foehnsturm
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Everything posted by foehnsturm
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After some not so pleasant experience with syringe-based paste extruding recently, I started thinking about a different way to do it. I'm not heading for food printing but more for a way to combine FFF-parts with stuff like silicone. So if anyone already has some experience with paste, please feel free to share. My main concerns with the standard approach are the following: Pressure - Syringes, especially with an attached tube produce huge back-pressure with highly viscous material Power - Therefore a highly geared powerful driving mechanism is required Control - Highly viscous material under high pressure seems to be very hard to control (think of those silicone cartriges) Ease of use - Prming /pushing the stuff through a bowden type tube can take ages Waste - With materials like silicone the entire drive-train is impossible to clean, you'll lierally throw away everything each time I'd like to have a solution to extrude a reasonable amount of highly viscous material (like 10-20 ml) with a special head for the tool changer. Even though they're way too big you can google "zombie blood bag" to get an idea of what I'm thinking about -
It's still happening
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BTW, currently doing another run with different settings. Now it looks like I'm on the right path. A big nozzle and thicker layers for PVA seem to do the trick. 0.1 mm layer and 0.4 nozzle for PLA & 0.2 mm layer and 0.8 nozzle for PVA almost works like charm. Way faster and consistent PVA depositing, less tool changes, less overall printing time.
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Just the old-fashioned style. Lots of warm water and a brush. As far as I know, an ultrasonic cleaning bath works best. Hopefully UM owns one
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Look what I found in the printer this morning. However, I'm not sure if I'll ever manage to totally dissolve the PVA ... But slicer generated support just doesn't work reliable with complex geometries where lots of tiny PVA support structures would start on top of PLA surfaces. If it'll ever see the light of day it should look like this.
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Servus @philipyeah, You might want to have a look at this topic https://ultimaker.com/en/community/20293-any-experiences-with-dual-extrusion-and-pva In short, PVA is somehow a pain to print with. New variants that recently emerged like Scaffold are easier to handle (but still demanding). If I run into printbed adhesion issues adding a thin coat of the well-known wood glue water mix usually helps. And yes, I'm witnessing extrusion inconsistencies every now and then as well (now idea why). However not a complete stop. I assume, the speed being too high, therefore too much back pressure and the feeder grinding the (quite soft) PVA filament.
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Any experiences with dual extrusion and PVA?
foehnsturm replied to foehnsturm's topic in Materials & profiles
Unfortunately I don't have a complete setting list at hand. It was too much experimenting (and continuous documentation is not one of my strenghts ...) As far as I can remember: 0.15 mm layer, PVA speed (20-30 mm/s), no fan, PVA (Scaffold) temp on the upper end 215°C to improve adhesion to PLA, support z-distance 0.0. I used join distance and horizontal expanson to connect support islands to one large structure if possible. And please note, I gave up on standard PVA after a few hours. Scaffold still is not that easy to print but considerably easier than regular PVA. If I find the time I'll do another test within the next two weeks. -
Any experiences with dual extrusion and PVA?
foehnsturm replied to foehnsturm's topic in Materials & profiles
Well, I'm on holidays so apologies for the brief reply. It's (grey) Scaffold, the E3D PVA (EDIT: PVA not PLA) variant. Yes it oozes, but as I'm using the tool changer that's no problem. Temp and retract are set via firmware. More next week .... -
I've been testing an upgrade which closes the gap between the knurled wheel and the bowden entry completley to avoid any filament tangling. In doing so, I noticed that Recreus Filaflex (which is quite soft) will start to slip at some point, even with the highest possible idler pressure. You can even pull it out by hand with some - but not excessive - force. It looks like the filament squeezes so much that there's not enough contact pressure. Anyone noticed the same thing?
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Hm, how can I open the logs when the user interface already became unresponsive and I've to kill the process?
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Hi @Jaxxson, ich habe mir die Datei kurz angeschaut. Das Teil besteht aus joined surfaces. Quasi wie ein gefalteter Würfel aus Papier bei dem eine Seite fehlt. Slicer brauchen aber geschlossene Volumenkörper, um zuverlässig zu arbeiten.
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Didn't use an overlap, works quite well without.
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Haha, you already know how to do it Well seriously I'm already waiting for a decision to be made ... On the other hand I don't want to spoil the Ulticreator project as I haven't seen any detailed prints. It has pros and cons for sure, but fact is: it's a complete kit and it seems to be available. If I will offer/publish my solution on my own I most likely won't be able to offer something that complete in the near future.
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Just to illustrate how fast (or slow) this has been printed for comparison. Not showing the tool change, but time for this only depends on the re-heating time, movements are just a few seconds.
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@shurik, You're greatly welcome Btw, you could do this as well.
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A first test piece to explore the possibilities and limits of the current setup. The tiny columns are 0.8 mm wide. Sliced with new Cura, 0.4 nozzle, no priming towers or wipe shield used, no z-hop, no post-processing / photoshopping. The slight blue shadows on the inside are caused by the blue nozzle catching white parts while traveling -> z-offset is off by some 0.05 mm. The more visible ones are either the z seam or an erratic movement generated by Cura on each extruder startup.
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Yes and no. Of course you want to have test pieces for special application areas. These will bring up a lot of additional issues caused by the varying filament properties. This piece is intended as kind of an entry test which mostly focuses on the dual extrusion hardware. In other words, how clean (the result) and smooth (user friendliness) can a dual extrusion setup perform if part geometry is the only challenge.
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There are already quite a few test pieces available. But I'd like to have something challenging which doesn't take ages to print. So I started this one. It's printing right now and "unfortunately" works too well. Any ideas to make it more demanding? There is still some room on the upper part. Feature size is already down to 0.8 x 0.8 mm. The only requirement is it has to work with new Cura and 0.4 nozzles.
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While the tree frog is a good test to check x/y/z offset and to see if the idling nozzle is smearing, color distribution is almost 50/50 and "color islands" are not that small. I found the dual color benchy a bigger challenge. There are longer idling times for one color and the door frames are really flimsy.
