Leg vise question

[Phil Mueller]

Planning out a leg vise for my workbench. I'm planning on the chop to be maple approximately 1 3/4" thick, 8" wide and 33" long. I plan to use a Veritas tail vise screw. Leg will be 5" thick.
Question; doesn't the weight of the chop put excessive force on the screw going through the leg...does it cause the screw to rub the bottom edge of the leg hole? Or does the metal guide on the backside of the leg keep everything aligned?
Maybe over thinking this...

[George Wall]

I did the exact same thing. Haven't had any problems at all.

[Phil Mueller]

Thanks, George. Quick follow up questions...what size hole did you drill for the screw...its 1 1/8", did you drill 1 1/4"? Also, the piece the screw threads through at the back side of the leg...did you recess the tapered end into the leg, or just or screw the flat side to the leg with the tapered end extending out?

[ian maybury]

Hi Phil. Others may have different views, but it's to my mind important that the screw in a leg vise stays precisely horizontal as that determines the placement of the chop - especially in the vertical and relative to the top surface of the bench top.

I'd be cautious about just relying on a flanged nut screwed to the back of the leg to do this on it's own - if nothing else it's quite short, and the inevitable clearance will allow the screw to droop. It could perhaps be allowed to rest on the hole in the wooden bench leg, but that might wear and cause some friction. I'd want to see some sort of more durable (or at least replaceable) support to the front of the leg.

Benchcrafted so far as i can remember use a block of acetal (a plastic that's used to make dry bearings and the like) of maybe 3/4in thickness set into the front of the bench leg so that the front face is flush and secured by screws. It's bored to a close clearance fit over the OD of the screw and supports it - it's not threaded as this would lead to issues if the wood of the leg moved. There's a green/blue UHMW grade used a lot as wear strips on pallet conveyors in industry that would probably be very good too.

PS A look just now suggests that there's enough on the leg vise and installtion instructions section of the Benchcrafted site to figure how they do it.

[Phil Stone]

Ian, I looked at that acetal bearing quite a lot when I was designing my leg vise, and from what I can discern from the latest drawings from Benchcrafted, it only prevents left-to-right movement of the screw. The hole is elongated in the vertical dimension so that it doesn't contact the screw. I don't think it bears weight, therefore.

I worried about this issue quite a bit until I decided to lay out for a CrissCross, which completely supports the weight of the chop and allows the screw to run free.

[Bill Houghton]

My grandfather's leg vise had nothing fancy done to maintain the orientation of the screw - in fact, the nut is a chunk of cast iron (I think) that was held in place with cleats on each side and a couple of bits of shingle tacked to the cleats to keep it from falling out. And it did fine, throughout its working life with him (1930s to about 1963, when he died) and for at least ten years with me. I've still got it, and hope to renew it, if I ever get around to replacing the temporary bench that I built 20+ years ago, when the boys (now 39 and 43) were teenagers.

[Joe A Faulkner]

I'm in the, "you are over thinking this" camp. I seriously doubt that the meager weight of the thick chop is placing excessive force on the screw, especially compared to the forces placed on the screw as it is clamped tight to hold work. My guess is that on most days you won't open up this vise more than 2 1/2", and if you work primarily with 4/4 lumber, most of the time you will only open it 1 1/4" or so. The point being, it is unlikely that you will have the leg vise opened very wide where you might get enough leverage out over the chop to tweak the screw or nut threads. Who is going to have access to your bench? If it is primarily intended to be used by you, do you intend to pound on items secured in the vise where the force would be transferred to the screw? If not, then I don't think for "intended, conventional use" you need worry about it too much.

[ian maybury]

Hi Phil(s). Pardon me. I was mistaken in suggesting that it controls vertical location of the screw, although it does from side to side. My errrrrmmm excuse is that I've just started building my bench, but not got into the detail of the vise yet. (it'll have a leg vise - i've bought the criss cross - but a DIY screw)

I have the original pre-criss cross Benchcrafted instructions bought several years ago - which listed an acetal bush with a round hole. Following a look at the current instructions just now it seems the hole was subsequently elongated a bit so that it only locates the screw side to side. The point being presumably that either the criss cross or the parallel guide (original version) prevent the chop dropping down anyway - so making the hole slightly oval reduces the risk of binding or other oddness while tightening. They also set out how to position the nut at the back of the bench leg so that the screw is at mid point of the available clearance in its thread as the chop comes up tight. Again to prevent binding as a result of the small angular changes that happen as the chop moves in and comes up tight.

BC are definite the screw should not contact wood though, and the acetal bush does play a role in stabilising it.

As Bill/Joe there's no argument but that a leg vise will work even if it flops about a bit or touches the wood. The niceties in the BC layout are presumably about ensuring their trade mark low friction and sweetness of action...

[Paul Sidener]

I believe you are over thinking this. If you are using the Veratas screw, are you using a parallel guide on the bottom of the chop? That should prevent the vise from sagging down too much.

[Phil Mueller]

Thank you all for the input. Ian, that was my concern exactly. Given the experience of George and Bill, and the reality check from Joe, I'll just do the install with the screw simply going through the leg. I figure if I can get even half the life out of it that Bill's vise has gotten, I'll be well served!

[Prashun Patel]

I do not have a parallel guide on my leg vise. I use shims on the floor. Even without a lower guide, my vise doesnt bind and still works fine and shows no signs of slack in the nut or wear on the screw.

[Phil Mueller]

Thanks Prashun. Appreciate that input. Schwarz's design for the parallel guide has it going through a leg mortise open to the floor...so the guide doesn't provide any vertical support...again, part of my original concern, which doesn't sound like a concern after all.

If if anyone takes another look at this thread, would appreciate knowing what size hole you drilled for the screw. The screw is 1 1/8"....should the hole be 1 1/4?

[Prashun Patel]

I believe mine came with instructions. I recently just made a moxon vise on a mini-bench and I used veneer press screws for my vise. Unlike the tail screw vise you're looking at (actually I think my leg screw is the same exact one) the press screw does not have a way of bolting onto the chop. The tail screw does; it screws right into the chop. This combats vertical racking that would occur if the hole through the chop were to be oversized. I therefore don't think it's overly critical that the hole is perfectly sized.

Similarly, through the leg, the collar gets screwed into the leg, so if the mortise for it is slightly too big, you probably won't notice a change in performance.

I would aim, however, for as tight a tolerance in the screw hole and collar mortise as is practical.

[ian maybury]

This by Chris Schwarz is a pretty decent satement of just how little is required at the most basic level to build a functional leg vise: http://www.popularwoodworking.com/woodworking-blogs/chris-schwarz-blog/leg-vise-parallel-guide-garter Beyond that it's seemingly down to personal preferences...

[Brian Holcombe]

Ian, The handle and screw on that one are really cool.

[Phil Stone]

Phil, I can't remember exactly which bit I used to drill the screw hole, but I do know that I cut it too close -- maybe I tried 1 1/8? There should be no contact at all between the screw and the leg, or else it won't run as smoothly as it should. I, too, used the Veritas screw. I ended up doing quite a bit of filing of the hole and refitting of the screw to get it to run smoothly. As long as the nut is held securely in the back of the leg, you can give yourself a little clearance with the screw hole.

[ian maybury]

:) Hi Brian. I think i must as my old primary school teacher used to say be a Philistine. (as opposed to a Neanderthal) It's a bit like the old tool versus new tool thing.

It's not that i can't see the beauty/attraction of an old style wooden screw like that. I can even appreciate that it does a perfectly acceptable job, and that it's mostly a case of getting used to its vagaries. (that it wobbles side to side, that using a strip of tapered wood on the floor as a spacer causes the chop to tip sideways and either twist or at least apply uneven pressure side to side of the jaw, that the bench has to be heavy enough and the floor flat enough that the chop can't rotate as a result of the friction from the collar under the screw, that the extra bit of friction isn't a big deal anyway, and that there may even be times when a bit of slop is useful when clamping tapered work and the like...)

I'm less keen on the loose handle - having spent years as a kid with blood blisters on my hands caused by getting skin pinched between the boss and the knobs at the end of the handles when a similar example of the latter dropped down on an old metalworking vise.

It's just that in my personal value system (and each to his/her own) i can't see the point in not going the extra 1/10 mile to install a criss cross or parallel and a hand wheel - and get everything lined up carefully so that it all works smoothly and predictably...

[Jason Lester]

I drilled mine 1 3/8" since that's what size bit I had. It seems to work fine.

[Phil Mueller]

Ian, can't argue with you. It's just that that extra 1/10 mile is the difference between $40 and $300....well over my bench budget. If I find this set up frustrating, I can always upgrade.

[Prashun Patel]

And its not 1/10 mile. Imho its less of a marginal improvement. i had the idea to add a proper guide to mine, and i have never felt it would improve things. The vise does not spin. Its heavy enough to stay true.

phil, adding a bell and whistle lower guide after the fact is always possible. Your instinct and plan in this case is not a bad one.

Ian, i respect your posts and have learned a great deal from your knowledge, but on the leg vise, i humbly suggest u try it this way before suggesting its not optimized for the things the average leg vise user would want. Benchcrafted and other proponents of those great guides may be creating a false perception that without the bells and whistles, performance suffers.

[Brian Holcombe]

:) Hi Brian. I think i must as my old primary school teacher used to say be a Philistine. (as opposed to a Neanderthal) It's a bit like the old tool versus new tool thing.

It's not that i can't see the beauty/attraction of an old style wooden screw like that. I can even appreciate that it does a perfectly acceptable job, and that it's mostly a case of getting used to its vagaries. (that it wobbles side to side, that using a strip of tapered wood on the floor as a spacer causes the chop to tip sideways and either twist or at least apply uneven pressure side to side of the jaw, that the bench has to be heavy enough and the floor flat enough that the chop can't rotate as a result of the friction from the collar under the screw, that the extra bit of friction isn't a big deal anyway, and that there may even be times when a bit of slop is useful when clamping tapered work and the like...)

I'm less keen on the loose handle - having spent years as a kid with blood blisters on my hands caused by getting skin pinched between the boss and the knobs at the end of the handles when a similar example of the latter dropped down on an old metalworking vise.

It's just that in my personal value system (and each to his/her own) i can't see the point in not going the extra 1/10 mile to install a criss cross or parallel and a hand wheel - and get everything lined up carefully so that it all works smoothly and predictably...


This is not from personal experience, but from what I have gathered from others;

Some prefer this method because they can choose a pinch clamp or bias the clamp to hold tapered objects.

[ian maybury]

Hi Phil. Sorry if i seemed to be negative about one or other approach, i didn't mean to be. It really is a horses for courses sort of deal. I certainly wasn't suggesting that everybody rush off and buy the Benchcrafted kit - it's very nicely made, but boy is it expensive.

It's beyond my budget too. I for example couldn't resist buying a crisscross on its own (although a wooden parallel would have done fine), but all of the rest of the hardware i've prepped for my own bench is DIY - built from modified parts pilfered from a face vise, and various bits of industrial scrap. That's a leg vise, and a wagon vise. A friend did a little milling for me. The handwheel was bought from a tooling supply place. Hopefully it'll work out OK.

What i guess i was pointing at more is that it's possible to DIY build in many of the features that give the BC its ease of operation. Perhaps because my personal instinct is typically to head off down that sort of route.

An engineering conditioned background means I hate to give away precision, because while it may eliminate a certain versatility in the finished item it tends to mean that it does a better job on those tasks it's optimised for. I'll usually trade time for money in this regard - although if you are working commercially that may not be a great option either. It's relatively easy for example to buy or dig up a block of 3/4in acetal or UHMW on the cheap (mine came from the scrap bin of a toolmaking outfit), and the rest is labour. (setting it in the face of the bench leg)

It's clear Brian that there will be situations where lots of clearance may be very useful - no question. So some will prefer a looser set up. I've not yet used a leg vise, so at this stage my actions are truly down to the instinct mentioned above...

[Phil Mueller]

Ian, didn't take it that way at all. I enjoy this forum because I can get a good variety of input. I appreciate the time you put into your posts.
Phil

[ian maybury]

Spot on Phil, not always sure since i don't really speak American...