you need to do that. With the Duex5 you would have stepper drivers for each of the 6 extruders, 1 for X, 1 for Y, and another 2 for the Z motors, each of which can drive two motors in series (in my experience) for four total. So just enough.

All the hotend cooling fans have to be powered parallel and handled as one.

There are 9 controllable fan outputs, so not quite enough to have independent hotend and cooling fans for each of your six extruders, but maybe you could do a bit better than having them all powered together. Hotend fans can be set for thermostatic control (hot only when the associated hotend is hot), so perhaps you could dedicate six of the fan outputs for hotend fans, and then the other three can each power two cooling fans. So at most it looks like you would have 1 fan running that doesn't need to be.

1. I would like to use external Closed Loop drives for X and Y.

I don't know of an easy way to do that. I know people have worked out off-board servo controllers that take the pulse output from the stepper drivers and convert to a servo position in real time. That's a bit tricky because it depends on the closed loop position not falling behind the current step number, but I think doable. I'm not sure I see the point myself as a well designed system with properly powered motors won't ever really lose steps.

The tool heads are going to picked and parked by the effector.

Whoa. I imagine that will take a lot of work to get going right, but maybe a lot of fun. Do you already have a design in mind? I don't know how CNC milling centers do it but I would imagine kinematic registration (3 balls in 3 vee-grooves, or similar) may be necessary. With a 3D printer the retention for the toolhead (the kinematic "preload") could be via magnets. My machine's toolheads are interchangeable and kineatically registered, but not by pick and place automation.

dc42 · 18 Dec 2017, 07:51

Justine has answered most of your questions. What's left:

1. You can connect your two closed loop stepper drivers to the CONN_LCD port, if they have standard step, direction and enable inputs. You may need to level shift them to 5V depending on the drivers because the signal levels are 3.3V, although many drivers specified for 5V signal levels work with 3.3V levels.

2. PanelDue uses a separate port, so you can still connect one.

theBohnanza · 18 Dec 2017, 11:19

Hi, well that was a quick reply! Thank you.
Justine, you're right, the pick and place automation is the hardest part, but it has been done before.
https://www.youtube.com/watch?v=viX_WLRqxYM

dc42, i forgot to mention, indeed i have to drive the external Motors via step, dir, enable.
Is connecting Motors to the CONN_LCD configurable with the stock Firmware? I have do admit, i didn't find any documentation about this.

Thank you.
Greetings,
Alex

justine.haupt · 18 Dec 2017, 15:22

Wow, cool!

dc42 · 18 Dec 2017, 17:13

@theBohnanza:

Is connecting Motors to the CONN_LCD configurable with the stock Firmware? I have do admit, i didn't find any documentation about this.

Yes the standard firmware supports it, but the documentation has not caught up yet.

theBohnanza · 22 Dec 2017, 22:46

Hi, Thanks.
I have to admit, i am blown away, how fast you Guys are responding.

dc42 · 22 Dec 2017, 23:09

I updated the documentation a couple of days ago to cover external drivers connected to CONN_LCD. It's at https://duet3d.com/wiki/Using_external_stepper_motor_drivers.

foehnsturm · 23 Dec 2017, 13:20

@theBohnanza:

Hi, well that was a quick reply! Thank you.
Justine, you're right, the pick and place automation is the hardest part, but it has been done before.
https://www.youtube.com/watch?v=viX_WLRqxYM

Thank you.
Greetings,
Alex

Nice being mentioned!
Curious to see your results.