Fix Prusa MK4 Weak Filament Grip
ฝัง
- เผยแพร่เมื่อ 20 พ.ค. 2024
- I modified a part of MK4 by 0.2 to improve the grip on flexible filaments.
Download the modified parts from: www.printables.com/model/5966...
Previous video where the issue is detailed: • Is Prusa MK4 Too Weak ...
00:00 Intro
00:50 Issue recap
02:25 Remarks for "loosen the screw" people
04:22 Remixing 3D parts
07:06 Modified MK4 vs MK3S+
09:16 Stress test at 4mm³/s
13:27 Quality control
14:08 Wrap up + model - วิทยาศาสตร์และเทคโนโลยี
Thanks for the full & comprehensive explanation of the problem & solution. I don't own the MK4 yet (only the mini+) but I was wondering: Did you reach out to Prusa service? What was their answer? Do they recognize the issue?
Had until I saw your Video the exact same problem. Watched Video, printed Idler, problem solved. Thanks a Bunch - I owe you a Beer!!
I have this problem as well, thank you for sharing your findings!
Glad to see you found a suitable fix, did you ever contact Prusa support to see what they had to say? Weird even after tightening the two screws at the top where the filament hole is that you still had this problem.
thanks for posting this!
Glad I found your video, I was about to buy 10 MK4s for my print farm to print TPU, TPE and NinjaFlex which is very soft
Since you seem commercial, give diamondback nozzles a try. Meant for abrasives but they work really well for a 82A TPE I use. The low friction high conductivity diamond tip seem to really cut down on the force required to extrude the filament which does wonders for flexibles.
I understand what youre saying but I'll try to explain. People suggest to loosen the tension as they have had experience in filament bulging and starting to fill the extruder cavity rather then be fed down the PTFE tube to the hotend. Your problem was quite different. You had too little tension. from my experience, more tension is better as long as 1) Your Z height is enough for your first layer (set the slicer to 0.3mm first layer if you are having blockage issues only on the first layer) 2) The nozzle temp is hot enough for the filament. 3) Your filament path is well designed (It doesnt look good on the Mk4 in the demo compared to the Mk3) but if you trim the PTFE tube as close to the main gear as possible then all should work well.
I'mglad you fixed your problem & I'll do the same mod when I get my Mk4. Thx for the video!
I had also an issue on my first try printing TPU. But it was my fault. The speed was just too high for the filament. I reduced the speed a bit and since that time it prints perfectly TPU...
But: I mounted the idler lever a bit different as shown in the manual. Instead of the locking nuts (the nuts with the nylon inserts) I use standard nuts. I seccured them with some blue screw lock. The reason is, that the mentioned screws are too short for the locking nuts. The idler blocks before the nylon part of the nut reach the thread of the screw, Works perfect on my two MK4...
Really good solution. I have no problems but I have only printed TPU 95. In any case, a possibility if I ever get problems. If you loosen the two screws, you should also be able to adjust the original contact pressure. In principle, you have only increased the possible margin for adjustment. Right?
Absolutely. My change does not affect the tension directly, it allows the lever to move closer to the extruder motor gear. In this video I followed Prusa instructions by aligning the ends of the screws with the idler nut (lower tension that I had on the previous video). But because TPU flexes, the lever is able to move closer to the gear, which results in lower pressure but better contact. And you can always loosen the tension screws
I thought that I had this flexible filament feed problem until I tried drying the filament. After I had dried the filament then I had no problems. Before I dried it it would not load properly and the Purge More option extruded very little.
My filament is Fillamentum Flexfill 98A and it is several years old.
I am currently printing your modified parts. When I first tried to print flexible filaments they worked just fine, but more recently they have been showing the same issues you described, they have been properly stored in dry environments so I think their tolerance isn't the best and it sometimes works with the default idler arm and sometimes it doesn't.
I found this video by random. TH-cam algorithm is the best.
I cannot believe it!! I had massive problems just loading TPU into my extruder.
Now it works!! I’m more than happy. Thank you so much!!!
Do I need to change back to the stock lever for printing PLA or PETG?
Hi. I’m glad this helped you! No need to revert. The change does not “modify” the way the lever works, it just extends the range of movement. So it will work with PLA and PETG as well as the original one :)
Loosening the screws can help. There is also some logic behind this. If the screws are set to tight the roll pressing against the filament is pressing a dent in flexible filament and making the movement harder. When you print with PLA you can clearly see and feel the teeth marks in the filament after unloading. Loosening the screws a bit can lead to less indenting and a better movement of the flexible filament.
On the other hand you can increase the pressure so the teeth of the extruder gears claw deeper into the filament. That can also improve the filament movement.
I was also having a lot of TPU jamming with my mk4 upgrade from the mk3s+, it would get loose and twist around everything in the nextruder, i'm not sure if its because its getting soft in the cold part and not able to get in, or because its too loose on the hold. I am also having problem when i use PLA that over the course of the print it slowly twists the filament to the point is starts to jump off the spool. Some groups said to reprint the same parts you have modified, I am going to try your version and see if it helps.
I am having some issues similar to yours. How did it turn out?
In the end, I bought some overture high speed TPU and that solved all my problems, much better TPU then I was printing.
Loosening the screws on the MK3 is for letting flexible filaments "slip" when there is to heigh pressure. My flex profiles over-extrude (higher flow multiplier), but I then loosen the idles to help with difficult parts such as the first layer on the bed. This helps prevent the flexible filament find other unwanted pathway's by bulging into it. Please maybe check why people loosen the screws before claiming we are living in different universes XD. I don't know yet what the nextstruder needs for Flexible printing, I only have a print shop with MK3's but I recently got my XL up and running pretty good. Flexibles is still on my list of things that I need to try out :).
Hey so did you figure it out? The needle gets clogged up and sometimes has to be changed. I have a bunch soaking in acetone now. Softens it up so you can get it out. And I hit em with a map gas torch, fixed it right up.
What version parts do you have? I have just received my mk4 and they are on version ‘F’. The manual still shows version ‘E’ parts. Hoping this has now been fixed?
do you have to take the whole nextruder apart to change out the idler lever and nut?
I printed all my mk4 parts. And I'm glad I did because the quality of their farm parts is horrible. I used the latest revisions when I printed them. I never had any issues with TPU on the printer side. I did have issues with stringing, but it got worse over time and the reason for that is my good dryer was non operational at the time. I had to use the crappy one that can only do 50 degrees. I did manage to fix it so it's possible the TPU can be printed cleanly now.
where did you get the parts?
@@AlexandruIonica1 printables
What print speed did you use on the mk4 after the idler tightening?
Regarding the stringing, consider tweaking retraction slightly.
i couldn't even get my printer to print pla for more then 2 hours at a time until i printed this part. i think this was just poor engineering on there part or bad QC on the part its self. prior to installing your version i couldn't get any tension at all from the retention screws until they fully bottomed out.
I have no problems. All loading up to 60A Filament works with the original lever very good and without problems.
Maybe contact Prusa support and tell them your findings?
my mk4 is doing great with any material.
The printer does not need any modification. If there is a problem then either you built the kit wrong or it came with a defect.
I have the kit and it prints perfect even with very soft ninjaflex tpu. Recently I upgraded to the newest input shaper firmware. No problems with that either.
Speak with prusa support and fix the problem with them the right way.
I’ve solved it differently - 0.6 nozzle. Nextruder is bad design it can overheat filament and this mod is not going to help when filament gets too soft. It’s going to fail push filament to metal tube…
Yeah, but I need to print at 0.25mm nozzle detail 😆
I dont get it i have had mine for four months now and i can print tpu with no problem at all and it does not slip when loading, unloading or when printing your doing something wrong to have issues with the mk4 you must have broke your 1100.00 dollar printer stop trying blame the printer did you buy this as a kit and you put it together cus you shouldnt have because you have broke your new printer and your blaming the company for you mistake's
My solution to problems I was having with my Prusa was I replaced the defective part with a Bambulab X1C. It was a somewhat expensive fix, but the replacement was very easy. Printer is running better than ever now. I highly suggest this modification.
X1C is dog shit with TPU
@@hackcasual not really. I print TPU with it perfectly. You just can't really run it in the AMS.