This section is from the book "Amateur Work Magazine Vol6". Also available from Amazon: Amateur Work.
The hubs for the drive wheels were cast iron, a pattern being made as shown in Fig. 5. The castings, four in number, were then taken to a machine shop, where they were bored and faced off on the inner edges, and a hole drilled and tapped in each for a set screw. This method insures a true running and firmly fastened drive. The outer surfaces are turned true and crowned after the treadle is attached, the services of a friend being utilized to turn the wheels while they are being turned true. After turning, should they be out of balance, by turning one or the other on the shaft a balance can be obtained, the weight of the treadle is counterbalanced by boring holes in the rim and pouring in babbit metal or lead after the wheels are turned.
The cranks J are made of two pieces of flat bar iron, 4 1/2 in. long, 2 in. wide and 5/8 in. thick; a hole for the shaft being bored with center 1 in. from end, a,nd a 5/8 in. hole bored and tapped for the stud of the treadle rod, with center 2 1/2 in. from the shaft center. These pieces are keyed to the shaft with round or flat keys as may be most convenient. The studs are short 5/8 in. machine screws, with no threads for about 5/8 in. under the heads. It was necessary to get larger bolts and cut them off to correct length, 1 1/4 under the head. The treadle rods, T are 13 in. long, 2 in. wide, and 1/2 in, thick; 11/16 holes with centers 1 in. from each end being bored for the stud at the top and bolt at the bottom. The hole at the bottom may well be lengthened out to about 2 in. long, so that the treadle will not pinch the foot, should it happen to be underneath on the down stroke.
The supports M, for the saw mandrel can now be made. They differ from the pieces E, only in having the upper corners cut out to fit the under side of pieces B, so that the upper edges will line with those of E. This is also true of the piece N, for the boring -arbor. The dimensions of the saw mandrel are carefully taken off and the pieces M, located in the correct positions for holding the bearings of the mandrel. They are fastened to the pieces B with lag screws, holes being bored for same, and washers put under the heads to give a solid bearing. Careful attention must be given to getting the saw spindle in line with the driving shaft, so that the belt will stay on.
The boring attachment may be fitted up in several ways, but the one used was to make boxes with babbitt metal, as for the driving shaft. The spindle was a piece of 3/4 in. drawn steel tubing, double thick walls, but a piece of shafting will answer quite as well. The length is 9 1/2 in. A bit-brace chuck was obtained from a hardware dealer, same being ordered separately. It had aligator jaws and will hold any ordinary bit firmly and true. It was fastened to the spindle by boring out the latter to size to fit the shank of the chuck, and a hole bored through both in which was driven a pin. The bits used in the chuck are ordinary twist bits, with the square taper shanks cut off with a hack saw.
The boring table consists of the pieces P, 14 3/4 in. long, allowing 2 3/4 in. for tenons, 1 3/4x2 3/4 in.; the pieces R, 16 in. long, over all, and 14 in. long on the under side in the clear. Stripes V, 1/2 in. square are fastened to the top of P, a little over 1/2 in. apart, and similar strips to run between them are fastened to the under side of the boring table at each end. The table consists simply of two pieces 28 in. long, Y being" 6 in. wide and F 8 in. wide; fastened together with screws, and strengthened with 6 in. angle irons put on the outside. At the center of Y a hole is bored to allow the bits to come through. In using this table, it is necessary to block up most of the work to bring it to the correct height, and for that purpose, several pieces of boards of varying thickness were kept at hand. The services of a friend are also necessary to push the treadle when using the boring attachment for heavy work; the drive wheel being run in the opposite direction to that for the circular saw.
The top of the saw table is 30 in. long, 28 in. wide and 7/8 in. thick. Maple is most suitable, but having some excellent oak on hand, this was used, but is not as clean as maple would be. Two or three boards are carefully planed up, and then glued together in clamps. Cleats 3 in. wide are put on the under side at front and back, so they will not interfere with the frame. The top is attached at the back with two heavy hinges, and ordinarily rests flat on the frame. For rabbeting or similar work, the front is raised by means of the two screws X, which are simply pieces of 3/4 in. iron rod 10 in. long, threaded for about 6 in. and then turned in a vice to form the cranks for turning them. Nuts, sunk into holes cut on the under side of the piece B, and held in place with 1 1/2 in. round head screws receive the screws. Bearing plates over the ends of the screws were made of small pieces of brass, holes being drilled at each end, and the plates sunk into the table top. The saw slot was cut by the saw itself, by slowly leting down the table onto the saw, which was turned rapidly and easily cut the slot. As the saw came through the top of the table the feed was quite slow. It was also necessary to cut the under side of the table to allow room for the belt, and the oil cups on the boxes.
The saw fences and grooves for same were made as follows: A piece of 1 in. heavy square brass tubing was split into two pieces, which were then a trifle over 7/8 in. wide and 3/8 in. deep inside. A grove was cut along the table top to receive one piece of this tube with a snug fit, and it was fastened down with a number of 1/2 in. brass screws, countersinking the heads deeply. This groove was located 3 in. away from the saw. A piece of bar brass 6 in. long, 7/8 in. wide and 3/8 in. thick formed a runner for the groove. In one end a 1/4 hole was drilled and countersunk for a 2 in. screw, which went up into a piece of maple 12 in. long, 3 in. high and 1 1/4 in. thick. On the bottom of this piece of maple, (oak) was fitted a 5 in. half disk of brass, the circumference of which was correct for the screw above mentioned acting as the center. This disk was cut out of a piece of sheet brass about 1/8 in. thick. In place of a brass disk, a wooden one may be used but will not be as durable. A thumb bolt was fited to a hole bored and tapped on the brass runner, so that the maple strip could be turned to any angle and fastened quickly and firmly in place.
A piece of the remaining half of the square tube 15 in. long was then sunk into the table top at the right side of the saw, and a similar fence made for it, but without the disk as the fence for ripping is always parallel with the saw. Or in place of making the fence in this way, a piece of wood 30 in. long, 2 1/2 in. high and 1 1/4 in, thick may be fitted with brass clamps at the ends and held in place by screwing up, but care must be used in setting it each time.
There is nothing to prevent using the saw mandrel for cutting dado or other narrow mouldings, by securing suitable cutters and a cutter head; also for grooving. A fret saw attachment is being planned and if it proves successful, a description will be given if desired.
A few words of caution about using a circular saw: if you would avoid souvenir markings of carelessness on the hands. Always see that the work is firmly held against the fence, and that the groove is clean so that the work will travel in line with the saw. In ripping, keep to one side of the work, as the strips will sometimes fly back with great force.