Official Luthiers Forum!
http://w-ww.luthiersforum.com/forum/

OM Bracing Critique
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=17650		 Page 1 of 2
Author:  Wes McMillian [ Thu Jun 19, 2008 5:39 am ]
Post subject:  OM Bracing Critique
Some folks may be tired of these bracing critique threads, but I always get a lot out of 'em. Anyway, I've never taken advantage and submitted my bracing for critique, so here goes.

This is an Englemann top, at .105", bracing is all 1/4" except for the UTB. I'll admit I just closed this one up a couple of days ago, so it's a little late for adjustments, but y'all's feedback will still be useful for the next one. Everything was glued with HHG.

Thanks!

Image

Image

And one with the PMTE. I almost forgot to make this little bugger! Any comments on the size or shape for those who have used one?


Image
Author:  Hesh [ Thu Jun 19, 2008 6:03 am ]
Post subject:  Re: OM Bracing Critique
It looks great to me Wes and I would not change a thing. It this top braced for any particular playing style such as finger style or flat picking or both?

Tell me - do you hear a difference and if so what do you hear when you tap the top with and without the PMTE?

Lastly, is that an Osage Orange bridge plate?

Very nice work. [:Y:] [clap] [clap] [clap] [clap]
Author:  JJ Donohue [ Thu Jun 19, 2008 6:09 am ]
Post subject:  Re: OM Bracing Critique
Wes...It looks like nice clean work. 1/4" is my preference as well. Glad to see you're using HHG! The scallopping looks reasonable...I'll assume you arrived at the height and shaping as a result of tapping.

The inlet ends of your X and UTB look a bit thick...I usually have mine thinned to about .070" where they tuck into the lining. The A-braces also look a bit heavy from what I have seen and been using over the years.

I also use the PMTE...on about half of my guitars. I make it up first so that it fits like a glove and only install it later if the tone needs a little more enhancement. I always make my brace from the same material as the bridge plate but I have never done a comparison with spruce. Mine are a bit lower than yours but the material on yours is less dense. You can always sand off material once you install it and fine tune the tone. Hopefully, Mario can chime in.

Nice work...thanks for posting.
Author:  Lillian F-W [ Thu Jun 19, 2008 6:24 am ]
Post subject:  Re: OM Bracing Critique
PMTE?
Author:  Rich Schnee [ Thu Jun 19, 2008 6:27 am ]
Post subject:  Re: OM Bracing Critique
Far be it for to criticize but your sound hole braces look a bit too beefy and two of them extend into the neck block area. Did you cut them back when you attach the top plate or did you route the neck block to accept the braces??? The ends on the X braces look too high also, did you trim these down??? And did you put a brace behind the bridge plate???
Author:  Arnt Rian [ Thu Jun 19, 2008 6:29 am ]
Post subject:  Re: OM Bracing Critique
"Proulx Magic Tone Enhancer"

Google that, and you'll get to Mario's web page and see how he does it on a guitar he documents the building of.
Author:  Hesh [ Thu Jun 19, 2008 6:30 am ]
Post subject:  Re: OM Bracing Critique
Lillian a PMTE stands for Proulx Magic Tone Enhancer. It's the brace behind the bridge plate, Mario makes them up for his guitars and sometimes uses them, sometimes not, it depends on how it sounds with and without.
Author:  Sam Price [ Thu Jun 19, 2008 10:22 am ]
Post subject:  Re: OM Bracing Critique
Arnt wrote:
"Proulx Magic Tone Enhancer"

Google that, and you'll get to Mario's web page and see how he does it on a guitar he documents the building of.


I got one of those!!

I would like to compare with a similar handbuilt without a PMTE, but my 20 year guitar playing experience ears says that it does make a guitar sound...pretty good. (my latest guit) Nice one Mario!
Author:  Wes McMillian [ Thu Jun 19, 2008 11:22 am ]
Post subject:  Re: OM Bracing Critique
Thanks for the feedback, everybody. Guess I should give a little more info.

Hesh, it will indeed be for primarily a fingerpicker. Somewhat Travis-style, but with a fairly light attack. It will be initially set up for light guage strings with a moderately low action based on my interpretation of his style. It is an Osage Orange bridge plate at .092". This is the first PMTE I've tried and I left it out initially as Mario had recommended. After it plays in a little bit, I'll glue it in. I'm interested in hearing the change.

So, JJ, what "enhancement" do you find with the PMTE? I admit, also, to the UTB and upper legs of the X being somewhat beefy as I look at them. I wouldn't think the inlet ends would matter much, would you? I can potentially see where taking the upper legs down some more as they transition from the X would allow more freedom of movement.

Rich, the soundhole braces do indeed extend through the UTB and are mortised into the neck block, typical of A-frame bracing. They very well may be too much. It just kinda felt right at the time for stiffening the neck extension area in the place of a full neck extension. I did thin them to a triangular cross section around the soundhole area but kept the full thickness through the UTB and into the neck block. And criticism is exactly what I'm looking for, good or bad, so bring 'em on!

Todd, I admit to not having tapered the scalloped sections before like this. I had seen it done on a couple, though, and in keeping with the "cube rule", felt I could continue to remove some material from the sides. I may prove to be wrong. Time will tell and will just further us along in the continuing learning process.
Author:  Wes McMillian [ Thu Jun 19, 2008 11:33 am ]
Post subject:  Re: OM Bracing Critique
I did pull this one out of the mold last night. First impressions are good. It's yet to be seen how it works as a tone generator, but as an air mover, it's doing a heck of a job. I first noticed when tapping on the bridge area, I could feel the air from the soundhole with my other hand a good six inches away. Tried the "match test" and it passed with flying colors, so I got my wife's Bic lighter and held it in front of the soundhole. The Bic had a good strong flame and a solid finger tap at the bridge area blew it right out. I think it'll have plenty of power, we'll just have to see how the tone measures up once I get strings on it.

Thanks everybody. All the feedback thus far has been very beneficial. I look forward to more.
Author:  Wes McMillian [ Thu Jun 19, 2008 1:14 pm ]
Post subject:  Re: OM Bracing Critique
Rich, here's a shot that shows the neck block mortise for the A-frame neck extensions. The box looks a little distorted in this pic. Partially a camera trick and probably partially because the guitar was built with a bit of a taper, as well. I figure it should make for a real strong upper bout with a lot of resistence to neck rotation, being locked in through the UTB and all the way to the X. At least, that's my thinking. In theory, I would like to think it allows some contribution from the upper bout as well?

Image
Author:  JJ Donohue [ Thu Jun 19, 2008 1:27 pm ]
Post subject:  Re: OM Bracing Critique
westex93 wrote:
So, JJ, what "enhancement" do you find with the PMTE? I admit, also, to the UTB and upper legs of the X being somewhat beefy as I look at them. I wouldn't think the inlet ends would matter much, would you? I can potentially see where taking the upper legs down some more as they transition from the X would allow more freedom of movement.



PMTE...when I have installed it permanently it seems to liven up the tone... I've noticed a more crystally effect as a result of its installation. Other times (about half) I have heard no difference, or a seeming loss of volume.

Brace ends...I have never left them as thick as yours are. Most I have seen are around .100" or less.

Other...I hadn't realized that your A braces actually "pass through" the UTB and that they actually fit within the neck block. IMO, this is not necessary and may even weaken the UTB.
Author:  Terence Kennedy [ Thu Jun 19, 2008 1:34 pm ]
Post subject:  Re: OM Bracing Critique
I think it looks fine as is. ( except did you cap the X ?) Should be a great guitar. Might think about thinning the edges of the top a little in the lower bout before you bind it. Maybe to 0.090 or so. I tap the top while I'm doing that and have talked myself into the fact that I hear it open up a little. Nice job.
Terry
www.kennedyguitars.com
Author:  Wes McMillian [ Thu Jun 19, 2008 1:41 pm ]
Post subject:  Re: OM Bracing Critique
Duly noted and agreed on the brace ends.

Curious about your thoughts on the A-bracing. I'm surely not being argumentative, as I know I'm discussing this with guys that have much more experience than I do, but I'm wondering why you think it would weaken the UTB? Both braces are as well fitted and glued as the X brace is, so it's one pretty solid unit. We view the X-brace as being one solid integrated unit, right? And a lot of folks use an integrated fingerboard extension with the neck block to support the fingerboard. My thought was that, by locking all these components together, it served all these purposes.

Ever learning....
Author:  James Orr [ Thu Jun 19, 2008 2:11 pm ]
Post subject:  Re: OM Bracing Critique
Wes, one of my past "learnings" was not to leave the brace ends too thick because they'll be too thick to be covered by the binding. gaah
Author:  Wes McMillian [ Thu Jun 19, 2008 2:21 pm ]
Post subject:  Re: OM Bracing Critique
Thanks, Terry. Yes, the X is capped and I was thinking about playing with selectively thinning the edges of the lower bout. New territory for me, though, having never done it before. I enjoy hearing the changes in the voicing process, although I can't say I fully grasp all I'm hearing, yet.

I hear ya, James, on the binding issue. Another new thing I did one this one was to notch on the linings, stopping short of the sides, whereas before I cut right through the sides. Should take care of that issue for this build, at least. I will definitely take them down thinner in the future.
Author:  SteveCourtright [ Thu Jun 19, 2008 3:22 pm ]
Post subject:  Re: OM Bracing Critique
JJ, Martin does this "A brace through the UTB construction" in one of their lines of instruments. Their laminated kit guitars are the same.

Interestingly, Alan Carruth does this also.

Since there is a brace running through each of the two slots, I would think the strength of the UTB would not be compromised by the kind of force experienced by that part of the UTB. Now, if the slots were empty or on the side of the brace away from the sound board, that would be quite different. Just thinking out loud.
Author:  Rich Schnee [ Thu Jun 19, 2008 3:50 pm ]
Post subject:  Re: OM Bracing Critique
It seams to me that The A brace construction is transferring some of the force from the neck block further down the top plate, there by dampening the sound board more than if the braces were not attached to the neck block. This force is also counteracting the dome of the top plate. I just don’t see the advantage.
I am not particularly crazy about the fingerboard being glued to the top let alone tying the neck block to the top in this fashion.
As far as the UTB, I don’t think you compromised the structural integrity of the brace, even if you held the sound hole braces back from going through. Once the brace is glued the top plate it will form a truss.
Author:  JJ Donohue [ Thu Jun 19, 2008 4:12 pm ]
Post subject:  Re: OM Bracing Critique
My purpose for using an A-Brace is to replace the popsicle brace and prevent any crack propagation around the FB extension. I want to free the upper bout and am not interested in additional structural support in that area. I wasn't aware that Martin and Al Carruth tunnelled the UTB. I would like to hear his rationale...hopefully he will chime in.

It's interesting to note that one of the more popular aftermarket hot rodding "fixes" on Martin guitars is to remove the popsicle brace, after which it is replaced by nothing. Bryan Kimsey has almost made a career of this on the UMGF. Of course, it voids the warranty but I guess a lot of players swear by the results.
Author:  Geordie Adams [ Thu Jun 19, 2008 4:54 pm ]
Post subject:  Re: OM Bracing Critique
hi all
you probably don't need reminded bout this A frame but - it’s inside my ‘86er.
In my experience as a player I have not come across a more stable neck to body solution than on the Lowden. Structurally its like new, I have pulled it from its case after weeks and the darn thing is in tune as well - rock solid. Also the notes lose nothing from the body joint upwards.
Geordie
Author:  Kevin Gallagher [ Thu Jun 19, 2008 5:47 pm ]
Post subject:  Re: OM Bracing Critique
I was at Martin and was a part of the development of their hybrid bracing system...which is what they were
calling that "A" frame in 1989 and 90 before it was patented.

It's a cool idea for really tightening up that are around the soundhole as it bears the load of the strings. The
system also employs that two piece neck block with the matching slots cut into it to receive the braces. It really
doesn't weaken the top bar since it bears a good portion of the load and just becomes collaborative with it in
the system's application.

They were originally going to use it on all models, but there was more resistance to it than they'd expected so
it only landed in a few model lines on the low to low-mid range.


Wes,
I like the bracing and just assumed that you weren't done at the ends of the upper "X" arms and the top bar. I
like to see them finish up at about .100" to be inserted into the kerfed linings, but have seen them well over
.125" on some great guitars.

I'm sure the top really rings with your current bracing, though. It looks great to me.

Regards,
Kevin Gallagher/Omega Guitars
Author:  Wes McMillian [ Thu Jun 19, 2008 5:58 pm ]
Post subject:  Re: OM Bracing Critique
This discussion is getting good, guys. Lots of information to chew on.

FWIW, JJ, Bryan has taken to removing the popscicle brace, but replacing it with a smaller block glued in between the neck block and UTB, serving much the same purpose and the integrated fretboard extension "foot" that some builders use. In his explanation, this effectively locks the neck block in against the UTB and helps resist neck rotation while also supporting the end of the fretboard. Pretty well the same thing I was hoping to accomplish here.

In theory, at least.
Author:  Rvsgtr [ Thu Jun 19, 2008 6:38 pm ]
Post subject:  Re: OM Bracing Critique
Forgive me if I'm wrong but I believe Huss and Dalton began using a brace similar to the PMTE around '97 or '98. This was done to reduce some of the belly they were getting with the first few years guitars. They did it as well to help add strength in that area and, hopefully, quell any unnecessary warranty repairs. As best I can remember they couldn't tell much difference in the tone, definitely didn't think there was any "loss" and stuck with it ever since I believe.
Author:  Wes McMillian [ Thu Jun 19, 2008 9:59 pm ]
Post subject:  Re: OM Bracing Critique
Kevin Gallagher wrote:
I was at Martin and was a part of the development of their hybrid bracing system...which is what they were
calling that "A" frame in 1989 and 90 before it was patented.



Ah, yes, this looks kinda familiar.... oops_sign [uncle] :mrgreen:
Author:  rgirdis [ Fri Jun 20, 2008 12:44 am ]
Post subject:  Re: OM Bracing Critique
Here is my observation.
OM's usually have tone bars that are more angled across the soundboard ( less parallel to the X brace leg) to keep more cross grain stiffness and at the same time lower the stiffness along the grain, which can help bring out the bass.
Your more parallel design, coupled with your top at .105", plus the scallops in the tone bars might take away some of the trebles that OM's are known for. I think that the cross brace below the bridge plate is a good stiffener for a top of this thickness.

At the recent GAL talk, I noticed that Dana Bourgeois uses thicker (and thus stiffer) tops (.115"-.125" for Adirondak spruce) as a starting point, and then uses less height in the braces than I have been using. I have been making my tops about the same thickness as yours.
That's what I am going to try next-more soundboard, less bracing.
Page 1 of 2 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/