Perimeter Layers Not Adhering

[LHawes]

I just finished a print that I have printed many times but with this print noticed all of the (4) outline perimeter shell layers did not bond with the side of the print. Printing in Poly Max PC Max and an AnyCubic Mega i3 printer. Never had this problem before but am constantly adjusting the S3D settings and don't know which one might affect a print in this way. Layer adhesion is great vertically but horizontally they just separate like there's no adhesion at all. Mystified...

Could it be layer width? Currently set at auto .48 and 100 extrusion multiplier.

Perhaps print inside out versus outside in?

Any help appreciated.


account deletion

[airscapes]

My first thought would be outside in.. especially if there is an overhang.. I use inside out for most everything..

[LHawes]

Thanks for the reply - am trying a test print with inside out instead of outside in. Will report back.

[airscapes]

As I sit here peeling the perimeter off a print i stopped 3 layers in due to underestimation.. That could be you issue as well.. If your filament has changed diameter you may need to re calibrate.. In my case I just needed extrude a couple hundred mm of plastic while wiping the nozzle to remove whatever was in there reducing the flow..

[LHawes]

Changed outline perimeters from 4 to 2. Changed direction from outside in to inside out and got virtually the same thing

In the original photo/print 3 of the 4 perimeters were loose, only the first adhered. In the last print (with 2 perimeters) there was a single loose perimeter and similarly only the first adhered.

My outline overlap was 50% and I'll up it to 65% and see what happens. Maybe bump the extrude to 104. Also drop the outline under speed to 50%. Default speed is 60mm/sec.

Test again.

[LHawes]

As I sit here peeling the perimeter off a print i stopped 3 layers in due to underestimation.. That could be you issue as well.. If your filament has changed diameter you may need to re calibrate.. In my case I just needed extrude a couple hundred mm of plastic while wiping the nozzle to remove whatever was in there reducing the flow..

This layer happens very late in the print on an overhang. The rest of the print is perfect so I am thinking the flow is OK?

[airscapes]

try a second process for those top layers and slow it down your speed to 35mmS

[LHawes]

try a second process for those top layers and slow it down your speed to 35mmS

That's a great suggestion but it's not really the top layers, it's the perimeter layers which occur for a far longer time and distance than simply the top layers. The top layers seem to print fine but I will not ignore your suggestion. Maybe dropping the outline speed will serve the same purpose as your suggestion? Trying everything.

The baffling part is that it wasn't happening before. I have maybe 30 prints with no such problem, now it's there. I also have a print dryer and an enclosed print chamber but can't figure out what's different from previous prints.

[airscapes]

So each time I print something I create a factory file with a V1 and name the gcode similar. Then If I change something I create another factory file and increment the V#.
This way you can make tweaks to the process and if it goes bad, just open the factory file and you are back to where you started. Always use save as otherwise it may overwrite your good one.. I know this does not help you now but it is a good habbit to get into.. If you have a process that works well with and you are doing a new model that is similar, you can open the factory file of your previous model , delete the model, import the new one and save the file with the new name V1 and go from there.. I don't do much in the way with profile, just the process.. if you know what i mean.

Can you save your factory file now and upload it? This way we all can take a look at the model and the settings.

[dkightley]

Rather than messing around with multiple process that get you nowhere, stick to one process and cure the problem!

Is the separation happening on all layers? If not, as I suspect is the answer, then what is the bottom of the first layer like? Is it smooth...or is it ridged, showing the individual extrusions.

If not smooth, then adjust the GlobalZ setting (on GCode tab) by a negative amount by minus 0.1mm and reprint. Check the finish again. If not smooth, repeat until the finish is smooth.


If the finish is smooth and you still get separation, try increasing the Outline overlap, slowing the perimeter print speed down, or even raising the temperature a tad. One or more of these has an effect on bonding around the perimeter. But NEVER adjust two settings at the same time unless you're 100% sure what you're doing! If one change had the desired effect, how will you know which one it was?