Cheap welds will get ya everytime

[ray benson]

Probably toe plate will bend. Like this other thread.
http://www.arboristsite.com/showthread.php?t=74629

 

[Wood Doctor]

crack and bend back

If they were given just a wee bit of support they would stay put.
(red triangle)

over engineer or under engineer that is the question

However, if you want to operate the splitter in the vertical position for splitting huge rounds, the triangle brace raises the foot off the ground and nullifies the advantage.

As usual, the solution may be a compromise. Make twin triangular supports parallel and no more than 4" wide underneath the foot. That's far better than no triangle at all. Before swinging the beam vertically, dig out a small 4" deep trench underneath the foot for the triangle and the end of the beam to drop into.

My "triangular" supports would not actually be triangles alone. Take a look at this sketch:

Note that this assembly allows a greater extension for the same size foot to get under the log and the supports take care of the strength. Weld the twin supports to the I-beam first, then weld the foot to the supports and the beam.