Page 1 of 1

Using "flexible" filaments in Lulzbot Mini

Posted: Mon Dec 17, 2018 10:45 pm
by zizumara
I have an unmodified Lulzbot Mini, and I'm trying to figure out from various sources how flexible a filament I can use for printing. I have some Gizmo Dorks flexible TPU filament, but I don't see any TPU profiles in the Cura Lulzbot Edition software that I am using. I'm assuming that filament materials with a lower Shore hardness are more flexible. When I did a little research on TPU filaments, I found a really broad range of Shore hardness, anywhere from 85A (Ninjatek Ninjaflex) to 98A (Gizmo Dorks TPU). Given that the Shore A hardness scale maximum is 100, 98 would seem to be very hard. So what am I missing? Why does Gizmo Dorks describe their TPU filament as "flexible"?

I'd like to give more flexible filament a try in my Mini, but I have seen several posts online that suggest that this might not work well without a modified extruder. However, all the complaints seem to be about 1.75 mm TPU filament, so maybe the thicker 2.85 mm filament would not experience the same problems in a standard extruder.

I tried some Inland PETG filament, and this is where it gets even more confusing. I found no discernable difference between this part when using Inland PETG and ABS. The only Shore hardness rating I could find for a PETG filament is 70A, but I suspect that there is a great deal of variability with supplier. Inland lists their filament hardness using the Rockwell hardness scale, and their PETG hardness is rated R 106. I found a conversion table on the web, but it seems to suggest that a value of R 106 corresponds to a Shore value of 43A. So unless I am looking at this wrong, this suggests a great deal of variability in hardness for different PETG suppliers.

Any suggestions?

Re: Using "flexible" filaments in Lulzbot Mini

Posted: Mon Dec 17, 2018 11:11 pm
by zizumara
Here's a follow up question. Since I don't see any TPU filament profile for my Gizmo Dorks TPU filament, I'd like to create one using Cura Lulzbot Edition software. The Gizmo Dorks site provides some guidelines, but I need to fill in some of the blanks. Gizmo Dorks provides

Extrusion temperature: 200 C to 220 C
Platform temperature: 80 C to 100 C
Print speed: 30 mm/sec to 50 mm/sec
Layer thickness: > 0.1 mm

Cura LE requests the following print settings.

Default printing temperature: I'll assume 210 C is good here
Probe temperature: ?
Soften temperature: ?
Wipe temperature: ?
Build plate temperature: I'll assume 90 C is good here
Part removal temperature: ?
Retraction distance: 6.50 mm (same for all materials in Cura profiles)
Retraction speed: 25 mm/s (same for all materials in Cura profiles)
Standby temperature: ?
Fan speed: 100% (same for all materials in Cura profiles)

The probe, soften, and wipe temperatures are almost always the same value for a given material, so I think if I get a value for any one of these I can set all three. Standby temperature is usually different from these three, so no clue there.


Re: Using "flexible" filaments in Lulzbot Mini

Posted: Tue Dec 18, 2018 2:26 am
by mrvanes
I can't help you with the shore questions, but this might help printing (semi) flexible filament on the Lulzbot toolheads.

Re: Using "flexible" filaments in Lulzbot Mini

Posted: Wed Dec 19, 2018 11:57 pm
by zizumara
Got it. Thanks.

Re: Using "flexible" filaments in Lulzbot Mini

Posted: Fri Dec 28, 2018 7:55 pm
by zizumara
I decided to ditch the TPU filament that I have and order the PCTPE filament for which Cura LE has a profile. From its description, PCTPE is pretty close to being TPU/TPE, though it is described as a blend of materials.