Bending top rail in the bow area

[Charlie pal]

Hello all, hope all are well

     Have been currently working on the vessel “Black Prince”, Benjamin Franklins personal transport across the Atlantic to France and back to the U.S., in an effort to secure French aid during the American Revolution. As my previous three builds, two steps forward and one step back….but I am making progress.

    Recently I planked the bulwarks on the interior of the hull. I planked horizontally, then vertically and finally with a walnut finish. The hull feels much stronger.

after doing this. when I attempted to install the top raiI, I realized that the top rail needed to be slightly wider than the plans indicated. So I soaked a couple of wider strips in ammonia and water, hoping that I could place a sideways bend in them as the rail curves toward the bow. I was able to get a smaller bend then I needed, and all additional effort to increase the bend resulted in strips being broken at that point. Any advice would be greatly appreciated.…….thanks…..Charlie

[Jaager]

33 minutes ago, Charlie pal said:

So I soaked a couple of wider strips in ammonia and water

Charlie,

The ammonia that ship builders used to bend wood was anhydrous ammonia.  The pure stuff that is either gas or liquid under bending conditions depending on PV=nRT.  The glue (lignin) that holds wood fibers together is soluble in pure ammonia - but not ammonia dissolved in water.  Pure ammonia, is explosive, corrosive, and a poison.   Soaking wood strips in an ammonia solution just messes up the surface of the wood.  Actually dry heat will bend wood just as effectively as wet heat.  If the heat source has too high a temp, the water may buy sometime before the wood surface chars. 

Water and steam transfer heat more efficiently than air,  but on a model size  piece of wood, the difference is probably measurable, but not significant enough to matter. 

 

Now about bending a rail:    a rail is usually wide and relatively thin.  The bend is usually along the thick dimension instead of the thin one.  Wood resists this.  It will try to twist.   Even if you somehow manage to do it, the wood will forever try to straighten back out.  

The better way is to do what actual ship builders did.  Break the rail up into shorter segments and spill the bend from a wide plank.   Mass market kit suppliers tend not to provide the wood necessary to spill a rail.   The way to achieve this is to source a supply of wide and narrow rail wood from a 3rd party supplier.  Get a species that is more appropriate than the crap that most kits provide.  You will be pleasantly surprised at how much better scale appropriate species of wood, look and work and if the model calls for it allows for a molding to be scraped on the outer edge.

Edited November 2, 2021 by Jaager

[allanyed]

Charlie

Depending on the wood, (forget using the walnut in the kit)  you can either try edge bending or spile the rail as Jaager suggests.   I prefer and use the method he suggests for heavy bends, but, you can try edge bending some species.   Soak the appropriate wood in water for a few hours and while it is doing so, cut a jig the shape of the bend that you need.  Then follow the method Chuck Passaro has detailed here at MSW on edge bending the wet wood and heating it so it will hold its shape.  If the bend is too severe, most/all species will break and you will be much better off cutting the rail to shape in two or more pieces for each side from a wide board as Jaager described.

 

I have had success with pear, castello, and holly using the edge bending method, depending on the thickness to width ratio and severity of the curve.   Holly is the easiest of these to bend  and will hold the shape with no problem once heated and left to dry in the jig.  (Hot air gun - her hair dryer - works well)   

 

Allan

 

 

 

 

[amateur]

laminating can also be a solution: bend a number of thinner strips and stack until the desired width has been achieved. 

When you use strips that are wide enough, you can then make two symmetrical rails from this laminated strips.

 

Jan 

[druxey]

The best solution to such pieces is to cut them from wider stock - in sections if needed.

[Charlie pal]

Thank you all for your input. I am still a “rookie” and the information many of you seasoned modelers provide is priceless. I must admit building these old ships can be daunting at times, but I do like the challenge and thanks to all of you, learn a bit more each time.….. Charlie