The following table gives the ordinary diameters and thicknesses of circular saws and the diameters of the mandrel hole:

Diameter.Thickness.Size
Mandrel
Hole.
4 inch. 19 gauge. 3⁄4
5„19„ 3⁄4
6„18„ 3⁄4
7„18„ 3⁄4
8„18„ 7⁄8
9„17„ 7⁄8
10„16„1
12„15„1
14„14„11⁄8
16„14„11⁄8
18„13„11⁄4
20„13„15⁄16
22„12„15⁄16
24„11„13⁄8
26„11„13⁄8
28„10„11⁄2
30„10„11⁄2
32„10„15⁄8
34„9„15⁄8
36„9„15⁄8
38„8„15⁄8
40„8„2
42„8„2
44„7„2
46„7„2
48„7„2
50„7„2
52„6„2
54„6„2
56„6„2
58„6„2
60„5„2
62„5„2
64„5„2
66„5„2
68„5„2
70„4„2
72„4„2

Circular saws are sometimes hollow ground or ground thinner at the eye than at the rim, to make them clear in the saw kerf or slot with as little set as possible, and therefore produce smooth work while diminishing the liability of the saw to become heated, which would impair its tension. They are also made thicker for a certain portion of the diameter and then bevelled off to the rim.

This is permissible when the work is thin enough to be easily opened from the log by means of a spreader or piece that opens out the sawn piece and prevents it binding against the saw.

Fig. 3079.

The shingle saw, shown in [Fig. 3079], is an example of this kind, the saw bolting to a disc or flange by means of countersink screws.