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Fluid extruder for 3D printer

High capacity fluid extruder.

nfknfk
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About 6 months ago, we got a challenge from an artist interested in printing with wax.
He want to print sculptures out of wax and with sizes of about 1 cubic meter!
Creating a big 3D printer wasn't a big deal (i'll detail that on another project), the challenge was printing with wax (bees wax!) continually.
Reprap's paste extruders where not up to the task so we start designing a new kind of fluid extruder from scratch.
This is a work in progres, i'll start documenting here our progress (and failures).

- Keys to success:

 * Continuous printing (no refilling allowed)

 * Fluid flow control

 * Fluid temperature control

 * Capable of delivering 500g/hour of extruded wax

- Testing a spur gears pump

This is our second attempt at extruding.

POC here: Naked spur gear pump test.

TODO: 

 * Add heating element

 * Add thermistor

 * Add stepper and 2:1 reduction (need to check this)

 * Wire to RAMPS

 * Add extruder tip.

    - need to check tip size. Current conduct size is 3mm. Will overflow printing. Start checking with 0.5mm tips and enlarge to fit :)

 * We would need some kind of cooling for the print, wax flows a lot since when liquid has a low density and it will make a mess if not cooled fast.

  • 2 × 14mm all metal Spur gears. 1st attempt we used nylon gears. immediate failure....they melted.
  • 1 × Pump block. Made with lathe. Will publish plans if asked. You can check on google for images to have an idea but you will need to turn it to your gear's size
  • 1 × Misc plumbing. (In and out pipes, depend on pump block and flow needs)

  • Finally some progress to show

    nfk08/14/2014 at 16:38 0 comments

    After a few weeks of calibration, it is time to show some pictures :)

    We made a cooling rig (in green) to help solidifying the wax.

    Previous prints where fine only in small sizes buy our goal is printing big objects with it so we have to deal with the object temperature.

    One of the biggest disadvantages of using wax as print material is the low melting point of 67C.

    Ambient temperature does not help in cooling the print fast enough between layers so we had to add a cooling rig.

    Once we added the rig we found another issue...the was is coming out almost liquid and blowing air will throw the wax away from the print. 

    Keeping the coolers below 50% power help controlling that and provide a better cooling.

    This improved the print A LOT, but proved insufficient on big and solid prints.

    The example below is 10mm high with 100% infill on every layer.

    Some perimeters failed to solidify completely and where dropping from the object like seen on the left.

    We are adding a peltier element to blow cold air and help cooling the wax.

    Nice thing about printing with wax is that all mistakes can be remelted and reused :)

    Here is a short video showing the issues we have when printing tall objects.

    You'll see the top layer is not solid enough and we had to constantly remove molten material to keep going.

    The biggest print we where able to complete was 250mm x 200mm x 75mm. 

    More news once we add the peltier to the cooling rig!

  • Quick update

    nfk07/28/2014 at 17:38 0 comments

    We spend the last few weeks tweaking the slicer.

    We found the layer height changes slightly while the wax cools down and you start noticing that after a while of printing (it's noticeable after layer 25 or so).

    Any slicing change need about 3 hours of printing to see the result.

    I'll upload a few pictures and videos if later, looks promising :)

  • Extruder mounted, begining calibration (and fixes!)

    nfk05/28/2014 at 12:35 0 comments

    After a few issues with the extruder's gears and axes, we are back in busines.

    We mounted the extruder to the printer along with a heated tank and pipe.


    The nozle is too far from the bed and the amount extruded wax per mm is wrong but you can see we where trying to print a calibration rule :)

    Notice the odd angle of the rule. The printer is polar and the extruder's tip was not properly aligned with the bed's center.

    Will fix that today.

    TODO next week:

     - Fix extruder's leaks!!!!!!!! #@#@!#$^%%$^&43$#fg542y%#

    - Z should be lower....

    - Reduce steps per mm on the extruder, way too much wax is being extruded now.

    - Move the thermistor near the tip (now near the pump's gears) to have a better temperature control. Wax is coming out way too hot.

  • Bad week

    nfk05/23/2014 at 11:51 0 comments

    This week we broke a few extruder parts :(

    Nothing unfixable but it's taking some effort to fix (and redesign i believe).

    Lessons learned:

    1- Do not use plastic gears.

    To move the pump, we used a small stepper motor with a 10/1 gear reduction.

    The gears where taken from a printer (same as motor) and where made of nylon.

    During a temperature test, we accidentaly tryed to extrude when the temperature was below melting point and the stepper gear pinion eated the nylon reduction gear.

    We replaced it with a brass (or bronze) gear and pinion.

    2- Clean and degrase all parts if using locktite

    The pump main gear is glued to the main axe using locktite.

    It's not a press fit so i glued it with locktite 640 (quite strong and support high temperature).

    After running the extruder for a few minutes with a smalish (0.5mm) tip, the axe got loose.

    I'll turn a new axe of a size that allow for a press fit, and i'll add some locktite to it just in case...

  • Wax extrusion successful!

    nfk05/19/2014 at 16:28 0 comments

    After finishing the heated tank and hoses, we managed to extrude liquid wax with great control.

    We had to keep the temperature quite high, about 3 degrees over the melting point, else the wax create a plug on the extruder tip when cooling the flow with a cooler.

    Tomorrow we'll mount all the components to the printer to start experimenting.

    I'll take some photos and videos!

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Genny Doss wrote 04/10/2019 at 04:18 point

I have been looking for such post with helpful information. I have faced many issues with my printer which I have tried to fix with https://errorcode0x.com/fixed-epson-printer-in-error-state-issue/ which have really worked.

  Are you sure? yes | no

OneShot Willie wrote 05/17/2014 at 03:31 point
Seems like you could cool the flow just after the deposit, and perhaps achieve a higher resolution...

  Are you sure? yes | no

nfk wrote 05/17/2014 at 18:37 point
I´ll let you know next week! I´m making some sort of heated deposit and heated hoses to transport the wax to the extruder.
I took a short video of it with a stepper attached, pumping engine oil with great flow control. I believe we´r on the right path but wax is a nightmare to work with due to the varying viscosity at different temperatures and the low margin between thick and fluid (about 2 centigrades, 65 being like a hard paste and 67 quite fluid at least for bees wax)

  Are you sure? yes | no

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