Tessellating flower coaster

I wanted a side project to iron out a few techniques for a larger project I am working on. Some time ago I went through a tessellation fad and I made quite a few designs but never had any idea what to do with them - until I discovered 3D printing:-). I dug up a flower design I'd made and set about turning it into a 3D model. Not only is the flower seasonal (and in theory, it's spring time in the UK),but I wanted new coasters for my study and the flower seemed a shape that would lend itself well to being contained in a circle.

I have included the following files:

1) A single flower with petal detail
2) A flower coaster
3) A single flower without petal detail (in case anyone just wants the basic shape)

If you want to use the coaster on any surface considered delicate, then I recommend you attach an additional base to it and test first. I also suggest you test how well your filament of choice can handle heat if you want to put hot cup of tea or coffee on it.

The single flowers if printed out in sufficient quantity and variation of colours, can make pretty toys/trinkets. I've stuck little magnets on the back of some of mine and use them to secure paper to a notice board I have in my study.

See here for awesome tessellation software: http://www.peda.com/tess/

Sadly I do not yet have a printer capable of dual extrusion, but I do like using multiple colours in a print where the model allows - it just takes a bit of patience to swap out filament. The trick is to slice your model first and then determine where you want to change the filament by looking at the gcode. I use Repetier-Host which has a very useful gcode editor which allows graphical scrolling through the slices to see what each layer does. Once you have identified the layer, start your print but be ready to pause it at the appropriate time. I advise that on pausing, you raise the head up on the Z axis so it isn't left cooking in the layer it has just completed. Moving the head up and out of the way will make it easier to change out the filament and bear in mind that you may need to change the temperature to suit the new filament. The print can then be resumed. Of course, if you are familiar with gcode you can script in pauses and temperature changes should you wish:-)

I had an interesting problem with my coaster prints. I have a heat reactive ABS filament which I thought would look good on the coaster, but I only wanted to use it for the petals - the rest I wanted printed using black PLA. I had read it was possible to print ABS on top of PLA, but given how picky ABS can be about sticking to things, I anticipated problems....and I wasn't disappointed:-). The print would progress well and look lovely, but just before the end, I would hear these crackling noises and a petal would detach there and then or shortly after print completion. Very frustrating, but because the combination looked so pretty I continued. Part of the problem was I was printing on a cold bed and just using hairspray as a fixative. This technique is great for PLA prints and makes it much easier to remove finished items, but ABS doesn't like printing on cold PLA.

I thought the petals could do with a higher infill not only for appearance but also adherence,but I didn't want the whole model to be solid. I sliced my coaster twice, with infills of 66% and 100%. The gcode was split up so I had a section from start to the beginning of the petals at 66% and the petals with 100%. That gcode was joined together to create a complete coaster.

Here is the basic printing process, although it has only been tested briefly. This also assumes that you know your filament well and can account for temperature differences and restrictions:

1) On a cold bed, heat the PLA to a 'first layer' temperature and then let it progress on a lower temperature for the rest of the PLA layers.
2) Two layers before the swap out, switch on the bed to temperature that your ABS is happy sticking to. This will allow the PLA enough time to warm up.
3) When appropriate, swap out the filament and let the extruder heat up to a 'first layer' temperature and let it print with the bed switched on.
4) Switch the temperature of the extruder down as you would normally and watch the filament, if it looks likeit is cooking, decrease the bed temperature.
5) Let the model cool completely before removing it from the bed.

I am sure there is an easier way to do this and I look forward to all feedback.