Question about use of co-polyester material in an Ultimater 2

mollihall · March 28, 2019

My name is Molli Hall and I'm the senior library assistant at the Marion & Ed Hughes Public Library. We own an Ultimaker 2 and do 3D prints for the public. We have a patron who wants to print out the pieces to build a CNC machine. The original creator of the print files says that we should use co-polyester material to print the pieces. We have never used that type of material in our machine before. We have only ever used PLA. We are just wanting to make 100% sure that our older machine will be able to print using this material before the patron orders the material for us to create the pieces for him.

owen · March 30, 2019

Hi

You just need to check the highest temperature your printer is able to print at and the required temperature for that filament. Which filament is it exactly?

fbrc8-erin · March 31, 2019

UM2 should be able to handle CPE/Copolyester from Ultimaker. If you're running older firmware, it will only list ABS and PLA though, so if you don't see CPE in the material options, you'll want to update the firmware.

geert_2 · April 1, 2019

On my UM2 I have succesfully printed PET, which I believe is a sort of co-polyester? Its brand was ICE from Trideus in Belgium. I had to download the file "materials.txt" from the UM2-printer to the SD card, and then make a new material-profile in that file, and upload it again to the UM. That profile lists the default temperature and material flow, and fan or no fan, and a chosen name. So I can now select PET from the printer-menu as material.

Usually I print PET at 25...35mm/s, and 215...225°C, no fan, bed temp ca. 80...90°C, layer height depending on the model 0.1 or 0.2mm. For me this works well, although most specs list higher nozzle temps.

Expect a "frosted glass" look when printing transparent materials. It survives summer days in the car, contrary to PLA.

It prints reasonably well, except for overhangs, due to the "no fan": it is very difficult to bridge and fill gaps. PET is more rubbery than PLA: while PLA tends to pull a nice string when bridging, PET rather tends to curl up on the nozzle, like a rubber band snapping back, and that blob gets deposited onto the next wall upon arriving there, instead of making a bridge.

I print it on bare glass, cleaned with salt water. If I would print with fan, then I would get better bridges. But then I also would need dilluted wood glue for better bonding, otherwise it warps. But then I risk chipping the glass plate (I had this once), so I don't want that.

On the long term PET is more likely to clog up the nozzle: it leaves a thick sort of very hard and glossy "varnish" inside the nozzle: hard to clean with cold pulls. Contrary to PLA that leaves a coating of dry powder-like ashes, which is easier to remove with cold pulls.

PET or co-polyester might be a good choice for printing accessories like knobs or enclosure shells. But I would not use it for structural elements: it is a bit flexible (think of PET bottles), so for a CNC machine it will not provide good accuracy. The structural elements should be absolutely rigid, thus made of thick steel, brass or aluminium, depending on the wear and loads they will see.

Personally I would also make this consideration: would I print materials unknown to me, for an occasional external customer, and take the risk of damage to the printer? No. I would refer them to services like Shapeways, Materialise, Melotte and various other. Would I take the risk for myself, if there was a need for it in our laboratory, and we needed multiple models? Yes, but then I would invest time to search it out well.

The models below are in PET, printed on my UM2: key chains (with hollow watermark text), test blocks in various layer thicknesses (0.06 ... 0.4mm) and in various speeds (10 ... 50mm/s) with a hollow watermark, and carabiners (only the green is PET, the cream are PLA).