BranchCrafted Glide - spacing question

[Dale Murray]

I have have the glide installed as low as possible and everything moves nicely. Next up is installing the screw but, at 6'2" I would like to increase the space between the top of the glide and screw so I am not bending over so far to reach it.

Will I lose clamping force by increasing the distance between the top of the glide and the screw?

I will maintain about 8" between the top of the chop and the screw.

[Malcolm Schweizer]

I am installing the Classic with the crisscross and the instructions say 1/4" from the top of the Mortice for the crisscross to the base of the acetal bushing is the "minimum" distance, but that it can be adjusted to fit your needs. It also says that there is a built-in canter to the mechanism so that the top of the chop lands slightly before the bottom in order to get maximum clamping force, and the more you move it the more that can be affected.

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[Malcolm Schweizer]

Another page regarding adjusting the height. (Note to moderators- this is taken from the literature they provide free public access to via a link on their page and not something that only people who buy the plans have access to or I wouldn't post it.)

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[Dale Murray]

I'm installing the same vise with the same instructions. I just wondered if anybody knows if there is a loss in clamping power by increasing the distance between the Criss Cross and the screw. I would think not, in fact it may increase. I could be wrong, however.

I built my bench to 33" high using my wrist as a guide. If I went with minimum clearance per documentation I would have a screw at roughly 22" from the floor - at 6'1"ish I really don't want to bend over that far. If I moved the screw to 24" from the floor I would still have about 8" between it and the bench top. Not really sure if I need more than 8" of vertical clamping surface on a leg vise, I've never had one before. Hell, I've never owned a bench before I built this one.

After opening this thread I realized I could just contact BenchCrafted, they seem to be very responsive.

[Pat Barry]

You would lose some workspace (working height) between the top of the screw and the top of the vise but you wouldn't lose any clamping force.

[Malcolm McLeod]

Raising the screw (but leaving the criss-cross low), actually increases clamp force.

As it tightens, the screw become the fulcrum of the chop. Raising the screw leaves a longer 'lever arm' below the fulcrum, and shorter above. So mechanical advantage increases.

Edit: Just a caveat: As the distance between the screw and the top of the criss-cross increases, you may see some increase in 'toe-in' on the chop as it tightens...? How much depends on the tolerances in the criss-cross.

[Jim Ritter]

A leg vise is a class three lever. The screw is NOT the fulcrum, it is the force. The parallel beam or the lower part of the cross is the fulcrum. The force of the screw is divided between the parallel beam and the wood you are clamping. Moving the cross further away from the screw will cause parallelism problems with the chop.
Jim

[Dale Murray]

Thanks for the feedback. I thought clamping power may increase but wanted to get the thoughts of others. Tonight I will lay out for the screw.

[Dale Murray]

Just to make it official, Beanchcrafted replied.

By increasing the space between the top of the Crisscross I will have have an increase in clamping force, this is, however, a very small increase but an increase no less.

I also asked about the mortise depth, I am about a 1/32-3/64th over 1-7/16". The deeper the mortise the less the toe in. If it is an issue I should just slide a space under the bearing plate at the bottom of the chop and leg. A veneer or cardboard from a cereal box will work just fine.