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dkightley
Posts: 2405
Joined: Tue Mar 10, 2015 4:09 pm

Re: Behavior of the first layer

So where's the difference to what i wrote?

I'll say it again..... there is actually no underextrusion. The only change is the height of the nozzle!!! Exactly the same amount of plastic is extruded.
Doug Kightley
Volunteer at the National Tramway Museum http://www.tramway.co.uk
Railway modeller and webmaster at http://www.talkingtgauge.net
parallyze
Posts: 372
Joined: Fri Jun 05, 2015 4:18 am

Re: Behavior of the first layer

dkightley wrote: I'll say it again..... there is actually no underextrusion. The only change is the height of the nozzle!!! Exactly the same amount of plastic is extruded.
I never said there was a visible indication of underextrusion. I said I'm not sure if the preview shows underextrusion at all.
(Do lines get thinner if playing around with the extrusion mutliplier? I've never tried).
parallyze wrote:I'm not sure if the g code preview shows underextrusion.
So... where's the difference between:
parallyze wrote: As you can see the preview always draws preview lines with a certain "thickness". I'd say it's just the way it is shown which may lead to think it's underextrusion. But if a layer is only 0,04mm (like it's the case with 20%) the preview somehow has to display this properly - hence the first layer
is drawn a bit lower.
and
dkightley wrote: As a first layer height under 100% results in the amount of plastic being extruded not being reduced, the simulation draws the layer height as the same as if it was 100%, but...and an important but...the simulated layer is drawn at a lower height so that the top is at the reduced height. The layer is consequently drawn part above the bed....and part below the bed.
AntonO
Posts: 5
Joined: Fri May 13, 2016 8:48 am

Re: Behavior of the first layer

Guys, I think I figured out what happens. The calibration procedure of my printer requires to apply much higher pressure to the calibration card to get a good offset ( In comparison with different printers I worked with before). So my nozzle was obviously too high, what caused separation of the first layer.
When i tried to regulate it using "First layer height " I could not make it close enough even saying that first layer height should be 80%-90% lower than it should be. But I have no idea why it start to print good when you make it the nozzle higher (like 200%). Some ideas?

Btw, the g-code preview doesn't display the under extrusion. You can see it if you would make extrusion multiplier very small, and the g-code preview wont change.

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