"tillius" wrote in message
oups.com...
I need to make a 4" riser block for my Delta Benchtop Mortiser and am
wondering about the suitability of MDF to cut and stack between the
base and the post flange?

Will it compress significantly to make my mortises out of square?

It would probably works as MDF does not compress much. Delta already has a
2" riser so you could always buy another and stack them. Of course, buying
a spare part may be almost as much as buying a new machine.