I am not sure how to answer that. Nothing is perfectly straight, you can always turn the bend until it is facing a direction that matters less.
I boils down to how perfect do you need the machine to be? are you going to be cutting PCB’S? Around here we get hardware store electrical conduit and it is definitely not perfect and usually to even perfectly round. You would be surprised at how far off it can be before it actually matters.
Be careful with that ABS I don’t think very many people have had much success printing the parts accurate enough. ABS shrinks. I do not use ABS there are many other materials that hold dimensional accuracy much better. I think PLA is the best, its shortcoming is its heat tolerance which doesn’t matter in the CNC, second choice is any form of PET.