Today I have bought some fancy blades which I am told should do a better
job than the standard blades that came with the jigsaw.

They are bosch "clean for wood" - "clean cut" blades with 1.4mm pitch
teeth. I will post an opinion when I try them out.

Thanks for the reply

Brian Whatcott wrote:

On Wed, 20 Apr 2005 23:08:28 +1200, Brian
wrote:


Does anyone have any tips on the best ways to cut marine ply (6, 9 and
12mm)? In particular I want to cut curved 8' boards for a dinghy. So I
guessing that a band saw is a good bet but I don't have one. Are there
any other methods that can produce good results?

Thanks


A power jig-saw does good work, if equipped with the right blade. A
fine metal blade might be better for thin sheets, which otherwise show
one ragged edge unless backed.

Brian Whatcott Altus, OK

You are right about the weight of the circular saw. I don't think the
beast I have would work very well. Using masking tape is an interesting
idea but it would of course require that the lines be drawn on the tape.

I have been looking at circular saw blades but have not found anything
specially of ply. I will look for something thin with lots of teeth though.

Thanks

William R. Watt wrote:

Depends on what kind of saw you happen to have.

An electic circular saw can follow a curved line because the blade only
has to be set very shallow. Use a thin kerf blade with lots of teeth. I've
used a blade with 40 teeth. They make a special plywood blade with many
more teeth but I haven't found it to be any better. The only problem with
a circular saw is they tend to be heavy so the plywood should be well
supported and you have to go slow. I've found the thin blade of a jig saw
(sabre saw) can wander off the line pretty easy to you have to be careful.
You can also try sawing through masking tape to reduce tearing along the
edge. The jig saw and circular saw blades cut on the upstroke so the tape
has to be on the top side.

Brian ) writes:

Does anyone have any tips on the best ways to cut marine ply (6, 9 and
12mm)? In particular I want to cut curved 8' boards for a dinghy. So I
guessing that a band saw is a good bet but I don't have one. Are there
any other methods that can produce good results?

Thanks



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I do like the idea of trimming with a router because my experience using
jig saws is wavey.

Thanks


Glenn Ashmore wrote:

One extra hint. When cutting splintery wood like meranti. Lay a batten
along the finish cut line and score the top side with a crate knife before
starting the cut with an up cutting saw like a circular or jigsaw. It
prevents chipping of the face veneer so you will end up with a much cleaner
edge. Not needed with a reasonably fine toothed a band saw.

Saw outside the line and trim to it with a plane, router or belt sander.
For long slow curves I use a circular saw set just deeper than the sheet. I
do the gross trimming with a power plane and finish up with a low angle
block plane.

Very interesting idea. I was wondering how much could be covered by the
taped seam. Also the fact that some overlap is built-in to the design to
be trimmed later means that for at least half the cuts I don't need to
be too accurate.

Thanks

Evan Gatehouse wrote:

On the first stitch and glue dinghy I built, I did it slow and carefully
with a jigsaw, and a block plane to finish.

The second I used just a jigsaw.

The third I used a jigsaw and tried to go as fast as possible. Errors
greater than 1/4" were trimmed with the jigsaw. But otherwise it all
got hidden in the tape seam anyway. :)

"Brian" wrote in message
...
Nice boat you are building! One day I would like to try something so
elegant.

Thanks. Well, it wasn't too difficult. After all, it was our first boat we
built.
I need to update the site, she's already sailing for two years... :-)

The idea with the router is so obvious. I have used the same idea for
straight edges with ply in the past and got great results. I don't know
why I didn't think of using a batten and doing curves the same way. I
also like the jigsaw jig idea.

The jigsaw jig made the job very easy. Once setup, it's just a matter of
tacking the batten in the right shape, run the jigsaw, run the router and 10
minutes later you have perfectly cut strake which looks like it's been
laser-cur. But indeed, the obvious solutions often aren't so obvious.. :-)

Thanks for this tips.

My pleasure!

Meindert

I built my first (and second) stich and glue dinghy with a POS black
and decker jigsaw. Difficult to drive in a straight or curved line.
Didn't matter, as the taped seams covered it all. It looked so good
after covering with fiberglas that I could have just varnished it.
Gaps in teh seams just couldn't be seen.

If this is the type of boat you are building, then I think you are
worrying a bit too much. A jig saw should do the job just fine. Tape
the back of the seam with a thick piece of masking tape to help protect
from splintering.

Oh yeah, don't use a POS black and decker. I have a Bosch 1690EVSK
now, and it cuts like a dream. It goes exactly where I want to drive
it, no vibration, easy to cut straight (and curved) lines. Wish I had
one of these 10 years ago (of couse $40 was all I could afford then).

Band saw will probably be more difficult then a jig saw sue to the pain
of handling sheet goods that large (although it produces a beautiful
cut with no splintering, and you can very precisely cut just about any
line you can draw.... an amazing tool).

tim
Gordon wrote:
skil saw


"Brian" wrote in message
...
Does anyone have any tips on the best ways to cut marine ply (6, 9
and
12mm)? In particular I want to cut curved 8' boards for a dinghy.
So I
guessing that a band saw is a good bet but I don't have one. Are
there
any other methods that can produce good results?

Thanks

No matter the saw you use, it's kinda like driving a car around curves
in the road. Be mindfull of the precise spot on the line you're cutting,
but also let you hands guide the blade more in general motions and not
so much "over-steer" it. Hope that makes sense.

Take your time and let the saw teeth do the work. Don't force it.

--
Matt Langenfeld
JEM Watercraft
http://www.jemwatercraft.com/


Brian wrote:

Does anyone have any tips on the best ways to cut marine ply (6, 9 and
12mm)? In particular I want to cut curved 8' boards for a dinghy. So I
guessing that a band saw is a good bet but I don't have one. Are there
any other methods that can produce good results?

Thanks

Well I have tried a lot of the advice given and have ended up just using
a jigsaw with the bosch "clean cut for wood" blades with a 1.4mm tooth
pitch. The results are very good. Well they are easily good enough for
what I am building. There is very little splintering even without any
tape on the 6mm and 12mm ply and the cut is good and straight (or curved
in most cases) if I take my time.

The pack of 5 blades cost more than the jigsaw but the jigsaw only cost
$10. OK it was on special, it should have been $15. But it cuts very
well. With a good saw I would expect even better results. The blades
where $15. I have cut out 8 large panels twice (rough then accurate) for
an 8' dinghy and the blade is still fine and looks as good as the 4
unused ones. I have tried a few other blades and not achieved anywhere
near the same results. I would recommend them as a good buy.

Thanks everyone for the help,

Brian

Brian wrote:
Does anyone have any tips on the best ways to cut marine ply (6, 9 and
12mm)? In particular I want to cut curved 8' boards for a dinghy. So I
guessing that a band saw is a good bet but I don't have one. Are there
any other methods that can produce good results?

Thanks

A handheld circular saw with the depth set to just cut through the ply
does the fastest neatest job. You can make a half dozen or more 8' cuts
in gthe time you'd make one with a jig saw and it would be a lot smoother.
Evan Gatehouse wrote:

On the first stitch and glue dinghy I built, I did it slow and
carefully with a jigsaw, and a block plane to finish.

The second I used just a jigsaw.

The third I used a jigsaw and tried to go as fast as possible. Errors
greater than 1/4" were trimmed with the jigsaw. But otherwise it all
got hidden in the tape seam anyway. :)