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Da Vinci Pro Clicking Extruder caused by Spring Tension

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Since purchasing this machine I have really struggled to get good prints. There was a pesistant problem with the extruder clicking and eventually clogging the hotend. I spent a long time messing with extrusion rates, temperatures and mods to the bowden tube. I replaced the original tube with an E3D capricorn tube. I removed the weird clip from the top of the hotend mount and replaced the short tube with a direct connection through a pneumatic coupler to the filament sensor. The short bowden tube that was removed actually had a small kink in it. All of this made no difference.

Eventually while adding some extra pressure to the filament goung into the extruder i noticed that if i pulled the lever arm back slightly the clicking would stop. I found a small bit of plastic to wedge the arm open slightly and it was transformational. Basically the extruder spring is much too strong and is crushing the filament. This has two effects. Firstly the filament is no longer round and will not fit into the hotend. Secondly after a retraction, the extruder idler needs to 'climb' over the step in filament thickness between the crushed and uncrushed filament.

How dare you pinch my name

ha ha ha. Your name is mine!! Ha ha ha

Well I'm 52 so I bet I had it 1st

You have my apologies, i was unaware of your prior claim. Hagster is not even my real name. It is just a name I have used on video games in the 80s. No online then so no harm.

Haha do you think hagster is my real name

The extruder will click when the filament is not moving freely through it. It could be binding anywhere between the roll and the nozzle. If the nozzle is clogged (whether fully clogged or imminent/partial clogging) or is not hot enough to melt the filament, the extruder will labor to push it and click. Capricorn tube has a smaller diameter and will make things worse. You don't want your extruder gears crushing the filament either.

It is 100% due the filament being crushed by the extruder. I tested everything else. If the filament is damaged or out of spec enough to jam in the ptfe tube then it will be even worse in the hot block. Hopefully the capricorn will help improve print results and reduce the need for retraction now the extruder problem is fixed.

And in that case, I assume that you have tested the hotend for jams, correct?

I cleared a lot of jams. All caused by the original extruder issue.

Judging from my experiences with similar issues, the clicking sound was from the stepper motor failing to push the filament through the hotend due to a jam. However, as for the spring problem, it is highly unusual that the spring exerts too much pressure on the filament such that it could deform it. However, if the filament is indeed deforming upon passage through the pinch point, that provides all the explanation behind the consistent jamming. Has the spring been modified since the last time the system has worked properly?

That's my experience too, but not in this case. I haven't modified the spring. The printer has never really worked properly. Often it starts off ok, but once it gets warm the the problems start and it just gets worse from there. I have attached pictures of some filament that has been through the mangle and the temporary plastic wedge that seems to fix it.

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Da Vinci Pro Extruder Spring Tension temporary fix
by Hagster

Another potential cause is the bearing on the extruder might not be spinning causing binding and a choke point at the driver gear. Mark the bearing with a marker and check for rotation before taking the covers off to replace the bearing or the extruder completely.

I replaced the extruder to an MK8 bi-directional (Gold) design and the motor to a new NEMA 17 with a V6 hot end and I have had great success printing.

Thank you for the images. Speaking from experience, I can also assimilate with you in the problems of the extruder design as the hotend in general is rather unreliable, so I am drawn to conclude that part of your issue is simply a poor design (especially if it has never really worked properly from the start). However, if the spring has never been modified, another likely cause of the clicking noise of the Bowden setup and other issues with the system is the filament diameter fluctuation and tolerance. Since the force exerted by the spring will increase with how far it is being pushed out, which could provide explanation for the deformation, under the assumption that everything else is unchanged. Do you mind providing the filament tolerance? Thanks!

It is difficult to judge a problem from afar.
So just my experience. I also had problems that the extrusion stopped in the middle of a print. After checking, i found that the filament was damaged by the gears pushing the filament in the bowden cable. I diagnosed the problem being a 1 kg spool of filament hanging at the back of the printer (see https://www.thingiverse.com/thing:2765511) The force needed to "unroll" the filament was too big.
When I wind the same filament in the XYZ cassette, then I the problem went away. Just another possibility you can check.

Spool Holder for XYZprinting da Vinci 1.0 Pro