Help with Archimedean Chords PLEASE!!  

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edged.in.starlight
(@edged-in-starlight)
New Member

Can anyone please give me a little help figuring out how to get "chords" to stay down for the first layer. I am printing a cylindrical file and am having nothing but issues with this first layer pattern. Yes, I've tried "concentric" and it looks alright. I have tried varying the print and bed temps, print speed, z-offset and printing both with and with-out (my general preference) glue. Haven't tried hair spray yet because glue was had enough to get off the bed between printing attempts.

What occurs is that the skirt goes down fine. As does the outside perimeter. Once it starts on the "chord" fill pattern it gets about 6 loops before it starts to peel away from the bed. Just curling up on itself. every 2 loops or so the nozzle seems to push the curl back down for a loop, but then it is right back up. Below are attached pictures and a video of this in action. Also included are my current printing settings. Thanks in advance for any constructive help.

layer height: 0.15           1st layer height: 0.35          solid bottom layers: 3

bed first layer temp: 65            extruder first layer temp: 215

infill speed: 80mm/s              solid infill speed: 20mm/s             1st layer speed:20mm/s

1st layer extrusion width: 0.3mm        infill/solid infill:0.45mm           perimeters:0.3mm[video width="720" height="480" mp4="https://forum.prusaprinters.org/wp-content/uploads/2020/08/20200808_181501_1.mp4"][/video]

 

 

Posted : 09/08/2020 3:23 am
h.waibel
(@h-waibel)
Trusted Member

Hi there,

quite a few issues at once seem to combine to your catastrophic results...

Although not a knowledgable as a lot of other people her, I will try and give a few hints.

Overall it looks as mainly a bed adhesion problem to me, so let's go through the usual troubleshooting routine for those:

Misconception number one is probably the glue thing. Counter-intuitively glue is not used to glue things down but to provide a separating layer between bed and printed object. The same goes for hair spray or glass cleaners. They form a thin layer between the bed and the object that keeps them apart from each other. Generally used for stuff that sticks too well, like PETG or TPU and therefore it is no solution for first layer adhesion problems at all.

Then of course the whole standard stuff about first layer issues, scrub bed with dish soap and HOT water, don't touch it and avoid alcohol based cleaning to prevent a nice thin layer of grease getting spread evenly over the sheet. Also revisit your Z-height, see: https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-assembly-and-first-prints-troubleshooting/life-adjust-z-my-way/

 

Lastly I don't understand why you chose such a high first layer height. I'm not enough of an engineering mind to understand that and hope to learn something from that.

hth

Hansjoerg

Posted : 11/08/2020 1:31 am
vince.calhoun
(@vince-calhoun)
New Member

Howdy - One trick I tried after seeing Thomas Sanladerer's Mini build video is making the first layer WIDER.  In his video he has a print that loses surface adhesion (he's using the wrong print bed material is the TL;DR), so he does this.  I tried it with some Nylon CF I was having issues with - it was bowing off the plate... and it worked quite well.. maybe too well.  🙂

Hope that helps!

Original video:

 

This post was modified 1 month ago 2 times by vince.calhoun
Posted : 14/08/2020 7:28 pm
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