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ABS - What am I doing wrong?

Posted by enrapha 
ABS - What am I doing wrong?
December 12, 2013 10:02PM
No matter how many curls or situps I do I just cant get that six pack! hah just kidding

I have some white abs plastic from makerstoolworks.com I recently built an enclosure for my reprap and allow it to heat a good 45-60 minutes before running a print. My hot end temp is 240 (although I have experimented with temps down to 220) and my bed is at about 115(anything lower then that and it curls horribly!) I have used katon tape, superglue, elmers glue ect and have found that the abs juice is the best bet. easiest to remove and makes it stick. I also make my juice strong as well to make it stick better. I get good adheasion on the first layer and everything is level. I check it every time before a print(both hot and cold). and my slic3r settings are all set to default. I'm using the mono mendel.

To my point. I just cant seem to get this abs to stop warping on the corners... any suggestions?

open | download - 20131212_215104.jpg (522.2 KB)
Re: ABS - What am I doing wrong?
December 13, 2013 05:10AM
Kapton tape on glass and a single layer of ABS juice applied to the tape with small paintbrush with bed at 110 deg C.

Turn bed down after half a dozen layers. 100 deg C first, another few layers then 90 deg C, ditto 70 deg C, then off.

Hot end set at 235 deg C. Also increase number of loops to 7 or 8.

Edited 2 time(s). Last edit at 12/13/2013 05:14AM by dave3d.
Re: ABS - What am I doing wrong?
December 13, 2013 08:15AM
A brim would also help.

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Re: ABS - What am I doing wrong?
December 13, 2013 07:50PM
I have done a lot of testing for ABS and sticking. My printer always curled up the corners at 110c and I found 95c to be the sweet spot for me. Also I use PET tape very lightly sanded (just enough to give it a tooth) and ABS juice wiped on with folded paper towel (too much can be a bad thing). And the most important thing I found and I have not heard mentioned before is to make sure the first layer is pushed into the glass hard, this means a very thin first layer, this means lower your nozzle. Now, the smaller the nozzle diameter the more critical this is. I use a .35mm nozzle and with the bed hot and nozzle up to print temp (this must be done hot as the parts expand with heat) I can slide a single sheet of 20lb paper (standard light weight copy/printer paper) under the nozzle with light force. Sometimes the first layer is so thin it's nearly transparent (this is just a hair to low) but will continue and layer 2 is fully visible.

I think making the first layer push into the glass (no matter the film or solution you use) is a major factor in getting prints to stick properly. All of my prints have a little lip on them where they were stick to the glass, this is due to the extra squeezing that happens as it flattens out thin.

Of course good quality ABS is also key. I like Ultimachine and Lulzbot filament best so far.

Good luck!
Re: ABS - What am I doing wrong?
December 13, 2013 08:38PM
likely the plastic will still cool and curl. you can add a skirt around the first 8-10 layers of the object. this should prevent the majority of the curl effects from the solid layers.

skirt feature should be in slic3r, and in skienforge, and is in cura. also their is a brime feature that extends part out at the base layer providing more surface area that grips. It produces sharp parts that need exacto knifed afterwards.

the basics still apply, first layer needs to be really put down good to stick well. you could increase flow rate for base layer, or lower base layer hieght. these also will increase sticking to bed. hope this helps a little.
Re: ABS - What am I doing wrong?
December 14, 2013 11:58AM
use hairspray on your build surface, have the bed at 110 for the first layer then drop it to about 80-90. Set up your slicing software so that the first layer is half your print layer thickness.

Keeping the bed a 110 will actually make a weaker bond to the bed, and will cause the side walls of the print to distort and curve inward. DO NOT turn the bed off completely, If you are running a bigger print, the part will release from the bed.

Edited 1 time(s). Last edit at 12/14/2013 12:00PM by Dirty Steve.
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