This question to Bob...

[Chris In Milwaukee]

BCone---- I was thinking about making my rib forming blocks from 2 sheets of MDF - either 1/2 +3/4 or 3/4 + 3/4

Also thinking about the idea of pressing the flanged holes with the rubber -press method. Im thinking of why not let the rubber - at the same time-
press the outer edges down. I expect it could/would fold them down part way- maybe 1/3 of the way. i would guess that most of the distortion might be
induced at the first portion of the bend. So if that first portion was bent vis rubber---- that might make it easier. Then I would finish the edge bends
with it in the MDF sandwich and mallet or flow forming tool. I think my ribber is about 12 by 18 so I can do the smaller rib parts.
Do you think that will work ?
Tim

I tried, actually. Even with a 20-ton press, there's not enough oomph to bend the edges over. It barely budged. I was able to get it started on the smaller ribs (aileron and flap nose), but it was only about half bent, and I still had to massage them (in the link Brooks sent earlier). For the wing ribs (nose, center, aft), there just isn't enough pressure to do the job. The factory and other hydroforming operations use at least a couple hundred tons of pressure with a larger set of rams to distribute a lot of pressure over a wider area.

https://bearhawkforums.com/forum/bearhawk-patrol-plans-build/19435-having-a-rib-party?p=21614#post21614

Wish it did work, though!