Skip to main content

#BuildBrighton - Printing in 3D

I've been pretty dismissive of 3D printers, chiefly because I view them as complex, fiddly, erratic, temperamental and inelegant machines.
If you want a lumpy thimble made very, very... very slowly they are perfect.
If you want anything even moderately useful, then you probably need a machine bigger than you can afford, and it will still be slow...
and probably breakdown...
or print 80% of the thimble then suddenly have a funny turn and stop, or bung up or something.
They are a bit like "classic" cars, where "classic" means poorly designed, 1970's British monstrosity.

However the #BuildBrighton folk organised a 3D group, so  I thought I'd rock up and see if they couldn't dispel my negativity now I actually have a part I need to make  (a collet for the "gun" on my Dalek.)

The #BuildBrighton 3D printer group started with a talk from Alex about OpenSCAD, which is a simple scripting language that allows geometric primitives to be combined (union) or subtracted (difference or intersection).

The OpenSCAD tool provides a swift rendering of the object, and ultimately a union is created of the whole model which is exported.
Because it's a scripting language it means models can be built programmatically, with all the usual loops and logic.

for (i=[10,20,30,40]) {
translate ([i,i*2,i*3])

OpenSCAD can import dxf files, however these are dxf-r12 - which was a CAD standard format for the last version of AutoCAD that ran on DOS, this should allow seamless transport of data/models/shapes... but r12 isn't supported by much outside of Inkscape these days.
OpenSCAD delivers something close to the final STL (Stereo lithogram) object, whereas Google Sketchup requires a deal more work.
Blender provides a GUI alternative to OpenSCAD, but may have a steeper learning curve.
My experience of teaching Vectorworks indicates that moving 3D objects around in space is a pain in the bum, and a few lines of code may be much easier.
Pleasant3D provides  way of checking and editing the final STL file.

There are a huge number of models already built, in a truly Object Oriented way, ready for re-use :

Next step is to dump out the object and chop or SLICE it into layers that the printer can print, a G code file.
Slicing software is pretty printer specific, but a tool like SLIC3R provides support for a wide range (RepRap (Prusa Mendel, MendelMax, Huxley, Tantillus...), Ultimaker, Makerbot, Lulzbot AO-100, TAZ, MakerGear M2, Rostock, Mach3, Bukobot and lots more. And even DLP printers.) SLIC3R also provides an option to add supports for geometry within geometry.

Stephen Cropp then talked about the types of plastics that can be used in the machines and the temparatures, PLA, XT (a type of polycarbonate) and nylon (619 grade)-  some of these need heated beds, some are very brittle, some need extra heat to melt.
Care of the plastic is important, if they are stored badly, the moisture in the plastic turns to steam.
Storing properly means keeping it dry - sealed container with dessicant.
Some new materials are super flexible which means there is an opportunity to mix rigid and flexible materials.
The materials come in different colours, which may be more successful than painting or dying.

Discussions then rolled into how to move things forward in the group, and the structure it should take - open sessions, practical printing or machine building, from basic simple printers to fancy machines - Reading Hackspace are apparently building a laser scintering 3D printer, which fuses metal powders.

So, have I changed my view of 3D printing?
mmmm, well I like the fripperies, of building gemotries, and the idea of the underpinning maths, I even came away liking the look of the Delta printer, which seems far better engineered, and elegant.

I guess I'll have to see, whether 3D grows on me.
I'll have a bash at printing something next week on the #BuildBrighton 3D printer... perhaps that will get me hooked.


Popular posts from this blog

ready for action

Just put the finishing touches to Meathammer
The whole setup works quite well.. I'm off to modelworld to run it through it's paces a couple of times.
The weak bits look to be the drive shafts, which I'd like to bulk up to at least 20mm and have some better bearnings for.
The battery packs are also a bit weedy, but we'll see how they last, and may invest in a few high output packs.
Of course it could also really do with running the 4QD 35's or 60's instead of the electronise speedies.. but we'll see how it performs and make amends.
Since I took this phot I've added a hinged scoop, so we can get under other feathers... it's a popular design in the states, should work over here.
I only need to wire in an LED to show power and then we are ok to roll.

The weakness of machines

All of the robots I have built have failed in fights, and usually at the axles/wheels, it's like a running joke.
So why should it be any different with this featherweight?
Meathammer was designed back in 2005/06 when using 4 drill motors was a bit of a novelty... it was made more novel still by mounting the epicyclic gear cages directly to the chassis, which unfortunately sends all the drive shocks back through the gearbox.

The original version ran for a number of fights at modelworld 2006? and even won some, especially the sumo, which favoured its very low profile.
I've just rebuilt the gearboxes with all metal gears, and tested it, and it seems it should last for at least one fight… but as I put it in the car after testing, I noted one of the wheels had nearly fallen off. Mark that bolt for Lockthreading!

All this got me thinking if I could make something less likely to lose a wheel, break a gearbox etc
I have a huge pile of bits and bobs that were destined for heavier machi…

Jansen Arduino

I bought two Gakken walker kits from ebay last Christmas, and finally got round to doing something with them.
I disconnected the propellors, and the reduction gears and fixed the couplings to a couple of rotation hacked servos.

I laser cut some servo mounts and hung them on some brass tubing to join the two sets together.