[LUTE-BUILDER] Re: Go-bars
> Dana, > I've had a devil of a time using go-bars with lute bracing. Lute braces > are narrow and it's difficult to position the go bar so it doesn't flip a > brace over. If the pressure is even a little bit off-axis, there goes > your brace. rather like balancing a caber on top of a board set on edge. Dont have to use a rod, use a thin stick, put a shallow saw kerf into the end. Preshape the ends some so you have thin flat ends to begin with. J- braces below the bridge might be spanned by a short wide bit with one or two gobars in the middle of the curve. Mind you, this is all speculation on my part, based on other shopwork I have done. I generally use whatever bits of scrap I have handy when building jigs and fixtures, they all look rather scruffy as a result; often my jigs are completely adfhoc and dont get saved, the components just get thrown back under the bench and reused. In the organ shop we had a long bench on one wall for rough cross cutting and dadoe work, two radial saw were set up, one on the end for dadoes, the other in the middle for cross cutting. A fence ran down the middle, behind the fence was an area that collected odd bits of wood and whatever sawdust escaped collection; a bucket under the middle was the official collector of offcut blocks, but they would go either way on whim. Cabinets overhead on the wall for spare blades, tools for the saws, routers and bits, planes and other odd tools and supplies of course. Periodically the boss declared the odd bits had to go, usually when prospective customers were being woo'd and a tour was scheduled. > shop-made wooden ones? I think the original versions were hazel rods. Oak and poplar for me; whatever is handy and gets the job done. Split bamboo if any grew near, no intention of planting any tho, already have enough trouble with rampant ivy, wild rose, and bittersweet; I understand that bamboo has super deep roots (6 feet at least) and is impossible to get gone once it settles in. -- Dana Emery To get on or off this list see list information at http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html
[LUTE-BUILDER] Re: Go-bars
Hello All: regarding the issue of go bars flipping over braces. This has never , I repeat NEVER happened to me and please note that the above statement is a complete lie. I have found out a few things though which REALLY help here. I do buy the go bars from Luthiers Merchantile , they are fiberglass / cabon fiber or something like that , with yellow rubber tips on the ends. I find that : 1 If I leave the top of the braces a little taller and most importantly flat on top , and remove the yellow tips from the end of the bar which goes onto the brace, the sharp edge of the bar sort of digs into the brace a little bit and stabilizes itself and doesn't slide off so easily. I can then plane down the tops of the braces after the glue is dried. 2 If the bend in the go bar is too much, due to it being too long, I alternate the ends of the go bars (the tips which articulate to the roof of the box ) right and left of the brace, so the bends in the bars (I usually use 5 bars per brace) oppose one another - thus equalizing out the sideways pressure.. This helps prevent the braces from being knocked over on their sides. The Process I use works in this order . The go bars on the ends of the brace go on first . As these bars go on one MUST hold the brace in place I usually sort of bow these first bars inward toward the brace so they mirror image one another making sure that the tops of the go bars as they touch the roof of thebox are absolutely directly above the brace itself so that there is NO sidways pressure at all, only a for and aft pressure which is compensated by the mirror imaging of the braces. . The next 2 bars go on as close to simultaneously as possible with each bowed as described above in a mirror image of each other right and left of the brace . These bars are for the middle of the brace. I do this while still holding the brace in place with my free hand .. The remaining go bars are easier as the brace is now pretty well stabilized in 4 directions and the glue is setting in. The main thing one can do , of course, is to have MANY go bars and then cut them into sets of sizes ... I use 3 sizes myself . The thing to remember is that you want the go bars to bend only as much as is needed to create the clamping force and no more. The least amount of bend in the bar will help concentrate the force DOWNWARD instead of toward the side as will be the case if the go bar is too long and therefore forced to bend a great deal (like a bow) and for these excessive bends, I don' think we gain all that much more clamping force anyway - for that, its better to use more bars. . I feel that anything more than 1/2 inch deflection of the bar is going to require equalizing the forces as described above by having the bent go bars alternating right left as described above and is border line too much of a bend in any case . The three general lengths are to get a good bend at the aforementioned 1/2 inch max for various heights of materials under the bar. The longest length is of course for small pieces .(this length is good for the tiny braces over the rose area of a top ) The next shortest length is for holding down braces onto a top and is perhaps 1/2 half to 5/'8s of an inch shorter , this is for general clamping of braces onto the top. The shortest go bar set is for clamping down bridges onto tops in which the braces have been glued and which tops are being supported underneath by a flat jig cut to lift the top up a little higher than the braces underneath and supply a flat surface under the area of the bridge (as described in David Van Edwards Course) these go bars are around 3/4 of an inch or so shorter than the second set. The 3/4 measurement is dependent of the thickness of the jig. hope this helps ... r - Original Message - From: To: Cc: ; ; Sent: Thursday, December 03, 2009 10:04 AM Subject: Re: [LUTE-BUILDER] Re: Go-bars Dana, I've had a devil of a time using go-bars with lute bracing. Lute braces are narrow and it's difficult to position the go bar so it doesn't flip a brace over. If the pressure is even a little bit off-axis, there goes your brace. I would imagine it's different with the wider bracing found on guitars. The reason I use go-bars when re-gluing bridges is because bridges are wider; then all of the advantages you cite come into play. I would love to hear if anyone on the list has advice for using go bars with lute bracing. Do you use the commercial fiberglass go-bars or shop-made wooden ones? I think the original versions were hazel rods. Tim --- dem...@suffolk.lib.ny.us wrote: From: dem...@suffolk.lib.ny.us To: "Santiago Ramos-Collado" Cc: rel...@sbcglobal.net, lute-buil...@cs.dartmouth.edu Subject: [LUTE-BUILDER] Re: hide glue gram strength Date: Thu, 3 Dec 2009 11:07:15 -0500 (EST) having an appropriate jig to be able to carry this out as fas
[LUTE-BUILDER] Re: Go-bars
Dana, I've had a devil of a time using go-bars with lute bracing. Lute braces are narrow and it's difficult to position the go bar so it doesn't flip a brace over. If the pressure is even a little bit off-axis, there goes your brace. I would imagine it's different with the wider bracing found on guitars. The reason I use go-bars when re-gluing bridges is because bridges are wider; then all of the advantages you cite come into play. I would love to hear if anyone on the list has advice for using go bars with lute bracing. Do you use the commercial fiberglass go-bars or shop-made wooden ones? I think the original versions were hazel rods. Tim --- dem...@suffolk.lib.ny.us wrote: From: dem...@suffolk.lib.ny.us To: "Santiago Ramos-Collado" Cc: rel...@sbcglobal.net, lute-buil...@cs.dartmouth.edu Subject: [LUTE-BUILDER] Re: hide glue gram strength Date: Thu, 3 Dec 2009 11:07:15 -0500 (EST) > having an appropriate jig to be able to carry this out as >fast as possible (forget about go-bars; I do not think they are a good >idea at all, unless one could tension several at the same time!) try it before you give up, I think you will find it a popular solution with many luthiers. The pressure possible from a gobar is just right for the work, the space available is appropriate, and every gobar is a deep-throat clamp with no reach problems. The only faster setup would involve pneumatic plungers, which means a low ceiling to attach them to and the risk there is an inability to see when things have gone wrong inside (a small rib mispositioned tipping over for example). > When I have it done, I shall share the >photographs. they would be welcome by us, but not sure the list will forward attachments. -- Dana Emery To get on or off this list see list information at http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html
