Query on PVA and Duel Head extruder model

This is for general discussions. Also FAQ can be found here.

Moderator: speedake95

Post Reply
Genaforge
Posts: 8
Joined: Thu Aug 29, 2013 6:20 am

Query on PVA and Duel Head extruder model

Post by Genaforge »

Loving the printer, and getting some great results from it... under the right conditions. What I'm looking to do is improve on those conditions to allow a greater variety of items to be printed.

Firstly, is it possible to print in PVA? I understand there's going to be a print temperature difference (160-170 degrees), but I'm not sure if there are other aspects that need to be considered. Will the print head supplied with the Felix 2.0 print PVA?

Secondly, I've seen a hack for the Felix to convert it to a dual head printer. I'd prefer not to mess about with this sort of stuff, and was hoping that Felix Printers had something in the pipe-line. Is there a Felix Printer supported modification to allow for dual extrusion? And, if so, will the second print head print in PVA?


My main barrier at the moment is with removing ABS/PLA supports, and the not-so-smooth finish it leaves behind. This leaves me being able to only print objects that don't need supports, which is far from ideal.

I'll add quickly that the quality of prints I'm getting from the Felix 2.0 is far greater than the quality of other items I've seen online. I'm a little amazed that it hasn't gotten the attention it deserves; other similarly priced printers are praised more despite producing inferior prints.

superhornet59
Posts: 60
Joined: Wed Apr 03, 2013 1:58 am

Post by superhornet59 »

Minimum extrusion temperature of the Felix 2.0 (in the firmware) is set at 170 degrees, so if that is the working range of the material you'll want to override that, but otherwise there shouldn't e any problem with it, and so long as the filament diameter is 1.75mm you shouldn't have any issues with the extruder.

I'm one of the creators of a custom dual-extrusion setup and I can tell you without a doubt that if you don't like to 'mess about with this sort of stuff' then you're not going to want to get involved in dual extrusion. The physical parts are easy to put together, the wiring isn't too bad, and the new firmware is easy to upload. The real problem has to do with the state of current slicing programs and lining up the extruders.

I use Cura for slicing, and while it has support for dual extruders, the G-code it generates doesn't *actually* switch extruders, just does it all on one. Silly glitch that should be fixed soon. I did try on Slic3r though, and I can tell you, leakage is a big problem. So, while you're printing with your primary extruder, the support one 'leaks' filament all over the place, then when it's time for it to start printing support it takes a while for it to start flowing. Meanwhile the primary one is leaking, and you've got the same problem on the part. It sounds like something retraction would fix, but the g-code I've gotten from slic3r has been lousy about it, and the nozzles don't like long-time retraction because the plastic at the end inside the extruder sort of 'bulges' and doesn't extrude right at the beginning of the switch.

Really stupid stuff, but I'm sure there will be a fix. Then there's the problem of adjusting the nozzles. I have mine set up so one is slightly loose and can be screwed in or out. This gives me some nice on-the-fly height adjustment which helps with getting the nozzles in-line, but it's tough because if they are not perfectly aligned, the higher extruder will not get proper bed adhesion, and the lower one will crash into what the other one printed and tear it all apart. This also happens if your first layer is too smushed. Basically, it's really hard to even get a first layer. I know it's not impossible, but damn, if you've ever had problems with single extrusion printing, dual extrusion printing is 10x worse.

As far as I know, only three people on this forum have a dual extruder set-up installed on their printers.. but last I've heard, zero of us actually use it. I for one just single-extrude everything, and like you I try to avoid printing things that require support, so I feel your pain.

I don't mean to sound discouraging to anyone, these problems will be overcome, but it will take time and patience before a reliable solution emerges.

dognotdog
Posts: 181
Joined: Tue Sep 04, 2012 9:22 pm

Post by dognotdog »

I printed PVA at similar temperatures as PLA, maybe a little lower, but not below 180°C.

EDIT: note that PVA has a problem sticking to the bed & PLA, making its use somewhat tricky. But when it works, it's real nice that you can just wash away the support.

seaton
Posts: 291
Joined: Tue May 14, 2013 9:04 am
Location: Bunbury, Western Australia
Contact:

Post by seaton »

Regarding the minimum extrusion temperature, it can be set in the firmware, I set it to a lower value myself, as I have one spool of PLA that will only print half decent at a really low temperature ~172DegC, and when the temp fluctuates it drops below the min value and would get cold extrusion problems.

When I researched this it was suggested that the low value in the marlin firmware of 170DegC is more for ABS cold extrusion protection, not PLA, I've dropped mine down to 155DegC and all good.

Stephen...
Stephen...

Felix 2.0 -> Felix 3.0 dual
Simplify3D Slicer, Kisslicer
Have you added your Felix to the Map? http://goo.gl/maps/HajnZ

http://blog.strobotics.com.au

Genaforge
Posts: 8
Joined: Thu Aug 29, 2013 6:20 am

Post by Genaforge »

Thanks for the informative replies. I've been aware of the extruder ooze when hot and not extruding, but didn't connect the dots between this and dual extruders. I've seen other 3D printers with dual (and triple) print heads, and somehow assumed it wasn't a problem. Now I'm left wondering how they handle the issue.

Two of us managed to put the Felix 2 together without any issues. Modding the thing isn't really an issue, but working with the firmware and adjusting the printer software (as commented above) is what's making me hesitant. Might be better off getting a proper dual head printer and using the Felix for other non-support prints.

I was partly hoping that Felix had something in the design phase; whether a Felix 3, or a Felix 2 mod, I don't much care.

Still, I'm grateful for the feedback you guys have given. Has helped me make a better choice on what to do next.

superhornet59
Posts: 60
Joined: Wed Apr 03, 2013 1:58 am

Post by superhornet59 »

The only closed-source reliable dual-extrusion machines I know of are very very expensive, and you generally have to use that company's filament only. Seeing as you already have a Felix, just keep an eye on the forum, I know a couple of members are trying out dual extrusion now and they may come up with some great stuff. For one thing, I believe keeping the upper part of the hot end cool is very important. Do you have the newest version, with the finned hot end? I also removed the jumper on the board which limits the fans to 5v, so now they are running at 12. My 'support material' hot end is still the old one (no fins), so I think when I replace it I may see better results regarding oozing.

Otherwise, the physics in our machine is the same as the expensive FDM machines, so we just need to uncover their secret techniques (or arrive at them on our own) and we'll be good.

Don't worry about modding firmware, it's actually not scary at all. Download the Felix 2.0 firmware, and the Arduino IDE, and open up the file "Marilin.ino" and just look through it... everything is labelled and you'll see it's not all that bad :)

As for an 'official' solution, try emailing Guillaume, he'd know best.

Genaforge
Posts: 8
Joined: Thu Aug 29, 2013 6:20 am

Post by Genaforge »

Sounds promising. Hopefully it's just a matter of time. We'll likely end up with several Felix printers, which will give us a bit more confidence with working on one to mod it. But in saying that, I'm not afraid of spending $8,000+ or a decent dual head printer.

The Felix for us was a trial run into the industry. The quality it produced was very encouraging, and it's made purchasing more a worthwhile option. But how many more will depend on whether this dual head / support material issue gets resolved.

Thanks again for the feedback and support. Very nice to see that people here know what they're doing and are willing to help.

Post Reply