Steaming Mahogany

[lewisboats]

How well does Mahogany steam bend...and don't ask what kind...I don't know. It is Menard's mahogany trim...1 1/4" x 1/4" thick. The stuff has too much tension in it and is distorting the shape of my shear so I need to steam it or soak in hot water or something to get it to bend easier so I can get a preset bend in it. I'll post a pic of it manana as I am just about to go out the door.

Steve

[PAR]

It's not a forgiving species to bend and likes to break, so especially straight grained, clear pieces will help a lot. I've learned to love a steamer cleaner my other half got for the grout lines on the tile floors. It produces steam quickly and can steam small diameter pieces quickly.

[lewisboats]

OK...here is the pictorial skinny.

This is the wood I want to bend.

http://www.angelfire.com/ego/lewisboatworks/Stuff/Designs/Tadpole/XMahog2.JPG[/img]

http://www.angelfire.com/ego/lewisboatworks/Stuff/Designs/Tadpole/XMahog3.JPG[/img]

And this is what it needs to bend to...without distorting the shape that you see here. Dry it wants to flatten out the curves. The sides are only 3 mm ply so the solid wood is twice the thickness of the base ply

http://www.angelfire.com/ego/lewisboatworks/Stuff/Designs/Tadpole/XStanding1.JPG[/img]

http://www.angelfire.com/ego/lewisboatworks/Stuff/Designs/Tadpole/XStanding2.JPG[/img]

So far I am leaning towards getting a long piece of PVC pipe, some caps and then fill with wood and water to let soak then fill with boiling water for a while before trying to bend it. I will make a form to bend it to that has a bit more cure to it than the boat sides so as to allow for some spring back. It doesn't have to be exact...just so it doesn't have so much tension in it that it straightens the curves out. I will hopefully be using the darker ones (left and closeup) for the outside and two of the lighter ones on the inside. My last resort would be to thickness plane it down to 1/8" and laminate...but I can't get all the same color so it would be funky (er) looking.

Steve

[Frank Hagan]

Looks like Philippine Mahogany to me, a cedar rather than a true mahogany (its the same family as luan, I think).  I have steam bent it before.  I think the problem you may have is that there is some spring back after bending it, and even if you get it well steamed and flexible, it might spring back and deform your ply sides.  Are you planning a seat in side the boat or knees or frames?  You could build temporary frames inside and then use smaller ones to control the deformation if you get it.

I did have a few pieces "feather" at bends.  The grain is interlocked, but if the bend comes on an area where the grain can, it tends to "fray". 

[PAR]

That's Meranti (red Shorea) not mahogany and it's bends worse the real mahogany. Even though it has a somewhat interlocking grain, several of the pieces shown above will want to break from "grain run out" if too much strain is applied. There are two main species groups, dividing about 50 sub groups, but commonly divided into 4 groups by heartwood color, white, yellow, light and dark red. That's the dark red it appears.

[Al Stead]

I've done a bit of bending wood when building my dog sleds.  The easiest way I found to soften up wood is to just go ahead and boil it up in a long gutter trough like spaghetti.  The pieces you have shouldn't take too much time to get soft, but even if they do, I'm going with what Paul says about the particular species.  If you want to try anyway, support the outside of the bend with a steel strap.  I made mine out of plumbers strap with angle iron bolted on at just the length of the piece that you are bending.  I never had a piece break when I did that, but I did have them collapse on the inside of the bend.  Most of my bending experience is with white ash.  For a hard wood, it took some pretty extreme bends if I supported it right. 

Al

[Barry Pyeatt]

Looks a lot like Meranti to me too.

If you are going to try to bend those strips around the compound curves of the boat, they need to be a lot thinner and then laminated.  Ideally it would take a multiple part form with the twist built into it.  Thinner strips and if steamed (or boiled) sandwiched around the form and clamped solidly in place.   Once they dry completely, you can then lay them up in the form with epoxy between the laminations.  Say three 1/4" thick strips laminated.  Once set up in the form with epoxy to glue them together after being preformed. you could expect to take them out of the form and they will stay almost exactly the shape of the form with little or no spring back.  Finishing them out with a nice mahogany gel stain and then varnish and they will not look funky.  They would be beautifully done.  But, is it worth if for this project to do that?

If you back up the plywood sides of the boat so they are held to the shape you want when finished, you could then drill oversized holes on the inside of the bend in the form and using clamps just glue up the strips with epoxy and they will stay the way.  Working with full thickness you will break them with this type of wood and they will splinter and crack.  Working with thinner strips to make up a full laminated strip that is full thickness they will bend far easier and take the twist as well as the bend.  But have lots of clamps available.  Once the bow curve is done, the rest of the way back is easy to manage.

Done lots of this in the past and it just takes the patience and the willingness to do it in thinner strips or set up a form and a steam box to do it right.  I would still expect that you might have breakage around the bow curve and twist.  Frustrating to say the least.   Patience and thinner stock will do the job.  If you can cut up a couple more sticks of this into 1/4" thick by full width strips you will have a much more managable project with little chance of not having it come out right.  But it takes the prep work to make up the form to be on the inside of the bend.  Not that it is particularly difficult to do. A couple layers of 3/4" particle board cut to shapeglued together into a 1 1/2' thick form and faired into the inside of the front curve.  Large enough holes drilled for a clamp to hold to on the inside and pull the strips into alignment and a strap or small blocks to hold the outer layer of the strips inplace with the clamps.  Let them cure for a couple of days before removing from the form or removing the clamps.

[Hirilonde]

That's Meranti (red Shorea) not mahogany and it's bends worse the real mahogany.

Shorea Platyclados to be really accurate.  It is sold by many lumber yards as deck planking.  It makes nice garden furniture as well.  Using it as trim on a boat is fine, but as many have said it doesn't steam or bend in any form well.  I wouldn't use it as planking though, not that anyone suggested doing so, just commenting.  I have used some as interior trim on my Renegade.  When varnished it looks quite nice. 

[PAR]

"Shorea polysperma" is what I think you're looking for Dave, though I think it's the dark red "Shorea negrosensis" I could find no references for your spelling. Though it could just as easily be "Shorea Acuminata" (red lauan), "Shorea contorta" (one of the few light red lauans). As I mentioned there are so many that an exact ID will be imposable without a microscope.

This is "Shorea Leprosula" which is another of the light red lauans and also a likely candidate for what Steve has.

[lewisboats]

Say three 1/4" thick strips laminated.

Barry...the strips you are looking at ARE 1/4" thick...1 1/4" wide. The wood seems to be able to take the bend...especially if I start at one end and clamp it often. It is just too strong for the 3 mm ply edge and the ply is more willing to comply to the strip than the other way around. I picked up 2 5' 2" sections of PVC (the 10'er wouldn't fit into my station wagon) and a coupler and a couple of clean outs. They are assembled and curing on the porch now. Whew... that solvent sure stinks...glad I did it outside. My plan is to put a test piece in and let it soak in water for 24 hours then empty and pour in boiling water a couple of times. Meantime I'll make a form to bend it to so as to try and get it to "Set" somewhat and ease the tension so when I clamp it to the shear it won't be so hard on the ply curve. Oh...and the shear when the panel was flat is virtually straight so there is no true compound curve...perhaps just a smidge of twist though.

The rest of you guys are just speaking Latin to me

[Hirilonde]

"Shorea polysperma" is what I think you're looking for Dave, though I think it's the dark red "Shorea negrosensis"

No, platyclados is what I meant.  I used to manage a garden furniture shop that bought the stuff directly from the kilns in Indonesia.

http://www.arkive.org/dark-red-meranti/shorea-platyclados/

The local lumber yard, which owned the furniture shop carries it as deck planking, but markets it as mahogany, as do many places.  This is what accounts for so many thinking it is a mahogany.

[Ken_Potts]

  Hi Steve,

  Even 1/4" wood that doesn't bend well should be bendable to the degree you're asking if the faces of the board are pretty parallel to the grain.  You don't have to get the bend perfect, just do what you said you're going to try and get the pieces bent about right - It's probably more important to have the two sides match somewhat closely than to have exactly the right curve for the gunwhales.

  You can use temporary frames to hold the gunwhales in the right shape during the glue up.

  If all else fails you can resort to laminating from 1/8" thick pieces.

[lewisboats]

Test Successful! I soaked for about 36 hrs but it didn't do a whole lot. Soaked in hot water for an hour or so and voila...much more limber. I'll let it dry and see how much of a set it will take. Even if it springs back 50%...that should be just about right for what I need.

http://www.angelfire.com/ego/lewisboatworks/Stuff/Designs/Tadpole/XSoaked2.JPG[/img]

[PAR]

Okay Craig, now I know what you mean . . .

Sometimes you do what you have to.

[lewisboats]

Wasn't that supposed to be Steve? By the way...it turned out perfect...just a tad more curve than needed but it straightened out with only the slightest of pressure and kept the shape. Now to do it for real...so I'll probably screw it up  :?

[PAR]

No, Steve, I actually meant Craig. Have faith, you'll get it. If you're lucky without breaking a bunch of stock.

[lewisboats]

Sorry...my mistake :-?

Got the real thing soaking now...hopefully I don't do something to screw it up. The two nicest and darkest pieces are the ones I want to use for the outwales. For any further updates...see the " http://www.messing-about.com/forums/index.php?topic=7211.0" thread...

This one has served it's purpose so time for the archives.

[GWB]

I was steaming some fir for laminated frames a while back.  I had built a jig with a series of block to clamp to.  When I bend the laminations(3/4"x3/4"), I'd typically get breakage as the lamination wrapped one of the hard points of a clamp block if I was bending a single lamination.  If I bent the laminations in pairs, they backed each other up and my breakage was reduced to almost nothing.

Long story short,  bend your strips in pairs and you'll have a reduced risk for breakage.

[Craig]

Some time back in Fla I built a hardtop for a friend's 52'er.  Doug fir supplied the ply and the solids. ( Ya I know, there is a lighter way but that was what he wanted) To bend the curtian rails we made patterns out of 2x stock for the forward curves and cut down the 90 degree bends at the back so they were ~16" long.  At the 90s ( not 90 but curved through 90) we used a 3 peice lamination and backed it with aluminum strips left over from another project.  A steam box of sewer tube, radiator hose, and a steel gas can made up the jenny.  We molded the corners wet and epoxyed them when dry and shaped.  Then we trimmed to fit.  Wonder of wonders all 7 peices fit like we planned with a minimum of straining to fit the back corners.  These are fun projects when they go right.

[lewisboats]

Well...this one went 50/50...one had too much grain run out and cracked across the outside face. I left it to dry but it doesn't have the shape I need. The curve is too much at the cracked area and the ends are too straight. I might just say Eff it and keep the test strip as one side and the other darker one as the other. I'll go check to see if there are anymore dark ones left at the store before gluing anything. The two problems I have with the test strip is that 1. it is significantly lighter than the other side and 2. It has slightly rounded corners on one side...go figure that that is the side that would have to be against the ply whereas the other strip has the rounded edges outside where they belong. Charlie Brown Syndrome strikes again... :shock: :(