Official Luthiers Forum!

I bought this ridiculous piece of hondo rosewood eye bur. Is it too figured for bridge? It seems dense with no voids, but maybe not stable because of what it is, an eye burl.
Do people use really dense burl for this purpose? Seems like part of a ponzi scheme, but there is a guy who knows a guy, who knows a guy, whose brother-in-llaw that claims he can get this stuff. Just would like to know if it would be more than just peghead veneer before I fall down the rabbit hole, ensnared by figured wood.

I would never use burl for a bridge. There is short grain running vertically, in the direction of the bridge pins, all the way through that piece. A split along the bridge pin holes or the saddle slot is much more likely. Also, the bridge is a brace and imo, should be treated as such. Nobody would consider using burl for bracewood.

_________________
http://www.chassonguitars.com

I have looked to try and find radial and tangential shrinkage rates for hondo rosewood, I would think if the tangential/radial ratio weren't too far off, it would be stable. All I have found are volumetric shrinkage rates and notes that there are really several(like 7) different varieties that are sold under the honduran rosewood name. maybe that is why I cant seem to find the data- maybe I have just not looked well enough, either.

Kent, I would agree 100 percent about the no one would use burl for a bridge, the short grain would bound to be along the pin lines- BUT- I had never seen a piece with little tiny eyes like this and it seems so dense(it feels like a piece of iron), I really can't believe it wold split.
So I thought if I asked the question here, somebody would surely already have done it if it could be done. This place is such a great resource, somebody here will has already had a piece just like this in their hand, and tried it, I figure. I knew it would make great headplates, or pickguards, or soundhole rosettes. I always figure nothing under the sun is really new.

Listen to Kent. I also would never use it for a bridge. Frankly, the thought seems rather silly from an engineering POV. Burled wood should not be used for structural components.
It would look great, but it would very likely have disastrous results.

_________________
"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

No, for bridge , might make an attractive headstock veneer .

This would have no bearing on a piece of burl. What ever numbers you find would be meaningless. The grain goes every which direction on burl. I would not consider it but OTOH if a guitar for you whats the worst that can happen ? You make a new bridge if this should fail. You could test it, make a slot, pry on the slot and see how it breaks and how easily or hard it is to break, drill some holes and do the same. Then you could tell us.
L.

_________________
Cut to size.....Beat to fit.....Paint to match.

I am of the opinion that if the tangential and radial shrinkage rates were equivalent(and as far as I know, cuban mahogany is the closest of any species I have found), then even the fact that it was a burl, would be not so significant- I think if tangential and radial shrinkage were equal, then after dry, it would theoretically move in all directions the same amount(stay true in shape).
Just my thoughts, could certainly be wrong, I am just trying to learn, and I figured someone else had already had a piece like this in hand and considered it. I am always trying to steal knowledge, and I am not afraid of where I might find it.
This forum is very valuable for those that are really trying to learn, and I greatly appreciate all who share.
I have made many pieces of furniture from walnut burl and crotch, and of course it always moves, and I expect it to- So I am sure walnut burl would be totally inappropriate- but this piece feels like a different animal from domestic burls, and so I wondered...

Shrinkage is not the issue. Be concerned about strength and grain direction. Burl has neither.

Why bother with equal shrink rate? My concern is streghth, as Kent states, you have short grain in places where you do not want it.

_________________
"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

It is not that simple. For one you picked one of the most stable woods there are to compare it too. How did you come up with that ? I don't think that is a reasonable assumption at all. Also even if as stable as Mahogany, it is still not 1:1. At best it is 1:4 (like the best Mahogany) and what you have has grain going in all directions and not going in all directions equally as you seem to have assumed. Also any stability figures for wood are perfect pieces. Well behaving wood has a lot to do with how nice a piece of wood you have. You could have reaction wood in a very stable species (like Mahogany) and a perfectly straight beautiful piece of white oak (not close to being as stable as Mahogany) and guess which one will be much more stable in service. Straight growing trees are much more stable than leaners or twisters or etc. and you have burl !
As I said before you can throw out the T/R numbers when dealing with burl.
Stability issues aside, as many have pointed out there are strength considerations that are as troublesome as lack of stability.
And even if someone had done what you propose to do it would not be relevant due to the variable nature of burl. No two pieces are alike.
So with all that in mind..........( I feel like you didn't hear what you wanted to hear) everything we have said is mostly true but as every piece is different maybe you have a 1 in 10,000 piece of burl and is strong and stable. So if we haven't deterred you (in this case I think it would be best) as I said, do some tests. Slice some thin pieces, dry and measure, wet and measure, test for strength, etc. Nothing wrong with finding out yourself.
It is nice looking stuff for sure.
L.

_________________
Cut to size.....Beat to fit.....Paint to match.

Link,
I see now my mental problem. I was thinking in two dimensions for stablilty, but really burl is so twisted, the third direction comes into play.
Thanks for helping my fuddled mind. I had become transfixed staring at the figure of this piece. Now I realized it does fail my notions of dimensional stablility. I don't see how I could have become so confused.
Thanks again.

I have seen cheap guitars that had bridges made of particle board..... I was amazed they actually held up - but they did.... Based on this - I think you could actually use that burl if you really wanted to..... It might work....

But.. I think as a few others here have mentioned... I would have a couple concerns...

1. Burl tends to be squirrely - it twists every which way.. even when it's been dry a long time... It also tends to be very splitty because of all the end grain going every direction.... Look at old burl top tables and boxes made of solid burl... How often are they cracked? Nearly 100% are.... It might hold up fine... It might split in half in a year.... Are you a betting man?

2. Super dense wood doesn't usually make the best bridges.... You don't often see Leadwood or Lignum vitae bridges.... Ebony is pretty dense stuff... Martin likes it on their guitars... but it's not my choice for bridge wood either.... Most of the bridge woods used seem to hover around the "Rosewoods" spectrum of density.... which tends to run lower than Ebony....

Thanks

Mike,
Sorry, I re-read my post and some of the things I said I didn't mean them as it might sound. I was in a hurry. Looking at them I can see where they could be construed as condescending and I didn't intend that.
For example : That sounds like, "Dude, suite yourself but you will find out we are right" I really meant that you may find out it could work. Real world results are sometimes quite different than what you could expect.
And: I just pulled that out of the air, looking at it now it sounds pretty sarcastic.
I did mean this but I didn't have a nasty tone in my head when I asked it.
My take was you were really excited to use this wood and were determined but were a little resistant to some of the info you were getting. But hey, sometimes it takes someone to not listen to everyone else and listen to themselves and forge ahead. That's how new ideas and things get discovered.
Anyway, I can appreciate the excitement of cool wood. I am a wood nut myself. I am encouraging you to test it. I would be interested in what you find out. However the information you have got is good and solid, but doesn't mean you can't do what you want to do or shouldn't try it. Again sorry for the clumsy writing on my part, I can assure you I didn't have a tude in my head when I wrote it, just came out that way.
Link

_________________
Cut to size.....Beat to fit.....Paint to match.

Link,
No need to be sorry, I was in no way offended-by any of the comments, your or others-
I really was confused and not thinking about the 3 dimensions of shrinkage.
So even though I feel like with the very timy eyes this wood would pass the strength issue, I now know I can't trust it glued crossgrain to a soundboard(but it would look way cool).
I will probably keep it on my desk. Don't have the heart to resaw it for veneers.
Thanks all, for the mental help!