80 - Heirloom Tool Cabinet, страница 45
THE SETUP When I'm getting ready to cut dadoes, the first item on my checklist is proper setup of the table saw. You'll find the better-quality cut is well worth the little bit of extra effort. IZen^Clearance Insert. One of the easiest ways I can think of to ensure a clean dado cut is to use a zero-clearance throat insert as shown in the photo at left. What a zero- THE WORK m The focus of the effort here is on ending up with a perfect work-piece. So it makes good sense to spend some time getting the work-piece ready for the cut. And there are simple ways to do this. 30vertridttl Wortcpleco. When the ends of your dadoes are going to be exposed, you want them to be crisp and clean. Tearout as the blade exits the cut ruins this effect. But the fix here is simple. I'll start with a workpiece that's slightly oversized, as shown in the first drawing at right. Then I can ait Uie dado without too much worry about tearout at tine edges. After the cut is completed, the extra width can be trimmed off, leaving crisp, sharp edges. 4 Scoring.One of the oldest tricks in the book is to score your cut with a sharp knife before you make it (left drawing above). This is a good way to prevent tearout on clearance insert does is support the workpiece right up to the edge of the cut. It essentially acts as a backup to tine workpiece. This allows the blade to cleanly slice the wood fibers at the shoulders of the dado instead of raggedly tearing them. 2 Hold-down. When possible, I always clamp a hold-down to the rip fence of the saw for a dado ait. First off, it keeps the workpiece snug to the surface of the table saw so that the zero-clearance insert can do its job. And next, it helps control any vibration or chatter of the work-piece that may cause a rough cut. The simplest hold-down can be a scrap of wood that rubs the work-piece, as in the photo at left. But a featherboard could also do the job. X # EXTRA WIPTH OF WORKPIECC _iL. A Two Remedies. An oversized workpiece can be trimmed to remove tearout. Scoring the cut at the edges keeps it from occuring. both the face and the edge of the workpiece. What you're doing is pre-cutting the fibers on the surface so that the dado blade can't tear them when you make the cut. It onlv takes shallow cuts to do the job, but they need to be accurate. If they're inside the lines of the cut, they won't do any good. 5 Masking Taue. I always keep a roll of masking tape at hand when I have the dado blade on the saw. As shown in the right drawing above, a piece of tape pressed firmly over the line of the cut acts like a back-up "veneer" to reinforce the wood fibers. This is surprisingly effective at keeping both the shoulders and the ends of the cut sharp and clean. Just be careful when removing the remaining tape. Peel toward the cut to avoid pulling any of the wood fibers away with the tape. ShopNote& To view a video on using these table saw techniques, go fo: www. ShopNotes.com MAKING THE CUT wmmi Mien it's time to make the cut, there are a couple of really effective strategies you can use to get good results. 6 A Shallow Pass. 1 sometimes use an initial, shallow scoring pass to establish a cleanly cut line along the shoulders. To do this, raise the blade only '/s" to V\b" above the saw table, just high enough to score the shoulders without chipping them. Then apply good downward pressure on the workpiece during the cut. After this initial pass, you can raise tine blade to tine full height of tine dado and complete the cut. 7 Provide Backup. A great way to avoid a rough exit to the cut is to back up the workpiece with a scrap (right drawing). Since the blade is cutting directly from the workpiece into the scrap piece, there's no chance of tearout. To do its job, the back-up piece needs to be in firm contact with the workpiece. So use a scrap with a straight, square edge and, when possible, clamp the back-up piece to the workpiece. This allows you to concentrate on the cut and not on holding tine scrap in place. NOTE: PRESS TAPE DOWN FIRMLY 2"-wide masking tape at location of cut A Tape Reinforcement. Masking tape pressed firmly onto the workpiece will reinforce the wood for a chip-free cut. A Back Up the Cut. A back-up piece clamped to the workpiece is a very simple way to prevent tearout at the edge as the blade exits the cut. 45 |
