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First calibration. Do I have a clog somewhere?  

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Bill
 Bill
(@bill-2)
Active Member
First calibration. Do I have a clog somewhere?

Greetings!

I purchased the assembled Mini+, because I'm impatient and don't want to wait for a kit.  The printer arrived this week and I excitedly set it up.  

During first-layer calibration, there just wasn't much filament being extruded.  This picture shows what happened.  I'm using Prusament PETG.  

I theorized that I had some sort of clog.  I tried the accupuncture needle, but that didn't make it any better.

I've done several cold pulls and ... well, they are weird.  Not what I'm used to from my Prusa MK3S.  

First, when pushing filament in during the load phase, it is REALLY hard to get any filament to flow through the nozzle.  I'm pushing very significantly and a small amount of filament is coming through.  The filament immediately starts curling around the nozzle, as well.

And, here's what I'm getting for cold pulls.  I'm alternating white PLA and orange PETG.  They are in temporal order from top (earliest) to bottom (latest).  You'll notice that I'm not getting the well-defined nozzle shape at the end.  Nor am I getting the long noodle shape that is so characteristic of cold pulls.  These are nothing like the pictures in the knowledge base article on cold pulls, either.

Here's my last cold pull.  It has these weird geometric cuts on the sides.  Does this mean my PTFE tube isn't tight against the nozzle?

Thanks for any help you can provide!

Happy printing,

Bill

Posted : 15/05/2021 11:07 pm
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(@)
Illustrious Member
RE: First calibration. Do I have a clog somewhere?

It looks like you have your nozzle too low. Live-Z adjust is too negative. I'd raise it in 0.025 steps until the calibration looks like it should. Then, proceed to printing a large test coupon where you have time to make Live-Z adjustments and see the changes. 

Also -- that last image is the only "successful" cold pull. The others are not cold pulls (something went wrong).

The appearance of the last pull is normal. Some stretch is expected and unavoidable. But there is a lot of gunk that shouldn't be there. Keep doing the cold pulls until the pull shows a clean tip with the same shade of filament over the entire length.

But I doubt you need to do pulls at this point. Fix the layer one issue and you should be fine.

 

Posted : 16/05/2021 5:55 am
Bill
 Bill
(@bill-2)
Active Member
Topic starter answered:
RE: First calibration. Do I have a clog somewhere?

Tim, thanks so much for your help.

I know the picture looks like the Z offset isn't set right, but if you look closer, you'll realize that there just isn't enough plastic coming out of the nozzle to make good tracks.  I had to Live-Z hte nozzle way low, just to get the meager flow to stick.  I wish I could get a better picture, but the tracks really are made up of lots of (very tiny) un-connected plastic islands, because not enough filament is flowing to connect them.

I'll take your advice and go back to doing cold pulls.  I'm really struck by how much force it takes to get filament to flow through the nozzle during the first phase of the pull. And, of course, the flow is really tiny.  It just feels that there must be some obstruction somehow....

Posted : 16/05/2021 1:43 pm
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(@)
Illustrious Member
RE: First calibration. Do I have a clog somewhere?

@bill-2

When the nozzle is too close to the bed, no filament flows. Same as a thumb over a garden hose. Trying lifting Live-Z 0.2 mm just to see what happens: you can always turn it back down.

 

As for cold pulls - I start with a cold loaded printer. Open up the idler (Mk3), set nozzle temp to 100c, and then when the nozzle hits about 60c I start pulling. Around 80c to 90c it begins stretching and eventually pops loose. Slow continuous pull works best for me: yanking will always break the filament before it releases. But I'm the first to admit it's more art than science.

 

Posted : 16/05/2021 4:19 pm
cwbullet
(@cwbullet)
Illustrious Member
RE: First calibration. Do I have a clog somewhere?

@bill-2

If you have it too low, it will now flow.  After the unloading and cold pull, is it still happening?

I would raise the Z, unload the filament, clip the filament, and reload.  After this, try again and post another image.  

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Chuck H
3D Printer Review Blog...
Posted : 16/05/2021 4:27 pm
Bill
 Bill
(@bill-2)
Active Member
Topic starter answered:
RE: First calibration. Do I have a clog somewhere?

Now resolved!

After about a dozen cold pulls, it was apparent that I wasn't getting that nice "conical" end point indicative of a clog free nozzle.  It was always torn and had geometric imperfections.

So, I changed the nozzle.  Now, everything is good with the world!

I guess the nozzle that was shipped with it had some manufacturing defects on the inside.  Made me sad for a week.  Now am happy!

Posted : 22/05/2021 3:49 pm
cwbullet
(@cwbullet)
Illustrious Member
RE: First calibration. Do I have a clog somewhere?

@bill-2

Great news.  Use a heat gun to clean the old nozzle.

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Chuck H
3D Printer Review Blog...
Posted : 22/05/2021 4:01 pm
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