jammy Posted December 10, 2006 Report Share Posted December 10, 2006 I've got to the point in setting up the home workshop when I've got to consider what type of clamp's I'm going to invest in. -At college we use cam clamps for most things (attaching bracing, clamping tops/backs to the rims etc) and they work great. The problem I'm having though, is that at £5-7 each, they're not cheap, and attaching a top usually uses about 40 or so... -Gobars seems like a nice way to go, but it concerns me somewhat that when used for clamping bracing on I'm going to have to make some dishes with correct curvatures on to support the work, and I'm sure that can't be easy (perhaps I'm wrong - suggestions?) -Third option - spool clamps. Look great, but I'll still need something for doing the bracing glue ups. Basically my question is to you acoustic makers - what clamps do you use? What are the pros/cons? Any tips you think I may find useful? etc etc... Pictures of your clamping setups would also be really good, just to give me some ideas Thanks for any help guys. Quote Link to comment Share on other sites More sharing options...
fryovanni Posted December 10, 2006 Report Share Posted December 10, 2006 Jammy, I have finally broke down and ordered parts for my vac. clamping system. Really what finally got me moving was when Russ mentioned he was getting ready to build his. You can build a number of clamping fixtures using the system which adds simple flexability. I am making a main clamping press for bracing(30"x36", and final depth may be 7.5" to accomodate top and back clamping). I am also making a bridge fixture(9x6). I am shifting over to more and more hot hide glue, and the speed of a vac. clamping system seems like it will be the right way to go. I wish I could give you a review on my system, but I am still rounding up parts and have yet to try it. Russ pointed me to the Joe woodworker site(great info), and LMI also offers systems and parts. BTW: I am using my air compressor to drive a venturi vac. pump. I have heard good things about them, and the price makes getting into a system much more reasonable(I will review it as soon as I take it for a test run). Peace,Rich Quote Link to comment Share on other sites More sharing options...
Setch Posted December 10, 2006 Report Share Posted December 10, 2006 Making radius dishes is pretty simple - Mattia has posted how he does his. Making cam clamps is also pretty easy, and inexpensive. I made one to reglue bridges a while back ,and I just wish I had to the time to churn out some more! All you need is some 4mm by 20mm mild steel or aluminium for the shaft, some 3/4" hardwood fpr the jaws, a few bits of 1/3" ply for the cams, and a few nails to pin the jaws to the shaft. With you workshop you should be able to turn them out in your sleep! Mine was based loosly one this design, but I substituted metal instead of the hardwood shaft they use. I used mild steel, but I'd suggest ali' - it's much lighter. Quote Link to comment Share on other sites More sharing options...
Mattia Posted December 10, 2006 Report Share Posted December 10, 2006 Radius dishes are dead simple to make; make an arch for the router to ride along (measurements at mimf.com in library, else just use cad), route away. Pic of my setup: Googling will reveal better explained 'how to make a radius dish' type of things, and the MIMF forum has a bunch. I love go-bars (5mm fibreglass) for brace clamping, and gluing top and back, and wooden cam clamps for almost everything else. Oh and some bar clamps (metal) for electric blanks and the like. I'd love to make a bunch of cam clamps, but I don't have the patience, so just ask folks to give me one or two if they run out of gift ideas, and add one or two to every order from a woodworking supply place.... Quote Link to comment Share on other sites More sharing options...
jammy Posted December 10, 2006 Author Report Share Posted December 10, 2006 I've done a lot of research tonight and it does indeed seem like go bar decks are the way to go! Good and simple... I've got a couple of questions about this radius lark, though. So far when making instruments I've been using measurements of deflection (3mm difference from the end of the brace to the middle, for example) rather than a specific radius. What radiuses do you lot use? Just a generic one for the tops and a different generic one for the backs? Or do you vary from instrument to instrument? Are there any specific books you'd recommend that use the radiused dish/go bar method of construction? I'd like to have a good read.. Quote Link to comment Share on other sites More sharing options...
fryovanni Posted December 11, 2006 Report Share Posted December 11, 2006 I have made my radiused dishes using the same method Mattia has shown in the pic above. It does work very well, and makes builds go smoother and more accurate. As far as common radius used. Back-12', 15', 20', 25' top- 25', 28', 30', 42' Some people even use flatter, but those are most common. I personally use 15'/25' or 15'/28' I don't recall a "good" read on what to use. I think you will find opinions vary. The basic concept is radius adds a bit of strength, but too much can hurt how well the plate can perform. Flat is more efficient, but when you build wider boxes they need a bit of added strength. There is also theory about the top/back radius and air coupling, but I have never really found good info relating to the subject. Maybe Mattia has a good link. I would like more info on the subject myself. Quote Link to comment Share on other sites More sharing options...
erikbojerik Posted December 12, 2006 Report Share Posted December 12, 2006 I made my own spool clamps...some big dowel chopped up, some machine screws with wing nuts, even covered with cork. I've now got a whole set of 1/4-20 machine screws with different lengths for different depth bodies (acoustics, thinlines, mandolins) color coded with spray paint. I just broke down & bought the cam clamps for bracing, 3 of the big ones and 3 of the shorter ones. They take up less space than a go-bar deck. Quote Link to comment Share on other sites More sharing options...
Mattia Posted December 12, 2006 Report Share Posted December 12, 2006 I just broke down & bought the cam clamps for bracing, 3 of the big ones and 3 of the shorter ones. They take up less space than a go-bar deck. Erm, this assumes you need an actual deck. My original go-bar deck was the space beneath my (very, very heavy laden with a 50lb tube amp and a computer and a TV and a stereo) desk. My current 'deck' is the space on the workbench beneath the 25"x25" shelf I've bolted to the wall above it. When not in use, it's regular bench space. When I want to clamp, just put stuff under it, grab the go-bars from the PVC pipe on the side, and go. You really, really don't need the stew-mac style standalone deck. Heck, if you really want to, you can just use the ceiling. Another reason I didn't go with spool clamps is speed, tbh; I want to try hot-hide gluing tops and backs soon, and I know I can get an acoustic top clamped, fully, with go-bars, in under a minute. I know I can't do that with a hojillion spool clamps. Quote Link to comment Share on other sites More sharing options...
erikbojerik Posted December 12, 2006 Report Share Posted December 12, 2006 Mmmm....very good points! Given my current bench layout, I'd need the ceiling-mounted versions, but that could be rearranged. How much longer do you make the bars, and how many do you use for a top/back glue-up? Quote Link to comment Share on other sites More sharing options...
Mattia Posted December 12, 2006 Report Share Posted December 12, 2006 Mmmm....very good points! Given my current bench layout, I'd need the ceiling-mounted versions, but that could be rearranged. How much longer do you make the bars, and how many do you use for a top/back glue-up? Bars only need to be 1.5-2" longer than the distance between plates. Further bending essentially doesn't increase the pressure applied at all. Since I didn't have enough bars, I broke this distance rule for my first projects: Those bars were cut for bracing a top, so floor to underside bench level. The only ones with the right amount of flex in them are the ones going into the box, gluing down the headblock tounge above the soundhole. The rest is just me tempting fate, although the rubber tips give plenty of grip. The rods are 5mm diameter (+-3/16") fiberglass, available at any kite supply place (in the us, I like intothewind.com), they also have little rubber nibs for the ends, which I superglue on (medium-thick) because they sometimes want to fall off. Quote Link to comment Share on other sites More sharing options...
jammy Posted December 18, 2006 Author Report Share Posted December 18, 2006 While in Brighton this weekend visiting a mate, I popped into a kite shop. Bingo! 36 gobars for less than £18 These will be my full length ones for doing bracing glue ups, I'll get some shorter ones soon for doing tops/backs. Quote Link to comment Share on other sites More sharing options...
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