ABS Layers Separating

[eric-lester 1]

I recently got a fair amount of ABS, and I've been really disappointed as it's been nothing but trouble. I can get the prints to adhere to the bed well enough (with a light coating of hairspray and plate at 110C), but my issues come from adherence between layers. For example, I recently designed a stamp with my school's logo and put my name on it:

You can see that the phoenix and letters are all raised off of the base. I printed overnight with 100% infill and woke up this morning to find this:

Based on the little dusty bits of plastic strewn about, it looks like it completely failed to adhere to the ABS layers beneath it. I don't really understand why, but this is obviously a serious issue--and this isn't the first time it's happened. I've also seen it happen with infill or support. For example, I designed a small box with 20% infill and printed. Here's a look at the infill and final print (ignore the warping--a brim takes care of it for me).

Obviously, something is going on. I've tried fans 100%, 50%, and off...temperatures from 225C to 260C with nothing seeming to fix this particular issue (that is, no combination of settings actually closed the box. Printing this model in PLA yielded no issues--the infill was solid and the top closed smoothly.

I really need help...this is crippling, infuriating, and just obnoxious.

 

[pm_dude 27]

Hi Eric,

I'm no expert in ABS prints but since it is requiring to print at higher temp and usually with less fan I would recommend to use higher density on the infill and print slow.

 

[eric-lester 1]

I've been hesitant to go below 50mm/s, though I might if this persists. Could material flow compensate a little as well?

 

[pm_dude 27]

The best quality prints are mostly around 30mm/s because you can print colder and colder mean the string of filament is more solid and will resist better to bridging.

 

[zoev89 73]

Abs does not bridge as well as pla. Add more top layers and increase infill. I use .8 mm top with .1 layer height and 25% infill. At .2 layer height i would try 1mm top layer. Do not drop print temperature to much otherwise you get layer adhesion issues. I print at 250 degrees or even at 260 for faster results. You can try some fan but not above 50% i would recommend.

[eric-lester 1]

Abs does not bridge as well as pla. Add more top layers and increase infill. I use .8 mm top with .1 layer height and 25% infill. At .2 layer height i would try 1mm top layer. Do not drop print temperature to much otherwise you get layer adhesion issues. I print at 250 degrees or even at 260 for faster results. You can try some fan but not above 50% i would recommend.

 

Thanks for the tip on top layers. It solved the issue with the top not closing correctly...but that still doesn't fix my issue--and it may be one not related to the filament. That is, when the infill is being added, it's going down onto a flat layer of plastic that's had much more time to cool. As a result, it isn't adhering correctly on the first layer. The next layers of infill then just adhere to the faulty first layer. Take a look:

 

[zoev89 73]

Strange I have not seen such a behavoir with the black um abs that i am using. Last weekend i printed a disk of 20 cm diameter without issues. For such an object the bottom layer had plenty of time to cool. What is the brand of filament you are using? What is the layer height you are using? Try .1 or .2 height. When the filament is hot enough without cooling it will fuse unless it is contaminated with oil or something. Is your flow good enough? I had a partly clogged nozzle and then i also got crums on the object.

[eric-lester 1]

I'm currently using .1mm hright and Form Futura filament. The tolerances and color constancy seem good, so the quality doesn't seem to be an issue. I recently cleaned the hotend as well. (Fully disassembled it and found it was clean) I have an idea as to what it might be, but I'll try myself before posting back.