Mk9 Extruder skipping

[Cassandra Brockett]

So, for various reasons (mostly related to melting of a connector) I rushed installing the Mk9 Extruder I picked up last week. I was intending to get a proper mount for it sorted out, but yeah....

Anyhow, I'm now running into an issue with it extruding, it is skipping on the extrusion.

I have tried:-

• Raising the temperature (helped, but not enough)
• Removed the feed tube (this had significant back-pressure, removing it helped immensely)
• Slowed the print (Very little change)

My next things to try are changing to a different filament (as it is possible this filament is narrow), and also pulling apart the pre-manufactured unit and seeing if there is any physical clogs/issues I can see (this will likely be this evening if I get time).

Is there anything else peeps can suggest for me to try?

I'll be bringing the printer to TechShop on Wednesday, but hoping to be printing/have printed a more-useful mount than my cable-tie monstrosity by then :)

--

Cass

[Bill Seiler]

How often does it skip?

Did you played with spring tension on the extruder?  

Maybe there is some binding in the mechanism that pushes the idler bearing into the drive gear?

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[Cassandra Brockett]

Hey Bill,

So, it was skipping intermittently, though between 1-2 seconds.
I _think_ I played with the spring tension, I haven't found much in terms of documentation, however I think I have it set to highest pressure possible on the filament.

Oh, and I should mention that I did adjust the stepper power on the ramps to give it a little more oomph (as part of my previous testing). I haven't tweaked that yet, it is fairly high, but 'free-air' extruding didn't skip at all with the higher power to the stepper.

What I can say is that this evening, I tried with a new spool of filament running on the floor beside the printer with my original extruder feed-tube-ish-thingy being used to make sure the filament came up and over cleanly and with as little friction as possible and it printed fine for almost three hours (two prints, one just over an hour, and one just under two hours). No skips noticed. This was with a filament that I measured at 1.78mm, while the one giving me problems was at 1.73-1.74 (quick measurement and not great lighting so I need to recheck that spool at some point to make sure it is actually equal sized all around and such).

So, two "major" changes to the setup, one removing as much friction out of the filament feed path as feasible, the other being a thicker filament, and it seems to be working reliably.

However, the filament size bothers me as while I could believe that .05mm might make some difference, given that both filaments seemed to be showing teeth marks from the extruder feed, I don't think that was the fix. I have to think the fix was removing all possible pre-extruder friction, which means I need to babysit the printer for any print... or else I've got something mis-adjusted and would want someone who has more experience with direct-drive systems than I to look at how I have it set up now.

Honestly, at the moment, it _looks_ like I might not be able to use this extruder to unwind off a spool like my former extruder did...

But I do now have a better mount printed for the extruder, so at least it won't be held together with cable ties and prayer :) Presuming I can get the right screws in the next day or two that is :) Finding M3 screws in any real length over the counter can be difficult sometimes :)

--
Cass

On Monday, October 3, 2016 at 11:13:39 AM UTC-7, BSeiler wrote:

How often does it skip?

Did you played with spring tension on the extruder?  

Maybe there is some binding in the mechanism that pushes the idler bearing into the drive gear?

On Mon, Oct 3, 2016 at 8:43 AM, Cassandra Brockett <cbro...@ophiuchi.net> wrote:

So, for various reasons (mostly related to melting of a connector) I rushed installing the Mk9 Extruder I picked up last week. I was intending to get a proper mount for it sorted out, but yeah....

Anyhow, I'm now running into an issue with it extruding, it is skipping on the extrusion.

I have tried:-

• Raising the temperature (helped, but not enough)
• Removed the feed tube (this had significant back-pressure, removing it helped immensely)
• Slowed the print (Very little change)

My next things to try are changing to a different filament (as it is possible this filament is narrow), and also pulling apart the pre-manufactured unit and seeing if there is any physical clogs/issues I can see (this will likely be this evening if I get time).

Is there anything else peeps can suggest for me to try?

I'll be bringing the printer to TechShop on Wednesday, but hoping to be printing/have printed a more-useful mount than my cable-tie monstrosity by then :)

--

Cass

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[Bill Seiler]

These extruders have a groove in the idler bearing that pushes the filament against the drive gear.  You may have a 3mm idler bearing. If you take it appart check that. Maybe they sent the wrong bearing.

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