Was making up a jig yesterday and found after the glue had dried that my
miter slider was a little oversized. With the alternatives being to pry
it apart, which never goes well with MDF, or start over from scratch, I
went after the slider with a shoulder plane, expecting dismal results.
To my surprise the stuff planes beautifully, with the only downside
being really continuous shavings long enough to form a solid mass in the
throat of the plane. I'm sure it didn't do the edge any good, but that
can be resharpened.

I'd never tried taking a hand tool to MDF before--now I'm curious.

I did learn not to secure MDF miter sliders with flat head
screws--they'll split.