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Shaping frames fore and aft


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Hi everyone!


First, the background to my questions:

 

I'm drawing up plans for a large sailing model of an Elizabethan trading vessel, closely based on Brian Lavery's Susan Constant. I'm happy with the plans, but I see that the frames will be around 12mm wide (there will be about thirty in total, each made of two 6mm sub-frames, bonded together, with futtock joints offset on each sub-frame for strength).
 

At 12mm wide, and especially as I near the bow and stern, the frames will clearly have to be shaped to accommodate the lines of the hull. Now, the frame shapes are individually defined by a number of 'control curves' (in 3d space) which determine the location of the centres of the floor sweeps, the beam sweeps and the toptimber line. I've made a spreadsheet of these three defining positions at each frames' station. So far, so good.

 

Interpolating the control curves* for the +/-6mm measurements at the fore and aft edge of the frames, the three positions can be up to 7mm 'off' that of the station.

 

Here are the questions!

 

1a/ Is it worth cutting the two subframes to shape following the largest shape required by that subframe, before frame assembly?

1b/ ...Or do I make each frame up to the largest shape required by that frame?

2/ Do I shape the frame off the boat or once in place? Common sense says 'once in place', as 'they would have', especially as large timbers might well sag a little under gravity.

3/ What's good practice for the inside edge of the frames? (These won't be on view, but there are always plus points for artistic merit!) Access will be 'ok' for power tools inside the hull once done, but the near-insane tumblehome will make it difficult.

 

My woodworking skills aren't bad - but I'm aware tweaking will be required, and can see I might be overthinking this.

 

Any suggestions will be gratefully taken on board.

 

Andy


* Parametric equations were used: I'm delighted to say that there were no serious injuries! ;)

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If I understand your dilemma correctly, you are concerned with having sufficient wood for the extreme bevels at the bow of your model. Each frame will have an outer contour for its larger edge and smaller edge, the difference being the amount of bevel. If you take the smaller edge and then plot the thickness of the frame inside that, it will define the inner contour of the (unbevelled) frame when coupled with the larger outer contour.

 

Does this help? And yes, bevelling and fairing the hull is easier when assembled!

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10 hours ago, druxey said:

...bevelling and fairing the hull is easier when assembled!

A pile of work with the 'long board', though!

 

Y'see, I'm all for an easy life ... I was wondering if I could save time and cut the frames almost completely pre-bevelled during manufacture. Has anyone tried this, or would I be attempting to hit 'stupid' levels of accuracy?

 

Andy

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