My first TPU - how to interpret speed settings  

RE:

Posted by: @greenpea

I'm about to print TPU for the first time, bought a gluestick 🙂 and half a kilo of 85a S-flex filament from Spectrum filaments. Now when I read

Prusa Help and Prusa Blog I understand that I should choose the „Flexfill 98A or Filatech FilaFlex40“ profile and that would have optimal speed setting.

But when I look at print settings - speed I can't see any difference between a PLA filament and the Flex filament. I was kind of expecting that choosing a flex filament profile would alter/lower the speed settings.

Is my assumption correct? Do I expect too much? Am I looking in the wrong place?

Should I manually enter all lower speeds for Perimeters, Small perimeters, External perimeters, Infill, Solid infill, et cetera, et cetera??

 

Your help is appreciated.

 

Pea

Before you even start I would see if you can feed that filament past the 2 filament sensors and into the extruder. 95A is reasonably easy but softer filaments might have trouble. I've read of people having success getting 85A to feed in with a stock setup but it takes patience. I've simply found it easier to remove the top, remove the Bowden tube from the Nextruder, disable the side sensor and just feed it in directly. If you have trouble getting past the Nextruder sensor then this mod really helps: Nextruder Filament Sensor Magnet Mod

For the correct settings, yes you can start with that but I recommend going to Spectrum Filaments website and read the technical data for that filament then modify if needed.

The problem with TPUs is not that they don't adhere well but that they stick too well to the plate and they can be hard to peel off without a separation layer. Adding an adhesive helps with part removal. Without this in some cases, removing the part can damage the coating on the plate depending on the type of plate you use. I've had success printing TPU on a generic textured plate without adhesive. 

RE: My first TPU - how to interpret speed settings

Technical data @ Spectrum's website mentions 15-50 mm/sec, Thanks for that @hyiger

Now I'm trying to understand which setting to adjust, I found max-volumetric-speed but that is about volume, not speed. I reckon there is a relation but I'll have to study the article again tomorrow after a good nights' sleep and a large coffee. I'll keep you guys posted.

RE: My first TPU - how to interpret speed settings

Assuming you are using PrusaSlicer, select Print Settings then on the left panel, select "Speed" then in the section "Speed for print moves" you can make adjustments there. I would start with generic TPU/Flex profile and tweak as needed. It will be on the slow side. You can test print a calibration cube and use it to help dial in the settings. Also, try changing the perimeter and infill speeds to 50mm/s. 

RE: My first TPU - how to interpret speed settings

Maximal Volumetric speed limits the amount of filament layered by the printer. That value overrides the speeds of the print settings.  

Translating max vol, speed to linear speeds, depends on the width and height of the layer. For 0.4mm nozzles, usual values are 0.45mm.layer width and 0.2mm layer height.   

 Short maths:  Volum. speed / area = linear speed.   Area in this case  being 0.45x0.2=0.09mm2 

If max. vol speed for this TPU was 3 mm3/s -> max. linear speed : 3/0.09 = 33mm/sec

 Therefore, regardless of the speed values that you have for perimeters, infill, supports etc., the max. linear speed would be limited  to 33mm/s.