Cutting plywood

[dalekidd]

I was given a Rotozip Heavy Duty Spiral Saw SCS01. I have never used a spiral saw before. What kind of bit would be best to cut 6mm and 9mm okoume plywood? I am on the verge of building another boat (my 4th but first lapstrake - the CIY 16 is at the top of my list). I'll be building from plans not the kit, so I'm looking for the best way to cut the plywood accurately and efficiently. I figure the Rotozip would at least be best for the smaller pieces with tighter curves. Needless to say, it will require a lot of cutting. I also have a circular saw, router, table saw, jig saw and band saw.

[StevenBauer]

I can’t really see a use for that saw in boatbuilding. I’d stick with the circular saw and jigsaw.

[sp_clark]

Rotozip's not up to taking on plywood for building a boat. Be fine for drywall or maybe plastic laminate but the heat from a spiral cutting tool of such a small diameter cutting marine ply is gonna make a mess of your material pretty quickly.

Use the circular saw, jig saw, maybe band saw & certainly that router (with suitable pilot fitted to your baseplate if you're working from patterns or templates) for getting out stuff to shape.

Maybe buy a decent Japanese pull saw too, get to know it well. I find mine to be invaluable.

[Mike Seibert]

Circular saw with straight edge guide for straight cuts. Jig saw for curved cuts.

[Todd Bradshaw]

...and get a real circular saw blade made specifically for cutting plywood, not some sort of combination or general purpose blade. The difference in the quality and smoothness of the cut edges left behind by the proper plywood blade is quite substantial.

[Heaver]

An 85mm circular saw. Lightweight, single hand, cuts long curves quickly, thin kerf. Corded or cordless. Some of them also have a bevel capability. Plenty videos on Youtube.

[swoody126]

the Roto-Zip and it's clones(large and small) have a tendency to take off on a tangent as it comes in contact w/ differing material densities so commonly encountered in wood

IMHO sticking w/ the circular and jig saws for power cutting and the pull saw for hand trimming is a good way to go

i will say that being right handed it is easier for me to use a circular saw w/ the blade on the left side of the body so my eyes can follow my progress

YMMV

sw

[cut3times]

Noise from a Roto-Zip is loud and piercing. Make sure you use ear protection if you plan to use one.

[sp_clark]

Noise from a Roto-Zip is loud and piercing. Make sure you use ear protection if you plan to use one.

Use ear protection with pretty much any power tool used for cutting / shaping / sanding. Drills aren't too bad but impact drivers can be.

I've lived with tinnitus since I was about 11, if I get to next April I'll turn 72. I have hearing aids but they're no substitute for what I've been slowly losing the past six decades.

Once your hearing's damaged, it's a done deal... no going back.

[sp_clark]

i will say that being right handed it is easier for me to use a circular saw w/ the blade on the left side of the body so my eyes can follow my progress.

Agree!

I was 'rebuilding' a house we were living in back in the '80's, bought a then-new Porter-Cable SAW Boss with the blade on the left side. The trusty Craftsman I'd been using never got picked up again.

Couple years ago I bought one of the new DeWalt battery circular saws, also a left-blade. Guess what's been abandoned after that joined my kit!

Any of the popular power saws can be used to cut close to a line. Then it's up to you to remove what remains, more than likely with a hand plane of some kind. It's easier to go slow, removing a bit at a time, than to go back to add what's been taken off in haste that should have been left attached.

Oh and something similar goes for body parts as well so mind your fingers & toes please!!

[dalekidd]

Great advice, guys. Thanks

Update: Porter-Cable 3.5" circular saw on order (@$200 new, getting a refurbished for $50 on ebay, reputable dealer); Japanese pull saw on Christmas list (seeing that I'm Santa, pretty sure I'll be getting one in my stocking - LOL)