The solution to this TPU problem was surprisingly simple!

this one simple trick can save your teeth oh hi in this episode I show you what I did to this Cube and what it means for TPU printing especially with softer TPU like 85a or less let's go this video is sponsored by PCB way more on that later so I was asked by one of our Discord members to test 78 TPU on the creality ender3 S1 plus we really need a name for that printer because it uses the Sprite extruder not the pro one just the basic one with the PTFE lining um because I've previously praised this extruder excessively for its normal TPU performance it's one of the best extruders out there for TPU at this time in my opinion it prints with zero problems on 95a even at relatively normal printing speeds the problem was when it came to the 70a TPU I couldn't get a good result and this was surprising because that doesn't make a lot of sense a printer that prints really well with 95a just can't do 70a I tried all the usual stuff slowing down to around 10 millimeters per second it didn't work it was still getting all these marks all over it they just looked like severe under Extrusion even increasing the flow to 140 percent wasn't really fixing it and that's what I would normally do and that's about the limit I would go to there was more to it than this but then I noticed something here's the thing with the tension up to absolutely full on the extruder using the tension setting so that's with absolute maximum grip which is on this extruder it's an insane amount but watch now that's going to take some explaining so let me try if we look at the tensioner which means we have to take it apart [Music] foreign [Music] if we look at it though what it does is increases the tension significantly between these two gears but and this is a big butt the distance between the teeth can only go so small the teeth will fully mesh here and that will be the most you can dig into the filament now on pla or petg or any other sort of solid filament that would be way too much tension you would never go that far but as I keep saying TPU is not like PLA and apparently it doesn't see any good reason why it needs to follow the rules even at full tension it's just not well held at all if you're already thinking ahead then this is going to be an issue with any extruder with dual gears for exactly the same reasons a single gear extruder with a flat opposing surface might work better and that's kind of hilarious another example of just one of the many engineering challenges involved in printing with TPU in the last video I spoke about loosening the extruder for TPU so if you watch that you're probably wondering why I'm now recommending to tightening it well I'm not because everything in that video is still the case we have stuff going on after the extruder and we've just discovered now that there's more stuff going on before the extruder that more than we previously realized and so the fix is to remove that variable to remove what's going on behind the extruder how I did that was to pull it off loose TPU off the reel to remove the resistance and that's the easiest solution for this printer it'll cost longer term if you want to solve this then you might consider bearings on the filament reel or maybe a special low friction reel or a smaller reel for TPU and you're definitely going to want to bypass the filament sensor so in case you still don't know what I'm talking about basically the force required to pull the filament off the Reel and through the filament sensor in this case was too high for the amount of grip the extruder could realistically maintain it could mostly do it but any slippage would cause under Extrusion and of course when it tries to pull in the filament it stretches which makes it thinner and that is making it much more likely to slip does this affect ordinary 95 atpu I would say it's likely but the extent will depend on the setup and most of the time probably not noticeably but I have had some printers with very high friction filament sensors for example to which I would say probably sometimes yes even 95a will be affected I guess we should test it to be sure I have some ideas uh let's let's do that let's test it after the message from our sponsor which as you already know is PCB way because I told you at the beginning remember it wasn't even that long ago PCB way does 10 color choices in their standard pcbs and 14 for their Advanced pcbs but you could also push the boat out and have five colors for silk screen too on those I've seen some examples of these and they look amazing in case you're a PCB ordering Noob like me the mask color here is the pink it and the silk screen is the writing in White in this case and the website is smart enough to know that you can't use white on a white PCB like here you have to use black and similarly white on purple anyway using the quick order PCB link here makes it all easier as for most of us the defaults are the values you're likely to need if you aren't sure what you're doing just upload your design and check down the list and pick a color and Away you go PCB way can also Supply any 3D printed Parts you need in a vast range of technologies that you probably won't have access to at home and also CNC or sheet metal too go check out PCB way in the link below in the description and thank you to PCB way for sponsoring this video and here's the results and by the way if I sound completely different on different parts of this video I'm recording it over several days so that's not usually the way I do things but anyway don't compare machines between each other because the cubes have been sliced differently in Cura so for example the three grams on the Ender three S1 plus is probably just higher infill or something there's not really much to read into that however the same G-Code has been used for that machine for every every print otherwise it wouldn't make any sense would it I didn't really think about this when slicing because I didn't I didn't know we were heading for a spreadsheet you know sometimes they creep up on you anyway this is though this is good news because it shows that the phenomenon I discovered wasn't particularly repeatable with lower elasticity filaments you can see a bit of fall off if you really add friction to the line um on some of the filaments by either moving the spool away which is what I did uh when I where I had the heading extra friction I was moving the spool to Another Printer just to just to add extra things in the way um or uh the reverse Bowden which was about 40 centimeters or so of PTFE tube and for TPU that actually adds quite a lot of friction uh surprisingly the point is I think that 95a filament really isn't appearing to be terribly susceptible to pre-extrude attention as I wouldn't expect it to be I think I said that um just like pla I don't think this is a huge factor and this is why in the past I have completely ignored pre-extruder tensions and pre-extruded everything's because the amount of um Force an extruder can pull the filament with is quite insane um it's over a kilogram it's significantly more than that in most cases as we saw in the last episode so it only seems to be an issue in this special case where there is a higher elasticity and that allows the filament to thin and Escape at least that's my working hypothesis and more slippery filaments like 40D and 70a are or can be susceptible to this in fact in the case of 70a it's highly susceptible to this to the point where you have to take measures to make sure that it doesn't happen I did mention just now that I didn't expect to get onto spreadsheets from a simple observation about under Extrusion in fact this started as a short video I wasn't planning on making a full video but obviously it escalated so there's probably a lot more you could do here this is still a relatively uncontrolled experiment which I would say contains one strong learning outcome and that would be to be careful with tension on very soft filaments so there you go what do you think I personally think it's hilarious TPU is always full of surprises and the idea that a single gear extruder could work better it just flies at the face of established knowledge but it seems like there might be some truth there but I should say that this part is still a working hypothesis I guess I may test it at some point anyway that is all for now remember to subscribe for more 3D printing stuff and I will see you next time thank you for watching [Music]

Channel: Lost In Tech

Views: 45,989

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Id: T5645IJNUt0

Length: 9min 44sec (584 seconds)

Published: Sat Nov 12 2022