A single-lipped reamer is very useful for reaming a straight hole. When the nature of the hole or the condition of the stock would cause the ordinary forms to run, the single-lipped reamer will cut a straight hole if started right. Having but one cutting lip, its action is similar to that of a boring tool used for internal turning in the lathe, and as a large proportion of the body of the reamer acts as a guide, it must cut a straight hole. Fig. 59 shows two views of this form of reamer.

Fig. 59. Single-Lipped Reamer.

Steel for this tool should be sufficiently large to allow the decarbonized surface to be entirely removed. After a roughing chip has been taken - leaving the piece about 1/15 inch above finish size - the stock should be annealed, and the portions A and B turned to a size that allows for grinding. C may be finished to dimensions given, and the size stamped as shown.

Milling

The reamer is now ready for milling. This should be done with the reamer in the centers in the milling machine, using a shank mill or a small milling cutter on an arbor. The depth of the cut should be about one-third the diameter of the reamer; for large reamers, it may be somewhat deeper. After the milling, the face may be smoothed with a fine file, and the end and cutting lip backed off for clearance, as shown in Fig. 59 at D and E.

Hardening

When hardening, the end A should be heated to a low red and dipped in the bath about one-half an inch up on the necked portion C. The temper may be drawn to a light straw. A and B are now ready for grinding. If the grinder has no provision for the running of water on the work, care should be used not to heat the reamer, as it is likely to spring.