Rip and Cross Cut Ideas (Click images to enlarge)
DISCLAIMER: YOU ARE RESPONSIBLE FOR YOUR SAFETY. READ AND USE MY TIPS AND INSTRUCTIONS AT YOUR OWN DISCRETION AND YOUR OWN RESPONSIBILITY.
Ripping/Cutting Full Sheets of Plywood
Before making the first cut, there are a few preparations you will need to make. You do not have to do this exactly how I do it, but these are some ideas to help you through the process.
MAKING RIP CUTS
This method assumes you will be using a circular saw and not ripping on a table saw. Considering that you will be working on a large table of sorts, start by building up your working surface using sacrificial or scrap materials for clamping and cutting clearance. 2 x 4’s work well, but will more than likely be good for C-clamps only. You may have to build-up a bit more for quick-grip type clamps. In that case attach some 3/4” scrap plywood strips to the bottom side of the 2 x 4’s.
Make (4) build-up boards 4’ long so that you will not have to cut different sizes as you process and cut the parts to size. These boards can be set aside and used for future projects if desired. Use the second and third boards as catch boards placing them near, but clear of the cut line to prevent the boards from falling and pinching the blade after the cut is made.
Lay a full sheet of the plywood on top of this built-up surface. Now you are ready to mark and rip your plywood sheets. The factory edges on finish grade plywood are usually straight enough to make a good initial rip cut. For economic purposes, to get a good first cut, use another piece of plywood as a straight edge to make your first rip cut. Use your first ripped panel as a straightedge for all succeeding rip cuts.
- On your circular saw, the base, or shoe assembly is the flat, rectangular part of your circular saw that glides across the material surface and keeps the blade angle correct. Set and check the angle using a combination or speed square and set your saw stop bolt accordingly.
- Determine your blade offset on your circular saw for the cut[i]. In other words, depending on how you intend to pass your saw across the materials to make the cuts, how much will you have to add or subtract from your final cut measurements to achieve the straight edge placement measurement? This offset will be the same for every similar cut to be made using that particular circular saw.
o NOTE: Always cut using the same process as your first cut. I.e. if you cut from right to left and on the inside, for instance, make all the other cuts the same way.
- The blade cutting depth should be no more than 1/8” past the bottom surface of the plywood. 1/16” is even better, but your working surface must be straight. You will NOT have to tape the cuts before cutting as tear out will be minimal assuming that your blade is sharp and the power output on your saw has not been compromised. Try to plug your power tools into an electrical socket that in not overloaded with wattage from other electrical items in use.
o VERY IMPORTANT: If your circuit breaker trips while making a cut, STOP the cut, hold the saw firmly in place until the blade stops, then remove the saw, turn the power off, unplug the saw, turn the circuit power back on and make temporary adjustments to the power being used on that circuit either by unplugging or turning off other devices or use a different electrical socket on a different circuit. To continue the cut, tilt the saw on the front edge of the base assembly, start the power then gently lower the blade back into the cut while holding the saw firmly and finish the cut.
o VERY VERY IMPORTANT: Make sure that your separated pieces will not fall after any cuts are made.
- As your sheet shrinks as a result of ripping, it will become difficult and dangerous to make other rips. At that point the sheets are more manageable to rip in your table saw.
MAKING CROSS CUTS
For cutting parts from the panel sections that you previously ripped to size, you should have a few pieces left from the rip cuts (96” long or the sheet length); use those pieces as sacrificial build-ups for making your crosscuts. Again, these pieces can be set aside if desired for future projects.
Lay the two pieces across the build-up boards used for the rip cuts. Lay a ripped board on top and you are now ready to measure and make your cross cuts.
If you made a crosscut jig like the one I use, follow the same procedure for determining your blade offset. Add or subtract that measurement to or from the final cut measurement and check to ensure the cut is true.
Here is a video I made on how to make a crosscut sled. The results are pretty doggone accurate.
[i] To determine your blade offset, I explained how to do an accurate offset determination in the “Make a Crosscut Jig” video. Otherwise, mark for and make your first cut line. Put an ‘X’ on the side to be cutoff (the side that is NOT the finished part). Set you straight edge on the side that the base, or shoe assembly will ride against. When the straight edge is clamped down, it will then become a fence. Line up the saw blade so that the cut will be made on the ‘X’ side of the material. Make a pencil mark against the base, or shoe assembly on the side that the straight edge will be clamped to. That mark will be used to determine your blade offset measurement. Measure the difference between the cut line and the straightedge mark. This is your rough offset measurement.
Measuring from the starting edge you used to mark your cutline, measure to the straightedge mark. Make another mark on the opposite side of the material. Align and clamp your straightedge to those marks. Measure from the starting edge to the straightedge on both sides making sure the measurements are exactly the same. Make adjustments as necessary.
Start the cut. Make a staring cut about a ½” and verify that the blade is cutting in the correct path. I like to use the center of the pencil line as my reference. If the blade is off a little, make the necessary adjustments to both sides of the straightedge measuring to new placements like before. Once you determine that the placement is true, measure the difference again. This is now the true offset you’re your saw. Write I down somewhere you will remember it, like on a piece of masking tape attached to the side of your saw. NOTE: Every time you change the blade, it will be a good idea to repeat this offset determination process.