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| Author: | crich [ Tue Jan 31, 2006 1:51 pm ] |
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Hi there, I'm a first timer here, and I can't wait to get started. I've been jigging and tooling up for year now. I've been sharping my woodworking skills, now that my children are never home. My first of many,I'm sure, questions is: should I raduis spherical or just cylindrical? it makes sense where I read on this forum that spherical stresses the vertical grain and thus restricting the top from vibrating. But how about the back, where, from where I read, you won't least amount of vibration.maybe, just a newbie here, cylindrical on front, spherically on the back? |
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| Author: | Dickey [ Tue Jan 31, 2006 3:32 pm ] |
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Well, most of us, not all, use radius dishes. I have two for the top, two for the back. One is a sanding dish, the other just for glueups. I use 15' radius for the backs, 25' for the tops. Lots of places to get these, or make 'em yourself. One of the ways we know newbies are progressing is by the "quality" of their questions. And we have to encourage you to ask the "dumb" questions too, because the only dumb question is the one that isn't asked. Welcome to the OLF. Now we want to see the pics of your shop or at least some of your jigs and tools, materials, heck anything, especially if there is a guitar involved. |
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| Author: | Serge Poirier [ Tue Jan 31, 2006 3:45 pm ] |
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Glad you made it here Clinton, as Bruce said, we're a big bunch of guitar nuts and voyeurs! The radius dishes is the way to go or Michael Payne's tip using a 2x4 with sand paper, if he chimes in, he'll tell you more about it. Welcome to the best of forums! 
Serge |
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| Author: | Rod True [ Tue Jan 31, 2006 3:51 pm ] |
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Welcome here Clinton I think most people use spherical on both top and back. Now having said this, there are many who only use spherical for the lower bout on the top and make the front flat, angled still just not spherical. There are many ways to skin this cat as you will soon find out by reading and asking questions. I do know of one local builder who just uses a cylindrical form when gluing the braces on the back, don't know how he forms the rims though. So either way is doable, just have to pick one and go with it. As Bruce said, there are many avenues to obtaining the "dishes", making them is very simple, but will create a ton of dust so be carefull it you decide to make your own, wear a dust mask. All the best with your build, I'm assuming it's your first. Also as Bruce mentioned (sort of) ask lots of questions, cause as you can see, there are many of us that like to talk (help)
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| Author: | Rod True [ Tue Jan 31, 2006 3:52 pm ] |
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Hey Serge, nice to see your a 4 star general now. |
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| Author: | Dickey [ Tue Jan 31, 2006 3:58 pm ] |
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Hey Rod, You gettin' any sleep? |
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| Author: | Rod True [ Tue Jan 31, 2006 4:00 pm ] |
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Sleep? Ya actually, things are going realy well. The boy is sleeping very well and we are getting about 2- 3 hours in between feeds every night. Not to bad. So on average we get about 8 hours sleep if we go to bed at 9pm and start the day at 6am. Gee, now that's weird math.  |
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| Author: | Serge Poirier [ Tue Jan 31, 2006 4:09 pm ] |
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Thanks Rod, those 500 some posts are mostly from welcoming, congratulating and laughing with others, everything except building. I guess i forgot to see a shrink for the little bugger there you know, the LOL button Give me 500 more posts by march and send me 2 guys with a shirt that ties in the back aweright?
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| Author: | Todd Rose [ Tue Jan 31, 2006 11:30 pm ] |
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One of the reasons for domed tops and backs is to make it easier for them to expand and contract with changes in moisture content resulting from changes in humidity, and therfore less likely to crack. A dome, it seems to me, will do this much better than a section of a cylinder, and will tend to maintain its basic shape better - a rounder dome when more moist or a flatter dome when more dry, rather than a cylindrical shape that's caving in and becoming actually concave in its lengthwise dimension. These statements are an oversimplification, because there are other factors that come into play, e.g. the moment you string it up and your bridge is torquing on the top, it ain't gonna look like no perfect dome anymore. Some builders make their plates flat, and some do cylindrical and other odd contours, and probably most of those guitars hold up well... but most builders (including factories), if I'm not mistaken, dome their plates, and this method makes the most sense to me. |
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| Author: | Dave White [ Tue Jan 31, 2006 11:48 pm ] |
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Crich, I suspect that the "dome" shape is very common as it is easier to make. You can make brace bottoms in this contour easily and you have radius dishes to glue down the braces and to contour the sides. Imho the dome is not necessarily the best shape to make a guitar in. The "cylinder" shape front to back probably has it's origins in archtop type guitars and has it's own tonal properties. Howard Klepper uses this shape as he believes it gives better balance of lateral and longitudinal stiffness in the top. I use braces of around 14' radius on my backs and 15' radius on my tops but the shape they assume is not "spherical" I like the cylindrical dome as I believe it helps projection and sustaim, but I also like some curving front to back as I think as well as for tonal reasons it helps with bridge/saddle angle relative to the neck/strings. Bracing builds in the structural stability for the guitar to carry string load but it also shapes the way the top moves and vibrates - I don't think you should always view this as "restricting" or that braces are a necessary evil that have to have their effect minimised. All part of the "fun" in building guitars and I sure you are going to have lots of that - welcome aboard! |
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| Author: | Michael Dale Payne [ Wed Feb 01, 2006 1:13 am ] |
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Welcome Crich. Those of us that use sanding bowls are imparting a spherical Radius to our assemblies. That said, the shape of the guitar and the short length/width to radius ratio renders a shape that to the eye appears to be more cylindrical, but it is not. Many builders flat sand the rims to the domes boundary profile then pull the backs and tops edges down to make contact with the linings as shown in C&N's book "Tradition and Technology. Or use a method similar to the one I learned with that sands a near spherical taper in to the rim. Check out my last weeks post on “Cheap alternative to sanding bowls where I explain how to use a sanding board to sand a near spherical shape with out the use of a sanding bowl. Keep in mind this is not perfect but twice as good as just flat sanding the domes boundary profile only. |
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| Author: | crich [ Wed Feb 01, 2006 3:26 pm ] |
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Thanks, I appreciate all the input. Seeing that this is my first,I should stick fairly close to the plans from Kinkaid's book. Maybe I'll experiment after I ascertain some experience. Wish me luck! |
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| Author: | Michael Dale Payne [ Thu Feb 02, 2006 1:04 am ] |
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Crich, I am not that up on Kinkaid's fabrication techniques, but I will say this. I would do every thing in you ability to reduce imparted stresses where ever you can. I am not saying that anyone’s method is bad but with both sanding bowls and a simple sanding block so available or easy to make and use, I would be sure to make your linings and blocks match the dome as close as possible. Next to the neck these joints are under some of the greatest stress. JMO |
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| Author: | Todd Rose [ Thu Feb 02, 2006 3:53 am ] |
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If you also watch the videos from Frank Finocchio, John Mayes, and Robbie O'Brien before you start to build, you may be very glad you did. Just a suggestion. |
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