# What is the cause of this ABS Problem? **URL:** \ **Category:** Filament\ **Created:** [February 8, 2016, 3:38pm UTC](https://forum.lulzbot.com/t/what-is-the-cause-of-this-abs-problem/2917 "2016-02-08T15:38:29Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![ehenrickson](https://avatars.discourse-cdn.com/v4/letter/e/c37758/32.png) [@ehenrickson](https://forum.lulzbot.com/u/ehenrickson)\ **Post date:** [February 8, 2016, 3:38pm UTC](https://forum.lulzbot.com/t/what-is-the-cause-of-this-abs-problem/2917/1 "2016-02-08T15:38:29Z")
Just wondering if anyone has seen this before. Did a print much bigger than this last weekend that turned out perfectly with the same settings. Thinking it could possibly be an issue with the wall thickness on this particular print? Any advice would be much appreciated. Current settings: Nozzle: 235 Bed: 115 Infill: 20% Layer Height: .15 ![IMG_20160208_082504_389.jpg](https://us1.discourse-cdn.com/flex020/uploads/lulzbot/original/2X/8/87c9e9bc465ffdd2bbf169d4199990e2ae4118f7.jpeg) ![IMG_20160208_082454_954.jpg](https://us1.discourse-cdn.com/flex020/uploads/lulzbot/original/2X/7/7bb1349df3eb72c6257875a3fb641cad8311d54a.jpeg) ---
**Author:** ![piercet](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.lulzbot.com/piercet/32/12_2.png) [@piercet](https://forum.lulzbot.com/u/piercet)\ **Post date:** [February 8, 2016, 3:46pm UTC](https://forum.lulzbot.com/t/what-is-the-cause-of-this-abs-problem/2917/2 "2016-02-08T15:46:16Z")
A bit of corner lifting, and some overextrusion. ---
**Author:** ![ehenrickson](https://avatars.discourse-cdn.com/v4/letter/e/c37758/32.png) [@ehenrickson](https://forum.lulzbot.com/u/ehenrickson)\ **Post date:** [February 8, 2016, 4:16pm UTC](https://forum.lulzbot.com/t/what-is-the-cause-of-this-abs-problem/2917/3 "2016-02-08T16:16:11Z")
Corner lifting I already knew about. Over extrusion is new to me though. How is it I would have this issue on one print and not the other? Seems like that would be a pretty consistent thing. ---
**Author:** ![hemocyanin](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.lulzbot.com/hemocyanin/32/62_2.png) [@hemocyanin](https://forum.lulzbot.com/u/hemocyanin)\ **Post date:** [February 9, 2016, 7:03pm UTC](https://forum.lulzbot.com/t/what-is-the-cause-of-this-abs-problem/2917/4 "2016-02-09T19:03:36Z")
I agree with piercet. There are any number of reasons the previous print might have been better. You say it is larger so the extra filament might have had more hidden places to ooze into. Maybe the other print didn’t have corner lift. Maybe the filament was physically thinner in the previous print so less filament got extruded. Maybe it was just a different shape which caused different tool head motions. In any event, take some caliper measurements of the filament and adjust the flow rate downward till it comes out nice. Use expert settings, basic tab, Filament heading to find these settings. Maybe start with a 95% flow rate – watch for underextrusion on the first layer which could affect adherence. Then just tweak till perfect. ---
**Author:** ![ehenrickson](https://avatars.discourse-cdn.com/v4/letter/e/c37758/32.png) [@ehenrickson](https://forum.lulzbot.com/u/ehenrickson)\ **Post date:** [February 13, 2016, 6:23pm UTC](https://forum.lulzbot.com/t/what-is-the-cause-of-this-abs-problem/2917/5 "2016-02-13T18:23:07Z")
Wound up asking lulzbot support about this one. Turned out to be an issue with how much abs contracts as it cools. Previous layer is cooling and contacting as the current layer is being laid down causing the current later to bunch up and produce bumps like this. Made a quick makeshift enclosure and the issue was decreased by at least 80%. Issues still present, but at least I got a useable part! I had tried reducing extrusion rate previous to this with no results.