Printing in Polyurethane Rubber using Fenner Drives' Eagle Orange
by pyrophreek, published
Following in the footsteps of others, I ordered some 3mm polyurethane belting from Fenner Drives (http://www.fennerdrives.com/non-reinforced-belting/?s=ZnwxNzc5). I went with the Eagle Orange 85, as I felt its softness and color were ideal. I will be posting an account of my experiences with it here.
I am printing on a slightly modified Solidoodle 2 using a 0.35mm J-head mounted in Lawsy's MK4 extruder direct drive system using the Repertier Host software and MLaws modified Marlin firmware.
Best settings so far (these are what have worked best for me, let me know if you get better results using others):
Temp- 190 C first layer, 180 C others
Cooling-active fan (not sure if necessary but I had it on)
Bed-Kapton with Hairspray, heating optional
Extrusion width-0.42mm (0.5 for infill, which I may increase)
-been working with this a bit now, and been having some fun. Printed a suction cup mount for lithopanes (will post it later) as well as a boomerang and some small feet I plan to use for another project. I noticed that at times the extruder is slipping on the filament, as it is very smooth and doesn't allow the teeth to really get a good grip on it. Increasing the tension helped, as well as turning up the temperature a bit.
-I also designed a small tag for my tweezers so that they are labeled as mine. Printed alright, although the text was hard to read.
-The first thing I did after receiving the filament was try directly extruding using the stock J-head extruder. Unfortunately I found that the gap between my drive gear and the head tube was too large, and the more flexible filament was prone to bending, resulting in kinks and no extrusion. I added a small tube of PTFE to the top of the head to compensate, and this prevented kinking from occuring.
-For adhesion, I first tried my Kapton heated bed treated with Hairspray without the heater on. Adhesion was excellent so I didn't worry about this.
-Speed was my next issue. Due to the larger diameter of the 3mm filament, and the tendency to string horribly, I found that lower speeds worked best. I will continue to push the speed as I optimize other parameters, but currently ~20mm/s for perimeters works well. Started to get delamination and stringing at higher speeds.
-Next up was temperature calibration. I started with a 2cm test cube, with 2 perimeters and 5 bottom layers with a layer thickness of 0.15mm. I initially started at 215C, but this proved very gooey, so I reduced temperature gradually until I found what I thought was optimum at 190. Final print had many defects early on, and I think there was some degradation at the higher temperature, but as I went lower the quality improved and I was hopeful for a good print.
-Following the Octupus theme of my predecessor, I went with Cute Octopus says Hello (http://www.thingiverse.com/thing:27053) at 0.15mm with 2 perimeters and 15% infill. I started at 195 for the first layer and 190 for the rest, but quickly noticed a large amount of stringing. To reduce this, I tried decreasing the temperature some more, and found that 180 reduced this somewhat and still resulted in good extrusion. The low infill level with honeycomb produced some nasty internal structure, with lots of stringers inside. I did notice that the flexible nature of the material meant that the upraised arm began to lose some detail as it got taller, so I presume tall thin designs will not print well (not really a surprise), although the slower perimeters went better than the faster infill. I also found that near the end, especially when trying to do solid infill over partial, decreasing the speed even more and temperature to 175C helped. It may be possible to print entirely at this lower temp to produce better results.
Final thoughts after first prints:
Finished product has the same feel as a bathtub rubber duck. Would be great for rubber bulbs such as pipette bulbs or rubber tires for model cars.
Top layer if small tends to melt horribly. Turning down temp for last few layers a must. Cooling increase needed?
Stringing is a major issue, even with high retraction settings. Low viscosity of melt means drooling is a given. Minimum temperature for extrusion recommended to help mitigate.
wanted to try a tire out of this rubber, so used http://www.thingiverse.com/thing:32023 as a test. Printed the tyre part out of polyurethane and was very impressed with the flexibility and feel of it. This was a flat tire, simply providing traction, but I think a puffy tire would be even better. Designing the tire to fit on a rim may be tricky, but not impossible. The printed tire turned out to be super flexible, similar in feel to one of those rubber wristbands, but a little less stretchy. Surface feels like acetone vapor treated ABS. Very nice and shiny.
I found that printing at 175 C produced the least stringiness and best quality. I also noticed that due to the low viscosity of the melt, it oozes alot as it is heating up (probably didn't help that I heated it to 200 initially). This led to poor initial extrusion, so to compensate I upped the multiplier to 1.5X until it was extruding well again.
Another note of possible interest, this material pulls out of the nozzle very easily, and completely (even pulled out of the tip) at just 100C. Makes for very easy cleaning of the nozzle, and may even be useful for cleaning other gunk out of the nozzle if it clogs.
Added a picture of the finished wheel with tire. Fit was perfect, and nice and tight. Tire was nice and stretchy, so even if the rim was a bit too small it would still fit over no problem. This was just a flat inner rim with a flat tire. No air cushion. This material would probably work just as well or better with cushioned tires, and the ability to custom print treads seems interesting. Rim was printed in black ABS.