Cura 3.6 with UMS5 Line Width Per Layer Consistency Issue

[AgelessRevision 0]

Hey guys. I was wondering how cura slices the first layer of the print. Dimensionally, it's not corresponding to the line width I have chosen and the overall length which to lay the line. On top of that the line width from this first layer, changes in every subsequent layer. To illustrate, I'm printing a 35 mm x 12 mm x 4.2 mm ( x,y,z) rectangular prism, with line width set to 0.8 mm. In cura, the first layer only slices 12 lines when I expect 15 to account for y-dimension length ( 0.8*15=12 mm). The layers after the first all have 14 lines, which is closer to the 15 I expected, but the fact that the number of lines has changed is confusing me. This causes the bottom of the rectangular prism to be fatter then the rest of the part. Even though it only prints 12 lines for the first layer, they are significantly fatter, definitely more wide than the input 0.8mm.  For my application its really important for all the layers to be exactly the same. I couldn't seem to find any settings in Cura where I could make sure the number of lines per layer stays consistent. 

 

Any assistance would be greatly appreciated!

[tinkergnome 681]

The line width can be set individually for all line types available.

Take a look at the manual: https://ultimaker.com/en/resources/52340-quality

Amongst others there's a setting called "Initial Layer Line Width", it's set to 120% in the default profiles (take notice of the tooltip).

 

[AgelessRevision 0]

Thank you tinkergnome for your detailed response. Changing that value from 120% to 100% solved my problem!