designing lead screw path for tail vise?

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Forum topic by luthierwnc posted 12-29-2015 01:30 PM 706 views 0 times favorited 3 replies Add to Favorites Watch
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146 posts in 1800 days

12-29-2015 01:30 PM

Hello All,

I’m going to be building a new bench that combines features of a quasi-roubo bench I built for guitar making and my original (for this shop) all purpose bench. I made the former too tall and it doesn’t get used much for everyday purposes but it does have a twin-screw tail vise where the lead screws are almost to the edges of the 27-in wide bench to hold an acoustic guitar body positioned horizontally. I have a pair of carpeted 2X6’s bandsawed with a curve that fit over the screws. The new bench will keep that but it raises a conundrum:

I’m using a pair of German-made 1 1/4” tail-vise screws that are very well made. I need them to work independently since guitar bodies are not symmetrical. The nuts are positioned behind a piece of 4/4 and a piece of 8/4 stock and the system works really well for that. The holes are oversized—which may be part of my problem. It has pop-up dogs that correspond to dog holes along the length of the bench. That vise will be doubling-up duty as a more traditional tail vise but I’d like to take out some of the vertical slop. When the vise is open with nothing in it, There is maybe 3/16 inch of play if you lift the jaw. When it closes with pressure (not on a guitar body) using the dogs the jaw bends back a little. Even as well machined as the nut and threading is, an inch or so of contact doesn’t maintain optimal verticality (sp?).

Do you have a favorite way of bushing-out the screw support so it holds the line? I’m playing with hanging a pair of pillow blocks of flange bearings under the top, linear bearings (if I can find the right size) or just an oiled bushing for two points of support along most of the travel. I also have a big chunk of UHMD plastic in the bin.

Thanks for any ideas, Skip

3 replies so far

View rwe2156's profile


2962 posts in 1504 days

#1 posted 01-06-2016 01:34 PM

I have a similar problem with a Moxon vise I built.
I think a standard bushing insert will help.
I got it from Enco.

I’ve toyed with the idea of some type of runner to have it both ways.

For face clamping, a work around is to close vise within a 1/4” or so and use a double wedge made of thin wood to shim the other end then when you tighten there isn’t as much rack.
Good luck

-- Everything is a prototype thats why its one of a kind!!

View luthierwnc's profile


146 posts in 1800 days

#2 posted 01-06-2016 05:57 PM

I’ve played with this and came up with something that would be pretty cheap and just might work. The problem is that the play at both the mounting for the screw and the nut gives the assembly a lot of vertical slop. This design is very close to what I have now but I would redo the chop as a 2×5/4 laminate with the your bushing buried inside. That should tighten the play there. The dog assembly would be easier to make than the version I chopped out of 8/4 stock.

From another Lumberjocks thread I borrowed the idea of a ball bearing on the receiving side. I could just sandwich that between the leg and the stationary vise face by routing a big circle—pretty easy as long as I do the steps in the right order to keep things linear.

This isn’t a traditional use for ball bearings and it does subject the inside to screw scratches. OTOH, I can’t spin the handles at 3600 RPM either so it will probably hold up until I’m too old to notice.

Thanks rwe2156 and let’s see if we get more ideas from our colleagues, sh

View Hammerthumb's profile


2853 posts in 1999 days

#3 posted 01-06-2016 08:31 PM

That is similar to what I did, but used delrin plastic instead of bearings.

-- Paul, Las Vegas

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