Cheap RepRap Cable Guide

I’ve come up with a cheap and easy cable guide hack for use with RepRap 3D printers. The trick is to wrap the electrical wires in sleeving along with a piece of piano wire. I’ve used 0.8 mm piano wire, but anything between 0.5 mm and 1 mm will likely work fine.

The photo below shows a close-up of the wrapped electrical wires and piano wire powering the heated bed of my RepRap Prusa Mendel i2.

As you can see in the following photo, the piano wire keeps the cable arranged in a nice arc at all times, thus making sure it will never touch the heated bed or get in the way of its movement.

The top end of the cable harness is secured to the threaded rod using cable ties. The end near the heated bed is secured using a self adhesive cable tie mount as shown below.

RepRap Thermal Imaging

Ever since I wired up the heated build plate and extruder hot end to my RepRap, I’ve wanted to verify the thermal temperatures and heat distribution. For starters, I have used a cheap infrared thermometer, which is fine for verifying the temperatures, but not very well suited for verifying heat distribution.

Last week, I got my hands on a Fluke Ti25 Thermal Imager – perfect for getting a good look at the heat distribution!

My heat bed is a sandwich with Josef Prusa’s PCB heat bed on the bottom and a 4 mm glass plate covered in kapton on the top. My thermistor for sensing the temperature of the heat bed is taped to the bottom side of the PCB. As shown by the image below, the glass plate does a good job of evening out the heat from the PCB.

Prusa PCB Heat Bed

However, I was surprised to see how much the temperature of the kapton-covered glass surface lacks behind the temperature on the bottom side of the PCB (which, incidentally, is where my thermistor is placed). On the image above, the top is 85.8 C while the heat reflection by the bottom alu plate reads 92.8 C – nearly the same temperature sensed by my thermistor at that time. The top glass surface catches up to the bottom temperure eventually, but it takes as long as 5 minutes for it to become stable. This explains why some of my prints have had a hard time sticking to the heated build plate – it simply wasn’t warm enough, when I started the print.

J-Head MkII Nozzle

The image above is of my extruders hot end, a 0.5 mm J-head MkII (or should that be 0.4572 mm?). Again, I was quite surprised by the thermal imaging – the heater resistor goes as high as 302.3 C when heating the nozzle to 200 C! That’s quite a lot more than I would have expected – good thing I’ve used cement that can withstand 1100 C for gluing in the thermistor and resistor.


Finally, the image above is of my RAMPS 1.4, which has small EnzoTech MOS-C1 heatsinks mounted on all the Allegro A4988 stepper drivers. Notice how cool the heatsinks are – and notice how hot the PCB gets. Good thing those heatsinks were cheap…

My RepRap Prusa – Iteration 2

In August last year, I was swept away by the idea of the Open Source/Open Hardware Replicating Rapid Prototyper, or RepRap for short. The RepRap project is a community effort to create a 3D printer capable of self-replication.

I first encountered the idea behind the RepRap at our friends at Labitat and shortly thereafter began self-sourcing the materials needed to build a Prusa Mendel v1, which – at that time – was state of the art within the RepRap community.

During the Fall and Winter, I managed to complete my Prusa Mendel build, and shortly before Christmas I had my first working 3D print!

For more photos of some of the items, I have printed on this machine, visit my Thingiverse page…

I have since then begun updating my RepRap to the Prusa Mendel Iteration 2 design, based on linear LM8UU bearings. The conversion is 66% done (X- and Y-axis are done, Z-axis still using printed PLA-bushings).

Stay tuned for posts with the small hints and tips, I have picked up while building this amazing machine!