On 1/25/2013 8:01 AM, Bill wrote:

I was hoping to use the 3/4" floor as a shelf, for stuff like drills and
what have you. Maybe in addition to the two2 2by4s shown, under the
floor, I could add 3 more going the other direction.

IME, you definitely want to keep those two by fours (see last below) ...
AAMOF, I would _strongly_ recommend framing the entire bottom platform.

With that style clamp rack, it is not unusual to have upwards of two
hundred pounds of clamps and accessories when loaded ... the bottom
platform of 3/4" ply, without being framed, will be subject to flexing
by racking forces when it is moved, particularly over uneven surfaces;
and sagging forces, when used at as a shelf, will likely be factor over
time due to the dimensions.

If you want to do have a functional mobile unit that will stand up to
both moving and loading over time, go ahead make that bottom PLATFORM
rigid with a frame.

Personally, I would rip those two by fours in half, and use the
resulting 2 x 2's to do the platform framing ... it won't cost you a
penny more, and I'm confident that you will glad for the extra rigidity
over time.

--
eWoodShop: www.eWoodShop.com
Wood Shop: www.e-WoodShop.net
https://plus.google.com/114902129577517371552/posts
http://www.custommade.com/by/ewoodshop/
KarlCaillouet@ (the obvious)