Last week I received my first commercial order for a part printed in T-Glase through 3D Hubs. The customer needed a large watertight part, printed precisely so that it fit into their current machinery. This print taught me some valuable lessons which weren’t obvious on the smaller prints I’d previously tried.
For those of you not familiar with the nylon filament producer Taulman, or their excellent products, do yourself a favour and go read up. T-Glase is a water clear nylon filament which is FDA approved for food contact/containers and prints with no odors or fumes released. There are so many reasons to love T-Glase, but you have to understand a few things to produce the print you hoped for.
Slow Down. 20mm/s
i’d read advice to slow down the print speed compared to ABS and PLA, which I did. At first I went down to 50mm/s, thinking that halving the print speed would be enough. Wrong. The base layer went down fine, then the infill began and that’s where the under-extrusion showed itself to be a problem. Regular printers seem to struggle heating the filament and handling the high pressures required to print at speeds higher than 20mm/s or so. This means very long prints. This last job took 57hours. Our power is reliable, but I seriously considered buying a UPS.
Turn up the heat 240C to 245C
To take advantage of the beautiful optical qualities of T-Glase, make sure you print at the upper end of the print temp range. The published temps are 235C to 240C, but I saw the best layer adhesion and optical consistency at 245C. I tried printing down at 230C. The result was still accurate, though the print was cloudy and the internal fill lines didn’t adhere the way the did at higher temps.
Goldilocks print bed, not too hot, not too cold, 70C is just right
Following the advice of a forum post, I pushed the heated bed up to 90C. This turned out to be a bad move. The print adhered first go on Kapton tape which I was pleased with. I left the print envelope closed to keep the heat in and prevent anything interrupting those precious 57hours. After the first night though, my print had slumped a little. I didn’t think much of it and assumed it was because we’d had a cold snap over night. By the time the print finished though, the bottom layers had slumped inwards, reducing the 58mm internal diameter down to 54mm. Unfortunately outside the customers’ fine tolerances.
why? the Glass Transition temp of 78C
The lower layers of the print were above their Glass Transition temp of 78C, this meant that they started to slump. A little quicker than the Pitch Drop Experiment at my alma mater. If only it took that long to deform. The Glass Transition temp of print filaments tells you the lowest temp at which it starts to become malleable.
I tried to print at 60C but that was too cool. The print curled up off the bed after only five layers and completely delaminated after 10.
70C seems to be in the goldilocks zone. I printed a 36hr job with the bed set to 70C and it didn’t deform one micron. There may be an ok range here, but 70 worked perfectly. Go ahead and experiment, just don’t go above 78C.
Again following the omnipotent forum posts, I turned off retraction in my slicer (SImplify 3D). This might have been fine on a print without any air travel between pieces. Instead I was left with a lovely print, with perfectly aligned ribbons of overprint strings, showing exactly where all the travel moves were. It gave a wonderful rainbow effect but was a real **** to remove. This all thanks to the strength and flexibility of nylon.
Better optics = thicker layers
I’ve printed at 100, 200 and 250 microns and there is a difference as you can see in the photo’s above. At 100 microns it produced a fine luster, at 250 I have an optical clarity that really does make me think of a nice long glass of water. yes there a are finger print style ridges along the sides, but it shimmers in the light.
I hope this helps you to produce good quality and optically pleasing results on your many and varied printers. Please comment below with your success stories or lessons learned from fails.
If you have a file you’d like to have in T-Glase, send it to me here:
My 3D Hub