Issues creating lithophanes need help

1

I am using 1/4" acrylic for my lithophanes and have done 8 so far using this material. The last 3 have had streaks where it seems its didnt cut deep enough it looks like a roughing pass. Can anyone tell me what is causing this? It is getting worst with every carving.

I’m using Aspire, feed rate is 2" per sec and plunge rate is 1" per sec

20180901_193942
20180901_1939423024×4032 2.61 MB
20180826_170317
20180826_1703172138×2851 1.52 MB
20180826_101428
20180826_1014282138×2851 1.66 MB

2

It looks like you might be loosing steps on the Z axis. Have you checked to be sure the z belt is tight and that the pulley is not slipping on the shaft (grub screws are in nice and tight). You can also try turning the Z by hand and be sure it is not sticking anywhere.