Sunday, January 24, 2010

Topic: Marking & Layout Tools

The Hand Tool Special Interest Group met Sunday, January 24, with William Johnston acting as moderator/facilitator.Sixteen members attended.

Mr. Johnston prefaced the meeting with a few remarks concerning the upcoming Lie-Neilsen Toolworks Hand Tool Event planned for March 25-27.

Schedule:

Rob Young reported that Junior Strasil, a retired blacksmith, will demonstrate 19^th century tool-crafting techniques.

Other demonstrations will include: Czeck Edge Hand Tools; the Kansas City Woodturners; David Roth on parquetry, and Eagle Jigs.

Mr. Johnston asked for suggestions for other demonstrations or other hand-tool makers to invite to the event.

In addition to the demonstrations, members will be needed to help with setting up and taking down the displays. Commitments will be sought at the next SIG meeting.

Mr. Johnston began the discussion of the day’s topic with a brief presentation on squares and marking knives.

Before the availability of inexpensive, factory-made squares, woodworkers made their own, usually of wood. Even if they weren’t perfectly square they were still useful, as the woodworker could scribe a line, then turn the square over and scribe another line from the other side, then find the actual square line by sighting down the middle of the two original lines. As the purpose of the square was usually to mark a line for a hand saw, absolute precision was unnecessary.

Machinists or engineers squares are more accurate than those made for woodworking. They are not necessarily more valuable for woodworking but are especially useful for tasks like setting up machinery (table saws) or checking the squareness or curve of plane blades, for example.

Combination squares are not as accurate as machinists squares, but nevertheless have many uses, for example as depth gauges or center-finders.

Although they often are inaccurate, framing squares can be tuned – by using a hammer and something that will dimple the surface of the square. This is done by striking the outside corner to “draw” the sides together or the inside corner to "spread" the sides..

Marking knives

Marking knives are easy to make; several members displayed knives they had made. One inexpensive alternative shown was a utility knife. When purchasing, note the difference between left- and right-handed knives. These blades are ground on one side only; the flat side is typically rested against a straightedge. (Blades that are cut like an inverted “V” can be used with either hand.)

One advantage of using a knife rather than a pencil or other medium (chalk, marker, etc.) is that the “knife wall” (the side of the incision made by the flat edge) can be used to position other tools – saws, chisels, etc. Also the pencil mark has a dimension (the width of the lead), whereas the knife edge does not.

Knives are easy tools to make in the typical shop. One consideration is to take care not to make the bevel too steep – generally, closer to 20 degrees than to 45. But it’s a compromise: as the angle becomes more shallow it becomes more difficult to see the line.

When marking up stock, a knife works better across the grain than with the grain. When marking with the grain it’s better to use a scribe or an awl.

Still, pencils have their advantages. One is that a pencil mark can be erased.

Mr. Johnston and others pointed out that drill rod is a good source of carbon steel for use in making tools. Drill rod is sold not in home centers or hardware stores, as a rule, but by sources such as Fastenal.

Rob Young also emphasized the importance of relative rather than accurate measures. For instance, it’s less important that the dimensions of a project be absolute than it is that surfaces be square and that joints and other elements fit properly.

Members displayed and discussed markup and layout tools they brought, including:

Members also discussed the possibility of having a session on hardening and tempering metals.

Recorded by:

John W. Beal

Jbeal3@kc.rr.com