|Forum topic by luthierwnc||posted 12-29-2015 01:30 PM||496 views||0 times favorited||3 replies|
12-29-2015 01:30 PM
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