Two different TPUs, same stringy, rough, ugly result

[covers911 0]

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 :)

[kmanstudios 1,120]

I have tried neither brand, but in other TPUs, I get a lot of grief for the most part due to it being more difficult.

 

Try to print a series of small prints to lock down your settings.

 

Try cooling or heating the material to find right temp for you.

 

Try to slow down the print.

[gr5 2,268]

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.

[kmanstudios 1,120]

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.

[covers911 0]

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 August 3, 2018 by covers911

[covers911 0]

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 August 4, 2018 by covers911

[kmanstudios 1,120]

I would still try to combine the TPU with PVA just to see how it works.

[covers911 0]

Well, I tried a few prints of TPU with PVA, and I can't get the materials to stop stringing into each other. Are there any hard and fast rules simply to stop a material stringing (temp and speed, rather than geometry of the slice/print)?

[gr5 2,268]

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.