Popular Woodworking 2008-06 № 169, страница 31
Round. When cutting round stock, the initial point of contact between the blade and workpiece is unsupported. Exercise caution, as your stock may start to spin and be pulled into the blade.
It is also important to know that the blade on a band saw will only cut on the front edge and not the sides or back. Since the sides and back have no teeth, wood that comes in contact with these parts of the blade will not be cut or pulled in any direction. Even if the sides or back ofthe blade do cause some kind of force to the stock, it will be minimal and more than likely not cause any risk. This is where some confusion comes in with the guides. The guides do not act as guards. Remember, the guides keep in close proximity to the side and back of the blade, yet they leave the business side of the blade totally exposed.
In order for a band saw blade to cut, the stock must be pushed or pulled into the descending teeth on the blade's front edge. Band saw blades will not cut stock that is idle. The cutting action requires that the stock be placed in motion toward the rotating teeth. With stock sitting flat and supported on the table, it is fine to "let go" of the stock to reposition your hands while cutting. Once you stop pushing, the cut at the point of contact stops. This safety feature allows the operator to always be in control ofthe cutting action/motion.
It is not recommended to do sculptural work, round or unsupported freehand cutting on the band saw without providing some type of control under the work. For example, round stock at the point of contact is unsupported, which in turn can cause the
stock to start to spin and be pulled into the blade. I recommend that a V-block be used to support all round stock to prevent this from happening.
Although it is not advisable to do sculptural work on a band saw, there are considerations that must be taken into account when doing this type of cut. It is important to set your work on the table to create the least amount of angle or "tip" between the stock, the blade and the table. When cutting wood that is "tipped" off the table, the support is gone and the blade will want to grab the wood and slam it toward the table. This pulling will be sudden and can create a major pinch point. If you ever make this unadvisable type of cut, set your work so that the angle of the pinch point is minimized.
Planning the Cut
Usually, the correct cutting position for operating a band saw is to face the blade. However, you can operate it by standing to the right-hand side or the back of the saw if it places you in a better position to see and control the work. (Be aware that if the blade breaks and is thrown from the saw, it has a tendency to whip to the right-hand side as you face the band saw.) Make sure you keep a well balanced stance. Think about your body position at the
starting point of the cut as well as at the finish point of the cut to avoid overreaching.
Before the saw is turned on, the upper guides have to be adjusted for the height of the wood being cut. A good rule is to set the guide about A" above the top edge of the stock. Keep in mind that the upper and lower guides are not guards, but are guides. The function of these guides is to support the blade and to help it run true. They also keep the blade from drifting and deflecting during the cut.
Two things are basic to properly functioning guides: feed rate and the amount of pressure applied to the stock as it is pushed into the cutting path of the blade. Both feed and pressure will depend on the kind and thickness of wood, and the size of the blade and speed that it is traveling. If the feed is too fast, the saw blade will chatter and squeak as the back of the blade is pushed against the ball-bearing blade support at the back of the guide. If the stock is fed too slowly into the blade, it could cause burning. Pushing too hard with one hand or the other could cause the blade to be pushed sideways, resulting in wear on the side guide system. This could cause the blade to dull or break and will more than likely result
Backing out. If you need to back the blade out a ofcurved cut, turn off the machine and wait for the blade to come to a complete stop. Then, use a stick of wood to steady the blade as you pull the workpiece out along the keif.