The blade is held on the arbor by the arbor nut. A saw is  usually  equipped  with  several  throat  plates, containing throats of various widths. A wider throat is required when a dado head is used on the saw. A dado head  consists  of  two  outside  grooving  saws  (which are  much  like  combination  saws)  and  as  many intermediate chisel-type cutters (called chippers) as are required to make up the designated width of the groove  or  dado.  Grooving  saws  are  usually  I/S-inch thick;  consequently,  one  grooving  saw  will  cut  a 1/8-inch groove, and the two, used together, will cut a 1/4-inch   groove. Intermediate   cutters   come   in various  thicknesses. Observe  the  following  safety  precautions  when operating the tilt-arbor table bench saw: Do not use a ripsaw blade for crosscutting or a crosscut saw blade for ripping. When ripping and  crosscutting  frequently,  you  should  install a  combination  blade  to  eliminate  constantly changing the blade. Make sure the saw blade is sharp, unbroken, and free from cracks before using.  The  blade  should  be  changed  if  it becomes dull, cracked, chipped, or warped. Be sure the saw blade is set at proper height above the table to cut through the wood. Avoid  the  hazard  of  being  hit  by  materials caused by kickbacks by standing to one side of the saw. Always use a push stick to push short, narrow pieces between the saw blade and the gauge. Keep stock and scraps from accumulating on the saw table and in the immediate working area. Never  reach  over  the  saw  to  obtain  material from the other side. When cutting, do not feed wood into the saw blade faster than it will cut freely and cleanly. Never leave the saw unattended with the power on. Band Saw Although the band saw (figure 3-3) is designed primarily for making curved cuts, it can also be used for straight cutting. Unlike the circular saw, the band saw is frequently used for freehand cutting. 3-3 The band saw has two large wheels on which a continuous narrow saw blade, or band, turns, just as a belt is turned on pulleys.    The lower wheel, located below  the  working  table,  is  connected  to  the  motor directly or by means of pulleys or gears and serves as the  driver  pulley. The  upper  wheel  is  the  driven pulley. The saw blade is guided and kept in line by two sets of blade guides, one fixed set below the table and one set above with a vertical sliding adjustment. The alignment of the blade is adjusted by a mechanism on the backside of the upper wheel. Tensioning of the blade—tightening   and   loosening-is   provided   by another  adjustment  located  just  back  of  the  upper wheel. Cutoff gauges and ripping fences are sometimes provided for use with band saws, but you’ll do most of your work freehand with the table clear. With this type  of  saw,  it  is  difficult  to  make  accurate  cuts  when gauges  or  fences  are  used. The  size  of  a  band  saw  is  designated  by  the diameter of the wheels. Common sizes are 14-, 16-, 18-, 20-, 30-,  36-,  42-,  and  48-inch-diameter  wheel machines. The 14-inch size is the smallest practical band  saw.  With  the  exception  of  capacity,  all  band Figure 3-3.—Band saw.