Poor adhesion between layers and perimeters

I'm having issues with adhesion between layers and perimeters. The attached picture shows a part that I broke apart and you can see the two laywers that separated. Notice that the perimeters are separating on the same layer that broke.


My machine is a home built Mendal Max 1.5, with a ramps controller, Marlin firmware, Slic3r, and Pronterface. I'm currently running 3mm ABS with a .4mm nozzle.

This was done at 250c hot end temperature, .25 layer height, bed temperature of 110C
I've tried a number of things to eliminate it:
- lowered the layer height - this helped a lot, but it does not seem like I should need to go lower than .25 for good adhesion
- increasing the hot end temperature - This has helped some, but 250c seems fairly high
- re-calibrated my steps per unit (I seem to be around .003mm tolerance now) - this helped a little
- enclosed the printer (got the interior up to 35c) - this did not seem to help
- raised the bed temperature - this not not seem to help
- lowered the layer height - this did help
- tried other slicing programs - this did not help

Any new ideas for me to try?

One thing not mentioned was speed.
How fast are you printing these in mm/sec
Normally I stay around 40-50mm/sec for good quality.

hmm, I'm not sure about the speed, I'll check when I get home. It does not seem very fast. That part is less than 2in long and about 3/4 in high and takes about 15-20 minutes to print. I guess it would not hurt to just try one really slow and see how it comes out.

A little advise, 35 degrees is not enough to prevent warping with ABS, put a 150-200 watts light bulb close to the part, it helps with keeping a 70 to 80 degrees ambient temperature around the part. I use this method all the time and I can keep my built area about 90 to 100 and I have never suffered delamination.

My speed was 60mm/sec so I lowered it to 30 and the print was much stronger! That is the first adjustment that actually made a significant difference on the strength. Thanks Floyd!

I'm still going to mess with the ambient temp and see if that helps as well.

Thanks!

No worries!
I find that printing too fast with ABS creates a ton of issues with layers bonding.