ABS delamination from heatbed

I'm printing on Prusa mendel i3, 3mm ABS, 230-240 degrees hotend, PVA mix for adhesion.

I'm facing delamination on models with big square.

First i've tried 100 degrees heatbed (default setting).
As it stickes bad, i`ve started to play around with bed temperature.
The PVA mix seemed to be the best adhesion soluton for me
(the only way to pick off the model - is to heat the bed back to something
around 120 degrees and hook it with a knife).
But the outer edges of the model still wrapping up after few decades of print layers.
I've tried 120,122 degrees (120 - seemed to be the boundary where ABS starts transition into
ductile state).
Here is the result:
[itmages.ru]
[itmages.ru]
[itmages.ru]
[itmages.ru]
Outer edges still wrapping.

Then i've tried to keep the temperatrure high (122 degrees) only when printing first two layers,
to increase adhesion and then lower it to 100 degrees.
Thats the result:
[itmages.ru]
Wrapping seemed to be even bigger.

Any advise?

Ive found you need to keep the heat up through the whole print.
I use 110deg bed for larger prints.
Have you tried adding a brim around the print, it helps to keep the heat in the part and helps it stick to the plate.
Also maybe try keeping the heat in by enclosing the printer to keep the heat in. Mzybe a large cardboard box to try it.

Ive also found kapton tape has given me better bed adhesion.
But before that used abs juice. Abs dissolved in acetone and got reasonable results.

Good luck
Gordon

Use brim, that should help alot.

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gordonendersby
Have you tried adding a brim around the print

I'll try and write about results.

And what about blowing on the model?
I see almost everyone uses fan to blow somewhere down to the nozzle area.
I've tried, and it seemed to dramatically increase delamination between layers...
should i use it?

Those people with the fan are printing in PLA and require a fan.
For ABS adding a fan on the extrusion will hurt your performance greatly.

You have two issues: adhesion to the bed and delamination.

Adhesion is a matter of getting the right material on the bed surface and leveling the bed accurately. I like kapton tape and rarely have adhesion issues when printing ABS on clean kapton tape. I wipe the bed with acetone before printing (don't use finger nail polish remover- it contains stuff like glycerin that won't help parts stick) I set the bed temperature to 105C. My bed is a 6.35mm thick aluminum plate so it spreads heat from the heater very evenly. You must make sure the bed is level and properly zeroed so that the plastic coming out of the nozzle is squished down on the kapton tape everywhere. Sharp corners in the printed object will tend to pull up off the bed. Use a brim (5mm wide is usually sufficient) to help hold them down.

Delamination is solved only one way: put the printer in an enclosure that gets warm while printing. I have found that 40-45C during printing is sufficient to prevent delamination. In my case, the print bed heater produces enough heat that the box achieves that temperature without any additional heating.

Sorry for being away for so long.
Performed a lot of trials and adjustments.
For now, printing with following conditions:
Environment: hermetic box from acrylic glass;
Adhesion: PVA/water 1/10 mix, brim 10-20 loops;
Heatbed: 110 C (for first 3 layers), than 70 C;
Hotend: 245 C.

Hermetic box not actually helping much: it keeps temperature inside around 30 C.
But I'm still using it because it keeps smell and toxics inside.
PVA/water mix doing very well. So, to tear off model I have to use sharp knife and heat the bed to 110 C again.
I found out that to 110 C makes adhesive material soft, so it doesn't matter which one to use: if I'm keeping 110 C during all process, it delaminates from bed almost completely. But, if I cooldown heatbed a little (to around 70-80 C), delamination is less expressed.
What for delamination between layers, I've been experimenting with hotend temperatures and find that values like 245-250 C considerably reduces it.

Still, with all that measures internal stress in the detail seemed to be so high that it continues to delaminate both from heatbed (a lot) and between layers (much less, but still...).
[imgur.com]

Now I'm starting to think that it may be a problem with my ABS filament itself.
Maybe, it is of bad quality?

Any other suggestions? Solutions?

First thing I notice is the space between the lines in the rim. looks like under extruding and would explain that the brim doesn't help as much as it could. Did you measure the average filament width and entered that value in the slicer?

Why the PVA/Water mix, why not the ABS/Aceton?

PS I'm seeing warping and not delamination?

Edited 2 time(s). Last edit at 02/28/2016 08:37AM by Frans@France.

What does the first layer look like? Can you take a photo? Also, try blue tape on the bed. Glass alone didn't work out well for me, but with ABS it would seem that it would never work.

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Frans@France
First thing I notice is the space between the lines in the rim. looks like under extruding and would explain that the brim doesn't help as much as it could.

No, it happens time to time, mostly when after I calibrate Z, it autohomes right before start printing and miss just a little bit, which is enough to make first layer's tracks not as wide as they should be. And of course, when it happens I'm restarting the print. As you can see on other photos, it still delaminates when there are no gaps. So, I'm talking about delamination with good solid brim, which I'm unable to tear off easily.

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Frans@France
Did you measure the average filament width and entered that value in the slicer?

Either I'm missing this step, or doing it in some other way, not knowing how).
How to measure average filament width and where to put it?
For slicing I'm using Cura 15.04. For good brim overlapping I'm setting initial layer thickness to 0.17 (instead of usual 0.20) and initial layer line width to 155%.

My other relevant settings are:
layer height: 0.2mm;
filament diameter: 3mm;
flow: 100%;
nozzle size: 0.4mm.

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Frans@France
Why the PVA/Water mix, why not the ABS/Aceton?

Mostly, because of smell.
But secondly, as I've said before, even PVA/water sticks very hard.
So I don't think acetone would make any difference.
If you think that I should try it anyway, I'll try.

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Frans@France
PS I'm seeing warping and not delamination?

Actually, I think yes.
As it seemed to me, the model warps so much, that it delaminates both from heatbed and from itself, if you may say so.

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Montiey
What does the first layer look like? Can you take a photo?

Will shoot on the next print.

I noticed that when my models delaminate more than what they used to that often my filament calibration is off causing too much plastic to be extruded.
Similar story for speeds and layer heights.
If I use my standard 0.3mm nozzle and go over 0.22mm layer height the result is disaster.
And if the speed in relation to the part is not a good match it peels as well, but I try to explain this a bit better:
A small part like the 3Dbenchy printed quite fast will stay hot throughout the print in the parts where it matters.
So here you only fight with the general layer time VS sagging/ugly looks.
But if you print something big with a lot of infill the perimeters can cool down quite bad and layer adhesion can suffer - if your perimeters peel apart but the infill won't you know why.
There are workarounds though like for example:
a) infill first and then the perimeters, but that does not always work on complex models.
b) use at least 4 perimeters and lower the speed for them, if you can incremental so the outer perimater is the slowest.
c) try to decrease wall thickness and infill amount - read below for example.
A thick 6mm wall will see two sides of perimeters with the infill between them.
If you have problems here it often helps to re-design the wall to be actually two walls with a tiny gap 0.1 or 0.2mm.
This way you avoid the massive infill and have seperated the object of offence into something that is less prone to peeling.

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stuff

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Frans@France
Did you measure the average filament width and entered that value in the slicer?

Either I'm missing this step, or doing it in some other way, not knowing how).
How to measure average filament width and where to put it?
For slicing I'm using Cura 15.04. For good brim overlapping I'm setting initial layer thickness to 0.17 (instead of usual 0.20) and initial layer line width to 155%.

You had to enter the filament diameter in the slicer (3.00) but the best thing to do is to measure the filament at a few places for a few meters and then calculate the average width. that average you enter into the slicer. You can also not do that but look at the layers and use the flow setting to increase\decrease extrusion to match your filament width.

I never bring the bed down to 70C during printing as the ABS object would pop off the bed, but those settings depends on your bed bonding techniek used. I also don't not use water near ABS