Hi, I am making my first guitar box out of local timber, 250 x 200, and wondering what depth it should be as a starting point? Our acoustic guitar is 110mm deep, by comparison.
The local hardwood timber for the neck is 40 x 19 ( +/-1mm), but I can plane that to a different dimension if necessary.
Do you recommend a rebate on the top and bottom of the box for the 5mm thick base and lid to fit in? Might look neat, but takes up space inside the box.
Nothing is set in concrete, will to have a go as long as it sounds nice and looks nice :)
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Hi Carl,
Quote: I can see CBG tops being sprinkled with glitter & vibration tested. :)
Haha, possibly no need for that carl. I know you jest. But some members have commented on the method of "tapping" in order to judge the response of their tops..albeit on dog bowls and the like when assessing suitability for a Reso build. I wonder who does it to judge wood top quality.
I use the glitter and frequency generator method to tune my acoustic guitars during the build, but mainly tapping gives me feedback that I can better understand, but I don't do that on a CBG.
Cheers Taff
"Did you check out Carleen Hutchins's work?"
Since the links I found on this website pertaining to her no longer pointed to info about her, here are some more:
https://www.nytimes.com/2009/08/09/arts/music/09hutchins.html
https://acousticstoday.org/historical-biographies-in-acoustics-carl...
Biography
https://www.amazon.com/American-Luthier-Carleen-Hutchins-Science/dp...
Pretty amazing woman! I can see CBG tops being sprinkled with glitter & vibration tested. :)
Hi jillB,
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hi Brian, what do you think is a good position for a bridge please? How do you find it?
Hi JillB, what I would try is to build the box, top back, and neck fitted [can be temporary] string up and with a movable bridge start at one end, tail, and move towards the centre whilst strumming. I would do this with no bracing under the top and a soundhole installed. This will indicate the most responsive area. The thickness/responsiveness of the top and back also contribute to the output.
Then you will have to select a scale length that incorporates that position for the box.
Did you check out Carleen Hutchins's work?
Cheers Taff
Hi, seems like I/we are moving away from the KISS principle of Cigar
Box Guitar building and I don't think for a moment that this is all that important to get a sound out of a small box, an instrument made of found materials. But it's an interesting subject. JillB talking of sound and small boxes, check out the work of Carleen Hutchins.Cheers Taff
Nice and timely reality check there for me, thanks Taff
Hi JillB, I like your style, you sound like my son, the person I made the video for, and the makings of a CBG in parts as a teaser to get him interested. He built the one I sent him and was so overcome with the challenges of "doing it better" he only built four CBGs before he turned his hand to making acoustic guitars. He now has a fully set up woodshop, and he also inherited half my collection of textbooks.
http://www.phys.unsw.edu.au/music/. Should get you started. Oh, and keep in mind that depending on the timber used for the top, 5mm might be as thick as you may want to go. Enjoy, TaffTry this, it should satisfy you till tomorrow. Haha
Thanks for this link, Taff, I am in my 7rth heaven with the page on Guitar Acoustics. All from my old alma mater too where I studied Electrical Engineering all those years ago (50+). Small world.
I used to do a bit of travelling wave study for damping of vibration on power lines.This brought back memories. The worst case was a steady gentle breeze that really got the vibrations going, so we had to determine where to put the dog-bone style dampers on the conductors.
I am still thinking where the best theoretical location of a bridge would be, and hopefully I can find some relevant info on this discourse of travelling waves and standing waves etc.
We are all looking forward to your video :)
Thanks again, Taff
Hi, I’m no physics type I work it out by experiment and experience and suspect you will do the same over time.
When I was asked to build a CBG for a guy I had never heard of one let alone seen one. The customer explained what it was, and I thought oh, a box with strings on it. Even though I had built many guitars over many years I still made three cbgs before I was happy with the one I would sell, changing each one as I went along.
Anyway, the size box and soundhole you mention will work fine. It will give you a baseline from which to work if you are going to build others. One would have to be very lucky to nail it the first time, I reckon.
The finished item is a great thing to behold and enjoy, but I think so is the mystery in the journey, which will be full of highs and lows and great light bulb moments.
I may be wrong, and this may be a case of too much info too soon… but it’s not just the size of the box that is the basis for the desired hole size, but the responsiveness of the top and the air it moves. Sorry.
People often say that the bridge is a third of the way up from the butt end on an acoustic guitar, which is correct. However, the bridge is where it is due to it being in the Centre of the effective vibrating area of the top. From the soundhole or waist area to the heal/neck end, the top contributes very little.
Jill, can you please stop asking such interesting questions. Haha
Taff
Just keep asking the questions Jill.
Really interesting answers and advice, so helping me tons and saves me having to ask ‘em.
Thanks.
"Jill, can you please stop asking such interesting questions"
Sorry, Taff, but it is such an interesting subject, and I am on a really steep learning curve. And being a perfectionist, I thought I would just read up on it, master the concepts and theory, and then draw it up and and then make the perfect CBG, without ever having seen one. I need to get real !! :)
And it is a classic case of the more information I get, raises even more questions.
I really appreciate you and others like BrinQ sharing your knowledge and experience, What a great Forum !!
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