Fluid extruder for 3D printer

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!

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 :)

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.

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...

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!