Is Anyone doing research into dual head RepRap?

Now that there has been advances into the pla/pva dissolving printing (as posted here and on MAKE), I was wondering if anyone has come up with a dual head unit for a reprap yet? and whatever changes in the software it needs to run it. I wasnt too concerned with this before, but now with the ability to print a dissolvable form, I think this is the next step in the 3d printer that needs to be pushed! I know makerbot has been doing it for a while now..
thanks!
Jeff

RAMPS electronics can do this from 1.3+. Most other electronics can't, they use integrated stepper drivers and a fifth driver hardly anyone would use isn't cost effective. This will improve when multiple extruders become commonplace.

Teacup firmware is listed as supporting unlimited extruders, repetier lists multiple extruder support as experimental. There may be others.I don't think any firmware provides full support in that they don't provide offset coordinates for additional tools.

Software support is the problem. Skeinforge can use a second extruder for support but you have to use the alteration files to swap extruders and set up offsets. As far as I know, there is no easy way to print an object in multiple materials, the workaround is to create multiple stls and combine the gcode by hand.

To be honest, I'm not sure what problem dual extrusion solves. Now, I can see the appeal of n extruders, but 2? Seems like you're not actually eliminating any mental legwork because you still can't print arbitrarily-colored objects, you've simply gone from mono-colored objects to dual-colored objects, and like before, you still need to prepare beforehand for which colors you're going to use! If multicolored objects are going to be a practical reality we don't need two colors, we need many. Maybe this will be multiple nozzles and extruders, maybe this will be a color mixing chamber, or a dye injector, or what have you… but I don't see how simply going from one extruder to two gives you much.

Now, I can kind of understand dual extrusion for the dissolvable support material. But honestly, I don't find normal support material to be that much of a pain to remove, and speaking of pains to remove, the PVA support material that MBI is pushing takes more than 12 hours to even partially dissolve. If someone could come out with a support material that dissolves semi-instantly, THAT would be something. Also, the PVA is $90 a pound. Yeesh.

i did a lot of research on possibly using a second extruder for support material on my mendelmax, though it doesn't seem like the software chain is up to the task just yet. how is makerbot doing it with the replicator? what is their process like in terms of the software side of things? they use replicatorg, no?

> be something. Also, the PVA is $90 a pound. Yeesh.

I think they just keep raising the price as their supply dwindles. When it first showed up in their store I believe it was $32 a pound.

The whole thing is chicken and egg. Since machines don't have dual extruders there is no big push for dual extruder capable firmware/software.

I recently started a post in experimental firmware about what marlin needs to be multi-head capable. Erik says there will be a dual material marlin released soon, but I have a feeling it still needs some work to be really usable via skeinforge.

Real dissolving support material makes a ton of things possible which we currently can't do. With some changes in support algorithms, we can make the most use of 'cheap' base materials for support and only put dissolvable support at the interfaces.

Also, the surface finished with the break away supports leave a lot to be desired, and having dissolvable support will allow very high aspect ratio features not currently possible (since they break as easily as the supports)

I also feel there can be a lot of improvements to the way PVA is dissolved.




Pointedstick Wrote:
-------------------------------------------------------
> To be honest, I'm not sure what problem dual
> extrusion solves. Now, I can see the appeal of n
> extruders, but 2? Seems like you're not actually
> eliminating any mental legwork because you still
> can't print arbitrarily-colored objects, you've
> simply gone from mono-colored objects to
> dual-colored objects, and like before, you still
> need to prepare beforehand for which colors you're
> going to use! If multicolored objects are going to
> be a practical reality we don't need two colors,
> we need many. Maybe this will be multiple nozzles
> and extruders, maybe this will be a color mixing
> chamber, or a dye injector, or what have you…
> but I don't see how simply going from one extruder
> to two gives you much.
>
> Now, I can kind of understand dual extrusion for
> the dissolvable support material. But honestly, I
> don't find normal support material to be that much
> of a pain to remove, and speaking of pains to
> remove, the PVA support material that MBI is
> pushing takes more than 12 hours to even partially
> dissolve. If someone could come out with a support
> material that dissolves semi-instantly, THAT would
> be something. Also, the PVA is $90 a pound. Yeesh.

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www.Fablicator.com

cool! its good to know that people are out there trying to make this happen!! I wasnt aware of the cost at this time of the material, but as it was stated - maybe another material will come into light as the dissolvable material comes more into use. I think this would be a huge step into 3D printing if it can be perfected!
Jeff

My understanding is PVA is a soluble support for PLA. Warm water and agitation should dissolve it in a reasonable time.
PLA is a soluble support for ABS with a strong alkali to dissolve it.
HIPS is a both a break away and a soluble support for ABS with limonene to dissolve it.

In think break way support would work a lot better if it had a solid top layer where it meets the object. That is what the UP printer seems to do and is the way I used to do rafts. It should just be a little lower than a normal layer so prevent it bonding too well.

I was thinking of mounting a pair of extruders on a see-saw with magnetic catches. Moving to each extreme of the X-axis could nudge the see-saw to the opposite side. That would stop the unused extruder dragging across the object.

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[www.hydraraptor.blogspot.com]

I've done some experimenting with limonene and HIPS, and have not have very good results, unfortunately

Limonene takes forever to dissolve HIPS, and mostly just makes it gummy. It's also a pain to wash off the part (and is somewhat expensive.) I also found the cheap "ABS" from china (esunpla) is predominantly styrene and also softens in limonene...

The whole way support is calculated is currently very poor, and should be a subject of development soon I hope.

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www.Fablicator.com

Skeinforge supports a dual extruder for support material with the startsupport and endsupport gcode files.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

nophead Wrote:
-------------------------------------------------------
> I was thinking of mounting a pair of extruders on
> a see-saw with magnetic catches. Moving to each
> extreme of the X-axis could nudge the see-saw to
> the opposite side. That would stop the unused
> extruder dragging across the object.

That's a nice Idea, if the nozzle also got primed & wiped on the see-saw down stroke you could do some nice dual colour printing.
With an extra solenoid or electromagnet tipping on the alternative X-axis extruder set you could have two see-saw's side by side giving 4 colour printing. That would be an interesting sight to see operational.

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[richrap.blogspot.com]

Pointedstick Wrote:
-------------------------------------------------------
> Now, I can kind of understand dual extrusion for
> the dissolvable support material. But honestly, I
> don't find normal support material to be that much
> of a pain to remove, and speaking of pains to
> remove, the PVA support material that MBI is
> pushing takes more than 12 hours to even partially
> dissolve. If someone could come out with a support
> material that dissolves semi-instantly, THAT would
> be something. Also, the PVA is $90 a pound. Yeesh.

After more testing, after the first test that took almost 24 hours in cold water, I was able to completely dissolve my gearbox test in under 12 hours by putting it in a crock pot with an aquarium pump bubbler. That, along with more sparse support (my test support was very dense) makes PVA dissolve quite quickly.

Also, the PVA is $90/kg not per pound. That's 2.2 pounds. So it's $40 a pound. More expensive than ABS or PLA, but still a lot cheaper than commercial soluble support. You'll probably not need it very often, but with it you can do some amazing things. Also with some more intelligent support structures, like: [fabbaloo.com] you'd hopefully not use very much at a time.

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--
Tony Buser http://tonybuser.com * http://reprap.org/wiki/User:Tbuser#Projects

Great,
Now that the materials and firmwares have been covered, has ANYONE built a dual head REPRAP as of yet to do the same prints as gRok has done with his makerbot?
Again, personally i feel THIS is what a dual head printer should be for - im not really into the color thing yet - but id love to be able to print with a
dissolvable support.
Thanks~!
Jeff

I've got all the parts, just waiting on firmware.

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www.Fablicator.com

I do though getting the makerbot firmware that Im using to work well is a problem due to several bugs. I know that using two seperate stl's works with teh makerbot firmware can be done. but I keep working to get dual extrusion support material printing functioning properly.

I've been playing with dual headed mod for Prusa (calling it X2) for quite a while now, alas the RepRap forums are hard to follow (wish there was an e-mail digest like in Google forums, I'd have replied earlier). All the details (hardware, firmware, etc) are here:
[www.thingiverse.com]

I haven't experimented much for the last few weeks. Working on making a couple of reprap machines for sale in order to refill my hobby budget before buying PVA (that stuff is pricy ). After that the plan is to try printing [www.thingiverse.com] or alike using the same technique as described (in the X2 mod link) for the 2 color printing.

As stated above I agree that it is a chicken and egg problem. There simply aren't that many dual-extruder capable 3D printers currently in 'the wild'. I think a lot of that has to do with the cost of having two separate extruders and the limited choices for an extruder that can be mounted side by side to another one (without majorly affecting x-axis movement) than anything else.

-Chelsea

Are any of you following the adventures of Hoss over on CNCzone? He's converted his Prusa to dual heads.

http://www.cnczone.com/forums/3d_printers/146896-hosss_3d_printers-41.html

Is Anyone doing research into dual head RepRap? - Yep, our mendel will be able to have three colours, or to build single objects with multiple materials (http://www.reprappro.com/Mendel)

Sally

I'd add to the chicken and egg problem the fact that there isn't that much content yet that makes good use of the second extruder. The way support is generated (at least in skeinforge 43 I've bee using) doesn't make the second extruder quite useful (surely because skeinforge was designed for printing the support by the same extruder and the same material). The only good way of using 2 extruders with current slicers I've found so far is to slice the object volumes for each extrusion separately using the same layer height and then mix the gcode. I've uploaded a couple of things done this way to the thingiverse, but didn't see anything else alike there. I'd expect that the situation is going to improve as it becomes easier to get access to the 2 headed printers and firmware (like Makerbot's Replicator or X2 mod).

The real cool thing would be to print in color using the 3D model textures, but that requires much more work and I'm not sure multiplying extruders is exactly right way to go there. In any case, even if color printing is done any other way, 2 separate extruders will be necessary to print the complex objects.

I had always thought it would be really cool to have a second extruder have a much larger diameter nozzle that was specifically used for doing infill quickly, with a fine nozzle for the exterior. Of course layer heights would be different but it could be corrected in software.

-Chelsea

Chelsea - QU-BD Wrote:
-------------------------------------------------------
> I had always thought it would be really cool to
> have a second extruder have a much larger diameter
> nozzle that was specifically used for doing infill
> quickly, with a fine nozzle for the exterior. Of
> course layer heights would be different but it
> could be corrected in software.

That seems like a good idea to me as well.

I might have to disagree with some of you here, I actually think having 2 printhead is almost essential in 3D printing. Let's not get into printing in colours because this is a lot more complicated, it involves texture maps, "ink" mixing, resolution, etc, simply I don't think STL file can handle that. As far as I know, ZCrop requires 3ds files with proper texture coordinates in order to print in colour correctly, and the skill requires to make a colour 3d model is kinda advanced stuff if getting into unwrapping the UVs, or at least very time consuming.

Having used the Dimension 3D printers, both the BST and SST model, I must say it is a pain removing the break away supports especially printing architectural models. Architectural models are much complicated than you think because they involve loads of overhangs, both exterior and interior and no matter what scale they are at. For example, printing a house might be simple because most of the overhand are in the inside of a room, eg ceiling to wall junction. However, printing something bigger like a bridge, or a train station, the break away support exist inside the tiny holes would either be stuck too strong to remove or being broken off with the actual part needed. I have loads of situations from the Dimension BST that merely 1 layer of plastic is supported by the breakaway structure, and this is the reason they have the SST model which uses soluble materials.

Extruding a second material (soluble) as support has tons of advantages, we can concentrate more on the actual 3d model rather than worrying the design wont print properly. Recently I made [adriantsang.info] this sheep model and I actually had to spend time altering the model in order to get a good slice to print the legs ad body separately to avoid overhang at the body.

Anyway I'm so glad to see that there are development going on with dual printheads, once there are better firmware / software that support dual printheads, I'll defo be the first batch to try it out! Shame that I don't have any programming knowledge so cant help with the development...

Multiple materials/colors: the new AMF format is designed to handle that. At its simplest, it is a replacement for STL. At it's most complex, there is a color for each vertex, however it is likely to be useful in the near term to represent multiple volumes with different single color/material.

If we can get past the chicken/egg problem, I think there is a lot of potential for this.. I am thinking about a design for a narrow extruder head which does not reduce X area too much, and with a quick change format.

HI there guys, I have gotten a reprap to use a dual head successfully. IT WORKS!!!
Sorry, I am excited. You can use my printer with Slicer to print support structures with no hassle,
or you can build two models of something and combine their .stl with CURA to print multi colors.
Its fun ans easy now. anyways, check out japica.com, which is where I have the Dual head listed.
If you want help making your own or want all the firmware, software and other info I combined for the dual printing
send me an email

I'm definitely interested in seeing some more info on dual head printing. What firmware/controller were you using? A tutorial would be great!

Video of the printer?

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www.Fablicator.com

I have a video at the bottom of the page: [www.okob.net]
There is a short description of the process on the "Printing" page: [www.okob.net]

Very well done.

I have been working on getting RAMPS 1.4, MARLIN RC2, with ReplicatorG 34 working with DUAL heads.

So far in ReplicatoG I have been able to display two heads, two tempatures, one heat bead.

I have my toolheads built as follows in my .xml file (See attachment)

In Marlin RC2 I have set the following under Configuration.h

RAMPS 1.4 = 34 (Power outputs: Extruder0, Extruder1, Bed)

#define MOTHERBOARD 34

#define TEMP_SENSOR_0 7
#define TEMP_SENSOR_1 7
#define TEMP_SENSOR_2 7
#define TEMP_SENSOR_BED 7

#define HEATER_0_MINTEMP 5
#define HEATER_1_MINTEMP 5
#define HEATER_2_MINTEMP 5
#define BED_MINTEMP 5

#define HEATER_0_MAXTEMP 275
#define HEATER_1_MAXTEMP 275
#define HEATER_2_MAXTEMP 275
#define BED_MAXTEMP 150

I have set the following under Configuration_adv.h

This defines the number of extruders
#define EXTRUDERS 2


The issues that I am seeing is that I am unable to register a temp for Toolhead0.

Toolhead1 works Shows temp
HBP works Shows temp

When I turn on the temp for toolhead0 LED4 comes on.
When I turn on the temp for toolhead1 LED3 comes on.
When I turn on the temp for HBP LED2 comes on.

T0 T1 and T2 are for the temps.

When I have a single head programmed in the firmware #33 profile. T0 and T1 works.

With a dual, I am only getting T1 and T2 to work.

I have looked over the PINS.H file and all looks to be correct.

My other issues is that under control panel in repg 34, It has both left and right extruders listed under control panel. I can get Toolhead 1 to move its extruder, but when I try Toolhead 0, Toolhead 1 moves instead of Toolhead 0


I am close here. I just need to get the correct motor to turn and the temperature to register for T0

You can download my firmware here using replicatorg.

[thefutureis3d.com]

I just started working on this. Once I figure it all out I will share it with the community.

Thanks

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Jeff Christiana