Hold down clamps, what do you use?

[Tenson]

Tenson,
hopefully this pic will give you a better idea of how it works. This is 25mm thick plate its clamping. At the moment I have a wooden bed so Im using a wood screw but once my ali bed is in place I can use a 6mm bolt.

Ian

Thanks for the picture, I imagined it the other way around with the flat part pushing down on the material. I might just copy some of these :)