Warped layers on the edge of print (not the base)

[modaniel]

Hi,

I am getting some problems with layer warping on the edge of my print (see the attached photos). I am printing with ABS at 240 degrees.
There were no problems with bed adhesion i.e. the print did not lift from the bed. The printer is a custom reprap-based printer and is surrounded by walls to isolate it from air currents

Also, you can see a shift in the printing pattern in the horisontal plane about one third of the way up the structure. What could cause this?

Any ideas of what I could do to avoid this?

cheers, Daniel
IMG_20170502_125733.jpgIMG_20170502_125718.jpg

[curious aardvark]

it's standard abs behaviour.

It's not enough to block breezes, you need to completely enclose the print area and let it heat up before starting to print.
Unless an abs model is kept at the same temperature during printing and can then all cool down at the same time, the layers will shrink individually, causing weak prints and cracks.

The other thing you can do is print slower. It helps a little.

But the best way to avoid this is to simply not use abs.
Unless you're printing it in a heated print volume, it's weak, cracks, warps and is generally a bastard to work with.

pla and pet-g is the way to go in an unheated print volume :-)

[modaniel]

Thanks for the advice, I suspected as much on the material properties. Setting up a heated volume might be tricky.

The reason I was printing with ABS is because of its processing abilities with acetone. I am looking to make an airtight part. Even solid prints are not truely air tight. I know that I can smooth and fill gaps with acetone processing and ABS glue.

I can disolve PLA with MEK or Tetrahydrofuran, but can it be smoothed and also flow in a similar way to disolved ABS?
Does it become solid when the solvent dries?
Can I make a PLA "glue" like I can with ABS or perhaps use abs glue to make the object airtight?

I tried disolving PETG with choloroform. All I seem to get is a tacky mess. Perhaps MEK works better?

[wirlybird]

What are your settings? Speed, layer etc.

You can cool down a bit to 230. Turn off any part cooling fan if there is one. What brand of ABS?

You are getting irregular cooling of the part. This can be influenced by a bunch of things like infill, supports, wall thickness etc. Protecting the print from drafts , even small ones like air vents, ceiling fans, will help. Having the printer in a room that is relatively warm will help also and a full enclosure is the most hassle free but not mandatory in most cases. Maybe even a heat lamp shining down on the top of the printer but not to close could help keep the air around the printer a little warmer.

ABS is very doable but it does take some work and reading up on.