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How can I copy the shape of the left hull onto the right side?


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Hello, I have a question about the shape of the hull before the first planking. Which one is the most accurate way to copy the shape of frames onto the other side? I'm considering three ways, but they have both benefits and downsides.

 

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1. Using the woodwork tool, I can copy the shape of one side of the frame easily. 

- Weaknesses; Inaccuracy due to difficulties in establishing a base line and insufficient size to measure all curves at once.

 

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2. Determining the length of the frame's edge. Simple.

- Weaknesses; I don't know how the curve goes.

 

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3. Adding mutiple guide lines to frames before assemblying.

- weaknesses; boring work, hard to check when the gap is filled with balsa blocks.

 

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4. Drawing the outline of the frame using a pencil.

- weaknesses; it needs space between frames.

 

Is there a legitimate procedure to make a model ship's hull symmetrical? 

Edited by modeller_masa
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26 minutes ago, modeller_masa said:

Which one is the most accurate way to copy the shape of frames onto the other side?

Why do you feel this is important at this point?

 

Small variations can be taken care of with shims or fairing to get a smooth run of the planking.

 

The only legitimate way to get symmetry is to have templates that you use to compare to both sides..

 

Did the kit come with bulkhead drawings..  These could have been used before assembly to make corrections.  At this point they could be used to make templates.

Luck is just another word for good preparation.

—MICHAEL ROSE

Current builds:    Rattlesnake (Scratch From MS Plans 

On Hold:  HMS Resolution ( AKA Ferrett )

In the Gallery: Yacht Mary,  Gretel, French Cannon

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19 minutes ago, Gregory said:

bulkhead drawings

 

I forgot it. Thanks, Gregory. Although my kit (AL Santa Maria 22411N) has no paper drawings, I'll use the technique in the next time.

 

By the way, I had had a heavy issue with planking curve lines. The hull's asymmetry was so strong that the waterline on both sides was usually 10mm different, a number of both sides of deck planking are different more than three, and rigging work was also strange. If this isn't a big issue in general, perhaps I should clean up a bad habit. 🤔

 

Edited by modeller_masa
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What you want is for them to be identical and precise.   Accuracy is secondary as long as the whole is internally consistent.

 

Scan the mold patterns from the plans.  Open the scan in a raster based drawing program.  Adjust for scanner scale distortion.  Isolate one side. Add register marks that will match locations on the physical mold ( and names - you may think that you can tell by sight, but even if you can, it will take time).  Flip horizontal  and print.

You should be able  several on a each sheet.

22 minutes ago, modeller_masa said:

hard to check when the gap is filled with balsa blocks.

Trash the Balsa. Use Pine.  The Pine from a builder's supply works well - just no Fir and no resin streaks.  Also, for your filler,  think vertical, not horizontal.  Like slices of bread.  Those same patterns that you use to check symmetry make excellent filler shape patterns. 

How to shape the fillers off the hull, so that they are a push fit:

When you do the scan and flip in the drawing program, also

CUT the white background of each mold pattern  - each is a layer and each layer is only the shape - the vertical center line and the horizontal baseline.

Make a series of consecutive pairs of mold patterns.

Add three small "o"  around the perimeter  but well inside -font size 4 works.   Use the holes for bamboo skewers.

The inside  can be cut away if you want a hold or less weight.  It can be any shape.

The filler slices - 1/4" for most is good.  smaller thicknesses can make up the difference for a tight fit - even poster board or cardboard fill fill a small gap if needed - liberal PVA makes it tough.

rough shape each slice as an individual.  Remove the patterns -except for the one at either end.

PVA glue them together,  Use the bamboo dowels and the section of layers is precisely aligned. 

 If you add a layer that is the same thickness as the mold plywood at the end facing the midline, bond it to the rest using a double layer of rubber cement, the whole section can be final shaped off the hull and still be just as precise as if it were done on the hull.

Remove the sacrificial end layer and push the section home.

 

Oh, and if you do this, the filler will make sure the hull is symmetrical.  If the actual molds are misshaped  and not symmetrical, it will not matter. The filler surface makes any contribution from the actual molds insignificant.

 

It is easier if this is planned for before the molds are bonded to the spine and the alignment holes are also done on the actual molds. It is easier to use the bamboo.  Even easier, the filler is made up before the actual hull assembly and the hull is done from the center out and each filler section is added with its mold.

NRG member 45 years

 

Current:  

HMS Centurion 1732 - 60-gun 4th rate - Navall Timber framing

HMS Beagle 1831 refiit  10-gun brig with a small mizzen - Navall (ish) Timber framing

The U.S. Ex. Ex. 1838-1842
Flying Fish 1838  pilot schooner -  framed - ready for stern timbers
Porpose II  1836  brigantine/brig - framed - ready for hawse and stern timbers
Vincennes  1825  Sloop-of-War  -  timbers assembled, need shaping
Peacock  1828  Sloop-of -War  -  timbers ready for assembly
Sea Gull  1838  pilot schooner -  timbers ready for assembly
Relief  1835  ship - timbers ready for assembly

Other

Portsmouth  1843  Sloop-of-War  -  timbers ready for assembly
Le Commerce de Marseilles  1788   118 cannons - framed

La Renommee 1744 Frigate - framed - ready for hawse and stern timbers

 

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Well, the next step up is to forego the spine and molds altogether.  Make the mold substitute a permanent part and just join up the sections.  But each pattern and each section would be the whole cross section /station.  The actual keel then goes last.  

Another part is that no baseboard is needed. 

NRG member 45 years

 

Current:  

HMS Centurion 1732 - 60-gun 4th rate - Navall Timber framing

HMS Beagle 1831 refiit  10-gun brig with a small mizzen - Navall (ish) Timber framing

The U.S. Ex. Ex. 1838-1842
Flying Fish 1838  pilot schooner -  framed - ready for stern timbers
Porpose II  1836  brigantine/brig - framed - ready for hawse and stern timbers
Vincennes  1825  Sloop-of-War  -  timbers assembled, need shaping
Peacock  1828  Sloop-of -War  -  timbers ready for assembly
Sea Gull  1838  pilot schooner -  timbers ready for assembly
Relief  1835  ship - timbers ready for assembly

Other

Portsmouth  1843  Sloop-of-War  -  timbers ready for assembly
Le Commerce de Marseilles  1788   118 cannons - framed

La Renommee 1744 Frigate - framed - ready for hawse and stern timbers

 

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