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Cutting 4 X 8 plywood sheets

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  • Cutting 4 X 8 plywood sheets

    Hello everyone,
    I am making cabinets and I am having troubles ripping and cross cutting large 4 X 8 sheets of plywood. I never seem to get a straight cut. What the proper technique to use at the table saw? It might be easier with a circular saw but I don't have one.

  • #2
    4x8 sheets of plywood or other sheet goods can be hard to cut on the table saw, in both quality/accuracy and safety. You really need extensive outfeed, extension and infeed support. Roller stands tip over, in my experience---(Ridgid Flip stand is much better, but limited), and you still have to lift either a heavy sheet of 3/4" plywood, or manage a thin sheet of hardboard, flexing all over the place.

    Believe me---if you're working alone, it's so much easier to use a circular saw and straight edge----you're simply not having to move a large sheet into a spinning blade, but instead have the sheet fixed and moving a small saw.

    While you can make cuts with just about any circular saw, last year, I bought a 6" PC Saw Boss and found it to be way above average----lighter weight----easy to set up and very smooth cuts. Between $100-120.


    • #3
      The problem with using a circular saw to make finish cuts on sheet goods is that, even with straigtedges and the like, it is hard (or in my case impossible) to get good clean straight cuts.

      So what I do, as the cost of some wastage, is to use the circular saw to cut a piece that is slightly (and inch or so) longer or wider than my finish dimension, and then I trim it on the table saw. Just make sure that you preserve one of the factory edges to guide against the table saw's fence.


      • #4
        Plywood can be a challenge unless you are setup as daveferg suggests. I like to use a combination of daveferg and RGads techniques. I try to layout the cuts on a sheet of plywood to maximize the factory edges. For my circular saw I made a zero clearance insert and use an 80 tooth carbide blade. For oak plywood this significantly reduces the splintering as the blade breaks thru the surface.

        For ripping I use a known straight edged board (either plane one or sort out at home center, two pcs - flip edge to edge until you find two that don't provide a resulting gap, then you have two straight boards). Use this board as a guide adding or subtracting the offset to the saw blade. Depending on the length needed I ususally cut the boards slightly oversized and rip to size on my table saw. But the cuts are clean and straight before this.

        For crosscutting I do the same thing. For anything over 15-18" wide this is how I crosscut everything as it does not work out well attempting this on my tablesaw.

        If you cannot obtain a circular saw you could use a jigsaw for the rough sizing but be sure to make it a bit more oversized as the jigsaw will do a number on the oaks surface.

        Another technique for cutting the plywood is to buy an additional sheet of 1/2" or 3/4" BC which you can lay on the floor/ground as a support that you can lay the good plywood on. Then when you cut through the plywood this piece supports the workpice, and acts as an additional zero clearance insert on the backside to reduce splintering. I have also seen the 2" blue contruction foam used in a recent WOOD mag article I believe.

        Well, sorry for the long note, hopefully you can find something usefull that will help you with your plywood dilema.
        Let me see... 1, 2, 3, 4.... Uh Oh.


        • #5
          Thanks guys for the useful tips. I guess my next buy will be a circular saw.


          • #6
            If I buy my plywood at HD or Lowe's, I have them rough cut it in one or two places depending on the sizes I need. The idea is to get something that is managable for the table saw. If I get it somewhere else and they aren't willing to cut it, I take along a cordless Makita trim saw that will handle up to 3/4" stock,a Japanese razor saw that works real well on plywood, and an adjustable saw horse. I am careful to mark a good factory edge so I have a reference for my rip fence. I waste a little this way, but I've found it impossible to get accurate cuts off of full sheets anyway.


            • #7
              if your going to buy a skillsaw look into the festo saw and guide combo wow wow almost replace your table saw!! bill


              • #8
                While I didn't get that far---agree----you still need to make your circular saw cuts a bit larger measurements. In fact, while I sometimes trust factory edges, I've found, on occassion, factory squareness to be a problem, so, generally, I cut a bit larger and square things up using, first, my ts pannel cutting jig, than rip fence----since I started this, I haven't had the slightest problem with my carcusses being square.

                BTW----This month's issue of Am. Woodworker has a great article on exactly this subject.


                • #9
                  Do you have any pictures of your ts pannel cutting jig?


                  • #10
                    Rafael----it's just a copy of the one Norm uses----if you catch his two-part jig show, you can build one from just watching the show----piece of 1/2" Baltic birch plywood----hardwood (or metal) slide to fit miter slot and a hardwood cleat to fit 90 degrees to the slot.


                    • #11

                      I noticed that it is a push motion against the fence of his jig, rather than pulling up against the fence like most crosscut sleds. Does this replace the sled for you or do you use both?
                      Patrick<br /><br />


                      • #12
                        Personally, I don't have a sled----too darned heavy, in my opinion---besides having to remove the guard---and reverse the process for your next rip cut.

                        The cleat in front vs. back is actually a good discussion topic.

                        I agree with you, it's better to have the cleat backing the stock---hence the force of the saw blade is forcing the stock against the cleat. However, the big drawback is that this limits the size of the stock you can cut----a 3' wide piece is going to require the panel cutter to be too far out of the miter slot, while the cleat at the rear (leading edge), allows you to fit larger stock on, since the width is trailing.

                        Norm's first cutter had the fence at the leading edge---the second had it trailing----I'm in the process of building a second panel cutter and will end up with one of each type.


                        • #13
                          Dave I two was wondering which would be better. Clet and the rear makes is much more stable. Clet up front give you more capacity. I am thinking of putting the cleat up front and attaching a couple of toggle clamps up front to hold panels in place. I think this would give me the best of both worlds.


                          • #14
                            The November issue of American Woodworker has plans for a panel saw jig that employs the novel approach of swinging down from the rafters when the need arises to cut sheet goods and simply stores up out of the way the rest of the time.



                            • #15

                              You said:
                              "I agree with you, it's better to have the cleat backing the stock---hence the force of the saw blade is forcing the stock against the cleat. However, the big drawback is that this limits the size of the stock you can cut----a 3' wide piece is going to require the panel cutter to be too far out of the miter slot, while the cleat at the rear (leading edge), allows you to fit larger stock on, since the width is trailing."

                              A fence on the front would create a whole differenct set of issues trying to cut a 3' wide piece. Unless you had a monster sled, a number of problems could occur:

                              1. The sled could very easily run off the back which would leave you cutting a large piece freehand.

                              2. Unless you have some way to support the sled on the back, the excess weight hanging off the back of the sled could cause the piece to lift. This could produce a number of different results, but most of them would be bad.

                              Dave, my sled is 2' X 4' with the fence on the back (pushing the panel) and I can cut pieces about 2' X 6' without any problems (except removing the overhead guard). I wouldn't want to exceed that size by much regardless of where the fence was.

                              Bob R

                              [ 11-03-2003, 09:12 PM: Message edited by: Bob R ]