Making some screw less vise hold downs

[fitterman1]

I would consider making the heel of the clamp slightly smaller than the width of the tee slot. Then make this end go all the way to the bottom of the tee slot so you don't bruise the bed.
Please see the video at:
0.11 Top left shows one clamp on it's side
0.41 + 0.49 Show the clamp in the tee slot with the heel going to the base of the tee slot.

Some good ideas in that video.
As Wobblyhand mentions, bruising of the table face by the heel of a clamp is something we all have to be wary of. The rounding of these heels to allow self adjustment is also a good idea but allows the clamping forces to be concentrated on a thin line. As he has learnt, there should be packing under this heel to prevent damage to the table bed datum surface, so we don't end up inadvertently causing damage and creating errors in future setups.
The is a formula that goes F= M x A, which states that force is equal to mass x area. In this statement you should be able to see that the higher the force applied on a given area, the more mass we are trying to push through it. Thats why packing, shims, a washer, scrap or anything is needed to prevent damage. Everything is "plastic" to some degree no matter how hard you think it is.

 

[Parlo]

The idea is predominately aimed at bespoke clamps for a single purpose, in this case a vice. I think it is well worth spending the extra time to incorporate the deep heel for future simplicity and repeatability. I would not want to look for packing pieces each time I mount the vice. If the heel is a few though higher than the clamping face to the tee slot base distance, the clamp will distort to have a flat contact with the base of the heel on the tee slot base. This will not mark the tee slot base and also aligns the clamp square to the vice edge. I use a captive spring between the tee nut and the clamp for even simpler installation.