Curved bottom - any way to eliminate/prevent it?

I was finally able to print X carriage for Prusa i3 after three failed attempt. Because the way this part is oriented on the hot bed (I believe it's for better structural strength for the stress points) it gets knocked down quite easily.

In my last attempt, I went crazy with the hair spray as if it's 1985, and started printing and went out for a lunch. I honestly expected to find another bird's nest made with plastic ramen noodle sitting on my desk right next to half way done X carriage knocked away somewhere. However, to my pleasnat surprise, it was completed! I think the extra hair spary hold up the part all the way... or maybe I should not be watching when it's printing..

Anyway, I'm satisfied witht he quality of the print in general. However, I can't help noticing a curvature at the bottom of the object. I've attached a picture.

I think (and hope) it isn't bad enough to affect the usability of the part. However, I would love get rid of this curved bottom if possible.

From my past experience, I believe the bottom tends to curve up with bigger objects - the object which takes longer time to print.

Is there any way to eliminate or at lease reduce this curving bottom? What's causing this curved bottom? I think the bottom probably curved up actually after the printing was done (as the heated bed cooled down) because.. if these curved got there while the part was still printing, I don't think it would've been knocked down before the completion, no matter how much hair spray used.

Should I set the heated bed temperature higher.. or lower (I had it set at 110C)? Or, anything else I can try?

That looks like typical ABS warping. Also, it looks like your first layer isn't squashed down enough, leading to poor bed adherence. Try getting the print head closer to the bed, or increasing the extrusion width for the first layer. Improving the bed adherence will also fix / improve the warping situation.

What's the part supposed to look like? Is that supposed to be a right angle at the sides?

I only have a month experience with the Replicator 2X printing ABS at school (still waiting on my own printer at home), but how's the airflow around your printer? You want minimal airflow hitting the ABS while you're printing. If the extruder fan in my printer was pointed straight at the build the same way it is in this picture < [rusai3-metalframe.jpg" target="_blank" rel="nofollow">reprap.org] > my ABS prints would be bending all over the place. That said I don't know how much air hitting the ABS matters for your hairspray method - I use heated build plate with Kapton tape only.

I print at 110 degrees C build plate for ABS, although the printer is "enclosed" by putting plastic over the whole thing - note that's easier with the Makerbot than with what you have since you'll have to make sure your cover isn't hitting anything, especially the hot parts!