Kevin, thank you going through that process. I’ve been considering making a radius dish of a different radius than the one I already have. I enjoy making my own tools, and this is a great help.
There is another method that you may want to look at: a "long compass". It's easier than the method I demonstrated and at least as accurate if not more. there are some useful videos on their use here on RUclips. Thanks for watching.
Kevin, your videos are incredible. I discovered your channel about a week ago and I think I've watched almost all of your videos since. You're great at both of your crafts, building and treaching. Thank you for sharing your time and knowledge with the rest of us!
You really knocked that out of the park,so glad you moved on from the mathematical equation method because the next method was exactly how I built my dish👍👍
The Liutaio Mottola website's Technical Design- Calculating the Sagitta of an Arc section has calculators for doing the math for those of us who need it. (My high school's "Open Math" experiment was a failure).
Thank you. It is both useful and entertaining. I do a lot of the same things that you are showing, but I would like to say that your methods and workmanship is much better than mine. So your videos are helping me refine my work quite a bit.@@thepragmaticluthier
Kinda gives the adage, "hind sight is 20/20", new meaning doesn't it? On the other hand, if math was taught from a real as opposed to a theoretical perspective, it would have been helpful to all of us.
That piece of wood is "Yellow Wood", Cladrastis kentukea. It is rare in my region of the country but quite prevalent in the southern region. My research made me aware that it had value in Colonial times, being prized as a gunstock wood. It makes a great guitar if you get large enough pieces of it.
I noticed that you do read these so... Check out Driftwood Guitars' latest creation if you haven't already. The finish is like glass; I never seen nothin like it! It's exquisitely beautiful and sounds pretty good too! 🎸
Wow! we here at Hampshire Piano "crown" the piano SB's in just about the same way. Only huge in comparison and usually 12 of them, on the longest sometimes 42" are curved 7mm in height the shortest ones about 4-5 mm curvature. Why do you have the radius amount/curvature height your using in your creations.? I'm very new to luthering, lol and I wonder if you know when guitar makers began to radius the tops that were referred to as "flat tops" once upon a time, and that was seemingly a very long time until the last few years or so---maybe. Are flat tops still being made by any one?
I cannot give you an authoritative history of doming guitar tops and I've heard and read so many ridiculous rumors that it makes things even more confusing. I dome my tops to increase stiffness and to provide for some shrinkage room during dry months. Generally, determine the amount of doming based on my perceived flexibility of a top and the desired result that I'm working toward, i.e., enhancement of low or high frequencies, or balance. I do this intuitively and keep notes which help objectify my experience so that more intelligent or predictable choices can be made going forward.
f (big if) I am correct that the upper bout above the sound hole is flat, does this mean the upper braces, the flat popsicle sticks, for example, are glued on after the radius X braces come off the radius disk/ go bars?
The entire top is domed. The area where the fingerboard will cross the top can be flattened . At a 25 foot radius, for example, the high point of the chord of the dome of the chord representing a 3 inch wide fingerboard would be .00376", not much to sand away:)
I agree 100% with the math used for the deflection at the center calculation. I puzzled over constructing a circular surface by point deflection of a simply supported beam. I agree this will make a smooth surface but I don’t think it is precisely circular. I did some internet research and the shape of your deflected rod is not circular. The curvature at the ends (by pin supports) will be lower than at the center. I used an excel spreadsheet to calculate the circular deflection at various locations away from the center when I constructed my dish. Worked ok. Microsoft did the math. 😅
@@thepragmaticluthier I oopened up my spreadsheet and added a sheet using the deflected beam approximation you used. for starters, I discovered that I estimate the central deflection should be .1499" not .16" for a 40' radius dish. The maximum error from a circle with a deflected beam (method you demonstrated) is .011" a bit less than 10 %. I am not sure how accurate you can cut your lines in the template but 0.01" is not an insignificant error.
This deflection method creates a catenary - the profile of the droop of a rope between two poles. Not an arc. It’s a pretty shape but is not a segment of a circle. I’m sure at this scale there is no measurable difference. But please be clear, I can argue with your method as it doesn’t achieve what your math correctly calculates.
You're correct. If you read the comments above, you'll se that another contributor has calculated the disparity to be .011". The purpose of the entire procedure is to create an even, consistent curve to work with. The calculations provide a quantifiable goal and the method demonstrated provides a technique to reach it at a level of precision that is beyond actual necessity and one that can be performed by nearly anyone. "To be clear", I pointed out the likely imprecision in this technique and also pointed out that departure from the mathematic precision was to be expected and is acceptable. If you demand mathematical precision in your dish, buy one or produce one with CNC equipment, then demonstrate how it makes a marked difference in the mechanical or tonal quality of a guitar made today and or before such precision was within the reach of even the best producers of them.
@@thepragmaticluthier I don’t demand excessive precision in the woodworking involved building an instrument, rather request that we be clear that this technique creates an useful approximation of an arc. Thank you for your demonstration of a method to produce a fixture broadening the accessibility of your craft.
A gentleman named Christopher Paulick has a video on how to make a radius dish using what he calls a long compass. Although I understand how straight boards, angled to each other, and joined together at the center of the router bit will make an arch (radius) as you move the configuration side to side over fences erected on each side of the dish blank, I have yet to figure out how make a long compass. Specifically how to calculate the angle of the boards to achieve said radius. Might you, having a better understanding of geometry than I do be able to explain it on a video? I really would appreciate it. It would eliminate the need to cut and sand the radius for the router to ride on.
Excellent question and suggestion for a video. I may try to present that in the future. In the meantime, I believe the short answer is; given a cord of the proposed radius, equal in length to the diameter of the dish you're creating, you will need to first calculate distance from the bisector to the arc as shown in this video. When that distance is plotted, you now have three points to work from. Draw a straight pin from each end of the cord to the calculated point. The resultant angle is the angle needed to construct the long compass.
I'm more similar to you in that regard than you may think. The upside is that when you arrive at a problem that is important to you, you will amaze yourself with the power you have to learn what you need to know. It's all a matter of relevance.
...and this is why we go to school to learn DIY......a door, a window is always a 90 degree angle....we need to also respect 45 degree angles and other such angles !
Видеоклипы
Kevin, thank you going through that process. I’ve been considering making a radius dish of a different radius than the one I already have. I enjoy making my own tools, and this is a great help.
There is another method that you may want to look at: a "long compass". It's easier than the method I demonstrated and at least as accurate if not more. there are some useful videos on their use here on RUclips. Thanks for watching.
Kevin, your videos are incredible. I discovered your channel about a week ago and I think I've watched almost all of your videos since. You're great at both of your crafts, building and treaching. Thank you for sharing your time and knowledge with the rest of us!
Thanks for your very encouraging comment. I enjoy making these videos and look toward more and better presentations.
Great, great video! You are a wonderful teacher and I appreciate your enthusiasm and encouragement to try to build our own tools.
Thank you. I appreciate your comment.
You really knocked that out of the park,so glad you moved on from the mathematical equation method because the next method was exactly how I built my dish👍👍
Thank you! If you can get the Math workable, the fabrication becomes straight forward.
Nice one!
Thank you for the explanation you are very thorough . Thanks Kevin for always keeping it real.
I sincerely appreciate your comment. It's very encouraging.
The Liutaio Mottola website's Technical Design- Calculating the Sagitta of an Arc section has calculators for doing the math for those of us who need it. (My high school's "Open Math" experiment was a failure).
Thank you for sharing that information! I remember Open Math and other subjects early in my career. You're absolutely correct: it was a TOTAL FAILURE.
I thank God all the time for you. You must be a very happy man because you have blessed so many of us.
Thank you so much for your comment. It is very encouraging.
👍🙂 right on, for sure. some handy tools and methods to get a good outcome.
Im' very glad that you found this useful or at least entertaining.
Thank you. It is both useful and entertaining. I do a lot of the same things that you are showing, but I would like to say that your methods and workmanship is much better than mine. So your videos are helping me refine my work quite a bit.@@thepragmaticluthier
Thank you for sharing that. Much easier than hanging the router from a 24' rope. 😁
Absolutely! And I'm afraid of heights. Tying that rope off way up in the barn rafters is a killer:)
Thank you for the laugh…definitely needed these days…!😂
Reminds me of my hand drafting days before CAD.
I remember classmates in school saying, "This is bullshit, when are we EVER going to need this stuff in real life?" 😉
Kinda gives the adage, "hind sight is 20/20", new meaning doesn't it? On the other hand, if math was taught from a real as opposed to a theoretical perspective, it would have been helpful to all of us.
@@thepragmaticluthier Absolutely.
Looks like Tree of Heaven wood there under your reddish template.
That piece of wood is "Yellow Wood", Cladrastis kentukea. It is rare in my region of the country but quite prevalent in the southern region. My research made me aware that it had value in Colonial times, being prized as a gunstock wood. It makes a great guitar if you get large enough pieces of it.
I noticed that you do read these so... Check out Driftwood Guitars' latest creation if you haven't already. The finish is like glass; I never seen nothin like it! It's exquisitely beautiful and sounds pretty good too! 🎸
I'll check it out!
Wow! we here at Hampshire Piano "crown" the piano SB's in just about the same way.
Only huge in comparison and usually 12 of them, on the longest sometimes 42" are curved 7mm in height the shortest ones about 4-5 mm curvature.
Why do you have the radius amount/curvature height your using in your creations.?
I'm very new to luthering, lol and I wonder if you know when guitar makers began to radius the tops that were referred to as "flat tops" once upon a time, and that was seemingly a very long time until the last few years or so---maybe.
Are flat tops still being made by any one?
I cannot give you an authoritative history of doming guitar tops and I've heard and read so many ridiculous rumors that it makes things even more confusing. I dome my tops to increase stiffness and to provide for some shrinkage room during dry months. Generally, determine the amount of doming based on my perceived flexibility of a top and the desired result that I'm working toward, i.e., enhancement of low or high frequencies, or balance. I do this intuitively and keep notes which help objectify my experience so that more intelligent or predictable choices can be made going forward.
f (big if) I am correct that the upper bout above the sound hole is flat, does this mean the upper braces, the flat popsicle sticks, for example, are glued on after the radius X braces come off the radius disk/ go bars?
The entire top is domed. The area where the fingerboard will cross the top can be flattened . At a 25 foot radius, for example, the high point of the chord of the dome of the chord representing a 3 inch wide fingerboard would be .00376", not much to sand away:)
@@thepragmaticluthier thank you!
I agree 100% with the math used for the deflection at the center calculation. I puzzled over constructing a circular surface by point deflection of a simply supported beam. I agree this will make a smooth surface but I don’t think it is precisely circular. I did some internet research and the shape of your deflected rod is not circular. The curvature at the ends (by pin supports) will be lower than at the center.
I used an excel spreadsheet to calculate the circular deflection at various locations away from the center when I constructed my dish. Worked ok. Microsoft did the math. 😅
Sounds very encouraging. Did your spreadsheet reveal how much deflection from a perfect arc there is?
@@thepragmaticluthier I oopened up my spreadsheet and added a sheet using the deflected beam approximation you used. for starters, I discovered that I estimate the central deflection should be .1499" not .16" for a 40' radius dish. The maximum error from a circle with a deflected beam (method you demonstrated) is .011" a bit less than 10 %. I am not sure how accurate you can cut your lines in the template but 0.01" is not an insignificant error.
This deflection method creates a catenary - the profile of the droop of a rope between two poles. Not an arc. It’s a pretty shape but is not a segment of a circle. I’m sure at this scale there is no measurable difference. But please be clear, I can argue with your method as it doesn’t achieve what your math correctly calculates.
You're correct. If you read the comments above, you'll se that another contributor has calculated the disparity to be .011". The purpose of the entire procedure is to create an even, consistent curve to work with. The calculations provide a quantifiable goal and the method demonstrated provides a technique to reach it at a level of precision that is beyond actual necessity and one that can be performed by nearly anyone. "To be clear", I pointed out the likely imprecision in this technique and also pointed out that departure from the mathematic precision was to be expected and is acceptable. If you demand mathematical precision in your dish, buy one or produce one with CNC equipment, then demonstrate how it makes a marked difference in the mechanical or tonal quality of a guitar made today and or before such precision was within the reach of even the best producers of them.
@@thepragmaticluthier I don’t demand excessive precision in the woodworking involved building an instrument, rather request that we be clear that this technique creates an useful approximation of an arc. Thank you for your demonstration of a method to produce a fixture broadening the accessibility of your craft.
A gentleman named Christopher Paulick has a video on how to make a radius dish using what he calls a long compass. Although I understand how straight boards, angled to each other, and joined together at the center of the router bit will make an arch (radius) as you move the configuration side to side over fences erected on each side of the dish blank, I have yet to figure out how make a long compass. Specifically how to calculate the angle of the boards to achieve said radius. Might you, having a better understanding of geometry than I do be able to explain it on a video? I really would appreciate it. It would eliminate the need to cut and sand the radius for the router to ride on.
Excellent question and suggestion for a video. I may try to present that in the future. In the meantime, I believe the short answer is; given a cord of the proposed radius, equal in length to the diameter of the dish you're creating, you will need to first calculate distance from the bisector to the arc as shown in this video. When that distance is plotted, you now have three points to work from. Draw a straight pin from each end of the cord to the calculated point. The resultant angle is the angle needed to construct the long compass.
I always had trouble with math in school. Things just never seemed to add up...
I'm more similar to you in that regard than you may think. The upside is that when you arrive at a problem that is important to you, you will amaze yourself with the power you have to learn what you need to know. It's all a matter of relevance.
...and this is why we go to school to learn DIY......a door, a window is always a 90 degree angle....we need to also respect 45 degree angles and other such angles !
Little geometry goes a long way and trigonometry goes even further.