Multiscale bridge over uncompensated bracing

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WilliamDavidReynolds

Multiscale bridge over uncompensated bracing

Post by WilliamDavidReynolds » Thu Jan 12, 2023 4:38 pm

So the title says it all. Not really

I like multiscale and rather build a spec or prototype multiscale, if I’m asked to keep it straight (single scale ) I do with no dilemma.
The new design I’m doing is a tweaked out Dreadnought. And the first build is “of course”, mine! Naturally I am planning on multiscale. After transferring the Xbrace pattern from some standard Dread plans to my shape, I ended up with uncompensated bracing for multiscale.
The competition of desire of practically started with the bridge plate, I cut out a compensated bridge plate and had to delete it because my Xbrace isn’t adjusted on this particular prototype.
Well,,, damn, so I, with my tail between my legs thought for 70 hours I’d be doing single scale,,, until I decided I could just compensate the bridge design to evenly land above standard Xbracing shape.
So this further invoked more thoughts of how a compensated Xbrace design would change the poles,, dipole, monopole, crosspoles,, all the shapes of vibration could potentially be altered and I can’t see how it would be positive.
It seems that a regular pattern under a compensated bridge allowed multiscale to occur while bracing allows for symmetry in vibrations rather than some sort of compensated pattern where the bass and treble sides of the Xbrace in lower bout get real wacky.

And experience with Xbracing multiscale either way standard or compensated bracing for the slanted bridge?

My solution here
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TallDad71
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Re: Multiscale bridge over uncompensated bracing

Post by TallDad71 » Fri Jan 13, 2023 5:58 am

I like your solution a lot. It gives the player a reasonable chance of resting the ball of their hand on a comfortable part of the bridge and still access all strings equally.
Alan
Peregrine Guitars

WilliamDavidReynolds

Re: Multiscale bridge over uncompensated bracing

Post by WilliamDavidReynolds » Fri Jan 13, 2023 8:14 am

TallDad71 wrote:
Fri Jan 13, 2023 5:58 am
I like your solution a lot. It gives the player a reasonable chance of resting the ball of their hand on a comfortable part of the bridge and still access all strings equally.
Thanks, I didn’t even think about the bass side of bridge serving as a hand rest.
Any thoughts on keeping bracing normalized and compensation in the bridge design as a better pursuit of allowing the the top to vibrate normally?

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kiwigeo
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Re: Multiscale bridge over uncompensated bracing

Post by kiwigeo » Fri Jan 13, 2023 8:54 am

A few years back I built a falcate braced multiscale OM. Given the bracing was falcate and not a conventional X brace affair but adjusting the position of the secondary and tertiary braces to fit the slanted bridge didn't significantly affect the main top vibrational modes.
Martin

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Mark McLean
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Re: Multiscale bridge over uncompensated bracing

Post by Mark McLean » Sat Jan 14, 2023 11:27 am

I like your design lot.
It is difficult to design a bridge that can accommodate a steeply sloping saddle but not look too strangely asymmetrical, and not be too massive. For example, I dislike the size of the Lowden multiscale bridge (even though I generally love their guitars).
lowden multiscale.jpg
I was experimenting with this a while ago and came up with something similar to yours. I like the idea of restoring some symmetry by having the treble end and the bass end of the bridge perpendicular to the midline (and the strings), and only the centre portion being on a slant. Mine is not particularly nice cosmetically. I was using an old guitar body as a crash-test dummy to experiment with some design ideas, so didn't fuss with fine appearance. But I was happy with the overall layout and will refine it for a proper new build in the future. I thought the slanted oval soundhole also fitted the overall look.
P2070708.JPG
My bracing was falcate, like Martin's. I rotated the whole bracing pattern to match the rotation of the saddle position (I think it was about 12 degrees)

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kiwigeo
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Re: Multiscale bridge over uncompensated bracing

Post by kiwigeo » Sat Jan 14, 2023 1:04 pm

The bridge on my multiscale build.
IMG_2913.jpg
Martin

WilliamDavidReynolds

Re: Multiscale bridge over uncompensated bracing

Post by WilliamDavidReynolds » Sat Jan 14, 2023 6:13 pm

Mark McLean wrote:
Sat Jan 14, 2023 11:27 am
I like your design lot.
It is difficult to design a bridge that can accommodate a steeply sloping saddle but not look too strangely asymmetrical, and not be too massive. For example, I dislike the size of the Lowden multiscale bridge (even though I generally love their guitars).
Thanks, yes sir that Lowden is huge and doesn’t fall in line with the Gore/Gillet 15-20grams SS advice at all. I’m not certain mine can lose any more weight without making myself unhappy with the way it looks now. There are some parts I could cut the fat, but dang,, it would have a loss of sexy to it.

I like the Oval sound hole matching the bridge slant.
My big question is about the X bracing being shifted out of symmetry. So I see everyone has great results with the falcate shifts and it’s sensible due to the bracing’s curvatures. Naturally seems like falcate is a better style than the Xbrace.
But for Xbrace enthusiasts, wouldn’t it be bad conditions under the hood (soundboard) with the treble side going off towards the guitar edge and the bass side of the Xbrace heading more south to allow the bridge to have contact footing above??
I had a block in my hand and looked at the band saw, and was about to mill out a new Xbrace for this top, already had a asymmetrical bridge plate ready, and realized the face braces would be shortened and it would not even look good. If if it sounded great and the frequencies impressed Trevor,,, it would still look wrong, unlike the falcate Mark and the others did, it looks natural and sounds good.
After a short novel I basically wonder if anyone has done some off center x bracing. I’m not even going to proof read what I just typed with my thumb, please excuse me

WilliamDavidReynolds

Re: Multiscale bridge over uncompensated bracing

Post by WilliamDavidReynolds » Sat Jan 14, 2023 6:16 pm

kiwigeo wrote:
Sat Jan 14, 2023 1:04 pm
The bridge on my multiscale build.

IMG_2913.jpg
Yes sir that’s pretty nice, I mentioned you in last comment and referred to you as Mark, sorry I felt wrong too… when I typed..

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Mark McLean
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Re: Multiscale bridge over uncompensated bracing

Post by Mark McLean » Sat Jan 14, 2023 10:08 pm

Lots of great builders make fan fret designs with X-bracing. Bruce Sextauer, Michael Bashkin, Simon Fay to name a few. Bruce S discusses his building quite openly on various forums like UMGF and Acoustic guitar forum. I think all of them rotate the standard X-brace layout to fit the slanted bridge. Bruce says that it is fine to have asymmetry, and even to take the X joint off the midline. The single unbreakable rule is that the main braces need to overlap the wings of the bridge. Everything else is movable. I think of it starting with the bridge position, then put a bridge plate in the corresponding (slanted) place, and then work the primary braces around that.
Bruce has some good comments in this discussion and there are some pictures of some multiscale bracing patterns.
https://www.acousticguitarforum.com/for ... p?t=277156

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