Planer bed not flat, and other questions.

[paulrussell]

I am giving my power stand mounted, aluminum bed, SS planer a thorough cleaning and adjustment. I wasn't able to align new knifes using the dial indicator method from Sawdust Sessions. After much head scratching I discovered it is because the bed isn't flat.
I reverted to the tried and true SS height tool to install the knives.
But that leaves me with the question of whether I should do something to address the longitudinal bow in the bed. The left and right sides are higher with a dip along the center. In the area under the rollers and cutter it dips to around 0.007" at center.
Is there any reason I should be concerned about this?
Also, my planer manual specifies a "feeler gauge" of EXACTLY 3" for synchronizing the four screws. Why is 3" so magical? I would think any height in the working range would be equally valid.

[JPG]

Another casualty of having a dial indicator.

0.007 'bow' across >12".

Will that be apparent when looking at a 12" wide board?

I think the 'exactly' part refers to at all 4 locations. 3" is probably a mid range setting.

[paulrussell]

I suspected as much, and probably never would have had an issue other than trying to set the knives per Nick Engler. Thank you.

[garys]

I agree with JPG. If you put the dial indicator away in a box, you likely won't have a problem.