First layer lines partially not sticking to bed

So I have been printing some large parts (almost as large as the heated bed) in ABS. I noticed that the first layer lines tend to partially warp and not stick to the bed:



This only happens in one specific part of the bed. I have this problem with ABS only. Increasing the print speed of the first layer helps but it doesn't make sense - normally the part sticks better when the first layer is printed slower.

I am printing on Kapton Tape covered with a very thin layer of highly diluted ABS slurry. I use very little of it because otherwise there is a high probability that the part will never get separated from the Katon tape as the first layer is nearly as large as the build surface.
I don't have the problem with PLA and I also avoid printing parge parts in ABS because of the warpage and shrinkage but this time I need solid temperature stability (>80 deg. C)

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Self-sourced Mendelmax 2.0-based Reprap Machine -- Ramps 1.4 & Mega 2560 -- DRV8825 (Z@1A, [email protected], [email protected], E@1A) -- genuine E3D v6 direct setup -- 350W custom silicone heated bed -- ABS 1,75mm -- Marlin 1.1.0-RC7 -- Cura 15.04.6

Looks to me like the nozzle to bed gap is too low in that region of the bed, is the bed a material that might deform at abs temperatures? The filament isn't lying down straight as there's not enough space for lines of extrudate to occupy. My corexy bed has a low corner when hot at front left too. Do you use mesh bed levelling/grid levelling? Might help.

I've been thinking for a while it might be nice if slicers allowed a slight reduction in flow for layer 1 given that some squash down is always going to happen, then gradually bring the flow back up to normal over the first 3 layers, sure I could do it in the gcode.

Edited 1 time(s). Last edit at 03/07/2017 05:29PM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Well, the heated bed is a 6mm thick machined cast aluminum plate. I tried mesh bed leveling but there was no difference to grid (using an inductive sensor)

Upon visual inspection the nozzle doesn't seem to be too close to the heated bed in this area...

Maybe I should reduce the distance to the bed and reduce the extrusion rate for the first layer...

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Self-sourced Mendelmax 2.0-based Reprap Machine -- Ramps 1.4 & Mega 2560 -- DRV8825 (Z@1A, [email protected], [email protected], E@1A) -- genuine E3D v6 direct setup -- 350W custom silicone heated bed -- ABS 1,75mm -- Marlin 1.1.0-RC7 -- Cura 15.04.6