Maguire Pin Less Leg Vice

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pgrbff

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I'm in the middle of a bench build. I quite like the idea of the lower metal bar on this vise, instead of a board with holes and a pin or an X link type similar to the Benchcrafetd version.
Has anyone seen or used one of these, or have any idea of the construction?

 
Richard Maguire used to make workbenches and provide the hardware for the vices but he hasn't for a good few years now

Here's a blog from someone else which shows how it's done

https://aroundhomediy.com/build-roubo-workbench-leg-vise/
Thanks for that. I realised it was a linear motion bearing but I got the impression it somehow held its position when you wanted to tighten, if that makes sense. I'm planning on using Hovarter Custom Vise hardware and I have a feeling it can be a bit fussy. The use of the wedge kind of puts me off, not because I'm lazy but because it takes away from the simplicity of function.
 
After a bunch of research I came to the conclusion that a linear bearing system couldn’t work effectively on its own.

The idea is that as you tighten on a board of set thickness it causes the vice to try and rack, or go out of square, the stiffness in the linear bearing bar resists the racking and hence it tightens up. I did some maths and the stiffness required in the bar and bearings to prevent significant racking, I think I said 1cm movement, was an order of magnitude greater than the expected stiffness.

I have a leg vice with a peg board at the base, which is better than the wedge in my opinion, and plan to build one with a St Andrew’s cross on my current build.
 
I designed but never built a foot operated quick release rack system for the bottom of a leg vice, fairly simple as are most good things. No time to give you it today as I’m driving to Heathrow.
Will draw it up tomorrow if it’s wanted?
Ian
 
I designed but never built a foot operated quick release rack system for the bottom of a leg vice, fairly simple as are most good things. No time to give you it today as I’m driving to Heathrow.
Will draw it up tomorrow if it’s wanted?
Ian
I'm probably going to go with the Hovarter mechanisms for wagon and leg vice but I was trying to avoid the St Andrews cross if possible. Any new alternative ideas are very welcome.
 
After a bunch of research I came to the conclusion that a linear bearing system couldn’t work effectively on its own.

I did a prototype with the linear bearing system, just two jaws and all hardware. It does work but there is a nuance.

While scissors or cross mechanism just restricts jaw to be in parallel to leg (almost) no matter what force is applied, linear bearing has to give in a bit. The more it gives in, the more it resists.

As a result, the jaw has to have some toe-in built in. And given amount of toe-in will result in specific amount of clamping force at which the jaw will become parallel to the leg for optimum work holding. Less of clamping force and upper part will be closer to the leg than lower part, more of clamping force and it will be opposite. So you have to "program" your vice to have certain amount of clamping force when you build it. In my prototype I have 1° of toe-in or roughly 1 cm of difference (for regular size leg) between upper an lower part of the jaw when not clamped. But hey, you can just mill the jaw on the inside to create more toe-in if need be.

The good thing is that some toe-in is recommended even for cross mechanism. And leather inlay makes it hold work much better even with not parallel jaw.

For work holding it works good enough indeed. If you want to use leg vice as a form of a press then it might be not a good solution (that is without any additional anti racking support).

I'm going to add it to my workbench hopefully this year. Got BENCHCRAFTED Classic Leg Vice screw for it and 30 mm shaft with long version of linear bearing (LMF-L type, 123 mm long). The main reason that I think I want to use linear bearing is that I can just unscrew the jaw to remove it. Why would I want to remove leg vice? Maybe for using other work holding methods (my workbench is only 180 cm long). There is nothing else to be undone and no sticking out parts remain. But don't think I know how it will be in the end. I just like to have options and like to experiment.

In any way with any vice you choose I would advice to make a prototype first with some cheap soft wood. I did that with this leg vice and with Veritas twin screw vice and I learned a lot!
 
I'm probably going to go with the Hovarter mechanisms for wagon and leg vice but I was trying to avoid the St Andrews cross if possible. Any new alternative ideas are very welcome.
I think you can "program" toe-in angle for this vice maximum clamping force. Or calibrate the angle to this vice max clamping force. I guess it has a positive stop when turning the handle. It would be perfect match if so. Though, I don't know if you want to always twist it to the max. If not then expect jaw to be less parallel. Or don't twist it fully. Might be still acceptable with leather lining.

By the way, is it also linear - the dependence between force applied and jaw and shaft flexing?
 
If you are fitting a leg vice the leg should reach the floor or you are defeating half the object i.e. to stand up to some heavy mallet work etc. The Macguire vice as shown, has all downward forces resisted only by the screw and the other guide thingy. A design mistake but I'm sure he will have realised that by now!
PS or to put it another way - it's not a "leg" vice if the leg doesn't reach the floor - that is the whole point of the "leg" vice design. This also makes the mechanisms much simpler.
The vid https://aroundhomediy.com/build-roubo-workbench-leg-vise/ is really odd - seems to be just about 1 inch short of being a leg vice! Why? Or have a missed some subtle detail? A leg in the air vice?
PS the vice below shows the essential detail i.e. touching the floor. Other detail can be varied of course.
Adjustment by dropping in a spacer or packing at floor level the same thickness as the thing being held. Very simple, very effective.

Screenshot 2024-05-21 at 20.18.30.png
 
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If you are fitting a leg vice the leg should reach the floor or you are defeating half the object i.e. to stand up to some heavy mallet work etc. The Macguire vice as shown, has all downward forces resisted only by the screw and the other guide thingy. A design mistake but I'm sure he will have realised that by now!
PS or to put it another way - it's not a "leg" vice if the leg doesn't reach the floor - that is the whole point of the "leg" vice design. This also makes the mechanisms much simpler.
The vid https://aroundhomediy.com/build-roubo-workbench-leg-vise/ is really odd - seems to be just about 1 inch short of being a leg vice! Why? Or have a missed some subtle detail? A leg in the air vice?
PS the vice below shows the essential detail i.e. touching the floor. Other detail can be varied of course.
Adjustment by dropping in a spacer or packing at floor level the same thickness as the thing being held. Very simple, very effective.

View attachment 181609
That’s an interesting thought @Jacob. I’ve read lots about leg vices and never come across that rational. I can see the merits of the idea though.
 
That’s an interesting thought @Jacob. I’ve read lots about leg vices and never come across that rational. I can see the merits of the idea though.
I've never come across the rational for the half-a-leg vice! Or raised leg vice? Reminds me of our dog having a wee.
I did have an engineer ( @Modernist ) explain to me the point of the blacksmith leg vice and it's much the same for the woodworker version which is also lot easier to rig up than the short leg.
And you can see it in the drawing of the Roubo bench.
PS and in the drawing you can see a slight bend at the top of the jaw which would keep pressure there rather than having it nip the workpiece bottom edge as it gets tightened up and bends slightly.
 
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I don't think it is the main feature of a leg vice - to drag on the floor. If it is it can be called a fifth leg vice then. ;)

But what do I know? Both attached to a leg somehow.
There's a clue in the name "leg".
Legs touch the floor (if they don't also have feet!)
Blacksmiths leg vice is intended to touch the floor.
The Roubo leg vice touches the floor.
I suspect that all leg vices on any old benches also touch the floor.
Not touching the floor is just a simple mistake and a pointless design.
Not uncommon as modern woodworkers try to re-invent the craft. Sharpening?
I'm impressed by the Roubo design - so simple, so obvious and looks very efficient.
If you want a Roubo leg vice why not just copy it? Don't forget the jaw detail at the top end.

PS just had a quick flip through images of "Roubo Vise" - lots of frantic activity but they nearly all have missed the point entirely! Or two points - first that it touches the floor and second that the floor level adjustment is with a spacer same thickness as the workpiece. https://www.google.com/search?sca_e...EAHZirB54QtKgLegQIDxAB&biw=1265&bih=607&dpr=2

PPS you could have a short "leg" vice but long enough to put packing behind it on the floor, but you'd lose the advantage of having the leg actually touching the floor and bearing the load of whatever bashing is going on above.
 
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PPS you could have a short "leg" vice but long enough to put packing behind it on the floor, but you'd lose the advantage of having the leg actually touching the floor and bearing the load of whatever bashing is going on above.

Now, that sounds... functional! I can see how it would help bashing. Thanks for that!

But for my workbench I would still prefer "floating" leg vice, not to care about evenness of the floor. And I hardly ever do bashing in the vice, as work can slip down still. Can also put some wedge between the jaw and the floor to support it if that ever comes to that.

I do want to make it more like angled leg vice also, like on Moravian workbench. Just by offsetting the lower guide from the screw center. But maybe it is overcomplication without much benefit... My prototype is like this and seems to work. The negative can be that the screw wouldn't spin so freely.
 
I'm a leg vice enthusiast and looked at the linear bearing option. It looked relatively expensive and fussy, so went with a parallel guide and pin in the latest bench.
I think when I originally built it, the leg also rested on the floor, but this has since been trimmed, presumably because I got sick of it dragging on the floor.
For me, the attraction of the leg vice is the depth of the vice chop, which can be set to match an apron. Even without it touching the floor, I'm happy to apply some considerable brute force to anything held in the vice without fear of breaking the vice/bench.
 

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There's a clue in the name "leg".
Legs touch the floor (if they don't also have feet!)
Blacksmiths leg vice is intended to touch the floor.
The Roubo leg vice touches the floor.
I suspect that all leg vices on any old benches also touch the floor.
Not touching the floor is just a simple mistake and a pointless design.
Not uncommon as modern woodworkers try to re-invent the craft. Sharpening?
I'm impressed by the Roubo design - so simple, so obvious and looks very efficient.
If you want a Roubo leg vice why not just copy it? Don't forget the jaw detail at the top end.

PS just had a quick flip through images of "Roubo Vise" - lots of frantic activity but they nearly all have missed the point entirely! Or two points - first that it touches the floor and second that the floor level adjustment is with a spacer same thickness as the workpiece. https://www.google.com/search?sca_e...EAHZirB54QtKgLegQIDxAB&biw=1265&bih=607&dpr=2

PPS you could have a short "leg" vice but long enough to put packing behind it on the floor, but you'd lose the advantage of having the leg actually touching the floor and bearing the load of whatever bashing is going on above.
Another interpretation of why it is called a leg vice is that it is attached to the leg. In the same book as your diagram is from "L'art du mensuisier" there are also workbenches with 'leg vices' that do not reach the floor.
 
Another interpretation of why it is called a leg vice is that it is attached to the leg. In the same book as your diagram is from "L'art du mensuisier" there are also workbenches with 'leg vices' that do not reach the floor.
Right. I'll have a look one day. Any pointers of where to look? I see it can be downloaded as a massive collection of PDFs https://www.e-rara.ch/zut/content/structure/4124136
 
Right. I'll have a look one day. Any pointers of where to look? I see it can be downloaded as a massive collection of PDFs https://www.e-rara.ch/zut/content/structure/4124136
where I saw the original discussion
https://workingbyhand.wordpress.com/2021/03/02/some-thoughts-on-roubos-bench/

link to the actual plates in the book
Plate 11
https://archive.org/details/gri_33125009321916/page/n31/mode/2up

Plate 279
https://archive.org/details/gri_33125009321973/page/n809/mode/2up
 
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