Saturday, February 25, 2012


RepRap Community Masterclass in Bath, UK

I wouldn't normally use this blog to trail my company's activities, but this seems an appropriate exception:

RepRapPro Ltd is running a RepRap Community Masterclass at Bath University - the home of RepRap - between 13-15 April 2012.  As this is for the RepRap Community we have tried to keep expenses as low as possible.  The cost is £688 including a RepRap kit for each attendant together with full tuition, accommodation and all meals.

Details and booking are here.

Labels: ,

Tuesday, February 21, 2012


Print any colour you like...

...with added stripes.

Some time ago I started to build a mixer nozzle for RepRap that would take four coloured filaments and combine them out of a single nozzle.

This is what I made.  Four 1.75mm filaments are led in by four Bowden tubes.  The filaments can be driven at any relative speeds to achieve any proportions of mixing.

Now Myles Corbett has taken that idea and made it work:

This is his adapted Mendel.  It has two RepRapPro extruder drives at the top leading by the Bowden tubes to the nozzle:

At the moment the drives are being controlled by the same stepper electronics, so they are both running at the same speed.  But we will add an extra electronics so they can be driven in any proportions soon.  He has blocked off two of the four inputs so we are just mixing black and white.

Here is the very first print:

As you can see, it is stripy rather than grey.  We need to increase the mixing in the nozzle.  Of course, molten polymer has a very high viscosity, so the Reynold's number of the flow in the nozzle is very low (and hence highly reversible).  This means poor mixing, hence stripes.  So the next step is to add a labyrinth in the nozzle to force more mixing.

In some ways, more interesting than mixing colours is to mix polymers with different characteristics, such as a hard and an elastic PLA.  Then you could make parts that are rigid in some places and flexible in others with any gradation you like in between.

UAV with warping wings, anyone?

... several hours pass...

Here's the second print.  The horizontal stripes are a bit of serendipity: as I said above, both black and white filaments are being driven synchronously for the moment while we sort out extra stepper drivers so we can rotate them independently; but Myles left the grip-screws on the white filament drive lose, so white was being driven intermittently.  Thus we have various ratios of mix here.

As the filament comes out of the nozzle in two stripes - one black and one white - because of the poor mixing, one side of the object tends to end up blackish, and the other side whiteish.  We might be able to do something clever with this effect.  See Janus particles, for example.

Friday, February 10, 2012


Make More RepRaps...

Interestingly, Cubify has belatedly added a free download section.  I haven't checked the licence conditions, but - unless they are silly - I think that it would be a good idea to upload as many RepRap designs as possible for printing on 3D Systems printers...

Tuesday, February 07, 2012


ImplicitCAD 0.0.1

For the last few months, I've been working on a new CAD program, ImplicitCAD. I'm now pleased to announce the release of ImplicitCAD 0.0.1.

One really awesome feature ImplicitCAD provides is rounded... well, everything. For example, look at the following extopenscad code (we provide a parser for an extended version of openscad, in addition to a Haskell API). The r=x is the rounding!
linear_extrude (40, r=8)
union (r=5) {
translate ([-10,-10]) square (30, r=3);
translate ([ 10, 10]) square (30, r=3);

ImplicitCAD also provides higher order modules, as this variable twist extrusion code demonstrates (note how twist is a function):

linear_extrude (height = 40, center=true, twist(h) = 35*cos(h*2*pi/60)) {
union ( r = 8) {
circle (10);
translate ([22,0]) circle (10);
translate ([0,22]) circle (10);
translate ([-22,0]) circle (10);
translate ([0,-22]) circle (10);

We also provide proper programmatic functionality, like variable assignment in loops, that was missing in OpenSCAD.

Check out ImplicitCAD on GitHub and the release notes for 0.0.1.

Important Aside: The third Toronto RepRap User Group meetup is happening on Feb. 27th at hacklab! If you're in Toronto/the GTA/Southern Ontario, please join us!

Labels: , ,

This page is powered by Blogger. Isn't yours?

Subscribe to
Posts [Atom]