Which Tool for Relieving Bulkhead ?
 

Imagine a freshly cut-out plywood bulhead lying horizontaly on a table
before you. The bulkhead will be attached to, or installed into the
fiberglass hull using 'bonding angles' i.e., several layers of 'glass
/ epoxy that will lap onto both the bulkhead and hull. I'd like to
relieve, or remove, about 1/8" of the plywood (face) material all
along the edge of the bulkhead (where it will bond to the hull) for
(say) 3" from the edge on both sides of the bulkhead. In this way,
the 'glass angles will lie flush with the bulhead surface.

How do I do this? That is, wat tool(s) would be used for removing the
plywood, leaving a clean cut of consistent depth?

Appreciate any tips.

Mike Worrall
Los Angeles

Which Tool for Relieving Bulkhead ?
 

mike worrall wrote:

How do I do this? That is, wat tool(s) would be used for removing the
plywood, leaving a clean cut of consistent depth?

A router.

Rick

Which Tool for Relieving Bulkhead ?
 

Rick wrote:
mike worrall wrote:

How do I do this? That is, wat tool(s) would be used for removing the
plywood, leaving a clean cut of consistent depth?


A router.

A belt sander
A power plane
A block plane if you are a real masochist.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Which Tool for Relieving Bulkhead ?
 

Two possibilities:
Start with a router. Cut a 1/8" rabbet of arbitrary(~1/4") width around the
panel. Grind the rest of the taper with a belt sander, a hand planer or a 7"
grinder. The rabbet will show you the depth. THis will be an ugly process.

Glenn's (justly famous) router scarphing tool might be a good start at a tool
for this. It's limited to 2-1/2" max., so a little touch-up with a block
plane or one of the above tools will be needed.

Rick wrote:

mike worrall wrote:

How do I do this? That is, wat tool(s) would be used for removing the
plywood, leaving a clean cut of consistent depth?

A router.

Rick

Which Tool for Relieving Bulkhead ?
 

Or if your really brave, you could do this with a large course disk sander..
Takes some skill to control the big disk sanders.

The builders of my hull, Blue Water Boats did a nice neat job of it and I
believe it was done with a very large belt sanding machine. The chamfered
the 1" bulkheads back about a foot all around and that is how far their
hull/bulkhead attachment was carried on my 38 ft hull..


--
My opinion and experience. FWIW

Steve
s/v Good Intentions

Which Tool for Relieving Bulkhead ?
 

I know nothing about router blades. Ignoring the possibility of a router
blade, you can get a consitent depth of recess by first scoring the area
to be recessed with a saw set to the depth of recess you want. Perhaps run
a hand held circular saw along a line parallel to the edge of the bulkhead
and then run a few cuts between this first cut and th edge. If the depth
to be removed is only 1/8" there will be no problem following a curved
line with a hand held circular saw set at that depth. Then take a power
sander and sand down until the saw cuts just disappear.

If working with plywood its pretty easy just to sand off the face ply. Its
obvious when you start sanding into the second ply. If the face ply is the
depth you want to remove, you're laughing my son.

--
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Which Tool for Relieving Bulkhead ?
 

William R. Watt ) writes:

... If the depth
to be removed is only 1/8" there will be no problem following a curved
line with a hand held circular saw set at that depth.

I should have recommended using a rip fence on the hand held circular saw.
Mine cost about $10 Canadian and has been very handy. I still mark the
line to be cut so I can see if I'm cutting correctly, but the rip fence
helps a lot to steady the hand. You can set it first to 3" and go around
the edge, then set it to 2" and go around again, then to 1" and score the
surface again. The three cuts should be enough of a guide to get a
consistent recess with the sander.

--
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homepage: www.ncf.ca/~ag384/top.htm
warning: non-freenet email must have "notspam" in subject or it's returned

Which Tool for Relieving Bulkhead ?
 

Which Tool for Relieving Bulkhead ?
 

mike worrall wrote:
: Imagine a freshly cut-out plywood bulhead lying horizontaly on a table
: before you. The bulkhead will be attached to, or installed into the
: fiberglass hull using 'bonding angles' i.e., several layers of 'glass
: / epoxy that will lap onto both the bulkhead and hull. I'd like to
: relieve, or remove, about 1/8" of the plywood (face) material all
: along the edge of the bulkhead (where it will bond to the hull) for
: (say) 3" from the edge on both sides of the bulkhead. In this way,
: the 'glass angles will lie flush with the bulhead surface.

: How do I do this? That is, wat tool(s) would be used for removing the
: plywood, leaving a clean cut of consistent depth?

: Appreciate any tips.

: Mike Worrall
: Los Angeles

How about a router table with the fence drawn back so that a straight
router bit protrudes 1/8" of an inch out from the fence, and, of
course, more than 3/4" high? Perhaps, instead of the fence you might
use 2 vertical dowels for the curve to run against.

I don't use plywood in my boat building but it's just a wild
thought. haven't tried anything like that.

--- Gregg


Replicas of 15th-19th century nautical navigational instruments:

http://home.comcast.net/~saville/backstaffhome.html

Restoration of my 82 year old Herreshoff S-Boat sailboat:

http://home.comcast.net/~saville/SBOATrestore.htm

Steambending FAQ with photos:

http://home.comcast.net/~saville/Steambend.htm


"Improvise, adapt, overcome."

Smithsonian Center for Astrophysics
Phone: (617) 496-1558

Which Tool for Relieving Bulkhead ?
 

I would taper the relief rather than have the relief end in an abrupt
cut edge 3 inches in from the end.
Is the bulkhead going to be painted? If it is then is won't really
matter if there is some variation in the inboard edges of the fillet.
I hate routers. noisey, dusty, too fast, and hard to control unless you
set up a jig.
I'd draw a line three inches back from the edge and hand grind a taper
with a disk grinder( also noisey and dusty but easier to control by
hand) being careful not to take off any wood beyond the
line. Use the glue line in the plywood to judge eveness of depth.
You could also bevel the edge off with a power plane or even a hand jack
plane if you are good at sharpening one.(sharpening the blade is the
secret) If you have a lot to do the hand plane would be tedious.
All this assumes that you are bonding the entire perimeter of the
bulkhead to the hull rather than just short little tab angles. I've seen
it both ways and I can't really tell from what you wrote. If using
multiple short tabs, I'd use a really sharp slick (a wide flat chisel
with a long handle) to bevel slots that the tabs would be built in.

By the time you figure out how to build a jig for the router, hand
grinding it with a disk sander would have it done.
The inboard edge of the glass "fillet" can be faired with micro baloons
and epoxy but if you use strips of glass cut from a sheet of fabric on
the diagonal, you will not have to deal with the hard edge of glass
tape. Cutting on the diagonal keeps the fabric from fraying and orients
the fiber correctly for this aplication.
Actually, you can fillet the bulkhead to the hull without cutting a
recess at all. The glass is not all that thick that it can't be faired
to the flat of the plywood so that it can't be seen if painted. Either
way will require some fairing and sanding to achieve a smooth joint.
SteveJ

mike worrall wrote:
Imagine a freshly cut-out plywood bulhead lying horizontaly on a table
before you. The bulkhead will be attached to, or installed into the
fiberglass hull using 'bonding angles' i.e., several layers of 'glass
/ epoxy that will lap onto both the bulkhead and hull. I'd like to
relieve, or remove, about 1/8" of the plywood (face) material all
along the edge of the bulkhead (where it will bond to the hull) for
(say) 3" from the edge on both sides of the bulkhead. In this way,
the 'glass angles will lie flush with the bulhead surface.

How do I do this? That is, wat tool(s) would be used for removing the
plywood, leaving a clean cut of consistent depth?

Appreciate any tips.

Mike Worrall
Los Angeles