Wednesday 19 October 2011

Made in (insert country here) – British Prusa Mendel

Hello everyone,

here is a progress update on my British Prusa Mendel build - (It's almost finished)
And just to get the chronology correct - This is the 1st son (Daughter?) of 'Mendel Bling' (Bling also has 12 other children in the big wide world) - Bling was the first offspring of 'Bath Mendel' - confused? - good, carry on -

Inspired and encouraged by comments and feedback on my Mendel Bling build and the wonderful colourful Faberdashery plastic that is also manufactured right here in the UK, I have designed and printed a British themed LM8UU Prusa Mendel.

The aim and purpose of this exercise is to promote local design and manufacture of everything and anything.
Wherever you are in the world !

I hope you like how it turned out...

One thing to note is the X carriage size of 450mm wide instead of the normal 406mm, this allows more movement for the Extruder - Allowing a dual extruder set-up to print over the entire build surface.

The X Carriage is of the 4 Linear bearing design - also allowing for future upgrades.

It's printed with Fire Truck RED, Lapis BLUE and White PLA from Faberdashery, the Extruder body and X carriage are printed with Natural ABS.

I wanted to try a few new different techniques in this design for getting interesting looking prints, the first was a double sided colour print on both the top and bottom, after some thought, it made sense to print the top as normal, and print out a second section that could be bonded onto the underside.

I used Sketchup to get the design and colour sequence correct for the layer selective colour printing.
So this is my plate of frame Vertex parts with the British flag as a layer selective colour section, in the real print I also added some colour stripes to the vertex body (See below).

And they came out quite well I think.

Here is a video of the printing progress If you view it on Youtube Here it's in Hi-Def resolution or you can watch it below.

(It's quite long, so skip bits if you wish, but please take a look at the end results)

Then I needed the other side set of flags to bond onto the vertex, again done in Sketchup and plated up as a single print job.

The Square flags are for another experimental technique, intended to be hot-wrapped around the Z mounts to give horizontal colouring, I need to experiment more with this process.

And spot the obvious mistake, I had a different layer sequences in the Square flags and the Vertex flags when I designed them, so the white and blue colours are accidently reversed on the Square flags, Doh! 

The flag is only 2.4mm thick so it was bonded with heat onto the six Vertex pieces.

X carriage motor end with LM8UU linear bearings on the Z Axis. 

All other parts are printed in a Blue, White, Red, White, Blue sequence.

Again a short video on the other printed parts - Check it out in Hi-def on Youtube Here of view below -

I also wanted an identification plate and some status indicators for the machine.
Designed in Sketchup, it's going to cover almost all my build area.

This was the largest single object I have printed so far, shortly after this photo I did start to wonder if it would actually come off of the build platform at the end of the print?

The print is only 17 layers high, 4 White layers all solid, 4 Blue, 6 Red and 3 Green.

Printed at 80mm/sec the total print time was just over 90minutes.

It popped off the bed when cold, not a single bit of warp.

The Indicators plate was done in a similar way.

Plate building on Youtube here - and below - 

All of my machine now have a T-slot frame around them, this allows me to fix all the electronics, power supply and cables onto and into the frame, it also doubles as an essential filament holder.

I printed out a set of 8MM Rod/Bar clamps from Antona and also the very neat 8mm rod holder from Kludgineer here - Well recommended if you are doing a similar thing.

The Electronics are housed in the same style enclosure I have used before, with cooling fan. 
An ATX Power supply is fitted to the T-slot frame to supply power for the electronics and heated bed. 

Last video of the completed build, just some wiring to do and it will be running !

I had many other suggestions on how to make it look 'British' including a great one from Bob "hang a teabag on it!"
Short of printing a bowler hat and walking cane I still think it needs a little more eccentricity and quirkiness, but I'm sure it will evolve over time to have some of those quintessential British qualities.

It's not fully built and completed yet, but I hope to get it fully running for the next local Reprap meet-up.

I started with 75M of 3mm Plastic filament 25M of each Red, White and Blue and only printed one complete set of parts. At the end of this print run I had less than 40cm of each, which was just enough for a Starfish.

Thanks again for reading and I hope you decide to source something from a local supplier today, happy building.



  1. Rich,

    Once again, quite impressive.


  2. Thanks Matt, This one was a lot of fun to do.

  3. Rich,
    Great work! A question or two for you...
    What kind of print speeds are you now comfortable printing at whith this type of set-up taking quality vs print time into consideration?
    How do you calculate how much of each colour to cut and join for a given multi-colour print? (if covered elsewhere simply point me to it).
    Tks for sharing.

  4. I am really impressed!
    You have really taken the Prusa to a higher level, technically and visually!
    Can you explain to me how to connect the indicator leds for the heaters and fan to the electronics?

  5. @Maakit - Thanks.
    The indicator led's are just normal LED's with a 1.2K resistor to current limit (just put it in-line with one of the LED leads. Then connect the Anode (+) of the LED to +12V anywhere on the board (Ramps or your electronics power supply) and the Cathode (-) of the LED to the Output of the thing you want to indicate (Heater / fan) when the output turns ON so will the LED.
    If you run into any problems, just let me know.

    I really like your Stanford Bunny print BTW. He looks hollow on the bottom? or is it two different colour yellow's?

  6. @#6 Hi Ivor - I'm happy upto 180mm/sec print speed but that starts to make most things start to look very faceted especially curves and round objects, that's a firmware issue with acceleration. I'm yet to try Marlin but what I can see it helps with the very high-speed prints.

    I have settled on print speeds much lower for most things - so normally now I do everything at 80mm/sec - even hollow objects as long as you have a fan on them while they are being built.

    Then I still do some things at 60mm/sec and 40mm/sec if I need more time to experiment or adjust things etc.

    I just completed a really complex print (the most complex one I have ever done) and that was 10.5 Hours even at 80mm/sec print speed and it was only 8% filled! With some prints things like retraction times /speeds on the extruder actually make a big difference to both the quality and also print time.

    Also when you get up past 120mm/sec Sprinter can't really keep up with what Skeinforge says in the report summary - so an estimated print time of 1 hour may actually take 1.5 hours if it's really complex with lots of start stop moves.
    Where as at 80mm/sec what skienforge estimates as the print time is usually what it will actually take to complete.

    Speed V quality at under 100mm/sec is not a bit problem - but you still need to do the outer perimeter slower - I usually aim at around 40mm/sec for the perimeter.

  7. The other question - I strip out the moves in Gcode per layer change, then put this into a spreadsheet and do some manual sorting and calculations to give me a length of extrusion, this can then give you length of feedstock to use,depending on nozzle size and feedstock. it's not a great method and sometimes needs a bit of tweaking to get a good print, but usually I only print things once so how it turns out first is how it is.
    I'm not a programmer unfortunately so I still don't have a nice way to do this, it's on my list of things to finish off with some community help at some point, but as usual other experiments and investigations get in the way of refining past work.

  8. Thanks, my Stanford bunny is printed with two different colors of yellow PLA with 10% infill.
    I did have some good results with combining 0% infill GCode and 100% infill GCode though. With yoda and the devils head this gives me a nice top of the print, with the holeprint at 0% infill some gaps form at the top.

  9. Hi Rich,
    Tks for the feedback regarding speed vs quality. It gives me some benchmark on what's reasonable and achieveable.
    The big question remains - what on earth were you printing that took 10hrs at 80mm/sec and 8% infil? :) Was it that slug you posted recently to Thingiverse? :)
    Tks again for sharing you experiences. It's invaluable.

  10. No, the slug was less than 80 mins, and he was completely hollow -

    I'm not sure any one photo will do it justice. I will post it up shortly but I can say I'm just printing the other half of it and that's going to take just under 8 hours at 55mm/sec and 8% infill.
    The Gcode for part 1 was 36MB and part 2 is 27MB, that's a LOT of machine moves.


  11. @ maakit - It would be really nice to be able to get Skeinforge to selectively print different layers with 0% and >>> evermore infill, it's a pain to splice Gcode, but it can give nice results.
    I did some similar tests with low% of infill on the tummy of a dragon recently, take a look here -

  12. Awesome job! :)
    Always nice to read your very precise written and infromative posts, been following this now for a while. Keep up good work!

  13. Great work...
    Im just curious on how you managed to print in 3 different colors in the same object .
    Also how the printer recognised the colors in your design files ?

    Really really excited with this one!!!

  14. Hi flokos,
    This process is done by joining lengths of filament together - see

    You can print almost any colour and any number of colours in a model using this method, with tiny sections joined you can even blend colours and also mix them across single layers.

    You can also swap-out filament colours during the print if you don't fancy joining filaments, but that's a little more hassle and problematic.

    The colours in the Sketchup image do not translate via the STL file, so the printer just sees it as a single object, the colouring is all down to using the change of layer height to build up colours at different sections on the model as can be seen in the video's.

    Soon - Multiple extruders will also help us get to full colour prints and also having colour data actually embedded in the model and Gcode files. - I hope a RepRap does this first... we just need the tool-chains.

  15. I actually have an idea on the coloring thing.
    I admit that I cant wait to assemble my makerbot and start experimenting though I have to wait till the summer (It is my last year in school and studying its kind of time consuming).So about the idea I mentioned above .I have seen people trying to color the fillament with markers and I thought that is great idea but not very accurate .I have also seen that cartridges on regular printers have some kind of pcb on them(that will probably be the way they connect to the printer).So I thought that if I could make a design that cartridges can be placed in then I could control everything ,for example how much color the cartridge has and how much to spoil on the fillament .And if I could make an add-on for replicator-g in order understand the designs colors then the problem will be solved .

  16. Colouring with a sharpie works, I have done it on clear PLA and you end up with a part that looks like it has been coloured with a sharpie! not very deep colour and for all the effort you may as well draw on it after printing - that actually looks better and is also much better than painting.
    The cartridge idea may work, but ink colour pigments are different to the ones used in plastic, so it will never look all that deep in colour.


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