What is it? CXCVI

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I could have done so -- but distrusted the accuracy, since it is a angular projection rather than a square on photo. But 0.41" is enough to say that it is *not* a 1/4" splice block.

I suspect that it is closer to 0.490" than to 0.410".

Thanks, DoN.

With the "handle" notch, this isn't a clamp per se, I'm thinking as it would be clamping anything like just a wire...

I have no real idea what it actually was, but the conjectures so far aren't convincing to me, anyway...

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The guy who sold it to me had said it was all wood, so I didn't look very closely at it, and I could tell by the weight that it wasn't metal. But after looking at it through a magnifying glass I believe you're right, the nuts and the threaded pieces are all bakelite! Thanks for pointing that out, I should have looked closer at them earlier.

Rob

According to R.H. :

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Thanks for the double-check. This feels better than plain wood with such find threads.

Enjoy, DoN.

This article by Fred Holder recommends that the beginner start with 16 -

24 threads per inch. Apparently coarser is more difficult.

His first obstacle was discovering what woods worked. He recommends lignum vitae, boxwood, Osage Orange, desert Ironwood, redheart, African Blackwood (the best).

He says oak, misquite, and black locust will also work, and he has used glue to harden apple enough to cut threads.

This article says wooden screws and nuts were very common in 19th Century tools. For example, carpentry clamps had wooden screws until the Jorgensen Patent Clamp appeared in the 20th Century.

It specifies the pitch of one screw. The beechwood handle of a plane was tapped for a 1/4" - 20 brass screw that clamped the depth gage.

The usual set of thread-cutting tools went from 3/8" to 3", but sets for sizes down to 1/4" were common.

Thread pitch wasn't standardized. Most were about the same as a coarse-pitch metal screw of that diameter.

I suppose that would date it after 1920 or so. The only bakelite screw I've read about is for one brand of coffee maker.

I wonder what advantage bakelite would offer for a clamp screw and nut. Reinforcement with paper, canvas, linen, or nylon can improve mechanical strength, but would that work in a screw? Fred Holder says before cutting fine threads in apple, he applies a special glue to harden the wood. I wonder if treated wood would look much different from bakelite.

I've read that the specific gravity of solid bakelite is 1.36, so it would sink. I guess some treated woods sink, too.

So will some untreated woods (e.g. lignum vitae, and some flavours of ebony).

African blackwood, which is supposed to be the best for fine threads, is one of the species called ebony. It has the same density as bakelite. It ranges from dark brown or purple to black and finishes to a brilliantly polished surface.

It's popular for woodwinds. Manufacturers discovered it because ships carried to for ballast. Apparently it was available for ballast because it was too hard to cut with an axe for firewood, so trees would stand alone in fields.

If it was used for ballast, it would have been available to screw makers in the days before metal took over. I wouldn't know how to tell it from bakelite.

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Close examination under a magnifying glass should do it. A Bakelite suitable for threading should be the fabric reenforced style, and the cross-section of a cut will show the pattern of the woven fibers. So will any angle of cut, for that matter.

Enjoy, DoN.

Yes, you can clearly see the fiber pattern on the nut in this photo:

The threaded rod had the same pattern visible in the middle section.

Something that I didn't point out about this clamp, the two nuts that sit on the shoulders are chamfered along one edge, as seen here:

Maybe a thin rope or rod could fit through the opening.

Rob

According to R.H. :

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Very clear that it is a fabric-reenforced Bakelite.

O.K.

I think that it was in case the notch towards which it faces was not cut fully square -- which suggests that both the wood parts and the Bakelite ones were mass produced -- at least somewhat.

BTW My spelling checker insists that Bakelite be capitalized.

Enjoy, DoN.