bending planks

[bluenose2]

I have run into an issue that has stumped me. I have on hand some old growth mahogany from the late 50's. I have ripped into 2 mm x 5 mm strips for the planking on the wales of my ship. When I try to bend it after soaking for 3 hours it breaks on the hardest bend around the bow. Am building the 1/60 Endeavour. I have ripped it the other way based on grain but still breaks.I know this is much thicker than say .05 mm planking. I am now soaking it for one week to see what happens. My concern is if this works, it may shrink after glue up and cause a later issues with gaps in the planking. What should I do? I am thinking that because of  it's age it has lost it's essential oils and become too brittle. 

[mtaylor]

A couple of questions.... Is the grain straight.  If not, it will break.    Soak and then heat (I use an old curling iron).  Repeat as needed to get the bend you want.  It is possible that the wood is just too dry to be used.

[hornet]

I have found mahogany to be very brittle at the best of times. I’m not sure that soaking it for an extended period will make much difference. I suggest you rip it down to 0.5 mm and use it as a veneer over limewood or something similar. 

[Jim Rogers]

I use a steam cleaner, a form and a heat gun.

 

[Jaager]

Wood contains a glue-like lignin - heat loosens its bonds  for bending -  the function of the water is to 

allow efficient heat transfer.  No part of the wood is soluble in water.  The prolonged soaking will only

rehydrate the wood - undoing 50 years of seasoning and encouraging any fungus present.

Lignin is affected by anhydrous ammonia - an explosive and dangerous industrial chemical.

Household ammonia is 5-10% - too dilute to make it anything other than smelly water as far as wood bending.

 

What plane are you bending?  Down on the frames = you are stuck with heat bending. Up/down in the plane of

the planking = spilling - not bending.

Now that I think about it-  while not a pleasant prospect, if your stock is thick enough - you could carve both curves.

 

Edited April 25, 2018 by Jaager

[BETAQDAVE]

    Another method would be to plane or sand the wood into much thinner planks which will bend much more readily.  Then soak or steam the planks to make them more pliable and bend enough layers of these thin planks to total the required final thickness around a form matching the shape required and clamp to dry.  When dry, laminate the layers with a thin layer of glue between and clamp the layers back on to the form and let dry.  With this method you can bend planks into very tight bends and there will be very little if any spring-back. Once trimmed and sanded they should be very easy to apply.

Edited April 25, 2018 by BETAQDAVE
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[bluenose2]

Thnx everyone. I have an electric plank bender and a custom jig. Worked well on the 1st planking and the 1 mm walnut. I believe I will rip some more mahogany at 1 mm and double plank this area. I was going for a variation of wood on the wales to break up a solid walnut look.If it still breaks oh well I will try another type of contrasting wood. 

[bluenose2]

On April 24, 2018 at 7:42 PM, mtaylor said:

A couple of questions.... Is the grain straight.  If not, it will break.    Soak and then heat (I use an old curling iron).  Repeat as needed to get the bend you want.  It is possible that the wood is just too dry to be used.

Thnx. I have an electric plank bender and a custom jig for bending. I suspect that the wood is too thick. I will re rip at 1mm x 4mm and see how it goes. I wanted a contrast in wood to ofset a solid walnut hull.

[hornet]

Ripping to 1mm and soaking, heating then bending should work. Maybe you could also score the rear of the planks at close intervals with a No 11 blade before attempting to bend. This has worked for me in the past. 

[vaddoc]

I used 2 mm maple in my current build. 30 secs under hot tap water and I could get the wood to take extreme twists but mahogany does not like bending much. My experience is also that it can have interlocked grain, same as walnut which often suddenly breaks instead of bending. 

[bluenose2]

On April 26, 2018 at 3:49 PM, vaddoc said:

I used 2 mm maple in my current build. 30 secs under hot tap water and I could get the wood to take extreme twists but mahogany does not like bending much. My experience is also that it can have interlocked grain, same as walnut which often suddenly breaks instead of bending. 

 

thnx vaddoc. I have maple and oak on hand. The reason for my choice of mahogany is it isn't too harsh of a contrast between the walnut planking but just enough to show another wood. Anything such as oak or maple would be too much of a contrast and draw your eye to this band. I know mahogany has a larger grain than walnut, so I will pick through my mahogany stock to find a sample with a much tighter grain. Hope it works.