Core XY with dual gantries using a duet wifi

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By gzcwnk 11 April 2017 22:20

Member · 131 comments

Hi,

Just toying with an idea, I'd like to build a D-bot coreXY with dual moving gantries (but only one at a time actually moves).  The idea would be to have a E3d aero (or something) for most use incl flexible printing so the form and mass is minimalised to keep the speed up, but then have a e3d chimera or even a e3d kraken for "complex" items on the second gantry where I need supports or maybe multicolours.  So the idea is one or other would be parked at opposite end of the axis while not in use.  (dont ask about the belt layout its mind boggling and probably just a crazy idea for later on, or just plain crazy and will never work/happen!

So the duet wifi would have to power 2 pairs of X and Y steppers and potentially 3~5 extruders by clicking the tool to use?   is this possible to link up?  Could the software handle such a config?  if not well the idea is dead.

Looking at the hardware.........duet5x addon this would run 3 of the nozzles on the kraken and the two extra X and Y steppers, the base duet wifi board has a spare extruder stepper for the last kraken nozzle so physically it looks like it can be done?

I'd need 3 pt100 daughter boards to run 5 sensors, that seems Ok as well?

Has anyone tried this sort of architecture/config? or maybe its just better to go to a Delta (or something else) with a kraken on it? or maybe just build 2 printers, LOL...

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By T3P3Tony 11 April 2017 22:31

Administrator · 789 comments

Dual (or greater) movement axis are supported in cartesian printers. have a look at this:

https://duet3d.com/wiki/Configuring_mul … an_printer

So a setup like the BCN Sigma or the IDEX bigbox works well. The issue with CoreXY, as you have pointed out, is that you need to use two sets of axis, XY and UV for example. That makes it mechanically more complicated for a start.

I think it would be a better solution to use an IDEX configuration where the X carriage had the Aero and your U carriage had the Chimera/cyclops/Kraken/Diamond hotend. This is mechanically much simpler and already supported in firmware. This also has the advantage that you can do "ditto printing"  (printing the same object with both hotends at the same time) as long as you level the hotends.


Duet Wifi Hardware Designer
www.duet3d.com
www.think3dprint3d.com

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By gzcwnk 11 April 2017 23:49

Member · 131 comments

Hmm yes this might be simpler, except with 2 moving heads on the moving gantry the mass goes up so maybe not. I might as well just fit a kraken on 1 gantry and be done with it.

http://www.thingiverse.com/thing:2073946

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By gzcwnk 11 April 2017 23:52

Member · 131 comments

So just to be clear for stupid ppl like me, the duetwifi can with the present firmware support 2 moving gantries as X and U as a core XY - IDEX?

Last edited by gzcwnk (12 April 2017 02:34)

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By gzcwnk 11 April 2017 23:56

Member · 131 comments

So in terms of high  level architecture / outcome  is a IDEX a good way forward or is a delta carrying 4 heads going to  give the better solution?

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By dc42 12 April 2017 05:34

Administrator · 2,672 comments
gzcwnk wrote

So just to be clear for stupid ppl like me, the duetwifi can with the present firmware support 2 moving gantries as X and U as a core XY - IDEX?

No, some firmware work would be needed to define which motors control the U axis.


Duet WiFi hardware designer and firmware engineer
http://www.escher3d.com
https://miscsolutions.wordpress.com

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By dc42 12 April 2017 05:38

Administrator · 2,672 comments
gzcwnk wrote

So in terms of high  level architecture / outcome  is a IDEX a good way forward or is a delta carrying 4 heads going to  give the better solution?

Personally i would avoid the issues caused by multiple nozzles, by using a Diamond hot end instead of a Kraken. If you want a separate extruder for support material, then IDEX.


Duet WiFi hardware designer and firmware engineer
http://www.escher3d.com
https://miscsolutions.wordpress.com

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By deckingman 12 April 2017 17:56

Member · 799 comments
dc42 wrote

Personally i would avoid the issues caused by multiple nozzles, by using a Diamond hot end instead of a Kraken. If you want a separate extruder for support material, then IDEX.

You can also use a different material for supports with a Diamond hot end.


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By dc42 12 April 2017 20:46

Administrator · 2,672 comments
deckingman wrote
dc42 wrote

Personally i would avoid the issues caused by multiple nozzles, by using a Diamond hot end instead of a Kraken. If you want a separate extruder for support material, then IDEX.

You can also use a different material for supports with a Diamond hot end.

Doesn't support filament usually need a different extrusion temperature?


Duet WiFi hardware designer and firmware engineer
http://www.escher3d.com
https://miscsolutions.wordpress.com

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By vvonplaten 12 April 2017 20:57

Member · 6 comments
dc42 wrote
gzcwnk wrote

So just to be clear for stupid ppl like me, the duetwifi can with the present firmware support 2 moving gantries as X and U as a core XY - IDEX?

No, some firmware work would be needed to define which motors control the U axis.

That said, if someone would be willing to solve the mechanics of a dual coreXY and actually build it, would it be interesting to create firmware support for that?

Like gczwnk said, it would allow for very low moving mass and independent extruders. If we look at current independent extruder systems the Y-axis gets very heavy very fast. As an extreme (and also what I would like to run), imagine dual independent direct drives. On a dual coreXY the moving mass on Y could be something as low as 250g, whereas on a current system we would most likely approach 1kg 😁

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By dc42 12 April 2017 21:39

Administrator · 2,672 comments

Yes, it would be interesting to support 2 moving gantries. In effect, each tool would be a separate CoreXY machine except that they would share the Z axis. We'd need to map the Y axis to the V axis on the second tool, and define the U and V positions as being defined by the U and V motors in the same way as X and Y. It doesn't sound difficult.


Duet WiFi hardware designer and firmware engineer
http://www.escher3d.com
https://miscsolutions.wordpress.com

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By deckingman 12 April 2017 21:45

Member · 799 comments
dc42 wrote
deckingman wrote
dc42 wrote

Personally i would avoid the issues caused by multiple nozzles, by using a Diamond hot end instead of a Kraken. If you want a separate extruder for support material, then IDEX.

You can also use a different material for supports with a Diamond hot end.

Doesn't support filament usually need a different extrusion temperature?

Yes but that's not a problem. Just use different active and standby temperatures for each tool. Of course one has to set the mix ratios to 100% for each tool(filament). It's just the same as having separate nozzles. If the "inactive" tool isn't extruding, there won't be any oozing/mixing (well not noticeably). Also, I think E3D's scaffold is best printed at 215 so you could probably print PLA and Scaffold at the same temperature - haven't tried it though.

Edit. I have printed something in PLA at 195 with a "T Glass" window printed at 235 with the Diamond - worked fine.

Last edited by deckingman (12 April 2017 22:11)


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By deckingman 12 April 2017 22:07

Member · 799 comments
vvonplaten wrote

That said, if someone would be willing to solve the mechanics of a dual coreXY and actually build it, would it be interesting to create firmware support for that?

Like gczwnk said, it would allow for very low moving mass and independent extruders. If we look at current independent extruder systems the Y-axis gets very heavy very fast. As an extreme (and also what I would like to run), imagine dual independent direct drives. On a dual coreXY the moving mass on Y could be something as low as 250g, whereas on a current system we would most likely approach 1kg 😁

For info, I run a Diamond hot end on a coreXY which alone weighs 250gms. I've lightened the axes a bit by going from dual X rails to a single rail but I'm not happy with the stiffness (or lack of) so I'll be reverting back to dual rails. So the total X carriage with fans and the Diamond hot end etc  weighed 690 gms (without the 3 off extruders). The Y axis including the X rails but without the X carriage weighed a further 1,210 gms giving a total Y axis weight of 1,900 gms. On top of that, I have 3 extruders suspended above the centre of the bed with a counter balanced pulley arrangement. Although the weight is counterbalanced, they still have to be dragged around. Despite all that, I still print at 90 mm/sec no probs, with non print moves of up to 300 mm/sec. Although I'd like to reduce the weight if possible, I have to say that I've never had a problem with ringing - I think it's all just too heavy and stiff to resonate.:)


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By gzcwnk 12 April 2017 23:19

Member · 131 comments

Well to do a dual gantry, I assumed there would be 4 steppers, one for X and one for Y for gantry1 and then one for U and one for V for the gantry2.

With a d-bot design using openbuilds 2040 and some 3d printing it wouldnt cost much to make such a test setup. Not sure if it achieves anything NET good, mind you it would look cool  😄

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By gzcwnk 12 April 2017 23:43

Member · 131 comments
dc42 wrote
gzcwnk wrote

So just to be clear for stupid ppl like me, the duetwifi can with the present firmware support 2 moving gantries as X and U as a core XY - IDEX?

No, some firmware work would be needed to define which motors control the U axis.

Um so it would be 2, actually U and V?  I sort of assumed the gantries and belts and steppers would be totally independent of each other.

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By lars 13 April 2017 06:59

Member · 5 comments

I’m currently (slowly) building a dual carriage core-xy printer. The kinematics were described in http://forums.reprap.org/read.php?397,737863 over at reprap forum and David wrote a bit about what would need to be implemented in firmware.
Would love to see the Duet/RepRapFirmware support it!

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By deckingman 13 April 2017 11:19

Member · 799 comments

I'm struggling to get to grips with this idea. From what I can ascertain, to keep the axes on the same plain, they share a common Y but have different X axes. This means that the X axis must be very wide and /or one would lose a lot of travel. So, the only advantage I can see over simply fitting two hot ends to a single X carriage is that there would be a weight saving on one of the X axes. However, the Y carriage would still have to move both the X axes so the Y axis weight will be the same. Therefore any speed advantage would be limited to pure X moves which is unlikely to have much of an impact on the total time it takes to print something. It seems a lot of complexity for very little practical gain or have I missed something?


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By lars 13 April 2017 14:12

Member · 5 comments

Well, you do have 4 steppers contributing to z-axis movement and 2 for x-axis. Although you have to move shafts and the two hotends for z-axis movement and only a hotend for x-axis. Differences in z offset of the two hotends should not be a problem using two carriages and you could use two very different hotends if you find that useful.

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By vvonplaten 13 April 2017 15:43

Member · 6 comments
dc42 wrote

Yes, it would be interesting to support 2 moving gantries. In effect, each tool would be a separate CoreXY machine except that they would share the Z axis. We'd need to map the Y axis to the V axis on the second tool, and define the U and V positions as being defined by the U and V motors in the same way as X and Y. It doesn't sound difficult.

Yes, that is exactly what I'm thinking of! Time to start setting it up in cad then! 😁

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By lars 13 April 2017 16:03

Member · 5 comments

Ahh.. two gantries, I was thinking one gantry (shared Y and Z and independent X). I’m too preoccupied with what I’m building so I missed that part, sorry 😉

Last edited by lars (13 April 2017 16:03)

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By deckingman 13 April 2017 16:10

Member · 799 comments
vvonplaten wrote
dc42 wrote

Yes, it would be interesting to support 2 moving gantries. In effect, each tool would be a separate CoreXY machine except that they would share the Z axis. We'd need to map the Y axis to the V axis on the second tool, and define the U and V positions as being defined by the U and V motors in the same way as X and Y. It doesn't sound difficult.

Yes, that is exactly what I'm thinking of! Time to start setting it up in cad then! 😁

I still can't get my head around the mechanics of how this would work. I can't see how you could have the gantry's on the same plane without one interfering with the other. Unless, the gantry's are stacked one above the other? But then you'd have to somehow deploy one hot end to move in Z by the thickness of one of the gantry's. I just can't picture it in my mind - be interesting to see a design.

I am in fact working on a stacked gantry design but that's a just a way of trying to mount 3 extruders above a diamond hot end whilst keeping the footprint small and the Bowden tubes short. In this case, both gantries will be active at the same time and the second gantry would probably be passive - i.e. linked to the lower gantry but without any motors or belts of it's own.


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By dc42 13 April 2017 17:06

Administrator · 2,672 comments

I presume you would part park one gantry at one end of the Y axis while you use the other one. Just as on an IDEX machine you park one X carriage at the end of the X axis while you use the other one. The printable length of the Y axis for each head would be reduced by the amount of space taken up by one gantry, and the printable length accessible to both heads would be reduced by the amount of space taken up by both gantries.


Duet WiFi hardware designer and firmware engineer
http://www.escher3d.com
https://miscsolutions.wordpress.com

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By vvonplaten 14 April 2017 16:49

Member · 6 comments
deckingman wrote
vvonplaten wrote
dc42 wrote

Yes, it would be interesting to support 2 moving gantries. In effect, each tool would be a separate CoreXY machine except that they would share the Z axis. We'd need to map the Y axis to the V axis on the second tool, and define the U and V positions as being defined by the U and V motors in the same way as X and Y. It doesn't sound difficult.

Yes, that is exactly what I'm thinking of! Time to start setting it up in cad then! 😁

I still can't get my head around the mechanics of how this would work. I can't see how you could have the gantry's on the same plane without one interfering with the other. Unless, the gantry's are stacked one above the other? But then you'd have to somehow deploy one hot end to move in Z by the thickness of one of the gantry's. I just can't picture it in my mind - be interesting to see a design.

I am in fact working on a stacked gantry design but that's a just a way of trying to mount 3 extruders above a diamond hot end whilst keeping the footprint small and the Bowden tubes short. In this case, both gantries will be active at the same time and the second gantry would probably be passive - i.e. linked to the lower gantry but without any motors or belts of it's own.

Like dc42 said, I'm thinking of dual gantries. A bcn3d sigma for example uses one Y-gantry where two X-carriages live. Imagine instead two independent Y-gantries with one X-carriage each. Each gantry+carriage is controlled by its own set of steppers.

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By gzcwnk 14 April 2017 22:42

Member · 131 comments
dc42 wrote

I presume you would part park one gantry at one end of the Y axis while you use the other one. Just as on an IDEX machine you park one X carriage at the end of the X axis while you use the other one. The printable length of the Y axis for each head would be reduced by the amount of space taken up by one gantry, and the printable length accessible to both heads would be reduced by the amount of space taken up by both gantries.

Yes that was the idea, ie parking a complete gantry each end was forming in my mind.  The original Dbot is a 300(x)x300(Y) corexy printer but its made from openbuilds 2040 so its easy to re-dimension (cut).  My original idea was to build something big enough to print my own storm trooper armour parts in one piece (to save glueing) for that I need 500~550mm in one dimension of X or Y and 450~500mm high and then maybe cut it back to something more physically manageable later if need be. 

Being lazy the 2040s come in 1500mm lengths so I just chopped up 2 lengths and ended up with 4 x 750mm pieces and did the same for Z and there is the frame https://ibb.co/dtCE35. I just added the HGR15 Linear rail on top yesterday giving an absolute max stoke of 670mm, or around 600mm~630mm NET stroke.  So the linear rails came with x2 boggies each anyway so I have added these both to the top rail since two were spare.  https://ibb.co/bKvqbQ   The second gantry will cost me 75~100mm at most if I hand and overhand them so on Y so I think I'm still OK for 550mm, Worst case I have to buy a bit more 2040 (4 x 1m), about $40US worth, that is not going to break the bank. 

So structurally I am set, linear rail I am set, next and biggest nightmare is  somehow running 2 sets of belts, hello fusion 360 and some evenings not to hard, its the multi-dimensional curves that drive me nuts.  The last part will be the firmware to allow it to work.   Would there be anything else Ive missed?

As an aside unlike the wanhao pile of crap mainboard that lasted 3 months (that would have cost me $165US to replace and they are dying like flies due to bad relays) v  the duetwifi at $200US has well proven itself, its quiet and the web gui is just nice.

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By MrBlom 15 April 2017 09:57

Member · 29 comments

Hello im also thinking of dual extruders 😁
i like this ide
http://www.thingiverse.com/thing:1446731
that way you dont need extra steppers motors
only need a way to power 2 magnets in the tool change script
is there a way to send a signal to the magnet to turn on/off

for example the tool script will do something likt this
->move left turn of magnet #1 (park extruder1)
->move right turn on magnet #2 (get extruder2)
->print

here is the magnet
https://www.aliexpress.com/item/16-25-H … 262.V23JLP


see here
https://www.youtube.com/watch?v=FiTmRHkiEUg

sounds simple ... 😁

Last edited by MrBlom (15 April 2017 10:03)