Posts: 1
Joined: Mon Jul 27, 2020 4:03 am

First layer massive gaps

Mon Jul 27, 2020 4:47 am

using cetus mark 2.
Anyone can help? I don't understand why the 2nd layer is so much better.

Posts: 7
Joined: Sun Jul 12, 2020 8:24 pm

Re: First layer massive gaps

Tue Jul 28, 2020 10:24 am

Don't suppose you've accidentally set the first layer line width instead of the first layer speed?

Posts: 1
Joined: Thu Jul 30, 2020 5:32 am

Re: First layer massive gaps

Thu Jul 30, 2020 5:43 am

Getting the same issue, first layer height = 120, width = 150, still getting gaps. Second layer is great.

I have tried increasing the extrusion multiplier (flow rate) to a higher value but it makes no difference, I have tried values from .90 to 1.20 and it makes no difference.

I have looked through the generated gcode and can find no instance of M221 (flow rate) Does s3d not use this?

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Posts: 2237
Joined: Tue Mar 10, 2015 4:09 pm

Re: First layer massive gaps

Thu Jul 30, 2020 3:52 pm


It looks as if your nozzle is too far away from the bed when the first layer is extruded. It should squish the plastic onto the bed so there is some adhesion.

I would suggest working on a smaller square model to save plastic......adjust the Global-Z setting (on the GCode tab) in a negative direction by approx a half of your layer height. The value can go negative. Try a print and see what the difference is....repeat if necessary in smaller steps until you get a good first layer.


I can't tell if you have the same problem...but remember that increasing the first layer width will never get rid of gaps....increasing the layer width is like replacing a row of pencils with a row of sausages. Instead of 20 pencils, you can only get 7 sausages! Its not 20 sausages crammed into the same width as 20 pencils
Doug Kightley
Volunteer at the National Tramway Museum http://www.tramway.co.uk
Railway modeller and webmaster at http://www.talkingtgauge.net

Posts: 410
Joined: Thu Aug 30, 2018 1:23 pm

Re: First layer massive gaps

Fri Jul 31, 2020 9:31 am

Thank you dkightley as always for your great explanation! Just to add on, Simplify3D does not use M221 to adjust flow rates. The Extrusion Multiplier is an internal setting used by the slicer to adjust the E values for your print moves so the M code is not needed for this.

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