Bubinga bending???

[John Bertotti]

Ok I am trying a project that requires some Bubinga bending. Am I in for some problems or will it bend fairly well?

[Marty Jacobson]

It bends nicely and smells great. If it's insanely figured, you may need to go slowly, keep it plenty moist, but don't let it get too crazy hot. It should be easier to bend than curly maple, in any case.

[John Bertotti]

No figure just plain straight and a very nice color. Thanks!

[amowry]

Yep, much easier than curly maple!

[John Bertotti]

Is there an optimal thickness for bending? I was hoping to go a bit thicker 3/16 to 1/4” thick if possible. Not for an instrument but you guys I trust to have the best bending knowledge on this. Thanks!

[buckhorn]

Think hard about going that thick with the rim.. It can be done but might scorch if you try to go too fast.. And think about weight.. If you are chasing the scroll with the F style it might get tuff...

[John Bertotti]

Not to worry this is for a box competition not instrument although the rules say stretch the definition of box it just has to have a opening lid. Hmm

[Marty Jacobson]

If it's 1/4" thick, it has enough mass to do via steam box and won't work with a bending iron. Otherwise, consider spiral lamination like some banjo rims.

[John Bertotti]

Hmm, steam box. I have seen some boil wood and steam but I have never done either. I will search quickly. I need to make some progress today!

[John Bertotti]

What is the thickest a piece could be on a bending iron? I might have to do a quick experiment or two and see.

[Marty Jacobson]

I think you could bend 1/8" (3mm) on an iron without issues, much more than that and physics takes over. Too thick and it's like you're trying to cook a brisket on the grill, it just doesn't work. You end up burning the outside, the inside is still cool, and you dry it out before you get the fibers loosened up internally.

[Richard500]

Steam works and has perfect temperature control, courtesy physics too. Surface may be a little furry, and you need a form or caul because it takes time to cool.

[sunburst]

What radius are we talking about here?
1/4" will probably bend on a bending iron to a large radius, but if the radius is very small you will need steam and a bending strap.
How much scrap do you have? Try bending some 1/4" scraps on a pipe and then fill us all in on how it goes.

[CarlM]

I had no success trying to bend 3/16 basswood and cedar over a pipe for the extensions on a removable top mandolin fixture like James Condino has. I ended up bending two pieces at 3/32 and laminating them. Glad to hear it is not just me. Like Marty says it seemed like somewhere between 3/32 and 1/8 was the limit on a pipe.

[HoGo]

I had no success trying to bend 3/16 basswood and cedar over a pipe for the extensions on a removable top mandolin fixture like James Condino has. I ended up bending two pieces at 3/32 and laminating them. Glad to hear it is not just me. Like Marty says it seemed like somewhere between 3/32 and 1/8 was the limit on a pipe.

Basswood or cedar are not the easiest woods to bend.

For that thick wood I'd suggest using aluminum foil sandwich method. Just wrap the piece of wood in strong aluminum foil with thick wet cloth on the inside of the bend and use steel bending strap if possible. This creates steam chamber around the wood. Slowly roll the piece on the surface of the iron and let the water boil and generate steam inside before you start forming the bend.
I managed to bend 1/4" pieces of walnut for banjo rim even without the foil using ordinary clothes iron - I put quite wet cloth on the inside wood and ironed it for a while over 1' of length to produce lots of steam and when it got pliable I immediately bent the portion around a form and continued with next still flat section till I finished the round.

[John Bertotti]

I will see what works. I have no scrap just two big boards. so it is going to be a learn as I go proposition. Worse comes to worse I'll pick a different wood for this. I have to have it done and turned in by the 25th with detailed instruction written up pictures and or a video. Its a wood working competition I am trying my hand at.

[HoGo]

I will see what works. I have no scrap just two big boards. so it is going to be a learn as I go proposition. Worse comes to worse I'll pick a different wood for this. I have to have it done and turned in by the 25th with detailed instruction written up pictures and or a video. Its a wood working competition I am trying my hand at.

What are the dimensions of the box you'll trying to make? Sometimes using several thin layers is the way. Like banjo rims.

[John Bertotti]

It is all up to the builder the only requirement is it has a lid. I have wasted way to much time on the what should I build rather than licking an idea and going

[John Bertotti]

How long does steamed wood need to try before any glueing or joinery is done on it? I have basic moisture meter I can use. Sadly it doesn't want to measure the bubinga in pan more only in pines mode then it is one green bar. A general amp meter. My softwood pine measure at 5.9%. Harwood on my cherry and Bubinga no readings in pin mode. But I need to finish up in the next couple days so will steamed wood be dry enough to work with at that point? I might be better off going to plan B.

[sunburst]

Weigh the piece before steaming, when it weighs the same after steaming it is dry.

[j. condino]

I had no success trying to bend 3/16 basswood and cedar over a pipe for the extensions on a removable top mandolin fixture like James Condino has. I ended up bending two pieces at 3/32 and laminating them. Glad to hear it is not just me. Like Marty says it seemed like somewhere between 3/32 and 1/8 was the limit on a pipe.

I don't bend those on a pipe. I bend them with a heat blanket based system where there is an inside and outside caul with the wood & heat blanket in the middle, so the wood is supported on both sides. .0200" cedar & spruce bend easy with that setup.

The biggest problem with bending thick materials is that you move away from simple bending of a plane towards bending an I beam. The inside layer lignum bonds slip but one outside gets crushed while the other shears.

If you want to get really rowdy with curved surfaces, thin your materials into veneer thickness an, make an mdf form, and then put it all into a vacuum press. Your options are unlimited for that.

In an upcoming issue of American Lutherie Magazine, there will be a huge article on my entire process for vacuum laminating sides all the way up to giant double basses where I go through about 50 different experiments of varying materials, adhesives, & cores that are stress tested to failure. About half of the well known guitar builders in the country are using double or more laminated side configurations these days; they just don't talk about it to keep the whining down...