Underextrusion after long travels I'm having problems when printing small parts over big areas.

I'm currently printing quite big casing (~180&nbsp;mm x 100&nbsp;mm), which has hexagonal holes on the corners. On the first layer the printer prints, in order:


Supports inside the holes, 
Borders around the holes
Border of the whole casing and finally 
Infill (since it is first layer, infill is solid)


When printing borders around holes, printer's head travels between all holes (so that's around 90&nbsp;% of the whole bed width), what results in filament oozing and the hole borders being underextruded (sometimes to the point, that filament doesn't stick to the bed).

My setup is CReality3D Ender 3 with Ultimaker Cura 3. Most important settings: 


Print speed 40&nbsp;mm/s
Nozzle temperature 215&nbsp;&deg;C
Bed temperature 60&nbsp;&deg;C
Retraction on travel turned on
Retraction additional prime amount set to 0.05&nbsp;mm3.
Outer walls printed after inner ones


What would help (I guess) is slowing down the print after long travels or priming more filament, but proportionally to the travel distance. There are no such settings in Ultimaker Cura though.

How can I deal with such problem?
it seems like retraction issue

i would say you should experiment with 


retraction length - so it would retract more
extra extrusion after retraction - so the printer could put some material before it will start your next hole :)


unfortunately there is no good guide how much it should retract and how much it should additionally extrude as it depends on "all your printing circumstances" but here is my arbitrary list in order of importance


filament (density - type and producer)
temperature (viscosity - hotter filament flows easier)
nozzle diam (as filament escapes easier through big hole ;)
heat barrier (cooling efficiency - filament should be cool as long as possible up to (or down to) the nozzle)
extruder gearing quality (good coupling makes precise retraction and extra-extrusion)
cooling (fan and duct should cool your printing right after it sticks to the surface)


and one more thing worth to mention

usually the first layer is not cooled which makes whole system hotter (so filament flows easier)

you could experiment with it too especially for big printouts 

so


overextrude first layer AND 
turn on cooling first layer


it seems like there is a bunch of things you can do to master it :)

good luck - it's definitely manageable