How to shape a dagger board?

"Toller" <Toller DeleteThis @yahoo.com> wrote in message
news:8kmWe.7138$cg.3846@news02.roc.ny...
> The blank is 44" long, 2" thick, and 15" wide. It weights 35 pounds.
> I originally intended to cut the corners off on my table saw, but it is so
> heavy that it doesn't seem particularly safe.
> So, I have been going at it with my 3" belt sander and my 2" power
planer.
> Both would work, but they would take hours and hours of work.
>
> Any suggestions for a good way to shape my blank into an airfoil shape?
> I am thinking of buying a better planer, but hope someone here will be
> resourceful.

I'd go for the power planer. A good one can take away 1.5mm (1/16") in one
stroke, which means you can take away half of the thinkness of your blank in
16 strokes.

Meindert
 >> Stay informed about: How to shape a dagger board? 

Toller wrote:
> My mahogany dagger board was damaged when I bought the boat used. I glued
> it with epoxy and put some fiberglass around it and it has held up for a few
> years, but I don't think it will last.
>
> I bought some 8/4 white oak on ebay for almost nothing (100bf for $1.25),
> and figured I will build a new daggerboard while I had something intact to
> copy.
>
> The blank is 44" long, 2" thick, and 15" wide. It weights 35 pounds.
> I originally intended to cut the corners off on my table saw, but it is so
> heavy that it doesn't seem particularly safe.
> So, I have been going at it with my 3" belt sander and my 2" power planer.
> Both would work, but they would take hours and hours of work.
>
> Any suggestions for a good way to shape my blank into an airfoil shape?
> I am thinking of buying a better planer, but hope someone here will be
> resourceful.
>
>
Use your table saw as a shaper by sliding the blank sideways over
the blade. It will leave concavities, a hollow ground shape you can
refine more easily. A well made slide jig should provide a reagulare
shape and remove most of the unwanted material.

Don't be afraid to drill a few bolt holes in your saw top to hold
special jigs, or use eccentrics to hold in guide slides.

Cut strips to sit in grooves able to slide, lay ply on top, pin with
brads, screw together from other side. with saw, route grooves the
other way, make side slider jig. Screw on a fence to enable milling.
Terry K
 >> Stay informed about: How to shape a dagger board? 

You can make transverse saw cuts and take out the wood with a chisel. Then
clean up with a plane or whatever. Dont' go all the way in with the saw
because the wood will not cut out smoothly. Practice on scrap first.
If you can figure out some way to do it with a power saw it allows you to
set the depth of cut.
--
------------------------------------------------------------------------------
William R Watt National Capital FreeNet Ottawa's free community network
homepage: www.ncf.ca/~ag384/top.htm
warning: non-FreeNet email must have "notspam" in subject or it's returned
 >> Stay informed about: How to shape a dagger board? 

On Sat, 17 Sep 2005 11:45:10 -0400, Matt Colie wrote:

<snip>
> Cutting guide reference slots is not a bad idea, you will have a lot of
> wood to hack off before you get close to the sand-to-shape phase. You
> might consider doing that before you even "cut the corners off" because
> it will be easier to handle the blank then.
>
Well put. This was what I intended to describe but your command of
the English language is clearly superior.

I recommend Western Red Cedar (or similar light wood) for two reasons:
1) Easier to handle both while building and on the boat.
2) Easier to work on than oak.

I have shaped plugs out of MDF-blanks this way. A plug for a rudder
1.8 m long and with a 30 cm cord took only one evening to shape.
Painting, wet sanding, rubbing and polishing took much longer.

> Thinking is the Cheap thing to do.
>
Indeed

Here are some more ideas on shaping foils if you don't want to
make molds.

* Strip planking using 6-8 mm thick WRC strips. Use external frames.
Glass+epoxy inside, join halves and don't forget that you need
a good structural member running down the middle of the foil.
The exterior will need some final shaping, then add carbon as
needed and wrap in glass and epoxy. Potentially lighter than
the massive board for big boards but more work and less robust.

* Central structural member made from WRC+carbon laminate. Foil
shaped from foam cut by hot wire. Cover in glass+epoxy laminate.
Note, this time the laminate is structural.
My current boards were build like this some ten years ago.
They are 2.5+ m long and has a 44 cm cord. New they weighed
12 kg each.

/Martin
 >> Stay informed about: How to shape a dagger board? 

On Thu, 15 Sep 2005 22:11:16 GMT, "Toller" <Toller DeleteThis @yahoo.com> wrote:

>My mahogany dagger board was damaged when I bought the boat used. I glued
>it with epoxy and put some fiberglass around it and it has held up for a few
>years, but I don't think it will last.
>
>I bought some 8/4 white oak on ebay for almost nothing (100bf for $1.25),
>and figured I will build a new daggerboard while I had something intact to
>copy.
>
>The blank is 44" long, 2" thick, and 15" wide. It weights 35 pounds.
>I originally intended to cut the corners off on my table saw, but it is so
>heavy that it doesn't seem particularly safe.
>So, I have been going at it with my 3" belt sander and my 2" power planer.
>Both would work, but they would take hours and hours of work.
>
>Any suggestions for a good way to shape my blank into an airfoil shape?
>I am thinking of buying a better planer, but hope someone here will be
>resourceful.
>
I congratulate you on eliciting a wonderfully practical, innovative,
and helpful thread. Even the most radical contributions ("Don't use
oak!") were well-meant. Notice that suggestion of using a wood carve
blade in a circular saw? Wow! Wood propeller carvers use a router in
a kind of copier frame, profiling an existing fair copy of the blade.
I notice the respect given to mahogany on the traditional end, but
also the foam core glass or carbon approach at the leading edge end.

Iobserve in passing that the center board on the SouthCoast 22 I am
preparing, is a hefty chunk of iron - its weight so low down is of
course desirable - but that has a wind up hoist.

Brian Whatcott Altus OK
 >> Stay informed about: How to shape a dagger board? 

> You can make transverse saw cuts and take out the wood with a chisel. Then
> clean up with a plane or whatever.

That's an interesting idea that none of the woodworker I spoke to thought
of.
I will try it out on some scrap.
 >> Stay informed about: How to shape a dagger board? 

> Question: Is this a massive plank or quarter-sawn strips glued together?
> If it is a massive plank you should count on it warping.

It is two pieces (both 2" thick) glued together. I don't need it until next
spring. I can get it close, leave it for a few months, and then finish it.
Would that help?

> This is probably the wrong answer but I actually mean this:
> Use the oak for something else. Buy some light wood like Western Red
> Cedar and shape a board. Add unidirectional carbon for bending
> stiffness and strenght. Sheat in glass-epoxy and paint.
>
Oak is about 50% heavier than mahogany, but I actually want the weight, so
that is not a problem. Besides, it is free and the cedar would be about
$50.
 >> Stay informed about: How to shape a dagger board? 

Toller wrote:

> Oak is about 50% heavier than mahogany, but I actually want the weight, so
> that is not a problem. Besides, it is free and the cedar would be about
> $50.


What you are describing is a disaster guarenteed to happen.

As someone suggested, use the oak for something else.

Might even barter it for some good foam, but these days, good white oak,
even 8/4 is cheap compared to foam, even Divinycell.

Cover the foam with some 17 oz double bias and epoxy.

SFWIW, the above describes how my rudder will be built.

Lew
 >> Stay informed about: How to shape a dagger board? 

> What you are describing is a disaster guarenteed to happen.
>
Why?
The mahogany board weighs 15 pounds. The oak board should weight about 23.
Even if I hadn't just lost 7 pounds, what severe problems will the 8 pounds
cause?

I am not being argumentative; I concede I don't know anything about boat
building, and little more about sailing. But I have sailed this with my 95
pound son in it, and it is fine (if a little sluggish); why would 8 pounds
of board matter?
 >> Stay informed about: How to shape a dagger board? 

"Toller" <Toller.TakeThisOut@yahoo.com> wrote in message
news:uaKXe.1559$am.634@news01.roc.ny...
>> What you are describing is a disaster guarenteed to happen.
>>
> Why?
> The mahogany board weighs 15 pounds. The oak board should weight about
> 23.
> Even if I hadn't just lost 7 pounds, what severe problems will the 8
> pounds cause?
>
> I am not being argumentative; I concede I don't know anything about boat
> building, and little more about sailing. But I have sailed this with my
> 95 pound son in it, and it is fine (if a little sluggish); why would 8
> pounds of board matter?
>
Without looking at the board and reading the grain, it is near impossible to
tell what it will do. Not knowing how old it is and how it was dried
muddles things further. I don't think the weight is a concern. I would
think warping, bending, settling, etc. of the board is the potential (big
word there) cause for concern. A guaranteed disaster? I hardly think so.
A likely disaster? Nah. It is yours, the board is free. The penalty will
be to redo it. Go for it, it might just work!

Ed
 >> Stay informed about: How to shape a dagger board? 

Toller wrote:
>>What you are describing is a disaster guarenteed to happen.
>>
>
> Why?
> The mahogany board weighs 15 pounds. The oak board should weight about 23.
> Even if I hadn't just lost 7 pounds, what severe problems will the 8 pounds
> cause?
>
> I am not being argumentative; I concede I don't know anything about boat
> building, and little more about sailing. But I have sailed this with my 95
> pound son in it, and it is fine (if a little sluggish); why would 8 pounds
> of board matter?
>
>


It is not the added 8 lbs although rudders are designed to be as light
as possible.

It is that this is not a good application for white oak.

Now if you quarter saw that 8/4 stock, you can make some very nifty trim
for tha boat.


Lew
 >> Stay informed about: How to shape a dagger board? 

"Toller" <Toller.RemoveThis@yahoo.com> writes:

> > Question: Is this a massive plank or quarter-sawn strips glued together?
> > If it is a massive plank you should count on it warping.
>
> It is two pieces (both 2" thick) glued together. I don't need it until next
> spring. I can get it close, leave it for a few months, and then finish it.
> Would that help?

Some but I think it will warp sooner or later anyway. A good
epoxy seal helps slow the process. But as someone else stated:
Without being able to see your blank and how the grain looks it
is very hard to be anything but rather vague about this.
>
> > This is probably the wrong answer but I actually mean this:
> > Use the oak for something else. Buy some light wood like Western Red
> > Cedar and shape a board. Add unidirectional carbon for bending
> > stiffness and strenght. Sheat in glass-epoxy and paint.
> >
> Oak is about 50% heavier than mahogany, but I actually want the weight, so
> that is not a problem. Besides, it is free and the cedar would be about
> $50.
>
I would say your troubles with the white oak is more about
handling and working on it in your workshop than all-up weight
on your boat. You will spend a lot more time shaping your oak than
it takes to shape cedar.

Oh, I almost forgot. It is my experience that oak and epoxy coats
don't always work well together.

--
========================================================================
Martin Schöön <Martin.Schoon.RemoveThis@gmail.com>

"Problems worthy of attack
prove their worth by hitting back"
Piet Hein
========================================================================
 >> Stay informed about: How to shape a dagger board? 

There is no need to worry about making a daggerboard, centreboard, or
rudder out of solid wood. Visit your nearest sailing facility and look at
all the centreboards, daggerboards, and rudders made of solid wood. The
fact that your board is glued up means it will not warp. You can look at
the end grain to see which way the two pieces are oriented. Put a couple
coats of polyurethane varnish on it and refinish it every few years.

I've never put epoxy resin on oak but peope who have say it's only
necessary to sand the surface of teh wood to roughen it up a bit. Oak
contains tannin, and acid, and acids dilute epoxy rdeucing its bonding
strength. One way to clean up epoxy resin that has not cured is to use
vinegar, lemon juice, or some other mild acid.


--
------------------------------------------------------------------------------
William R Watt National Capital FreeNet Ottawa's free community network
homepage: www.ncf.ca/~ag384/top.htm
warning: non-FreeNet email must have "notspam" in subject or it's returned
 >> Stay informed about: How to shape a dagger board?