I ocassionally need to clamp something down on my woodworking bench that is 
very tall, so I came up with this tall tee clamp.

To make two tall clamps, I used: 
Two pieces of 5/16" threadded rod
Two short 5/16" threadded rod couplers
Two 5/16" by 1-1/2" tee bolts
Two 5/16" nuts
Two Stanley Ell brackets (1" wide and 5" long)
Two tee knobs and 3/8" washers.

I drilled a 11/64" holes in each ell bracket then drilled out the 5/16"
nuts and welded them to the ell brackets. 

One of the clamps, you can see all it's component parts and how it is assembled.

Closer look at the ell bracket, the extra hole drilled parallel with one leg in the other and the drilled out 5/16" nut welded to it as a bushing.   Actually I used a flat Stanley bracket and bent it, the steel was heaver guage than the ell bracket, but an ell bracket would work.

Krumby weld, but it holds.

The hole in the top leg of the ell bracket allows the threadded rod to be parallel with the other leg of the ell bracket.

5/16" by 1" tee bolt with threadded rod and coupler.

Tall clamp in use holding down the frame of a chest of drawers while I glue on the top.

Closer look at the tall clamp in application.