This is a multi-part message in MIME format. ---------------------- multipart/related attachment ------=_NextPart_001_001B_01C40CBD.DA0A5900 Hi David, Looks like Ron N covered most of it. Letting an appropriate number of = laminations terminate to form the doglegs, IMHO, is key to trouble-free = vertically laminated bridge root lay-up. With this approach, there is no = reason to ever use less bend at a dogleg than optimal. Below is a = picture of my last bridge under clamps. I bond my laminations together = with West System epoxy. I like epoxy because it takes the worry out of = getting the right clamping pressure - just squish the assembly together = so you get the proper shape and the clamps hold it until the epoxy cures = - that's why I use so few clamps! The picture below shows the basic clamping set-up (epoxy has been = applied). The picture below shows the raw root right after coming out of clamps. = The pic is zoomed onto the two doglegs at the tenor/treble and = treble/hi-treble breaks. You simply round off the terminated laminations = and you have your dogleg. These and other pictures of this process are available if anyone wants = to email me privately. Terry Farrell > >I need a crash course on bridge building (long bridges, bent = laminated > >type). Could use some suggestions on how I might go about getting > >information, how to make a template, what tools I might need, = materials, > >etc.. Whatever can be offered would be appreciated. > > > >David Love >=20 > Hi David, >=20 > I use a rubbing (paper template) from the original configuration = (before I=20 > take the strings off) as a point of departure. After re-scaling, I = use that=20 > template to establish the new speaking lengths, which I use to lay = out the=20 > new bridge. Once you have the template for the new bridge, you need = to=20 > decide how you are going to build the bridge. You can cut it out = from solid=20 > stock, joined at the scale breaks to keep the grain running roughly=20 > parallel to the bridge, or you can laminate it. You can laminate it=20 > horizontally, putting the joints in each lamination in random places = so the=20 > strength of the assembly won't be compromised, which works fine. Or = you can=20 > laminate vertically, which means building a jig of some sort for = clamping=20 > the laminations to the required curve. I've done bridges with = continuous=20 > vertical laminations, but it's a lot more work than should be = necessary for=20 > a one-off bridge. You need laminations at 2mm or under to make the = dogleg=20 > bends at the struts to maintain a semi-log speaking length = progression, and=20 > a tremendous amount of clamp pressure. >=20 > An easier way to do a vertically laminated bridge root is to use the = > lamination thicknesses to supply the dogleg offset and not have all = the=20 > laminations continuous for the length of the bridge. Terry Ferrell = asked=20 > about this a while back, and it looked like a good idea to me, so I = tried=20 > it. It works very well. Thanks Terry. You just have to build half a = jig to=20 > accommodate it, clamping the lamination stack against it without = needing a=20 > caul on the far side. Actually, I used backing strips to spread out = clamp=20 > pressure, but still didn't have to cut out a full caul. Since the = core=20 > laminations don't have to be forced into an extreme bend, it's = considerably=20 > easier to manage and takes much less clamp pressure. It just takes a = little=20 > more pondering and planning before the fact. >=20 > That short stack of maple just above the bridge in the photo is the=20 > laminated cap (1.5mm laminations), waiting to be cut and fitted to = the=20 > root. The bridge root is still rough cut here (hacked, actually), = and will=20 > be smoothed and contoured before the cap is installed. >=20 > The laminations in this bridge vary from 2mm to maybe 5 or 6mm. I = used what=20 > I had lying around from previous projects that added up to the = offsets I=20 > needed for the doglegs. It's a tad over 30mm wide overall. >=20 > To do this, you need a way to produce the required laminations - be = it a=20 > table saw or band saw, and (ideally) thickness planer. You need lots = of=20 > clamps (naturally), and scrap(able) lumber for building the jig. You = also=20 > need a glue that is reasonably hard and creep resistant. I use = Titebond.=20 > Realistically the glue used for laminating doesn't need to be able = to hold=20 > continents together without shifting under billions of PSI. Gluing = the cap=20 > on top, and the panel on the bottom of the root laminates will = effectively=20 > insure that nothing is going to slide apart with a reasonably decent = glue. >=20 > The rest is just the usual bridge work - or you can send me the = original=20 > rubbing and the offset revisions (or?) and we can work something = out. > Ron N ------=_NextPart_001_001B_01C40CBD.DA0A5900 An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/26/91/c1/52/attachment.htm ------=_NextPart_001_001B_01C40CBD.DA0A5900-- ---------------------- multipart/related attachment A non-text attachment was scrubbed... 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