Unusual Vise

[Stew Hagerty]

I was browsing eBay and ran across this bench for sale. I wouldn't have given it a second look if I had not seen the way the vise worked. I thought I would pass it on...

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[Bill Houghton]

Interesting concept. I wonder how it works in practice?

That bench has sure worked for a living!

[Shaun Mahood]

That vise looks really easy to make - I might give it a try over the weekend (mainly out of curiosity). Thanks Stew.

[Stew Hagerty]

Interesting concept. I wonder how it works in practice?

That bench has sure worked for a living!

I know... It's sure seen a project or two.

[Bob Strawn]

I am not seeing a flaw. I think I rather like the idea!

Bob

[Bill Houghton]

I am not seeing a flaw. I think I rather like the idea!

Bob

Well...all of the stress/pressure is transmitted, one way or another, to the nut and the hole through which the steel screw passes; and there'll be bending pressure on the screw itself. I can see the possibility of a lot of wobble when the screw, nut, and hole get old and worn; and, at least in theory, some bending of the screw. Not sure this is a great design, but it's sure an interesting one. I'll be waiting to see what results experimentation yields.

[David Paulsen]

If I understand the concept of the vice correctly, wouldn't it be an idea to add a tiny wheel underneath the front board of the vice? Wouldn't it otherwise scrape across the floor?
Or is it simply hanging by the threaded rod?

[Stew Hagerty]

Well...all of the stress/pressure is transmitted, one way or another, to the nut and the hole through which the steel screw passes; and there'll be lateral pressure on the screw itself. I can see the possibility of a lot of wobble when the screw, nut, and hole get old and worn; and, at least in theory, some bending of the screw. Not sure this is a great design, but it's sure an interesting one. I'll be waiting to see what results experimentation yields.

I see what you mean. As a piece is clamped, the force causes the bottom to want to move inward, which in turn pushes up on the back of the screw. What you will get as a result is a torque on the nut/hole wanting to twist it. The nut in this case is actually a pivot point.

[mike holden]

I see what you mean. As a piece is clamped, the force causes the bottom to want to move inward, which in turn pushes up on the back of the screw. What you will get as a result is a torque on the nut/hole wanting to twist it. The nut in this case is actually a pivot point.

Yes, and the top of the vise will move vertically as the screw is turned. I think that vertical movement is why this simple design is not seen more often. Think of it as vertical racking as the vise is tightened.

Edit: Re thinking the movement thing. the closer the upper pivot is to the nut the less movement, but the less resistance to racking. Need to make a full size proof of concept model to really see what is going on. It may work well for a small range of opening - which really is all most of us need.

[Stew Hagerty]

Yes, and the top of the vise will move vertically as the screw is turned. I think that vertical movement is why this simple design is not seen more often. Think of it as vertical racking as the vise is tightened.

Edit: Re thinking the movement thing. the closer the upper pivot is to the nut the less movement, but the less resistance to racking. Need to make a full size proof of concept model to really see what is going on. It may work well for a small range of opening - which really is all most of us need.

I'm not sure I see where you get vertical movement at the jaw.

If you were to put in two nuts spaced apart a few inches (or one very long nut) the it would minimize the twist. But of course, then it would put more strain on the screw.

I'm not going to be around my shop for a few days, but I'd love to hear from anyone that makes one.

[George Gyulatyan]

Looks like a Nicholson bench. Where is The Schwarz when one needs him?

[Jeff Wittrock]

Looks like kind of a neat idea. I'm guessing the nut block under the bench pushes against the underside of the bench as you tighten the vise. So you would just have to have a good hard runner under the bench that he block would slide on and probably waxed to reduce friction. I guess as long as the length of the chop below the screw is fairly large compared to that above, it wouldn't bend the screw too much.

[george wilson]

Actually,the play in the screw in its hole would allow the front jaw to rise up an undesired amount. Some way of preventing the front jaw from rising would be helpful. If the diagonal piece were wider,and firmly attached at both ends and the sliding block rode on tracks to prevent it going downwards,it would help.

[mike holden]

I'm not sure I see where you get vertical movement at the jaw.

The connection between the angled brace constitutes one leg and two vertices of a triangle, the movable jaw and the point where the threaded rod comes through is the second leg, the connection at the top of the angled brace and the point where the threaded rod comes through is the third leg. If the third leg becomes shorter, the leg must rise as the angled brace length cannot change. Simple geometry.

[george wilson]

Loose or slightly worn parts will negate things and let the jaw rise anyway,I think.

[Bill Houghton]

I've been assuming that the block to which the diagonal braces are attached at the top, under the bench, (let's call it the top diagonals block) is fixed to the screw in its length (that is, not moving back and forth on the screw)but not to the top and that the screw turns freely in it. If that's the case, then the vise assembly is a triangle moving back and forth vertically, with none of the legs changing in length.

If the top diagonals block is fixed to the bench instead, then the vise is useful over a very, very short range of opening indeed, and the design's terrible as a general vise. And the moving jaw would rise (as it approached the bench) or fall (as it receded from the bench.

If my assumption is correct about the nature of the top diagonals block, then I would expect the moving jaw to splay out at the top as soon as any wear in the nut or through-hole in the bench occurred; indeed, with the necessity for some play in the assembly, it would probably splay out at the top immediately, to some degree.

I always follow these discussions of Cool Leg Vise Innovations with some bemusement. Granted, it's been a while since I had my grandfather's leg vise mounted on the bench, but I don't recall that it was all that much effort to put a pin in the right hole in the oak 1x2 strut at the bottom of the vise; and the classic design is easily made and easily repaired.

[Jeff Wittrock]

I always follow these discussions of Cool Leg Vise Innovations with some bemusement. Granted, it's been a while since I had my grandfather's leg vise mounted on the bench, but I don't recall that it was all that much effort to put a pin in the right hole in the oak 1x2 strut at the bottom of the vise; and the classic design is easily made and easily repaired.

I enjoy seeing the ideas presented (whether new or old) even ones that are at an obvious disadvantage as compared to a more typical way of doing things. Maybe it's just the tinkerer in me that is fascinated with different ways to accomplish the same goal. In this particular case, I suppose it depends on a persons primary motivation for using a leg vise.
1. Utility (It performs the job efficiently for my work)
2. Nostalgia (I'm doing things the way Grandpappy did)
3. Curiosity (I wonder how this would work...)
4. ...?

If (1) were the primary motivation for most woodworkers, I suspect the sale and breadth of quality woodworking tools would be far less than what it is now. I can't speak for others, but I suspect my motivation will always be some mix of 1-4 and more :).

[george wilson]

I thought it was a very clever idea. Trouble is,I never saw a wooden device like a vise that would be put under strain,and not have some slack in it. I saw a very nice Ulmia bench that had a double screw vise. Screws connected by a chain,like the LV vises. It was nearly new. Sure enough,it would not close evenly enough to hold a scraper inserted into 1 side. Just a little off,but you couldn't hold a scraper to sharpen in it.

[Stew Hagerty]

The connection between the angled brace constitutes one leg and two vertices of a triangle, the movable jaw and the point where the threaded rod comes through is the second leg, the connection at the top of the angled brace and the point where the threaded rod comes through is the third leg. If the third leg becomes shorter, the leg must rise as the angled brace length cannot change. Simple geometry.

It's a simple triangle. One leg of that triangle is the screw, which passes through a nut. The entire triangle moves in and out as the screw is turned. That connection at the point where the angled leg meets the screw moves. Nothing goes up and down. Even simpler geometry.