The ABS Challenge

[ex-egll]

Well, now I have the machine built, ABL set up and PLA printing working fairly well it's time to work with ABS. My biggest fear was adhesion, but the Walmart hair spray is 100% effective at keeping everything on the bed. My problem comes from strange "bumps on the top surface of the print.
20150514_104230.jpg
Which on cooling went to this.
IMG_20150514_110626.jpg
I am assuming this is a temperature issue. I am using the .4mm nozzle with 3mm ABS. For temperatures I have tried:
Bed Temp 120 for first three layers then 100 for the rest
Extruder Temperature 240 for the first 3 layers then 200 for the rest

AND

Bed Temp 100
Extruder Temperature 200

Both settings gave similar results.

I am using Cura with a layer height of .1mm with 20% infill
Any pointers as to how to improve the print?

[Roxy]

In Slic3r, I think the first step would be to adjust the number of top layers to 5 or 6. But I don't think you can do that in Cura.

[voodoo28]

Isn't 200 a bit too low for ABS? Usually between 225 to 245 is where i print at, and never change the temps on the layers.
I agree with Roxy on the number of layers...bump it up.

[ex-egll]

In Cura there is the option to set Bottom/Top thickness, which I have as .8mm. With a layer height of .1mm this should equate to 8 layers. Should this be reduced to 5 or 6, or was your original intent to increase it to 5 or 6?

Will try a print at 240 throughout.

[usarmyaircav]

All my ABS prints at 235 (only 2 brands so far though), with a bed temp of 110.

[dunginhawk]

i have the same issue... its caused by the gaps in infil at 20%.. either up the infill, or easier yet, just make it 5-6 top laters, should fix it

[jasay]

I don't really use an Ultimachine, ABS or Cura, but have found the following page generally useful: http://support.3dverkstan.se/article...uide#pillowing.

They suggest that in addition to have enough layers on top, you may also need part cooling during the top layers.

[ex-egll]

I don't really use an Ultimachine, ABS or Cura, but have found the following page generally useful: http://support.3dverkstan.se/article...uide#pillowing.

They suggest that in addition to have enough layers on top, you may also need part cooling during the top layers.

Umm, hadn't thought of part cooling, another project lurks on the horizon.

I upped the layers to 5 i.e. 1.0mm top thickness, extruder at 240 throughout and bed at 100. I also increased the print speed from 50 to 60mm/second, I know stupid idea to change multiple things at once. I also used 3dsimplify to print the piece as well. The Cura print has improved, but using pretty much the same parameters on 3dsimplify I must admit to being very disappointed with the results. 3dsimplify on the right!

IMG_20150514_183158.jpg

More research needed. Thanks for the input.

[ex-egll]

I printed a couple more small items last night, then took the plunge and printed off a new X-carriage. It came out not too bad, there was slight lifting at one corner due to over confidence on my part (I forgot to cover the larger area of the bed with hairspray!). Overall the pillow effect has gone and the bridging seems pretty good.

IMG_20150515_081743.jpg

Settings used

Nozzle .4mm
Bed Temp 100
Extruder 240
Top/Bottom 1mm (5 layers)
Initial Layer Thick .2mm
Initial Layer Wide 100%
Fill Density 20%
Print Speed 60mm/s

I'm sure the above can still be tweaked further, but they produce a usable print. Now to find out why S3D does such a lousy job

[voodoo28]

Just out of curiosity...did change the preset in S3D to ABS? I know the multiplier for PLA is set to .90 and ABS is set to 1.
S3D is all I use and it seems to work better for me than the other slicers.