Angled Leg Vise guide

[Bill Haumann]

I'm planning on a leg vise for the workbench I just started.Design is based on the English workbench in Chris Schwarz book.I'm considering whether the parallel guide mortise for the leg vise would be betteraligned perpendicular to the floor, rather than at the same 20 degreeangle of the legs.It seems that a roller setup (such as benchcrafted's) would work best if perpendicular.Any experience or thoughts re: this?- Bill

[Bill Houghton]

The point of greatest force on a leg vise will be in a straight line between the screw and the fulcrum beam/guide. You'd like that point to be in the center of the jaw.

As to whether that part is perpendicular to the floor and angled in relation to the vise - I'm not sure that would make a difference in vise function, nor whether it would help with smoothness. Why not mock it up and see?

[Chris Griggs]

I made mine at the same angle as the vise chop, for the reason Bill explained above. You should see if you can setup the benchcrafted type setup so that it is angled with the vise chop. My hunch is you wouldn't get enough force in the proper location if you put it perpendicular to floor.

[Jessica Pierce-LaRose]

Just thinking out loud here - I haven't really sat down and looked at things, but isn't the force at guide focused more on the pin and the surfaces it bears against than the guide itself? What if you have a guide parallel to the floor (to aid in installing a roller guide, whatever) but the holes drilled through it for the stop pin are angled the same as the vise chop?

[Bill Houghton]

I don't think it much matters whether the pin at the guide is angled relative to the length of the vise body or perpendicular to it. Imagine a leg vise in which the guide is a long bolt with a point on the end pushing against a countersunk plate. In theory (see note below), that would work as well as any other guide. I am, in other words, saying that the guide could be considered a point that serves as the fulcrum for a third class lever (force/effort in middle, load at end opposite fulcrum). My original point, not made very clearly, is that a line drawn from this theoretical point through the screw should hit the center of the vise jaw where it will be clamping the wood.

I don't know the Benchcrafted hardware at all - I've seen pictures - but my impression of the products is "very well made/substantial." I doubt having the hardware operating at an angle to gravity would affect it much; but don't know (again, see note below), which is why I suggested a mockup.

If you do angle the pin in a leg vise relative to the floor and thus to gravity, it should have a head or a bend on the uphill end to keep it from falling out every time you loosen the vise; otherwise, you'd better buy your cuss words at Costco, because you'll need a large supply.

“In theory there is no difference between theory and practice. In practice there is.” – Yogi Berra

[Chris Griggs]

Just thinking out loud here - I haven't really sat down and looked at things, but isn't the force at guide focused more on the pin and the surfaces it bears against than the guide itself? What if you have a guide parallel to the floor (to aid in installing a roller guide, whatever) but the holes drilled through it for the stop pin are angled the same as the vise chop?

Seems like it would work in terms of how force is applied at the top of the vise... But wouldn't that put a lot of tork at a funny angle to the guide itself - Normally the force/tork on the guide from the pin is being applied across 3-4 inches (e.g. the witdth of the board that makes the guide). If you applied that force at an angle I'd worry that it would snap the guide.

Not trying to poo poo your idea - it makes a lot of sense - just thinking that might be a risk.

[Salem Ganzhorn]

I think it would also make the mortise weaker. Also consider you need clearance for the rollers and pin. Clearance for the rollers makes the mortise a little weaker anyway because the bottom of the chop must line up with the bottom of the guide. That is unless you mortise in the roller which I saw someone on the creek recently did.I wouldnt worry about it. The original design is tried and true.Salem