1 Topic by w_smith

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Topic: SD4 - Poor layer-layer adhesion?

I'm printing off a bunch of 'fidget' rings from http://www.thingiverse.com/thing:188275 ad most of them are turning out OK, but I'm getting what looks like poor adhesion between layers, which causes strings to cross the inside of the circles:

http://geekho.com/push/RingStrings.jpg

You can also see that the rings aren't solid, though I've set RH to 100% fill concentric.

Is this under-extruding, or too low a temperature, or something else?

I'm using Octave white filament, though it did the same thing with Monoprice green.

Extruder feed and flow are calibrated, and the calibration cube comes out to about 0.43

What else am I doing wrong?

Thanks!

2 Reply by grob

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Re: SD4 - Poor layer-layer adhesion?

If that's an SD4 stock extruder I'd recommend aiming a little higher with the wall thickness: 0.48-0.50 (it has an 0.40mm nozzle)... Also try a finer layer height (say 0.2mm?) to get a bit more squish each layer.

Regarding the unfilled rings, the ring looks about 2 and a bit perimeters thick - you could either change the extrusion width to 1/3 or 1/2 of the ring's thickness (if convenient) or change the thickness of the ring so it adds up to a whole number of extrusion widths.

Could be temp too low, or a partially blocked nozzle, but save that thought for later... smile

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3 Reply by w_smith

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Re: SD4 - Poor layer-layer adhesion?

I'm already at 0.2mm (0.1976), I'll try turning up the extrusion width.

I'm using 210C for the head temperature, which has always been the default, but Monoprice specifies 230C while Octave says 210-250, which is why I was wondering if I'm a little cool.  Of course, that's not calibrated, so a setting of 210 could be just about anything.  8*)

Thanks!

4 Reply by jagowilson (edited by jagowilson 2015-04-25 14:00:55)

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Re: SD4 - Poor layer-layer adhesion?

I think you're printing too far from the bed. Print a 40x40mm cube, just the first layer, and post a picture. The gap is a slicer issue - your wall thicknesses should ideally be a multiple of your extrusion width for perimeters.

5 Reply by w_smith

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Re: SD4 - Poor layer-layer adhesion?

Swapped out the glass with something flatter, so that might help some, now ready to print the cube again.

Looks like the first layer height on all my print settings in Slic3r is 0.35mm, so I guess it doesn't matter which one I pick...

6 Reply by jagowilson

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Re: SD4 - Poor layer-layer adhesion?

Try 0.2963 for all your layer heights.

7 Reply by w_smith

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Re: SD4 - Poor layer-layer adhesion?

OK, here's the first layer (at 0.35mm):

http://geekho.com/push/FirstLayer_01.jpg

Looks like the bed's not quite flat, I've raised the 'bad' corner a bit and will retry as soon as it comes back up to temp...

I've resliced the calibration cube for 0.2963 on all layers, so I'll use that...

8 Reply by w_smith

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Re: SD4 - Poor layer-layer adhesion?

Tweaked the bed leveling again, gonna retry...

Oh, and it turns out this Octave filament is really precise at 1.70mm, so setting up for another calibration cube using that filament diameter, 0.50mm extrusion width, and 0.2963 height on all layers.