The reason I'd cut out the rectangles in the vise support was that I'd intended to put a benchdog hole through each, and I wanted the thickness of the top to be the same for all of the benchdog holes. Where I messed up was in not cutting out the ends, between the bolt tabs. I'd intended to put a benchdog hole through there, as well, but I'd forgotten to cut out the segments prior to glue0up.

Be careful. Single 24x60" sheets of 3/4" MDF are pretty easy to lift. A doubled sheet is manageable. The countertop - 24x72" panel of 1-1/2" oak - weighs something over 100 pounds. It takes real care to lift safely. The joined top - 3" thick of oak and MDF - is past the range that can be lifted safely by one person. Don't try. Get a friend to help, or rig a block-and-tackle.
Thanks Chris! I found this page while looking for a link to your e-mail address. I recently finished your erudite volumes on workbench design, and am about to embark on my own bench inspired by your take on the Holtzapffel design. As my vices and planer arrive, I’ve been agonizing over whether to use SYP or rough maple for the top. I don’t have a big budget, so all-maple is not an option. But after reading your ten tips here, I’ll stop agonizing — all SYP it is! This is, after all, my first of what I hope are at least several handmade benches. Your scholarship and craftsmanship are truly inspiring.
For one, the bench itself is a good size. While its width as a tad short at just over 1 ½’, the length is a great 5’ long. Even better, this bench is made out of birch wood. Birchwood is similar to beech in that it is strong but soft enough to prevent inadvertent dulling of your tools. However, birch has a bit of an advantage over beech in that it is not a porous which makes staining on the Windsor Design a more worry-free affair.
Beyond the weight capacity, the Grizzly is also the largest table top on our list and in more ways than one. For a workspace, the Grizzly provides 5’ of length by 2 ½’ of width. There is not another table that really comes close to that size. Another size advantage of the Grizzly bench is the table top’s thickness. While the standard thickness of the table top for a quality woodworking bench is 1” with lesser models often offering only ¾” of thickness, the Grizzly provides a 1 ½” thick table top.