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chuckmcgee

First layer squish

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Since I have owned two Ultimaker 3 Extended printers in the past several months, I have an almost predictable issue where my first layer is too squished to the bed, causing there to be a minor single layer flare out on the first layer which at times has affected the quality of the surface of many of my prints - especially ones with dual extrusion lettering.  I can send pictures if no one is familiar with this, but I have heard of others having the issue (and can't find those references now, of course).

 

I have done countless manual and automatic bed levelings to no avail.  Wondering if there is another approach?  Maybe be a little looser on the manual bed leveling to the point where I can barely feel the calibration card?  Maybe there is a z-offset I could change?

 

The issue isn't a show stopper, but my CR-10 outperforms the UM3E for the quality of the first layer and that feels wrong to me given the quality differences in the two printers.

 

Thanks.

 

Here are some examples from a print I did in December.  The model was a phone case and the sides were a 45-degree chamfer.  You can see, even had I modeled a lip to be more accommodating, I am losing integrity between the lines of the lettering.

 

 

IMG_0081.jpg

IMG_0089.jpg

Edited by chuckmcgee

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Short answer: I usually set "initial horizontal expansion" to around -0.25 to fix this.

 

The most common name for this is "elephants foot" or I sometimes call it "micro brim".  The problem is that "elephants foot" refers to another phenomenon as well.

 

If you level such that you have no microbrim then your part won't stick as well.  This is fine for small parts (less than 3cm in X and Y) but can be a problem for parts >= 10cm in either x or y.  And having a part come loose can really cause a major headache and destroy the print head of the UM3 sometimes (that's called a "head flood").

 

So you can play it safe (recommended)  and level the way you are doing now and use "initial horizontal expansion" to correct.  Or if you aren't afraid of ruining your print head when the part comes loose you can just level higher up.  I never do autolevel and when it's printing the brim or skirt I just adjust on the fly.  I turn the 3 leveling screws exactly equal amounts until the brim is .4mm wide (if I want no microbrim) or nicely squished (if I want the part to stick really well).

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This is very helpful, gr5.  Thank you.  I get the need for some squish and did know it as elephant's foot.  Good reminders.  I am comfortable with the adjustments on the fly and will give that a go.  I also find it interesting that you don't do the auto bed leveling.  That makes perfect sense!  I often wondered what good manual adjustments would do, assuming you are in the ball park, if auto leveling would correct your manual leveling adjustments.

 

I will also give the initial horizon expansion a try.  Is that set in Cura or on the printer?  (I could of course Google the answer, but asking here).

 

Thanks again

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Initial Layer Horizontal Expansion is a Cura setting. It's an advanced one, so you may have to go into the configuration dialog and make that setting visible before you can adjust it in your prints.

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 Thank you. I did find it before and have already done a couple test prints. I try to 0.3 and it made quite a difference. I also turned off the automatic bed levelIng.  

 

 Thanks for the suggestions and help! 

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When using cura I almost never make settings visible anymore - I just type one word in the search box and it shows only relevant settings.  So for example I might type "layer" to find and change layer height or "line" to adjust the line widths or "infill" to adjust my infill percentage.  There's just too many settings to show them all.

 

And if I want to quickly review what settings I overrode I click the star in the profile/quality area.  That lists in italics the things I overrode.

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