A Bowden extruder, an E3D clone hotend, and cooling fans

I have been working on the Bowden extruder for the Delta Pi these days. To test the extruder and the hotend before actually installing them in the Delta Pi, I decided to finish assembling my heavily customized Prusa i3 Twelvepro and to design a Prusa i3 X-carriage mount for the Bowden hotend, complete with both an E3D fan duct and a layer fan system. This is the result of my design effort.

The setup as it stood untested, a couple of days ago. The layer fan was not quite reaching the correct position and angle, so I designed some new parts.

You can see the new Z-shaped arm. The fan duct is also new, this is version V3.

Here it is positioned so that the airflow reaches very exactly the extruded material under the tip of the nozzle

Top view of the print head, ready for the first print tests. The left fan is to cool the E3D aluminum body by providing a proper airflow over the fins; it must be connected to the 12V supply and is on whenever the printer is powered. The right fan is the layer fan, controlled by the PWM D9 output on the RAMPS.

And then the long-awaited first print!

This is a calibration object from Thingiverse. As can be observed, retraction was not properly adjusted yet, but apart from that the print came out surprisingly good, all things considered.

These are the parts required for assembling the Bowden extruder (which is a simple remix of Dominik Scholz's design on Thingiverse): basically two relatively small printed parts (the extruder body and the idler), a 608ZZ bearing held in place by a M5 screw and washer, a MK8 gear, a NEMA 17 stepper with good torque (40Ncm), a push-fit Bowden connector, a small spring, and some M3 screws, nut and washers.

Calibration, sweet calibration

Another video, this one about calibration:

Upgrades!

LED lighting! A new Z-probe! And more!

A better video

I don't have a Bowden extruder and print head with a hotend to show for yet, but at least I made a better quality video of the Delta Steel plotting/printing the Kossel Mini effector. Here it is:

The noise you can hear (apart from the steppers grinding away) is the pen itself shaking! Printing speed is 60mm/s for perimeters and infills and 100mm/s for travels.

First "print"

I have seen this done with a Prusa i3 and I thought I would give it a try with my Delta Steel prototype, until I have my Bowden extruder and hotend ready: use the printer as a plotter by attaching a pen to the carriage/effector. This is quite easy to do with the Kossel Mini effector design that I am using.

The next step was to go through the basic 4-point calibration procedure and adjust the endstop screws on the X, Y and Z carriages, as well as roughly leveling the heatbed. This took a lot longer than I thought it would, I guess because of my inexperience in dealing with linear delta printers. I learned a lot in the process, though, and I'll write about it later in a separate blog post.

After I had reached the point where I could barely insert a small piece of paper under the tip of the pen at the four different points in the calibration procedure, I was ready to test the printer as a plotter, so I sent it the very same Cura-generated and edited G-code that I had used in the previous "in the air" print video. It worked better than I expected:

So this is my first "print" and on the whole, I am quite happy with it!

That, by the way, is the effector that I am using on the Delta Steel itself, as you can see in the first picture above. This is exactly what a RepRap 3D printer should be able to do: print its own parts!

A few details sorted out

I had left a few details to sort out until I got more or less to this point, the purpose of this post is to go over these details, well... in more detail!

It's alive!

YouTube video coming soon!

In the video the Delta Steel is "printing" the G-code for its own Kossel Mini effector, but to get the Marlin firmware to start printing I had to comment out the temperature setting commands at the top of the G-code file I had generated with Cura. Here is a screenshot of the editor showing my edit:

Note that the printer is printing "in the air", way above the heated bed, because I have not set the correct Z height parameter yet in the Configuration.h file in Marlin. I'll adjust this parameter once I have installed the hotend in the effector.