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Fitting scarf joints for wales

Joined
Mar 17, 2021
Messages
410
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278

Location
San Diego, CA
Hi everyone,

I'm having some problem with the scarf joints on the wales of my HMS Alert from Trident. The stock is 3/32" cherry and the pattern of the scarf is slightly complex. I scraped off the char and filed until I got a snug, mostly "no daylight" fit. On my first shot of affixing to the hull, I bent the wood with water but ended up with these awful, malformed, splayed joints. I tried to finesse it, but they just looked terrible. That first scarf joint sits at a spot with a respectable turn radius and even a little curvature from the top to bottom.

I had to laser cut a few more pieces (I don't trust myself to get things right the first time with kits, so I always scan parts first). I got a tight fit again off model. This time I put up one segment of the wale at a time and let constant tension slowly bend the scarf flat to the hull after a long soak, banding up, and drying overnight. I did the same for the next segment with the first segment in place. They both look like they took the form properly, but the joint, overall, looks splayed outward.

Here's my question. Do I file along the scarf joints at an angle through the thickness to get a match? Or did the train leave the station when I fitted the two pieces off model and I need to start again and fit once bent? I know there are plenty of modellers that make fantastic scarf joints and anchor joints in their wales, I could use some pro tips.

A word about bending the wood. I found wetting the 3/32" stock with water, adding newly heated water every 5 minutes for a total of 20min gives you something bendable but you have to let the tension do the work on the scarf joint overnight to flatten it completely while it is drying. I was hoping to get more pliability and ammonia was recommended, but that seems to discolor/bleach the wood and the dried form is a bit brittle. If you think the bending step is the problem, I could use some proven techniques to get it right. Everything but a soldering iron. The curves are too complex for a 1D heat curve (the hull at the joint sites are curved both along it's length and width).

Thanks for any help you can offer.
 
Hi Glenn,

I have used two solutions. I have found success by pre-bending the stock and only then cutting the scarf (tricky, but doable). But my most recent solution was to keep the strake full length and put in a faux scarf joint with a sharp blade (and that includes the top and bottom, not just the outward face). The problem with this approach is the grain pattern gives away the fake joinery. Then again, if the wale is painted...
 
Hi Glenn,

I have used two solutions. I have found success by pre-bending the stock and only then cutting the scarf (tricky, but doable). But my most recent solution was to keep the strake full length and put in a faux scarf joint with a sharp blade (and that includes the top and bottom, not just the outward face). The problem with this approach is the grain pattern gives away the fake joinery. Then again, if the wale is painted...
Thanks Paul, it's appreciated
 
the wale scarf was actually talked about in the school here is a link

 
the wale scarf was actually talked about in the school here is a link


The "search thingie" is our friend. Before asking a question, it's best to check it. More often than not, there's been a long discussion posted previously which will answer the question and then some. This forum has been around long enough that there aren't that many possible questions which can arise that haven't been answered already.
 
A word about bending the wood. I found wetting the 3/32" stock with water, adding newly heated water every 5 minutes for a total of 20min gives you something bendable but you have to let the tension do the work on the scarf joint overnight to flatten it completely while it is drying. I was hoping to get more pliability and ammonia was recommended, but that seems to discolor/bleach the wood and the dried form is a bit brittle. If you think the bending step is the problem, I could use some proven techniques to get it right. Everything but a soldering iron. The curves are too complex for a 1D heat curve
It is heat that softens lignin and causes wood to bend easily when heated and to hold that bent shape when cooled. Not water! Not amonia! Not steam! Heat. Just plain dry heat. I really don't know why this message just doesn't compute with so many modelers.
In large sized stock, steam is frequently used to permit "steam bending." (Actually, "heat bending.") This is because steam is an efficient vehicle for distributing the heat through the wood under slight pressure in a "steam box." The steam heat is applied for a minimum of one hour for each inch of thickness of the piece's smallest dimension. However, with small pieces used for ship modeling, a clothes iron, electric plank bender, soldering iron, or an electric hair drier or heat gun are all far more efficient and far less messy ways of heating wood in order to bend it.
If "the hull at the joint sites are curved both along its length and width," it's no surprise you're having problems bending wood to fit. What you're describing is like trying to teach a fish to ride a bicycle. It's not in wood's repertoire to bend in two directions simultaneously, AKA "compound curves," isn't something God made wood wanting to do naturally. The required solution is to shape the piece to create the curves, rather than trying to bend it. To get the flat of a plank to lay tightly against a curve, the faying surface on the plank must be shaped by "backing out" if a concave curved plank shape is required, or the reverse if a convex curved plank shape is required. Cut your wale a bit over size as required and plane to fit. Trying to incorporate a scarf in the middle of it all is truly crazymaking. Use a solid piece of wood and forget the scarf. If you feel the need to show the scarf (something that would never have been intentionally visible on the real ship,) then draw it in with a sharp hard-leaded pencil and straight edge after it has been shaped.
See:
 
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