Help with TPU through UP Mini - Clotting

Hey guys,

I've been trying for a while to hone TPU printing through an UP Mini.

I am using Feetek's 'Flexible' which is a TPU advised for printing at 200-210 degrees.

Using a physical temperature hack I had experimented with printing between 200 and 280, with my best results surprisingly coming at 250 degrees. Some of these prints were very clean and practically perfect though lately the printer has started to clot and is extruding small lumps at a time connected by spider like webbing.

To fix this you can withdraw the filament and start again though the print will only last 10 minutes maximum before it starts to clot again.

I have replace the print head, the nozzle and tried several different printers and am also using an A-frame to hold the material above to reduce friction.

Any advice on what I could try next would be much appreciated, I'm stumped at it has only recently started happening and my supervisor at university has not come across this problem on his machine.

Attachment 7621
(Good print)
Attachment 7622
(Failed print)
Attachment 7623
(Failed print)

Quote:

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Originally Posted by baynesstua

I am using Feetek's 'Flexible' which is a TPU advised for printing at 200-210 degrees.

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Ah, if it really will print at less 225 C, I May give it a Try.
Since that's as High as my little Heaters will Go ! LOL ;)

I could not find any prices on their website though ?? :(

They don't have prices, I believe they only do wholesale. They sell on for about 60NZD a reel here at my university.

the tpu based filaments do tend to print best at fairly low temps. I suspect running it at 250 could be your problem.
At that temperature it'll be so liquid that you might not be getting it all through the nozzle, and as residue builds up it'll interfere with the print.
Just a thought.

The trick with flexible filaments is finding the optimum temperature for your printer that give a clean print and also allows the filament to be pushable through the nozzle.
I've gone off the tpu based filaments at the moment and use polyflex flexible pla. It prints best at 220 - on my machine - makes very clean prints and is a little stiffer than the tpu. It's at least as tough and flexible. But has way fewer printing issues.

eagleseven your ctc should print as high as 260 without any issues.

Quote:

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Originally Posted by curious aardvark

eagleseven your ctc should print as high as 260 without any issues.

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Maybe it "Should" but it does Not .:(

I've even changed heaters and added thermal-compound around them to better conduct heat.

I'm thinking maybe there is a Maximum limit set in Firmware,
since they seem to turn off just below 230C,
which I've read is the recommended Maximum temp.