Bending mahogany......whats the best way?

[Kevin Sjostrand]

I don't know if you all remember, but a few months ago I put some pictures of a slab of wood up to get some ideas what I had. It has turned out to be (best as I can tell) Santos Mahogany. My wife's uncle cut it for me, and I got 4 sets out of it. They are not the greatest as this board was rift sawn, but one set is quite nice in particular. I'm going to build a dred out of next instead of using the cherry. It sprayed some shellac on a cut off tonight, and this stuff is georgous! It has that Koa like shimmer and even has some curl in it. Anyway, It will be my first try on the bender with this wood. So I had some questions:

Does mahogany like water when bending? Is it best to spritz it, soak it, or bend it dry?
What temperature does it like to bend at?
Should I tape the curly maple bindings I'm going to use to the sides and bend them together?
Anything else I should be aware of? The sides are mostly quarter sawn.

I will be using my new light bulb bender, if that makes a difference.

Thanks for your help.

Kevin

[Dan Bombliss]

Hey Kevin,

I've bent mahogany and I bend all my wood basically the same. When I use a mold I make a sandwich that's: Heating blanket down first, water soaked linen, the wood which I get wet just by brushing the linen over both surfaces for it to be wet enough to look wet, a dry linen cloth on the opposing side of the wood, and then thin brass or spring steel.

Assuming you thickness the ribs to a thickness that feels good enough to bend, which I can always tell by holding each end of the rib and kind of bouncing it up and down seeing how floppy it is, you can judge it pretty well that way, it should bend with that sandwich just fine.

I learned that method from my instructor and I've used it on numerous guitar sets, my violin, and cello ribs.

-Dan

[Jim_H]

Kevin,

I haven't bent enough of anything to be giving advice, other than check these out.

Todd Stock has a (figured) Mahogany bending video on youtube. It's a 3 parter. Here is the first.
http://www.youtube.com/watch?v=Q7vd9wGG4LM

John has a series of bending videos as well. Here is the first.
http://www.youtube.com/watch?v=JFNy93PM0Kc

I always review these before I fire up the bender.

[tippie53]

They one thing is WATER , just how much is too much . I never heard the linen trick. I prefer paper as it won't carry as much. Too much water can cause some funny things to happen . My best advice is to bend a set . I use kraft paper or white untreated paper. I will go to white untreated paper as I can use it for tracings
Anyway use that as a barrier and a light spray of water. Be sure you start bending lower bout at about 250 then the upper at 275 then pull the waist just check to see there is moisture before you do the upper bout , take it to 375 then 15 min at 220 to help get the water out. You may need to to the 220 thing twice. It you take the set out while warm and wet it will spring back

[nkwak]

I don't know if this applies, but when my friend and I bent my first two sets of African mahogany sides we only lightly spritzed some parchment paper with distilled water then wrapped the wood in that. The steel slats went on either side and the heating blanket went on top. We set the thermostat for 290 and the whole bending/cooling process only took an hour per side.

[kencierp]

Honduran Mahogany that is just off the 1/4 bends easily. Material that is perfectly quartered will tend to ripple -- with or without water. This is a concern, so you must take care to keep the material compressed and as flat as possible, otherwise it will crack in the ripple high spots. Its not likely your bender is going to get over 250 degrees with 500 watts but that is not a concern if you spritz water and it makes steam you are good to go.

You need to make a practice run to see how the material reacts to the heat and water. With the exception of Rosewood and Walnut -- I do this with every single set we bend it only take a few minutes but minimizes surprises. I use the cut off from the side profiling operation.

[Kevin Sjostrand]

John,
Is the baking parchment paper available in the grocery with the aluminum foil okay to use? I don't think it has wax or anything in it, but it doesn't say on the box. I haven't seen the brown kraft paper anywhere yet.]

Ken, thank you, I had not thought to use the cut off from the side...that is perfect. I am a really smart guy (or is that a smart alec) and I did not even think of doing that.

I am also going to block off the open areas on the bottom of the form that hangs out of the jig with some foil coated 1/4" plywood to help hold in the heat. If it doesn't get hot enough, I'll go to 3 x 200 watt bulbs and try that.

Sounds like minimum water is the way to go, which I can agree on. When I bent the Macauaba by hand it did not like water. I found that out real fast.

Thanks gents.

Kevin

[tippie53]

I never had a problem until the last set with Kraft. Like Ken I went to a white untreated paper . I was lucky the stain sanded out for me. If I think I have something that will ripple or cup I tend to bend the sides at .095 that gives me a good .020 to sand out and if I have to I can build a finish fill .

[Darryl Young]

I use spring steel slats which can, and do, rust, so after I ruined a set of sides for Tommyboy that were only wrapped in white paper, I have been wrapping my wood in foil. Wrapping is incorrect. I use two sheets of foil. If you wrap the wood, the folded edge will cause the foil to crinkle and make marks on your sides. Using two layers of foil(or paper) will bend easily and not cause the crinkle marks on the sides.

I'm curious, what happened with the sides for Tommyboy? Did the metal leave rust on the sides that couldn't be removed?

This thread is timely for me as I will soon bend Cuban mahogany sides. Would I use the same procedures and temps mentioned above for Cuban Mahogany? (not curly......ribbon figured)

[Kevin Sjostrand]

Parchment paper it shall be! And perhaps just enought water to give off a little steam.