ABS clyinders look like hour glass

[mmchupp]

Hello.
Any suggestions of what to try to fix this issue?
As the print gets taller, straight vertical walls start "pulling" in.
What should be a cylinder, looks more like an hourglass.

I'm printing ABS on ROSTOCK MAX
Bed at 110, Nozzle at 228
Perimeter speed is 45mm/s
Infill at 40mm/s

[geneb]

You need to enclose the printer - moving air is causing the problem. Even walking by the printer can ruin an ABS print.

g.