Thickness of extrusion

[Mjolinor]

My Wanhao is confusing me again. I changed the extruder from the normal one with a pinch wheel with fixed pressure that it came with to this one: http://www.thingiverse.com/thing:147518

My nozzles are 0.3mm and the extrusion thickness prior to changing was 0.6 mm, once changed it is coming out at over 0.8 mm and I have no idea why, same plastic, same temperature, same everything apart from the roller now applying pressure from a spring instead of being fixed.

Makes me think that this is going to affect the printing but I can't see any difference on the finished prints.

I suppose if the new extruder is not pushing as hard onto the toothed stepper gear then that means that the diameter is effectively bigger and more plastic will get through maybe.

Any thoughts?

[curious aardvark]

hang on - if you're using a 0.3mm nozzle - why are you extruding at double the width ?
I use 0.4mm nozzles and extrude at o.4mm - I know this because a 2 shell object is exactly 0.8mm thick :-)
I'm making cutters with moulds at the moment and the cutting end is 2 shells and around 0.83mm thick - which is close enough for me

I know you're on linux - so what slicer are you using, and why doesn't it let you adjust your extrusion width ?
And why would you have a 0.3mm nozzle and then try and squeeze that much plastic through it ?

I suspect I'm more confused than you are :-)

[Mjolinor]

Extrusion width is related to how fat it is when you are printing. I am talking about loading filament and letting it dangle (the filament that is).

Dangle yours and measure it.

Green is 0.8 (new extruder), transparent (Ha) 0.6, is old extruder.

[curious aardvark]

And I'm talking about what matters. IE: the width that the machine actually lays down when it's printing.
But yeah you definitely need to lower your extrusion %.
And is this with pla or abs ?

The bit of filament s3d spits out prior to starting printing and it squeezes it out pretty fast - is between 0.5 - 0.6.
The bit that just oozes out when you heat the extruder is between 0.25 and 0.4.

I'd say you've got some weird issues there :-)

[Mjolinor]

ABS, I don't do PLA.


It does not seem easy to calibrate this. I just extruded yards of the stuff from both heads and it certainly is the Mk8 versus original extruder so it can only be the virtual diameter fixed by the pressure on the wheel.

It is most odd methinks.

Like this:
http://reprap.org/wiki/Volumetric_Dimension_settings

[curious aardvark]

yep very odd.
the klic-n-print has dangling bits at 0.4 and extruded at 0.5 - from a 0.4 mm nozzle.

But that's with good pla - can't stand abs :-)

I'm thinking you've maybe got damp abs and it's expanding a lot more than it should.

[Mjolinor]

But it doesn't do it with the other extruder so can't be damp or at least the damp must apply to both. It is the difference that is puzzling. Even more strange is the fact that it prints the same with either extruder.

[Davo]

I don't see how you can be putting out something that is twice the width of your nozzle unless there is some backpressure to deform it. If you push more through faster, you should get longer output, not thicker.

[Mjolinor]

Worn nozzle and water are the two immediate things that spring to mind I suppose.

I will check the nozzle, I think it is time to make some stainless ones.