1 Topic by pirvan

  • pirvan
  • pirvan
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  • Registered: 2013-03-27
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Topic: Water Soluble PVA for support

Given the proliferation of controller boards like the RAMPS or the Rumba, we now have the ability to use multiple extruders on our Solidoodles.

I'm currently waiting a for a RAMPS board, which comes with 5 steppers, so I've been really thinking about a 2nd extruder, but not for printing a second color, rather for printing support using PVA filament.  At the moment PVA is still expensive (about 4 times the cost of ABS or PLA), but if you consider you only use it for support, then it's not that bad.

SO there's a lot of questions I have.

What's the current state of support for multiple extruders on the Solidoodle platform
Does Repetier/Slic3r support slicing so the support is printed by a different head?
Any suggestion on a dual extruder head design?
Considering the weight, it would most likely have to be a Bowden type.

Anyway, has anyone else considered this?  Need feedback.

Thanks.

To print or, 3D print, that is the question...
SD3 printer w/too many mods,  Printrbot Simple Maker Ed.,  FormLabs Form 1+
AnyCubic Photon, Shining 3D EinScan-S & Atlas 3D scanners...
...and too much time on my hands.

2 Reply by RTRyder (edited by RTRyder 2014-02-08 03:22:37)

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Re: Water Soluble PVA for support

Can't say I've thought about using a dual extruder with one exclusively for support material but I have given considerable thought to adapting my SD3 to dual extruders. There are compromises to be made, a dual setup will result in some amount of printable area loss if you want to keep the stock enclosure and have both heads capable of reaching the same end of the printing surface. To keep the existing print volume you would need to widen the X carriage assembly so the head closest to the edge doesn't bump into something while the inner is trying to reach the limit of the printbed. Obviously the closer together you can space the hotends the less this is of a concern but sitting here watching my SD3 print I just can't see how its possible to get two heads in there and not have one hit the X stepper with the other trying to reach the limit of the existing platform on that side without widening the entire X carriage assembly to provide clearance.

Yes, a dual bowden would make the most sense, trying to fit another stepper on the X carriage platform to drive the second hotend will reduce the useable space even more and the added weight probably require much slower print speeds to maintain print quality.

Now, that said I have all the necessary bits and pieces on hand to do a dual extruder build for an SD. I have a pair of Jhead MKV that are easily adaptable to use with a Bowden and are rather compact compared to the E3D currently in use. After the 3DR Delta project I have enough bearings, stepper motors, and other odds and ends to build a pair of geared bowden extruders, just need to print a few ABS pieces to make them complete. Only thing I might be a bit short on is teflon tubing between the extruder and hotend but that's easily obtained.

This could also be justification for upgrading the RAMPS on the Delta to a Rumba so I can utilize the RAMPS for the duals, Hmmmmm....

Only thing missing is an abundance of available free time to do it in. I'm off to Las Vegas for a business conference early Tuesday AM and I'll be there all week so I guess I'll have plenty of time to pencil and paper some ideas for building the platform to hold the hotends, any real design and prototype work will have to wait until I get back home next weekend.

3 Reply by Fel

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Re: Water Soluble PVA for support

I think PVA is probably the best soluble support solution for the Solidoodle 3 or 4.  The old Stratasys machines use PLA as their support structure which dissolves in sodium hydroxide solution.  PVA just requires water.  HIPS is also selectively soluble, and is what I run in my Makerbot Replicator Dual, but it requires a fairly expensive solvent, d-Limonene, which is about $35/gallon.  HIPS also requires higher temperatures than the Solidoodles are recommended for since there are plastic parts close to the hot end.  In the Makerbot I set the HIPS to 258 with my ABS part material as high as 238 to maximize adhesion and a 118 bed temp to minimize warping.  Bed temp is also something neither PVA or PLA deal well with since they don't like to stick to hot tape, so you have to turn the bed heat off if you use either of them as support, which can exacerbate warping.

I tried using PLA supports with ABS part material, but in the open-air environment of my Makerbot, I can't get the ABS to stick to the PLA.  ABS would not adhere to PVA supports either.  My Solidoodle 4 still only has a single extruder but I suspect that, if I forced a little heated air into the enclosure to try maintaining something like 140F air temps, I might be able to get one or both of the two combinations to bond after a dual extruder upgrade.  I probably wouldn't go to the trouble though. 

I found that using PVA as a support and PLA as part material works very well.  I run the PVA at around 190 and the PLA at around 220 leaving the bed heat off and just throw the prints in a crock-pot full of water when they're done.  I imagine the same recipe, or one with slightly reduced temps would work in the Solidoodles.

4 Reply by Staffordknot

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Re: Water Soluble PVA for support

Where do u buy water soluble pva from?

5 Reply by ronsii

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Re: Water Soluble PVA for support

^^ ultimaker sells it  https://ultimachine.com/category/catalo … /pva-175mm

so does a bunch of other filament retailers. smile

6 Reply by osmanharac

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Re: Water Soluble PVA for support

RTRyder wrote:

Can't say I've thought about using a dual extruder with one exclusively for support material but I have given considerable thought to adapting my SD3 to dual extruders. There are compromises to be made, a dual setup will result in some amount of printable area loss if you want to keep the stock enclosure and have both heads capable of reaching the same end of the printing surface. To keep the existing print volume you would need to widen the X carriage assembly so the head closest to the edge doesn't bump into something while the inner is trying to reach the limit of the printbed. Obviously the closer together you can space the hotends the less this is of a concern but sitting here watching my SD3 print I just can't see how its possible to get two heads in there and not have one hit the X stepper with the other trying to reach the limit of the existing platform on that side without widening the entire X carriage assembly to provide clearance.

Yes, a dual bowden would make the most sense, trying to fit another stepper on the X carriage platform to drive the second hotend will reduce the useable space even more and the added weight probably require much slower print speeds to maintain print quality.

Now, that said I have all the necessary bits and pieces on hand to do a dual extruder build for an SD. I have a pair of Jhead MKV that are easily adaptable to use with a Bowden and are rather compact compared to the E3D currently in use. After the 3DR Delta project I have enough bearings, stepper motors, and other odds and ends to build a pair of geared bowden extruders, just need to print a few ABS pieces to make them complete. Only thing I might be a bit short on is teflon tubing between the extruder and hotend but that's easily obtained.

This could also be justification for upgrading the RAMPS on the Delta to a Rumba so I can utilize the RAMPS for the duals, Hmmmmm....

Only thing missing is an abundance of available free time to do it in. I'm off to Las Vegas for a business conference early Tuesday AM and I'll be there all week so I guess I'll have plenty of time to pencil and paper some ideas for building the platform to hold the hotends, any real design and prototype work will have to wait until I get back home next weekend.

Maybe  you can use one hot end with a regular setup and use a second hot end bowden style, so you can save some space.