This is my first delta (from makerlibre indiegogo campaign) and with my first prints

This is my first delta (from makerlibre indiegogo campaign) and with my first prints i seem to get these ridges on the back of prints towards the z tower? Any help wouldbe great

Could be drag on that one tower (or drag on both X and Y), could be binding on the effector. Is it brand new (breakin may be necessary)?

Or are you talking about the ooze at each level when it move upwards? Level change randomization can help for that.

rotate the model and print again, see if it happens in the same place,

This is print 3 and it happens on the same side each time

Is there a heat source near that side of your print bed? inversely, is there greater air flow on the other sides that may encourage those areas to solidify while the back side remains hot enough to slump under the weight of subsequent layers?

no heat on that side, open build area with no heated bed just the hotend and mirror for a bed

looks to me like some sort of overheat/cooling problem. I have a fan on one side of the effector, printing PLA, sometimes the side that does not get good airflow re-melts, or cools to slow and droops. Lower heat? put a blower on the ridge side of the print plate?

PROBLEM SOLVED. I went ahead and posted here while I was at work because i currently have no internet at home. So when i got home i did two more test prints and watched the hotend whilst printing and notices it shook more that usual in those spots. So watched to see which tower moved more during those specific movements. I assumed it was the z tower before these tests but it was not. The x tower had a missing set screw and would slip momentary at the same location. Replaced the set screw and all is well.