Nozzle wear

[UK Chris]

Hi Folks,

I have a couple of printers and fitted them bot with E3D hot-ends around six months ago.  Good results mostly, but I noticed things getting progressively worse over the last two months.  Am using natural and white PLA at around 180 C.  Pretty heavy use - perhaps 6 hrs/day.  Printed parts began to fit very poorly.  Decided to design and build a simple calibration cube ( box really 40 * 40 * 40mm, with 4mm walls, no top).  The external dimensions of the cube were pretty much spot-on, but the width of the walls were 4.5mm.  I really can't understand this.  Anyway, did an extrude into free space and the resultant, cooled, PLA is around 6mm! (the original nozzles were 4mm).  Both machines are the same.  I could understand it if I were extruding something abrasive (unless white is abrasive).  Larry K has previously mentioned 'die swell' at about 5%, but 50%!!!

Have bought another couple of 4mm brass nozzles and a couple of hardened steel ones too.  I know brass is a soft metal, but should I really expect that much wear.  Perhaps you all should periodically do a free extrude.

Regards

Chris H

[UK Chris]

Hi again Folks,

Co-incidentally the new nozzles just arrived.  Fitted a new brass one and...  exactly the same problem - free air extruded PLA going through a 0.4 nozzle and extruding at about 0.7 - 0.75 !!!  Tried both natural and white - almost similar results.  Having looked at the extruded material and the new nozzle with a magnifier, the extruded material is definitely about twice the diameter of the nozzle hole.  So I can only conclude that the material is expanding to nearly twice the extruder diameter.  Has anyone seen this before?  Obviously, my nozzle isn't at fault.  Both neutral and white came from the same supplier. 

Regards

Chris H 

[Dwayne Williams]

I would look at your extrusion multiplier setting. If that's is not at issue take a look at nozzle pressure in the firmware. 

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[UK Chris]

Dwayne,

Thanks for that - I will.  Further research on the E3D reveals that I shouldn't take any notice of free air extrusion width anyway.  Apparently it's more revealing to build a test piece whos wall thickness is the same as the nozzle size ie 0.4mm.  I'll give that a try.

Regards

Chris H

[Michael Anton]

I believe this is considered normal, and the phenomenon is called die swell.  It shouldn't affect your printing results.  It could be that you are extruding too much filament, or that your machine has developed increased backlash.

Mike

[UK Chris]

Mike,

Thank you for your input.  I'll try reducing the 'multiplier' for the filament.  Backlash seems OK.

Thanks again

Chris

[Larry Knopp]

Hey Chris!

Yep, that's all about die swell.

I would recommend running through Triffid's advanced calibration (you most likely have already, but do it again), and really fine-tune e-steps for that specific material.  I have a number of profiles that I use for different materials.

Specifically, dial-in your solid infill to be baby-butt smooth on a 100% infill flat top surface.

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[UK Chris]

Hi Larry,

Good to hear from the 'Master' again - will re-do Triffids calibration again (haven't done it for a while) - Thank you.

As an aside; am working on a new type of material cooling.  It's very simple and effective.  Need to do more testing, then I'll tell y'all about it.

Thanks for your advice.

Chris

[Larry Knopp]

You too, Chris!

And "Master"...  LOL Thx

Look forward to hearing what you got going on!

As always.

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