It is important that the circular saw be jointed before it is filed. Jointing serves as a guide for filing as well as making the saw round. The operation must be carefully performed because even the ideal circular saw will not cut properly unless it is perfectly round. Only then is it possible for each tooth to do its share of the cutting.
The saw is made round by first mounting it on the machine and jointing the teeth with a jointing stone or piece of hard grinding wheel while the machine is running. Raise the circular saw to a point so that the teeth project slightly above the table. Check the height by pushing a piece of wood over the saw with the aid of the cut-off gauge. If there is a possibility of scratching the table or throat insert with the jointing stone, tape a piece of drawing paper over that portion of the top.
Overhead saws, such as swing cut-off saws and radial saws, can be jointed by clamping a stop on the machine to regulate the travel of the saw. The blade should slightly touch the jointing stone when it is placed against the cut-off fence. It is advisable to test the set-up with a piece of wood before jointing the saw.
There does not seem to be much agreement among manufacturers as to how to mount the saw for jointing. Some joint the teeth with the saw mounted in its normal running position, whereas others suggest that it be turned around so that the teeth point in the opposite direction, but with the manufacturer's name placed in its proper relationship to the mark on the arbor. Experiments indicate that there is little preference. Either method gets the job done satisfactorily.
To joint a circular saw:
- Mount the saw on the arbor. The saw, big size or mini model, may be mounted with the teeth pointing in either direction.
- Adjust the saw so that the teeth are slightly higher than the table. Test the height by pushing a piece of wood over the saw with the aid of the cut-off gauge. Score the wood very lightly.
- With the saw running, joint the teeth by pushing a jointing stone over the saw. A piece of hard grinding wheel is excellent for this purpose. Never use a soft stone or wheel because the groove cut in the stone will round the corners of the teeth.
- Stop the saw and examine the teeth. If any have been missed, it will be necessary to repeat the process. Circular saws can also be jointed in specially built motor-driven jointers.