Name Plates - to fit hull curve

[Paul H (admin)]

Alan Craig has kindly sent me two off-cuts of oak 370mm x 90mm and 20mm thick. I intend to use them for nameplates either side of MilliBee's bow.

I will beg steal or borrow some CNC time to get accurate lettering and a carved, artistic border. Agricultural types should stop reading now, especially rat-catcher John, in case they get overwhelmed with artistic detail and need a stiff drink of moonshine to recover.

One clever trick is to copy the hull curve at the bow and CNC the back face to ensure a flush fit. The hard bit is copying the hull curve, but there is roughly 4 mm at each end if I hold the wood with the middle touching the hull.

So an arc between the three points (start 4, mid 0, end 4) might be ok, assuming plywood bends to form an arc. Hang on, I can hear CW thumping the keyboard saying he can bend plywood like any origami wizard, and its always a parabola anyway. What's a parabola? Well it curves in the middle, but a long way from the centre it becomes straight.

-Paul

[Alan]

I finally remembered the word for taking off curves of boats with a view to fitting the next plank, nameplates etc. it is spiling. Plenty of information out there.
But I think the easiest way to transfer the shape of the hull to a computer might be to measure directly from your straight edge temporarily fastened to the hull, at maybe 8 or 10 points, then fit these dimensions to a spline curve in CAD which can then be transferred into your router software.

[Paul H (admin)]

Ah Spiling..I hope its not a Grauniad speeling mistake.

I had the same thoughts Alan - a length of 2x1 with holes drilled for two pencils each end and a screw to clamp each pencil. Mark the chosen area for the plates with masking tape, hold the pencils on the tape and when the 2x1 just touches lock the pencils, so there are 3 points of contact.

Then mark 20mm steps along the tape and record the offset from the hull for each point. There will be about 19 points of "height" for a curve - we have software in ArtCAM that can fit a smooth curve through any number of points (technically a collection of Bezier curves with tangent continuity to the next curve).

I may need the Assistant of all things Magical to help me, holding the 2x1 steady is difficult??

-Paul

[Paul H (admin)]

Here is a nice example of a spiling batten in use:





At the bench you can transfer the "curve" onto new stock:



Pictures taken from http://www.duck-trap.com/building.html

[Port-Na-Storm]

Dear Sir, I recently noted your recent discussion on spiling.

I think this is what you need.



Shape found and transferred to stock like so



available for rent at very modest prices.

I remain as ever............................

[Timmo]

I've done a similar job with scraps of ply and a hot glue gun. But Graham's is so much more elegant and reusable! 

On my boats it would be important to repeat the spiling process for the other side of the hull. To assume it is symmetrical would be to overestimate my skills considerably!

Tim.

On 20 Jan 2015, at 14:33, Port-Na-Storm [via UK HBBR Forum] <[hidden email]> wrote:

Dear Sir, I recently noted your recent discussion on spiling.

I think this is what you need.



Shape found and transferred to stock like so



available for rent at very modest prices.

I remain as ever............................

---

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[Paul H (admin)]

Port-Na-Storm wrote

Dear Sir, I recently noted your recent discussion on spiling.

available for rent at very modest prices.

I remain as ever............................

Jolly good, rent payable in beer?   Can Postman Pat deliver it?

-Paul

[Port-Na-Storm]

For what you want to do it doesn't need to be so hi tech.

You will need.
A piece of ply.
Three bits of wood.
A sheet of paper
Some glue or gaffer tape.
A pencil.
A drill.
A responsible adult.

Take a bit of ply a bit longer than the nameplate.
Glue/tape a couple of bits of wood along the short sides so they protrude by a couple of inches.
Stick some paper onto the ply.
The other bit of wood needs to be maybe three-four inches long, ask the adult to drill a hole in one end for the pencil.

Method;
Hold the ply horizontally with the sticks against the hull where the nameplate will be.
Now turn it over so that the paper is uppermost.
Take the other stick with the pencil in it (pointy end down ) and place it on the paper perpendicular to the hull. Slide it along the hull and the curve will miraculously appear on the paper.

I suspect your hull will prove to be fairly flat.

Have Fun.

[Chris Waite]

I've been avoiding reading this

On the grounds that I have a stack of other stuff I should be doing, but it's a lovely day and I've found a couple of minutes to spare.  Never mind three bits of wood (he contradicted his betters)....

1.  Take a ply off-cut a tad longer than the name plate.

2.  Cut a rough curve into one long edge - it only needs to be deeper than the 4mm you have already measured, hold it (horizontally unless you want the name vertical) over the intended location.

3.  Holding your pencil spaced with a biddy off-cut (say an inch thick) of whatever, run it along the hull and your desired curve, within less than you can squirt some epoxy at, will appear on your ply off-cut.

4.  Take your trusty jig saw and cut along the curve you have drawn.

5.  Lo and behold, you have a 'ruler' with just the curve you always wanted and you can always offer it up again and sliver off any excess if you're really that Obsessively Compulsively Disordered.

6.  Better than all that, you can now take your heart-of-oak and draw that curve straight onto each side.

7.  Lastly you can use anything from a rasp, to a Surform, to a spoke shave, to one of your fangled planes, or CNC routers to remove the excess.

Four millimetres; massive, just massive - Mmmmm!

And TimmO's right, do one for each side; they won't match.

How am I doing?

CGW Bodger in Chief

 

[Chris Partridge]

Well, there's a coincidence. Today I finally tackled the nameplates on the Hampshire punt I am restoring (hull now varnished with traditional varnish, thank you for asking).
The boat had a nameplate on either side of the bow, and when I unscrewed them two largish habitats for assorted insects and grubs were destroyed. So I have taken a rather different approach to replacing them.






1) Go to Express Signs in the railway triangle, Protsmouth.
2) Order a copy of the lettering on sticky-backed plastic.
3) Slap one on either side of the bow and chuck the original nameplates in the bin.

Of course, I won't have a glorious confection of carved oak, but I won't have had to faff about with spiling boards for hours either.