Tag Archives: Wade’s Geared Extruder

Wiring the electronics, testing the motors and heating up the extruder

With the mechanical part of the RepRap largely completed, the next step was to wire up the electronics.

I had underestimated the amount of wiring required for the printer, so I braided the wire before wrapping it around the printer’s frame in an attempt to keep it as neat as possible. The wires have to be kept away from many moving parts, hot points, etc. Keeping them isolated should also minimise any cross-talk noise between the large lengths of cable. However, as the printer is going to have to be disassembled, packed and moved in the near future, I haven’t fixed the wires up with cable-ties yet.

The Danguinololu successfully communicated motor and temperature signals so everything seems in order, except for the extruder motor which is behaving in an irrational manner and only intermittently accepting movement signals in one direction. Leaving this problem aside, I moved on to testing the heated extruder tip.

The heated tip temperature was incremented in steps up to 210 °C, while manually feeding some PLA plastic into the extruder. The plastic flows out of the tip effortlessly at around 200 °C, so things are looking positive for the extruder assembly! The remaining step is to calibrate a working motor to extrude plastic at the right speed for printing.

: Testing the electronics for the first time. The birdsnest of wires needs sorting out before the axes can be moved to their full range!

: A close-up of the Danguinololu in operation.

: The wires were tidied up by braiding, before wrapping them around the printer frame to keep them out of the way of moving parts.

: Labelling the wires helps greatly during the inevitable troubleshooting stage.

: Another close-up of the board and LED light show!

: The push-connectors are fairly hard to press down on, but guarantee a good contact and are much better than screw-based connectors.

: First test of heating the extruder. The plastic flowed out the tip without pressure and with a good flow at around 200 °C.

: Close-up of the working extruder. The plastic solidifies almost instantly once deposited.

: Another close-up of the working extruder.

: Yet another close-up of the working extruder. The solder which reinforces the copper wire did not show signs of melting from the high temperatures, as it is futher away from the tip, with a large area exposed to the air.

: Top view of the working extruder, with plastic being manually fed through.

As I’m experiencing some issues with one of the motors, unfortunately the long-awaited calibration and test-printing stage has to wait!

Extruder continued and start of RepRap frame

Leave a reply

Continuing from the first post, I made some progress on the extruder while also starting construction on the RepRap frame.

For the extruder idler block, a piece of threaded rod was cut down to size. Based on instructions this should have been smooth rod, but since it simply sits through a bearing there isn’t any issue of friction.

Fitting two hex nuts to the top of the extruder where the idler is attached required some extensive filing which ended up in the plastic splitting at the weakest points and a small part of the plastic breaking off, but the issue was easily fixed with some two-part epoxy. Once the epoxy has set and I get the required M3 bolts, the extruder assembly can be completed.

Extruder idler block, 608 bearing and a threaded bolt piece sawed to the right size (2 cm).

Fitting the M3 nuts into the top of the extruder (drill bits used as rough guides).

Repairs on one of the bolt holes using epoxy glue..

Switching to the frame construction for a change of scenery, the first task is to put together the two “frame vertex triangle”, i.e. the triangular frames which make up two opposing sides of the printer.

The first frame vertex triangle

Both frame vertex triangles completed.

Next, the frame starts taking shape by connecting the two vertex triangles. A few more threaded rods attached and it starts looking like an actual printer!

The frame taking shape

Close-up of one side.

Close-up of side with bracket where y-axis motor will be mounted.

Top view of the frame, with z-motor mounts on either side.

Basic frame connected, before calibrating and tightening.

The frame remains untightened for now, as I need to replace the large washers (M8, 24 mm diam.) on either side of the 608 bearings with even larger ones (M8, 30 mm diam.).

Next step will be to calibrate the frame, start attaching the remianing rods and complete the extruder. Coming up soon!

Prusa Mendel building begins

1 Reply

This is the first post in a series which will cover the build process of a Prusa Mendel 3D printer.

The Prusa Mendel is a fully open-source 3D printer. Its main features are its low cost relative to other 3D printers out there right now, its many interchangeable modules, as well as the fact that one printer can print the required plastic parts for subsequent printers. This last point is where I begin my building work log …

I’ll start off with the plastic parts, which have all been printed using our first printer.

RepRap #1 – The mother

RepRap #2 – The soon-to-be son(?)

The first RepRap has given birth to the (mostly) green parts you see above. Next step, gather all the pieces (easier said than done)!

A collection of almost all of the required RepRap parts and tools.

While I was waiting for the final pieces to be delivered (mainly the long treaded rods and M3 bolts) I decided to start off with the hot end and the extruder.

The hot end main components are a PTFE thermal barrier which attaches to the extruder, the brass barrel which acts as the output nozzle for the melted plastic, the nichrome wire which will provide the heating, and a temperature sensor.

Hot end parts.

Some good instructions for the hot end can be found here (even thought the page is deprecated, it has good instructions on how to construct the thermal barrier and brass barrel, as well as how to wire the up the nichrome wire and temp. sensor). The hot end took a few tries before I was happy with the result. A useful modification we have added is the hex bolt and brass washer with two drilled holes that you can see in the pictures. I’ll later show how these provide a good resistive force which holds the brass barrel firmly into place inside the thermal barrier. From experience we found that the force from the incoming melting plastic tends to push the brass barrel out of the soft PTFE barrier, so this mod solves the problem!

A drawing of the extruder tip assembly.

The assembled hot end.

Another view of the assembled hot end.

The images above show the final assembly (the black insulating tape was replaced with some more high-temp. resistive Kapton tape as it would melt from the high temperatures generated by the nichrome wire). Getting the nichrome wire and temperature sensor to fit around the large washer resulted in an extruder tip which might not look refined, but should get the job done!

The extruder model is an upgraded version of the original Wade’s Geared Extruder (not sure of the exact iteration number, but it’s the the one with the hinged extruder idler block and spoked large gear, but without the filament guide of herringbone gear).

Beginning of extruder assembly

Green Sugru.

Green Sugru opened.

Aligning hobbed bolt with 608 bearings and filament guiding hole.

Large extruder gear with Sugru used to fill in imperfections and hold bolt in place.

Hobbed bolt and large gear in place and correctly aligned.

The hex nut placement on the large gear was slightly out of place. This was promptly fixed by filing down until the bolt fit. Luckily I had some Sugru lying around (and in the right colour!) which worked perfectly in holding the bolt in the correct place with the gear aligned straight. It also helped to keep one of the 608 bearings firmly in place.

This concludes the first post on the build process. Stay tuned!