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Leg Vise Question

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Forum topic by OleGrump posted 06-21-2019 02:23 PM 774 views 0 times favorited 40 replies Add to Favorites Watch
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OleGrump

322 posts in 766 days


06-21-2019 02:23 PM

Topic tags/keywords: leg vise design question

I’m asking this question in THIS forum, because many of the others A) Have no knowledge of hand tool and workbench relationships, their machines work the wood, not them and B) Have expressed an inherent dislike for the leg vise, just because some fancy, “trendy” magazine tells them which vise is “in” nowadays.
In many of the vintage leg vises I have seen, whether in person, in books and on line, the movable jaw is several inches shorter than the fixed jaw. One would understand some variance due to decades of dragging across shop floors being opened and closed constantly, but these examples show a difference sometimes of about six inches or more. It’s not like these jaws were all cut this short later in their lives, they all appear to have been made this way purposely.
Not having a fancy degree to interfere with my thinking, it seems that the wider you open a jaw made like this the greater the “slop” will be. OK, I have heard “old timers” talk about putting blocks under the front jaw to keep it level, but why should they have to go through that headache? It just seems like an unnecessary extra step which only creates more trouble when you’re clamping stuff in the vise to me
If any of y’all have any input or ideas on why this design should be, please share them, as I’d be most interested in hearing them.

-- OleGrump


40 replies so far

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Ocelot

2275 posts in 3060 days


#1 posted 06-21-2019 03:42 PM

A picture would help.

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bondogaposis

5456 posts in 2773 days


#2 posted 06-21-2019 03:46 PM

I’m not sure what you are getting at here. I don’t really think that it would be a good idea to have the bottom of the leg vise chop contact the floor. Mine is several inches above the floor, the parallel leg glide takes care of the slop.

-- Bondo Gaposis

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SMP

1198 posts in 327 days


#3 posted 06-21-2019 03:48 PM

My guess is the first time a guy opened it up and smashed his toe, he grabbed his panel saw and cut the bottom off just below the parallel guide. Just like the first guy that made kitchen cabinets cut off the bottom after stubbing his toe. I’ve seen a benchcrafted criss cross leg vise where it was almost a foot off the ground.

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HokieKen

9962 posts in 1560 days


#4 posted 06-21-2019 03:51 PM

In my case, the fixed jaw is the leg of my bench. The only reason I can see that I would have extended the movable jaw any longer would be to increase clamping force by moving the parallel guide further from the screw or to increase capacity by moving the screw and the parallel guide lower. However, I have plenty of capacity and clamping force as it is and if either one were lower, using the vise would be far less ergonomic. Just my thoughts (if I understood what you’re asking correctly).

-- Kenny, SW VA, Go Hokies!!!

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chriscarter

16 posts in 513 days


#5 posted 06-21-2019 05:39 PM

A picture would be great. I think you might be mistaking something else for a leg vise. There’s no “fixed” jaw – the inner face is the actual bench itself. The screw and guide at the bottom should prevent any significant sag.

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OleGrump

322 posts in 766 days


#6 posted 06-21-2019 09:41 PM

Not ALL vintage leg vises were built as an integral part of the workbench itself. In the late 1800s and early 1900s, it seems to have been just as common for someone to make a separate leg vise from two boards, the rear one having the nut mortised into it, and the front one having the screw and handle attached to it. The builder would then screw or bolt the rear board jaw a whatever point along the bench they found expedient, and screw the front jaw into it once in position. There are several examples of such separately made vises currently listed for sale on Ebay. (Some of them carry a pretty reasonable price tag and shipping costs, BTW)
Also, not all of the parallel adjustment beams were rigidly fixed. Some were made to pivot up, and lowered onto a bolt through the rear jaw once whatever notch needed was aligned. This system would not provide any support to the front jaw. It would however, allow the worker to flip the beam up with his foot while he adjusted the jaw. That would leave both hands free to hold and clamp material in the vise.
Under these circumstances, one would think the front jaw would be a bit longer, not necessarily full length, but a bit longer. Perhaps a block of the proper height to correct this slop was kept in the bench at the ready.

-- OleGrump

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Smitty_Cabinetshop

16143 posts in 3040 days


#7 posted 06-21-2019 10:10 PM

My leg vise chop reaches the floor. And I like it that way / have not experienced difficulty having it so.

-- Don't anthropomorphize your handplanes. They hate it when you do that. -- OldTools Archive --

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OleGrump

322 posts in 766 days


#8 posted 06-21-2019 10:40 PM

Perhaps the answer to this design enigma lies in the fact that these leg vises were probably made by Farmer Brown, Anytown, USA, with a mail order bench screw. He would have built his leg vise as an entirely separate entity and attached it to whatever he was using as a workbench. If the “bench” fell into disrepair, or if Farmer Brown had to move to another farm, it was easy to remove his complete vise and reattach it somewhere else. Then, as now, the bench screw was the most vital and often most expensive part of a workbench.
Farmer Brown would have only used this vise to make or repair whatever was needed as needed, and not as regularly as would a jointer or cabinetmaker. Therefore, whatever slop there may have been in his vise would not have been much of a bother to him. It worked to do what he needed, and that’s all that concerned him.

-- OleGrump

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theoldfart

10698 posts in 2873 days


#9 posted 06-21-2019 11:12 PM

Like Smitty, my chop is just off the floor by less than an inch. It was 1/4” off the floor but I needed to get the floor mat under neath it. There has been no noticeable sag in the last four years or so.

I use a St. Peter’s Cross rather than a parallel guide so no need to make the bottom end accessible.

-- "With every tool obtained, there is another that is needed" DonW ( Kevin )

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SMP

1198 posts in 327 days


#10 posted 06-21-2019 11:26 PM


Perhaps the answer to this design enigma lies in the fact that these leg vises were probably made by Farmer Brown, Anytown, USA, with a mail order bench screw. He would have built his leg vise as an entirely separate entity and attached it to whatever he was using as a workbench. If the “bench” fell into disrepair, or if Farmer Brown had to move to another farm, it was easy to remove his complete vise and reattach it somewhere else. Then, as now, the bench screw was the most vital and often most expensive part of a workbench. Farmer Brown would have only used this vise to make or repair whatever was needed as needed, and not as regularly as would a jointer or cabinetmaker. Therefore, whatever slop there may have been in his vise would not have been much of a bother to him. It worked to do what he needed, and that s all that concerned him.

- OleGrump

Possibly. Another guess is that it looks like it originally just copied the old blacksmith’s post vise(sometimes also called a leg vise). Just made it look similar but out of wood instead of steel.

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CarlosInTheSticks

408 posts in 794 days


#11 posted 06-22-2019 02:28 AM

Here is a plan for what farmer Brown’s vise might have looked like. Mr. Brown was very innovative though, he came up with the idea of the scissor leg vise to support and keep the legs parallel. It also allowed him to raise the legs off the floor without loosing any support and totally avoiding the sliding bar and locking dowel methods used back then to keep things parallel.

The idea was posted in a 1920,s Popular Mechanics Shop Notes. Their are expensive commercially available models nowadays. I chose to build my own, with a few improvements such as bearings on the lower sliding arms of the scissors for smoother operation.

The blacksmiths leg vise is different. The movable leg almost never reaches the floor (I have pictures of at least one exception), but rather pivots at a fixed point usually 2/3 of the way to the floor. Here is an example.

If your interested here is a link to an easy, but very heavy build plan, of a similar acting blacksmiths leg vise.

https://hobbyworkshopprojects.blogspot.com/search/label/blacksmith%20vise

-- "There are no utopias, chaos theory reigns, anyone who says different is selling you something"

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Don W

19251 posts in 2989 days


#12 posted 06-22-2019 03:41 PM

Like most, I don’t really understand the question either. Post some pictures of what you’re trying to show us.

-- http://timetestedtools.net - Collecting is an investment in the past, and the future.

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OleGrump

322 posts in 766 days


#13 posted 06-22-2019 10:52 PM

OK, we’ll try a little different approach. The object in this picture is called a leg vise

https://s3.amazonaws.com/vs-lumberjocks.com/ptiui7f.jpg! People who do things with wood use it to hold wood from moving around. This one was made a really long time ago, about 1900. Sometimes, these are built right into a workbench. This one was made as a separate piece, and was held on to the workbench with bolts through the two (2) holes in the back board. You can see these in the picture:

The handle on the front board lets you turn a screw which moves back and forth to hold wood of different sizes. If you look at the first picture, you will see that the front board is shorter than the back board. The long metal piece sticking through the board near the bottom does two things:1. Acts as lever to help the vise hold things tight, and 2) keeps the front board from bending too much when you put wide pieces of wood in the vise. Sometimes these are held tight to the front board. This one moves UP and DOWN on a bolt and hooks over another bolt in the back board to keep in different places, for big or little pieces of wood. If the metal piece near the bottom on the front board was held tight and could not move, the front board could move back and forth easily. But we just said that the metal piece on this vise (and a whole lot of other ones made about the same time) is not held tight it moves up and down. That means, when you turn the big handle on the front, and the board moves out toward you, it gets heavy and starts to drop down toward the floor. (by “Gravity”) If whoever made this leg vise had made the front board almost as long as the back board, the front one would NOT drop down so far as it does with the shorter board. To use this vise the best, you have to either HOLD the front board UP while you make it tight, OR put another block of wood UNDER the front board to keep it from falling down. The question for the class is why would someone put a short board on the front, knowing that it will fall down when it is opened toward him?

-- OleGrump

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Don W

19251 posts in 2989 days


#14 posted 06-23-2019 10:53 AM

My assumption would be it’s the same reason you put a toe kick on cabinets. Move the vise out holding a 12” piece and you couldn’t stand in front of it without straddling it.

-- http://timetestedtools.net - Collecting is an investment in the past, and the future.

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CarlosInTheSticks

408 posts in 794 days


#15 posted 06-23-2019 01:57 PM

+ 1 Don W

If you are putting the question to the class, that indicates you already know the answer, but that is not so clear in your explanation. The main reason for the toothed bottom bar is to keep the two legs parallel so that you can maximize clamping surface contact at the jaws. The toothed bar works with a ratchet effect and many of these designs have a latch mounted under the bench to disengage the toothed bar for adjustment. This keeps the legs parallel and gives some support to the moving leg, though not very well for this design. In my opinion the scissor design is the best and cleanest, design solution for both problems.

Countless designs have been tried over the centuries since the leg vise came into use to get around this problem. You only need to do a search to come up with many examples. Here is an extreme version built by Klaus Kiefer:

In the two blacksmith examples above the movable jaw adjusts on a pivot to maximize clamping and get around the parallel problem.

A adjustable leg that goes to the floor is a toe stubbing, and tripping hazard, and nowadays a pinching hazard for portable power tool cords.

-- "There are no utopias, chaos theory reigns, anyone who says different is selling you something"

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