Low profile finger plate fixture - video

[Jon]

Low profile finger plate fixture. By Engineering hacks & tricks. 13:26 video:

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[Toolmaker51]

A+ for idea, high marks for execution, C- regarding clamping ratio less than 1:1.
Common example, in slotted step clamp straps; is not the slot predominate at one end?

[carl blum]

Hello:

The fixture looks very handy. Is it commercially available, or a "one off"?

Thanks, Carl.

[Mook]

A+ for idea, high marks for execution, C- regarding clamping ratio less than 1:1.
Common example, in slotted step clamp straps; is not the slot predominate at one end?

Strap clamps need to exert high clamping forces as friction is their primary holding force.
In fixtures, the primary resistance to cutting forces are the solid locations. In the case of this fixture the vee & the step provide resistance and the clamps have very little cutting forces acting on them. The examples prove that only finger tightening is sufficient to machine the parts.

[Jon]

Welcome Mook - the builder of this fixture, who runs the excellent Engineering hacks & tricks channel

[Mook]

Hello:

The fixture looks very handy. Is it commercially available, or a "one off"?

Thanks, Carl.

Hi Carl.

The fixture is a one off, although it would be nice to sell them the price would be too much outside industry. The principle can be easily copied & modified to suit individual applications & I urge you to make something to suit your needs.

Don't be put off by the " clamping ratio " comment. I have tested the fixture today to calculate this ratio see below.

The mechanical advantege can be calculated like a lever where the input distance divided by the output distance gives this increase or reduction factor.
In my example the input distance is the distance the perimeter of the thumbscrew in one turn & the output distance is the vertical distance the clamp tip travels per turn. The distance travelled by the perimeter of the 11mm diameter thumbscrew is approximately 34mm, the measured distance of the clamp tip is 1.2mm per revolution.
Using these figures - 34 divided by 1.2 = about 28. So in conclusion the mechanical advantage of the clamp lever is 28:1.

If you would like some overall dimensions or a Cad file please let me know.