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covers911

Two different TPUs, same stringy, rough, ugly result

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Hi,

 

I'm a newcomer and would greatly appreciate your help. I'm using an S5 with default settings.

 

I've now tried two different TPUs, Ultimaker's own brand and Sainsmart's 'equivalent', but I'm achieving the same stringy, rough, ugly result in each case. The first layer has good adhesion (I'm using Dimafix spray on the glass plate), but is stringy.

 

I've seen some really nice TPU parts out there that look great, with a clean, hard, shiny finish.

 

Could you give me some pointers on what settings to change?

 

Thanks :)

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7 minutes ago, gr5 said:

Please show a photo.  I've printed TPU and TPC before and gotten over most of the issues.  Also what size nozzle?  I've only tried 0.4 cores but I assume it will leak a lot more with a 0.6 or larger core.

I will agree. My best results have been with the 0.4 on any soft material.

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Well, the answer turns out to be quite simple: Before printing, cook the filament (3 mm diameter) at 100 deg C for 1 hour in your oven, and ensure that retraction is disabled.

 

TPU is hygroscopic.

 

Decreasing speed can help, too.

 

The results are amazing. I'll post some comparison pics when I have time.

Edited by covers911

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OK, I still have a few problems:

 

1) Blobbing when the nozzle dwells in one spot. For example, just as the print finishes, the nozzle stop and dwells. A blob forms. Yuck. How can I stop this happening?

 

2) The ceilings of overhangs being craggy and uneven. I am creating support structures underneath overhangs in the same material (I wouldn't DARE using a second nozzle/material for this, as TPU is hard enough to deal with on its own), but when I break them away after printing, the ceilings look very rough and nasty. Any advice?

 

Oh, I'm using a 0.4 core.

 

Thanks 🙂

Edited by covers911

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On 8/3/2018 at 7:32 PM, covers911 said:

Well, the answer turns out to be quite simple: Before printing, cook the filament (3 mm diameter) at 100 deg C for 1 hour in your oven, and ensure that retraction is disabled.

 

TPU is hygroscopic.

Oops.  Sorry I didn't mention this.  I don't know why I didn't say anything the first time.  I printed some TPU yesterday and was reminded that you have to dry it first.  I usually dry it on the heated bed with a towel over it.

 

On 8/4/2018 at 6:45 AM, covers911 said:

just as the print finishes, the nozzle stop and dwells.

Known firmware bug on the S5.  It's somewhat high on the list of things to fix so should make it into the next firmware release.  I hope.

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