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A Mulga Bridge (pics)
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Author:  Kim [ Sat Jul 21, 2007 11:14 pm ]
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Hey Folks,

I made myself a bridge today from WA Mulga (Acacia aneura ) this stuff is typical of Australia's arid region woods insomuch that it is very dense, very hard, very stable and very pretty. To give you an idea of how hard and dense it is, West African Ebony weighs in at around 820kg m3, Mulga weighs in @ 1220kg m3.

I was a little concerned about Mulga being too heavy, but as I said it is very stable and is also incredibly strong. In my opinion, this should allow thinning down in less crucial areas such as the wings and the back of the belly more than I think most would approach, but if you think I am wrong, feel free to let me know.

Mulga is quite nice to work with, it does not irritate and it machines to a knife edge (literally, it will cut you before it will splinter). Also the smell easily rivals BRW, it's beautiful with such a sweet, sweet perfume. Being so very hard also means that it polishes like glass as can be seen in the images of the bridge which I swear has only been micromeshed, no wax or any other kind of finish, just the mesh.

The bridge is my first and the design my own, it is pretty much free hand insomuch that whilst the basic dimensions of the blank and initial shaping of wing thickness and belly are easily repeatable, no jig was used and the contouring or blending was done by eye. The images appears to show next to no definition at the shoulders but this is an optical illusion, however the transition at this point is softer than standard.

The bridge is based upon a Martin belly style but has also been influenced by the Scott Van Linge "sound is round" modifications which lend to my own liking for a more organic look. The pin holes are set for a string spacing of 2.200. The highest point of the bridge is just 1/32" lower than a standard martin bridge at 5/16". The length and width are pretty much standard however the wings have been thinned to just 1/16" with the belly being contoured back into the pinhole area to reduce some weight.

I had originally polished this out when it weighed 34 grams. But there was a chip out, as can be seen in the first image, on one of the bridge pin holes. This foepah was caused by my own carelessness and I just could not stand to look at it so I reshaped and contoured the belly across the pin holes removing the divot.

This knocked off another 2 grams which is fine by me as I did intend to brace light anyhow and by my calculations, this weight should be fine on the broader expanse of an SJ style guitar.

Anyhow, here is the 34gram version complete with tear out.





And here is the 32gram version.










Anyhow, I have posted this stuff, images and info for honest critique, it's OK I can take it. So if you see a problem with what I have done here please, please speak up because for me, that is what this place is all about.

Cheers all

Kim
Author:  Dave White [ Sat Jul 21, 2007 11:53 pm ]
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Kim,

I love the Aussie French for faux pas - I'll use that a lot if I may

That is lovely wood and the bridge design is nice too. I like the idea of bridges with smooth lines and flows rather than abrupt changes and the only think I would alter if I were making this bridge (remember a lot of what I do is very quirky) would be to slant the area behind the saddle down at more of an angle so that the rear of the bridge would feather down to almost nothing, and also go more of a spline curve across the bridge rather than having the concave curve in the bridge wings. I know this brings all sorts of issues with having the bridge pin holes on a slope etc. This is what I did on the ladder braced guitsr:



Author:  Dave Anderson [ Sun Jul 22, 2007 12:06 am ]
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Wow Kim! That Mulga is sweet lookin' wood and your design
is very cool.
Author:  Sam Price [ Sun Jul 22, 2007 12:46 am ]
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Wow, very nice wood!
Author:  Sam Price [ Sun Jul 22, 2007 12:50 am ]
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What a Fascinating tree!!
Author:  Aust Tonewoods [ Sun Jul 22, 2007 1:51 am ]
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In the link to the Mulga tree they didn't seem to mention its use in musical instruments. Definitely a better use than charcoal!
To that end, here is another image of some Mulga in standard, wide and radiused forms. There is a bridge blank of some Curly/fiddleback Minnerichi in the back ground. At least one US luthier found that the Mulga was very similar to Texas Ebony, if that is a good comparison for those who have used it.

Tim
Aust Tonewoods
Author:  Rod True [ Sun Jul 22, 2007 3:41 am ]
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Kim nice bridge dude.

I love the saddleless bridge design, but just wondering where the strings are going to break over

I'm looking forward to working with the Milka Fret board & Gingrich bridge that came in the auction I won earlier this year. Better make sure my fret saw blade is nice and sharp eh?
Author:  Billy T [ Sun Jul 22, 2007 4:36 am ]
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Ha! I thought it was spelled "Foe Paw"!

    You get any more contact with these weird Ozzie woods, I'd like to hear about their characteristics too!

    I have this fascination with Bunya, never seen it, or know anybody, in my area, that has any!

    Looks like the chip out turned into a good thing!

   Thanx Kim!
Author:  Kim [ Sun Jul 22, 2007 8:58 am ]
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Thanks for the kind words all,

Dave, your bridge looks to be a masterpiece of function and form, I realy like the look of the split saddle and may adopt that myself some time.

Sam, yes Mulga is an amazing tree alright and your link makes mention that the wood was used to make yokes for teaming up bullocks. These teams would literally drag overloaded wagons weighing tons across boggy sand and mud, through driving rain and desert and the yokes would last for years. This gives an indication of just how incredibly strong this wood is.

Rod, strings???,,,,strings,,,,,Oh crap STRINGS!
I have one of those Stewmac thingy-ma-jigs to cut the slot when glued onto the guitar. The complete area of the bridge where it will be slotted has been left at 5/16". Oh, and the wood that came with your Aussie kit had Mulga and Minnerichi as I recall, have not seen any Milka and Gingrich in these parts

Billy, it would appear that Bunya is as elusive as the BUNYIP As for the chip, yeah, lemons from lemonade

Anyone want to comment on the weight of this bridge??

Cheers

Kim
Author:  LaurieW [ Sun Jul 22, 2007 10:15 am ]
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Looks great - sorry I can't comment on the weight, I've never weighed my own ebony bridges, but it is a good point for the future ones....


Laurie


 
Author:  PaulB [ Sun Jul 22, 2007 10:24 am ]
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Looking good Kim.

I'm going to be making one a lot like that out of ringed Myall(Acacia Pundula) which is another desert acacia that's hard as nails and polishes to such a degree you'd swear it was lacquered.

Billy, Bunyas grow all over the place here, they have pinecones about the size of a medium sized watermelon - never park your car under one when it's dropping cones, a 15lb pine cone falling from 50' can create all sorts of problems.
Author:  Dennis Leahy [ Sun Jul 22, 2007 2:34 pm ]
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Wow, Kim, that stuff is beautiful! I'll bet a fingerboard made from Mulga would last for generations - far beyond Ebony or E.I. Rosewood.

Dennis
Author:  Dave White [ Sun Jul 22, 2007 7:39 pm ]
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Kim,

The weight is going to depend a lot on the other design features of the guitar - top thickness/bracing, arch etc etc. Mine are around 30gms either pinless or pinned plus bridge-pins
Author:  Kim [ Mon Jul 23, 2007 12:06 am ]
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Thanks Dave,

I guess that 32 grams is in the ball park for what I have planned which by the way is a relatively lightly braced SJ with a thinnish <2mm feathered edge lutz top.

Cheers

Kim
Author:  nickton [ Mon Jul 23, 2007 12:26 am ]
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This brings to mind the way Tacoma guitar bridges are shaped, supposedly in a computer analyzed way to improve string resonance. I wonder if anyone knows how they work. Is it connected to parabolic bridge shaping? Is a thicker amount of wood on bassier strings better? I would also tend to want to make mine fairly thick, to allow future thinnings before neck re-sets. But I am just learning and don't yet have years of experience with this.
That mulga looks excellent and I agree with saving it from the charcoal workers. What a sad state of affairs for the world's many poor people. I hope that isn't too political.
Author:  bob_connor [ Tue Jul 24, 2007 1:29 am ]
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Looks great Kim.

I'm really keen to hear what you think of it.

I'm about to glue a Gidgee bridge on an OM and I see that PaulB is about to do a Myall one.

I've been doing a bit of playing around with desert acacias for bridges in the last couple of weeks.

The Mulga seems as though it comes in around the same weight as Gidgee and Myall. (32-34 grams)

Another that looks promising as a lighter alternative is Brigalow. (25-27 grams)

I got home today to find a very pleasant and unexpected surprise from Tim Spittle in the form of some bridge samples of Beefwood, Gimlet, Lace Sheoak and Mulga.
So many bridges - so little time

I'll get some pics up of of all this exotic nonsense in the next couple of weeks.

Cheers

Author:  Dave White [ Tue Jul 24, 2007 1:34 am ]
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[QUOTE=bob_connor] I got home today to find a very pleasant and unexpected surprise from Tim Spittle in the form of some bridge samples of Beefwood, Gimlet, Lace Sheoak and Mulga.
So many bridges - so little time
[/QUOTE]

Beefwood    Now that conjures up some interesting images
Author:  Kim [ Tue Jul 24, 2007 2:01 am ]
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Beefwood is great stuff, hard as a rock and very attractive. I have a bridge blank and fretboard matched up to go with a Lace WA Sheoak B/S set, all courtesy of Tim Spittle, should make a great guitar.

Cheers

Kim
Author:  Sam Price [ Tue Jul 24, 2007 2:58 am ]
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I wish there was a conclusive thread or website about all the tonewoods used ALL over the world, plus unusual hardwoods that can be used for guitar building. To me, it seems there are some real tempting exotic species of wood to use out there!
Author:  Sam Price [ Tue Jul 24, 2007 2:59 am ]
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Did I say conclusive? I mean exhaustive...
Author:  Michael Lloyd [ Tue Jul 24, 2007 1:59 pm ]
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That's a very pleasing and graceful design Kim. However, I have a concern with an area of the bridge. In the picture below I've circled what look to me like a knot. If this is so it may present problems in the future as wood around knots contracts and or expanse differently during humidity changes and a knot may eventually loosen and fall out. If it's not a knot then disregard my comment and the bridge should be fine.

Author:  Rod True [ Sat Jul 28, 2007 4:35 pm ]
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[QUOTE=larkim] Oh, and the wood that came with your Aussie kit had Mulga and Minnerichi as I recall, have not seen any Milka and Gingrich in these parts
[/QUOTE]

Wow, that's one of the worst typo's I've never done

I bet that's what my spell checker changed them to. I should have looked closer.
Author:  gratay [ Sat Jul 28, 2007 8:16 pm ]
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sure looks beautiful.....its certainly going to add lots of character to the instrument.
Mulga really is striking
Author:  Steve Walden [ Sun Jul 29, 2007 5:51 am ]
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Great looking bridge!!!!


I had a question on the use of radiused (smile-faced) pin holes.  How does this affect the break-over angle and therefore the tone?


Thanks,
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