Popular Woodworking 2009-10 № 178, страница 7

Popular Woodworking 2009-10 № 178, страница 7

- Letters -

FROM OUR READERS

Why You Should Get Really Hammered

I have a question for you regarding Warrington hammers. Looking through the Lee Valley Tools catalog, I can see that there are different types that come in various weights. What weight is appropriate for most cabinet and furniture making? Also, other than the weight, are there any other differences that might make one more desirable than the other?

John Leko Huntsville, Alabama

A little Warrington (3.5 oz.) is best for adjusting tools and driving (at most) veneer pins.

Slightly bigger hammers (6 oz. and 7 oz.) are good for thin brads, finishing nails and the like. I prefer a bigger hammer (more like 12 oz. to 16 oz.) for driving the nails that are used for carcase construction. (This is speaking, however, as someone with a hammer problem.)

The cross-pane of the Warrington is good for lots of things, especially starting small brads, knocking the sneck on plow planes to remove the iron and anything that requires a gentle controlled tap.

The illustration at right shows three common styles of woodworking hammers. At top is a Warrington with a cross-pane. The one below it is an earlier form of hammer called a "strap hammer." The straps are

Warrington hammer

Adze-eye hammer

used to secure the head to the handle. The bottom hammer is the common and modern adze-eye hammer in which the head is wedged to the handle, and the hole through the head has a special shape that keeps the whole thing together.

— ChristopherSchwarz, editor

Grinder Jig Defense

Larry Williams' August 2009 letter, "Grinder Tool Rest Jig Flaw" (#177), which was written in response to my "Grinder Jig Tool Rest" article from the April 2009 issue (#175), is absolutely correct in that the tool thickness is a significant factor in setting the tool rest angle. But he overlooked that the taper angle of the chisel and the grinding wheel diameter also figure into the j ig design. That these factors were included in my calculations was mentioned in the next-to-last paragraph.

I measured a number of different brands of bench chisels of 1" or less and found them to have similar taper angles of 1. 5°, and thicknesses of about 0.15". For these numbers, an 8"-diameter wheel and a desired bevel angle

of 25°, the tool rest angle is increased by 1°. I plead guilty to a math typo which caused an error in the published design; the angle in Step 1 should have read "... at bevel angle plus 91°." For a 6" wheel, 2° should be added to the bevel angle.

For those interested in exact angles for making myjig, I offered the detailed analysis, "Hollow Ground Geometry," at the end of the second paragraph. I'd be happy to send this to you via e-mail (contact me at wedlock@alum.mit.edu). Graphs are presented showing the exact correction angle for a variety of bevel angles, thicknesses and wheel diameters. You can then design jigs to exactly match your tool's parameters.

The stability of myjigs arc resting against

the grinding wheel allows precise adjustment of the tool rest for regrinding at a future time. Eye-balling is not required; you can't beat geometry and trigonometry for accuracy.

Bruce D. Wedlock, Ph.D. North Reading, Massachusetts

Clamp Pressure Questions For Benchtop Build

I have questions regarding benchtop lamination.

1) In Christopher Schwarz's book "Workbenches," I noticed that several boards that comprise the rear-most sub-assembly of his benchtop have grain that runs horizontally. The front assemblies are more in a vertical

CONTiNUED ON PAGE 14

12 ■ Popular Woodworking October 2009

ILLUSTRATION BY HAYES SHANESY

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