Compensation for accurate prints using ABS

[Dom186 0]

I have been having trouble getting reasonably accurate prints using the Ultimaker ABS in the Ultimaker 3. PLA seems to work without a problem and is usually slightly undersized within 0.2mm which is great when for fitting components. However the ABS seems to be giving me trouble as outside features are oversized by as much as 0.4mm or more and holes are undersized by up to 0.7mm which is far outside of advertised printing tolerances for the Ultimaker 3. That’s over a millimeter tolerance! As a result I have been compensating the designs heavily but I wish to fix this at the printer level.

 

I have spent two days trying to fix this problem at work without much success. I printed test prints to determine the linear thermal expansion coefficient for Ultimaker ABS which is inconveniently left out of the data sheets. I measured it amazingly low at like 4 x 10 ^ -5. Then I also tried reducing the excess size using horizontal expansion but can’t quite get it right. I’m still in the process of tuning and am getting closer each time but I was wondering if anyone else has ran into this specific problem with the Ultimaker ABS and if there is another way to compensate to improve the accuracy.

 

On this specific printer I have also noticed that the Y axis is typically measuring lower than the X axis by 0.2 mm so if anyone has a solution for that problem that would be great also.

[Dom186 0]

So I screwed up and I accidentally had adjusted the horizontal offset for the first layer rather than the whole print. I have been able to get the print to +-0.8mm on a 20mm cube. I have yet to test internal dimensions so I made an complicated part to test  internal and external dimensions with of various sizes that I will be comparing different filaments with.

 

After this I this I will try and dial in my first layer horizontal offset and I should be good.

 

My current settings for ABS is to scale everything up by 100.25% and -0.15 horizontal offset. I'm currently using a 0.4mm extruder.

Edited November 6, 2019 by Dom186