Cracks in ABS prints  

Re: Cracks in ABS prints

Hi,

this is typically what happens when ABS cool down too quickly. The most effective way to fix that is an enclosure that keep the warm air.

Re: Cracks in ABS prints

I already turned the extruder temp up by 15 degrees total but this didn't make a difference. It's now printing at 255 degrees.
It actually made things worse.
You need to eliminate thermal expansion as much as possible, so you need to print at the lowest possible temperature. Try 230-235 instead of 240. You also need to keep the output hot, so set the bed to 100 or 110 degrees.
Also, don't use linear types of infill. Try honeycomb.

But, to be honest, I don't think you will manage to print such large model from ABS without enclosure.

Re: Cracks in ABS prints

With ABS you need an environment enclosure. The Prusa I3 Mk2 open frame printer is not good with ABS unless you do so. Prints warp and lift and upper layers need work. Try Simplyfy3d as your slicer and you can do better. ABS is on its way out, look to new materials coming out, ie PLA Plus.

Re: Cracks in ABS prints

I built an enclosure around mine using a sheet of 1/2" rigid foam insulation cut into 2'x2' squares and taped together. It made a huge difference in printing ABS. I also switched the default warm up G-code in slic3r so that the bed warms up fully before the hotend starts to warm up. It adds a few minutes to the print time but nothing significant and it helps heat up the enclosure a bit before starting. If an enclosure doesn't help, a draft shield around the part might also help.

I disagree that ABS is on the way out, although things like PLA Plus or PETG may be gaining popularity, ABS still has it's place. I personally use it anytime I need to be able to solvent weld multiple parts together. It's also cheaper than PETG or PLA+ per cm^3.

What brand ABS are you using? I've had good results with larger parts using Makergeeks ABS and a 5mm brim.

Re: Cracks in ABS prints

There are cheap and easy ways to have an enclosure even a black plastic bag over it prints a lot better. There are people using plastic tubs with good results.

If the plastic bag over the printer doesn't work try printing as cold as possible. I mainly print ABS and just started printing in other materials but always go back to ABS. Also if you print it cold you won't get a lot of layer strength in the print but if you brush some acetone on it will make it solid

Re: Cracks in ABS prints

thanks for the tips. an enclosure is hard because i barely have room already for the printer.
I use ABS because this is very heat resistant and i use it for cosplay parts that i wear in the sun and need to be black. (thus soaking up heat).
I obviously transport these in the car as well and sometimes leave some parts behind in the car.
I know PETG is a other good solution, but does apparantly not easily bond parts to each other. Exept with super glue, but super glue has a very easy breaking point.
ABS can be "melted" together.

Re: Cracks in ABS prints

The bad layer bonding could also be a result of water absorbed from the air in your ABS filament. If you hear small pop and cracks from nozzle when extruding, this is a sign of water in the filament.
The moister can be removed by heating up the ABS filament to 60-65 degree C for a least 2 hours.

I have good results "heat treating" my filament if it has been out of the plastic storage bag for too long.

Re: Cracks in ABS prints

> this is typically what happens when ABS cool down too quickly. The most effective way to fix that is an enclosure that keep the warm air.

Well, the most effective way to fix it is to avoid ABS altogether 🙂
For many functional prints PETG is a great option.

Re: Cracks in ABS prints

You might try one of the high temperature PLAs like Raptor PLA. Much more forgiving to print than ABS and has similar resistance to high temps.