Stupid question of the day-cutting wide pieces straight

[DigitalGriffin]

So I'm looking at my 4'x8' board last night, and my nifty new table saw. The guide rail goes out to 18". I need 30".

I guess I could just cut "down the pencel line." But is there a better way to help ensure the cut stays straight?

[davekelly]

Digital,

Do you have a circular saw? There are metal guides that you can get and clamp on to the plywood. Works pretty good.

BTW: This might sound like a dumb question, and please don't be offended by it. Are you planning on cutting lengthwise? Seems to me if you cut 18 inches off, you'll be left with a 30 inch piece. If you are cutting along the other side, there still is a possible solution. If the goal is to get two 30 by 48 pieces, you can take the fense off and cut the piece into two 48 by 48 pieces - reinstall the fence and the cut off a 18 inch piece leaving a 30 by 48 inch piece. Of course that first cut will take quite a bit of patience to do.

[mgruber]

Another possible sollution would be to screw in a 1x2 to your plywood to use as a fence.

[dwRavenstar]

mgruber is on the right track. Screw the guide to the plywood and invert the piece so the guide runs along the edge of the table saw as you run it through the blade. Same concept with the circular saw, screw the piece so it acts as a fence to keep the saw running straight.

Dave Wyland (dwRavenstar)

[DigitalGriffin]

QUOTE: Originally posted by davekelly


BTW: This might sound like a dumb question, and please don't be offended by it. Are you planning on cutting lengthwise?

Not a dumb question at all. I needed a 48"x30" piece.

Looks like I'm going back to Lowes.

Thanks guys.

[SpaceMouse]

I bought two things to use as jigs. There is a guide-clamp you can buy that will span a 4x8 sheet of plywood widthwise. For the length I use an 8 foot level and vise-grip clamps. The edge to blade measurement is 1 /716 on my saw.

The problem with a 1x2 is that you can't get a straight one. You would be better of ripping a piece of you plywood off the side you are going to cut and using that as a guide.

Table saws are very awkward at best for cutting full sheets of plywood.

[davekelly]

mgruber and dwravenstar have posted what I had been thinking about since my last post. I would use the clamp on guide instead of the 1 by 2 to ensure a straight piece. Using the guide on the bottom of the board to butt up against the table seems like it would work.

[SpaceMouse]

QUOTE: Originally posted by davekelly

mgruber and dwravenstar have posted what I had been thinking about since my last post. I would use the clamp on guide instead of the 1 by 2 to ensure a straight piece. Using the guide on the bottom of the board to butt up against the table seems like it would work.

If you have a circular saw you are working too hard to try to make a table saw work. Table saws are great for what they are, but not for ripping plywood.

Just set the plywood on a couple of saw horses. Clamp on your straight edge and run your circular saw down the straight esge.

Think about it. Which is easier to keep straight along a straight edge, a 7 lb saw, or a 4x8 sheet of plywood that weighs 30-40 lbs? At best, running plywood on a table saw is a two-person job.

[Anonymous]

Hmmmmmm....is it easier to cut 30 inches off this side or eighteen inches off the other side.....Hmmmmmmmmmmmmmmmmmm?

[MisterBeasley]

Measure what you need before you go to Lowe's or Home Depot. They will do cuts for you. My Home Depot allows me 2 free cuts, but I've never had to pay more for 3 or 4. Comparing the 2 stores, my local Home Depot could handle cutting 4x4's, while my local Lowe's saw wasn't big enough. (No, the 4x4 wasn't for my layout.)

Easier to get into your car that way, too.

[nfmisso]

I had a similar challenge; in my case make 23" wide shelving that fit overhead in the garage from assorted piece left over from other project.

What I did: first remove the fence, lower the blade all the way, then take a piece of ½" plywood (¾" would have been much better) roughly 2 x 4 feet, clamped it to the saw table by screwing it to short pieces of 2x4 under the table (through the holes in the table). Next power up the saw, bringing blade up through the new plywood table top about ¼" higher than what you want, then drop it back that ¼". Power it down. Next carefully measure from the blade (a larger square is great for this), and mark a line at what ever dimension needed from the blade. I then clamped a 24" steel level along this line to act as the fence.

Why did I go to this amount of trouble when I have a circular saw? Because I have 100 feet of shelves to cut. It would have taken several hours with the circular saw. It took about 15 minutes to set up the table saw, and then less than a minute a cut - with my wife helping.

[davekelly]

Nigel,

Interesting solution!

[SpaceMouse]

NIgel,

I like it too. Like I said though, plywood and a table saw are a two person job.

I also think I could have matched your speed by myself with a circular saw. You are only talking 13 cuts. Since I have a bunch of vice-grip clamps and an 8 foot level, for me it would be simply a matter of taking each board marking the four edges at 24 9/16, clamping the 8 level and running the saw. And like you less than a minute a cut--but no set-up time.

And my cuts can vary in width without reset-up time.

I may be dumb as a rock with model trains, but construction production I know.

[dave9999]

How about a chalk line, a circular saw and a steady hand? Set the blade depth just a little deeper
than the plywood. This will keep the saw from "wandering" as you cut. It will also keep the tail end
of the blade from taking out the material as you cut. The more blade you have making contact with
the wood, the more your cut will stray. Good luck, Dave

[bogp40]

How perfect/ straight a cut do you need? For hidden benchwork/ framing, snap a chaulk
line and cut with the skillsaw. Any wandering and chipping of the cut edge can be placed to the rear keep the factory edge to the visible front.
For a better/ straighter cut use the straightedge/ skillsaw method. I would not use a table saw, unless you are experienced with cutting sheet stock , especially w/o the proper fence.
The panel saws at the big box stores are the best way to go. They could make the cuts for you. Should be close enough for benchwork.
The most important thing to remember, always use a sharp blade designed for proper use. In my 30+ years in the trade, I have found it imperative to always keep tools in proped working order w/ sharp cutters/ blades. Guard against using shortcuts and keep safety in mind. I may be preaching to the choir, but just like to reinforce "safety" when it comes to power tools.
Bob K.