Cutting marine plywood

[calvin]

I am ready to cut the 9mm plywood for the foredeck of my runabout..I have a 4305 makita jig saw with the bearing behind the blade but the only blades I can find is the b-10 for wood and the b-22 for metal . scoring should help but what other blades are out there that are better?

[Robert W. Long]

I have had good luck using a relitively fine metal cutting jig saw blade. Slow but leaves a very clean cut. My jig saw is an old makita with no guide behind blade.:) Try one out on some scrap.

[would work]

i have found that a little tape on the cut line will go a long way preferably use 3m silver, pricey but effective. Think along the lines of cutting Formica, also you may want to consider purchasing reverse tooth blades,or cutting from the bottom of the piece, but iwould try the tape on a piece of scrap first.

[Paul Fitzgerald]

You can buy blades which cut on the upstroke, not downstroke.
The saw baseplate with an insert in the keyhole stops the ply chipping on the edge, or you can use masking tape and draw the cutting lines along the tape if you want a really clean edge.
I have also used fine toothed metal saw blades, slow and hot, but they leave a nice line.

[Paul Fitzgerald]

Newbie beat me by two minutes.
Thats the problem living half way across the world.
Still, nice to know there is strength in numbers.

[Spokaloo]

Unless its a really tight radius, I prefer the circular saw.

E

[epoxyboy]

Just go and buy one of those cheapie Bahco/Sandvik hardpoint handsaws (the kind where you put the effort in). Seriously dude,for cutting big things with long curves like decks and planks and they cut faster than a jig saw, more accurately than a jig saw coz the blade is so wide, more quietly than a jig saw, cost way less than a jig saw, you dont have to put all that safety crap on and you get some exercise too. There is a little bit of breakout on the bottom of the ply, but if you hold the saw at a shallow angle this is minimal, and if you cut the panel the right way up any breakout is lost in the glues joint.

Pete

[S B]

You could try a router, tack a guide strip allong the line to be cut, offset the exact distance from cutter blade to base plate edge, and take off 1/8" each pass.No spall, splinters and very accurate.

[P.L.Lenihan]

Use whatever circular hand saw you normally use or jigsaw for that matter,cut broad of the line and bring it in sweet to the line afterward with a block plane.

Peter

[JimD]

If you're going to fiberglass it, glass it first, then cut it with just about any blade you like since the glass will prevent any chipping. Then throw out the blade because the glass will ruin it.

[SchoonerRat]

You can prevent tearout by clamping a thin piece of scrap wood beneath and above the ply you are cutting. Cut through all 3 pieces of wood with just about any old blade.

[boylesboats]

a circular saw with fine toothed hollow ground plywood blade work like a charm.. Cuts smooth and fast

[JBreeze]

You might want to experiment by decreasing the orbital action of the saw (it's an orbital, correct?)

I think, but am not positive, that turing off the orbital action will give a cleaner cut in ply with less tearout, but it will be slower.

What style blade does the makita use? Bosch makes a huge selection of blades that might be useful in this case.

I like the "cut wide- then hand plane to the line approach":)

[Mike Vogdes]

A fast moving circular saw with a combo blade is all you need to cut a piece of plywood..

[Christine DeMerchant]

Hi
I used a jig saw to cut out the pieces of my skerry and used a metal blade. It worked well with minimal tear out. However it was S L O W and my (already limited) attention sometimes wandered. As a result I got little waves in the cut that were tedious to fix.
On my next boat (If I can convince Sweety) I will use a skill saw or one of the smaller saws that look like a little grinder. I think it will be much easier to control.
Good Luck
Christine

[fstrumpf]

I've been using a heavy worm drive Skill Saw for quite some time. I recently got one of those reasonably priced Ryobi 18 Volt systems. I find the small diameter circular saw was the answer. Cuts well with the right blade, minimizes tearout, and the smaller diameter allows me to follow a curve quite closely and cleanly. I was also surpised with its power and battery longevity.

I use it for Stitch and Glue fabrication, typically 1/4 ply, occasionally 3/8s.

I am a Neanderthal wood worker at heart, but use the power tools where appropriate.

Regards

Fred :cool:

[RodB]

As above, unless the radius is very tight and demands a jigsaw... use a circular saw... with a quality combo carbide blade.

Note: Sidewinders can self steer so worm drive saws are a better choice.... they have a "gyro" effect and are much easier to control. Just cut close to the line... and finish to perfection with a low angle block plane.

I have cut tons of ply with a Makita Hyphoid saw...blade on the left..allows good visibility when following a line... This is one of the lightest worm drive saws...and a very good value. A good clamp'n'guide works great for straight cuts.

If you deal with lots of ply panels... look at the Eurekazone "Smart guide" and smart guide table... which is fantastic in handling ply panels..

eurekazone.com

Good luck.

RodB

[boylesboats]

another trick is.. Lay the sheet of plywood out on the snow and cut with an cordless saw with 5" blade.. Snow make a nice sawhorse for plywood..

[Mike Vogdes]

What?
Saw horses make good saw horses... Snow will make a mess of your material your tools and could could be dangerous at the very least.

[JOBBER]

For cutting larger radius curves I prefer a circular saw with a triangular shaped blade over a jig saw. I have an old, old Acu-Edge (Redmond, OR) Triad blade. I could not find them on searches. I did find however this site. http://www.bladesllc.com/triblade.html#The%20Multi-Directional%20Cutting%20Saw%20Blade
It seems similar.

[Ian McColgin]

I'm with epoxyboy except I like my japanese style pull saw.

[boylesboats]

What?
Saw horses make good saw horses... Snow will make a mess of your material your tools and could could be dangerous at the very least.

Done it lot, snow must be dry powder, at least frozen, and must be not wet..
Plywood hardly gets wet, blade is still clean and dry.. beside that cordless saw is being used..

[sv Lorelei]

I'm with Ian. A good combo Japanese Pull saw will leave a nice thin kerf and virtually no tear out. Cut goes faster than you'd think and once you get the knack you can cut pretty much right down the finish line. Bevel with a sharp block plane afterwards.

[Ray Frechette Jr]

You know I must have cut close to a hundred sheets of Marine BS 1088 ply both in Merranti and Okoume.

I haven't noticed any tendancy for tear out of grain at all.

It just sin't anything like household plywoods.

I use a skill saw with a thin kerf blade with blade set just below ply panel. Cut wide, plane down. Doesn't matter what saw you use, I can't reliably saw to the line and neither can you. That is what the hand plane is for.