Design Flaw: Extruder gears clicking/slipping causing under-extrExtruder gears clicking/slipping causing under-extrusion
I have an issue that I have noticed many people with the MK2x and MK3x extruder designs have. The axle for the idler gear is not long enough to fully bridge and fit the supports that hold the axle for the idler gear in place. This causes the gear to flex outward during printing and therefor causes the gears to slip producing the clicking noise and the under-extrusion. This video shows the problem much better than I can explain it:
On my printer, I re-center the axle and I can print perfectly for a while, but then the axle works its way out again and my prints fail. This makes it impossible for me to run prints that take any extended period of time. It has also wasted a lot of my time and a lot of my filament.
The suggested solution is to either make the axle long enough to fill the space or to design the idler gear axle supports with one end closed and filled to the depth that will keep the axle properly centered.
Re: Design Flaw: Extruder gears clicking/slipping causing under-extrExtruder gears clicking/slipping causing under-extru
On my printer, I re-center the axle and I can print perfectly for a while, but then the axle works its way out again and my prints fail.
The shaft could be really slightly longer and this would prevent such issues. I'm also printing a lot with my MK3 and had never this issue. So I wouldn't call it design flaw, more design weak point.
Anyway, the question is why your axle is moving. Either you have too much friction or the holes are too big (loose shaft). This is something I would check/change.
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
Re: Design Flaw: Extruder gears clicking/slipping causing under-extrExtruder gears clicking/slipping causing under-extru
Thanks for the ideas, you have good points. Printing the part again, I think is a good short term suggestion. I am looking at remixing the part but I have no CAD experience so it might take a few tries to get it right. It is interesting how there are many videos, complaints, etc.. about this issue, but it only effects some of us. As for whether or not it is a design flaw or design weak point, I suppose that depends on your definition of the word "flaw" and if the problem is actually affecting you 😉 For you it is just a possible weak-point, for me it is definitely a flaw.
Re: Design Flaw: Extruder gears clicking/slipping causing under-extrExtruder gears clicking/slipping causing under-extru
It is interesting how there are many videos, complaints, etc.. about this issue, but it only effects some of us.
Well, this is a nature of a media. You don't get clicks for "It's working fine". Most of the "design flaws" don't bother most of the people as they are easy to fix or just don't have such a big impact as it is being called out.
Yes, I've seen a discussion also in this forum about it. My plastic part was pretty good printed. The axle sits very tight inside. The only thing I needed to pay attention is a correct placement.
I wouldn't spend much time on this. If both extruder gears are perfectly aligned and axle sits tight fit inside, there will be no movement. As you shouldn't have any big friction against the axle or the plastic part. If you still worry about it, put some glue inside.
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
Re: Design Flaw: Extruder gears clicking/slipping causing under-extrExtruder gears clicking/slipping causing under-extru
Thank you for your reply. I see that you have not fully understood the issue. My axle is properly placed and I have had to constantly re-position it, as it moves out of place over time. I agree that people want attention paid to the issue. It is frustrating to spend $1000 US on a PRUSA MK3S 3D printer, only to have it bested by a $179 Ender 3. Besides all of the wasted time and filament trying to get it to work.
I created this part to fix the issue. My problems have gone away (so far): https://www.thingiverse.com/thing:3504682
Re: Design Flaw: Extruder gears clicking/slipping causing under-extrExtruder gears clicking/slipping causing under-extru
Also, it looks like one of the reasons that slowing a print down and turning up the temperature can also reduce or eliminate clicking/under-extrusion issues is that the “custom” PRUSA e3D heatbreak changes bore size from 2.2 to 2 close to the heat zone. Proto-Pasta did a bunch of testing that showed that this was probably the major cause of the click (stepper slips) and under-extrusion sometimes leading to jams. If this is your problem, the solution is to by the non PRUSA custom e3D heatbreak https://shop.prusa3d.com/en/mk2-spare-parts/121-e3d-heatbreak.html