I love the guitar CPR technique! Definitely will try it. I use Spanish heel construction so the soundboard attaches to the sides first, back last. But a 1/2” plywood plate with the body interior shape + kerfing cutout would allow the top to be flexed with the CPR technique…
There are many things you can try. Do you have enough time in your life to study everybody's junk guitar building science? How do you love some goofball process? Hurry, 5000 more bogus luthier tips just flooded youtube.
Hi Eric- I am curious if you also have set a Deflection gauge here atop the X brace in the same position (ie measure the deflection of the “CPR” motion with say a 4lb weight) would love a ballpark # as a newer builder
Modern neurology discounts the left brain / right brain thing as physiological phenomenon. Creativity doesn't occur in just the right hemisphere, the left hemisphere doesn't necessarily have an affinity with analytical thinking. However, the left /right view can be used as an analogy to differentiate creative and analytical processes. The good thing is that you can learn to be strong in both talents. The key to creativity is 'flow'.
Thanks for posting this. Roger Siminov talks about deflection in his book as well. He is pretty left-brained, I would say, but he actually uses a dial caliper to measure top deflection against a set weight. I never went that route, but it bears mentioning.
Eric, I'm very happy to have happened upon your videos and sharing of experience and results. I think of the following topic everyday just about: How to fine-tune the guitar after it is closed up? I wonder if some luthiers, when doing a cutaway guitar, take advantage of the potential space to fine tune bracings/mass after the guitar is built.
Have you got a copy of Contemporary Acoustic Guitar Design and Build - 2nd Edition by Trevor Gore and Gerard Gilet? If not I suggest you get yourself a copy, it is well worth a read.
The factories use engineering to deliver constantly sized parts, but what a good guitar needs is specifically sized parts that take into account the material properties of the actual wood being used. There are some larger manufactures such as Furch and Breedlove that are willing and able to start incorporating techniques of individualized component processing, but it’s actually kinda difficult (obviously) to work that into a Ford style production line. The sad fact is that the majority of the world’s dwindling resources are being used to create instruments that with only a small bit of extra effort could be far better than they are.
I would have put 2 f holes in the upper bout and then left the large soundhole out of this guitar. Just insert a sitka spruce bass bar down the center of the top and then set the bridge and saddle. I would put a chunky neck with a dovetail joint on the parlor guitar like on an old Martin O-21.
Rather than 'feeling' how much flex your CPR-pressed top moves, use a standard weight and a dial indicator with your top supported around the rim. Every guitar you make will be consistent that way.
I love the guitar CPR technique! Definitely will try it.
I use Spanish heel construction so the soundboard attaches to the sides first, back last. But a 1/2” plywood plate with the body interior shape + kerfing cutout would allow the top to be flexed with the CPR technique…
There are many things you can try. Do you have enough time in your life to study everybody's junk guitar building science? How do you love some goofball process? Hurry, 5000 more bogus luthier tips just flooded youtube.
Thanks. Learned something today.
very good tip eric love your insight
Hi Eric- I am curious if you also have set a
Deflection gauge here atop the X brace in the same position (ie measure the deflection of the “CPR” motion with say a 4lb weight) would love a ballpark # as a newer builder
Thanks as always!! Yes, it was helpful and I'll be trying it on my first guitar.
So, how did it sound?
thank you Eric . what you are talking about is muscle memory it does work .
Modern neurology discounts the left brain / right brain thing as physiological phenomenon. Creativity doesn't occur in just the right hemisphere, the left hemisphere doesn't necessarily have an affinity with analytical thinking. However, the left /right view can be used as an analogy to differentiate creative and analytical processes. The good thing is that you can learn to be strong in both talents. The key to creativity is 'flow'.
Yeah, exactly. If only the brain were so simple! It's far more complex than anyone ever imagined!
Thanks for posting this. Roger Siminov talks about deflection in his book as well. He is pretty left-brained, I would say, but he actually uses a dial caliper to measure top deflection against a set weight. I never went that route, but it bears mentioning.
I addressed your comment in this Q and A episode: ua-cam.com/video/QmdjDklOk80/v-deo.html
Very cool. I have never heard of that technique but it makes sense.
Eric, I'm very happy to have happened upon your videos and sharing of experience and results. I think of the following topic everyday just about: How to fine-tune the guitar after it is closed up? I wonder if some luthiers, when doing a cutaway guitar, take advantage of the potential space to fine tune bracings/mass after the guitar is built.
You know that you can literally measure how much your top deflects aka main top mobility?
Have you got a copy of Contemporary Acoustic Guitar Design and Build - 2nd Edition by Trevor Gore and Gerard Gilet? If not I suggest you get yourself a copy, it is well worth a read.
Amen.
The factories use engineering to deliver constantly sized parts, but what a good guitar needs is specifically sized parts that take into account the material properties of the actual wood being used. There are some larger manufactures such as Furch and Breedlove that are willing and able to start incorporating techniques of individualized component processing, but it’s actually kinda difficult (obviously) to work that into a Ford style production line. The sad fact is that the majority of the world’s dwindling resources are being used to create instruments that with only a small bit of extra effort could be far better than they are.
Perpetual acid trip here, coming down long enough to say"good video!" Tetragrammaton, by the way.
Great Explanation and intresting information
So, if the "CPR" at the bridge felt very stiff and unyielding, what would you do? Cut the bracing down some more, or start over?
I would say rescue breaths into the sound hole. :) . But yes. I would say carve the braces down more would give more flex to the top.
I've responded to your comment in this Q&A video. Check it out! ua-cam.com/video/Ma-I2E0HwkI/v-deo.html
i like your integration of the craftsman's art. that's why its not all cnc to build a beautiful instrument. Engage both brains!
I would have put 2 f holes in the upper bout and then left the large soundhole out of this guitar. Just insert a sitka spruce bass bar down the center of the top and then set the bridge and saddle. I would put a chunky neck with a dovetail joint on the parlor guitar like on an old Martin O-21.
Rather than 'feeling' how much flex your CPR-pressed top moves, use a standard weight and a dial indicator with your top supported around the rim. Every guitar you make will be consistent that way.
You could be consistently building less than optimal guitars?
Well, I was lucky enough to be the first 'liker' today! Have a great day, Eric.
A luthier and a brain surgeon.
What about a robot on an acid trip?