Thread: A question on geometry

I've been looking at different razors and looking through post and the internet and maybe I'm just missing it, but I am having a hard time finding the info I want. My main question is on pivot pin location and tang taper. If I'm understanding the basic design correctly, the blade spine is the same thickness throughout to just past the pivot pin location then the tail tapers? Or is the pivot pin located in the taper? Or do you put the pivot in the taper and use a wedge, and put the pivot in the flat and use a flat spacer in the handle?

Thanks

Good question! Hard to answer! All the above styles you have asked about happen to one or another type of razor.

Most common is the taper starting at the heel of the blade. The pivot is along the taper.

Next would be frame backed having a thin blade full length and a cap of wider material as a spine.

Next would be "Rattlers" sometimes called faux frame backs. Usually having a taper with the pivot along the taper.

Over the many years man has shaved, local preference and marketing have been the driving force for blade shape and size.

Do a Google for straight razors and click on images!
I've been doing that for many years.
Fun and enjoyable, to me at least...
~Richard

Thanks, part of the problem is I've been looking at a lot of google images of razors! One of the issues is I can never get a good image looking down the spine and also see the pivot. So far the only razor I have made is somewhat loose in the handle, of course a big part of that is the pin was on the soft side and I did a poor job of peening it, will replace the pin before long.

You'd think after making folders for a few years I'd be able to figure this out.

A side effect of the taper is that it allows an increase of friction when properly fitted scales are rotated into a shaving angle. The wedge is made at an angle the same as the tang. This bows the scales which gives the constant tension on the blade tang.
Geometry is not as simple as it may seem on such a "simple" utilitarian item!
~Richard

Geometry is not as simple as it may seem on such a "simple" utilitarian item!

Man, that's the honest truth!

I guess part of it is I'm having trouble visualizing it. With a wedge spacer in the scales it points the tang ends out and wider than the tang of the razor, so then your relying on the peened pin and washers to hold friction on the tang as the scales are constantly trying to pull away from the tang. Or, if on a properly fitting wedge the ends are the same distance apart as the thickness of the tang? Keep in mind I've only got one store bought razor, a gold dollar and if I took the pivot pin out the ends would spring open.

Thanks.

Originally Posted by will52100

Man, that's the honest truth!

I guess part of it is I'm having trouble visualizing it. With a wedge spacer in the scales it points the tang ends out and wider than the tang of the razor, so then your relying on the peened pin and washers to hold friction on the tang as the scales are constantly trying to pull away from the tang. ...snip...One store bought razor, a gold dollar and if I took the pivot pin out the ends would spring open. Right!

Thanks.

Cheerz you got it quickly!
~Richard

OK, I think I got it, now to get time to try another.

Thanks

My understanding is that spread with only the wedge in place should be around 3/4 of an inch more than the thickness of the tang at the pivot. But this is from a newbie so take it with a grain of salt.

Glen (gsixxgun) did some research and posted it. Sorry can't seem to find it right now...He gave some dimensions on how thick he made wedges, great info and worth a look IMHO.

Hi again! Now, before you try to make a razor, go to the Library and really read all you can about honing and restoration. Along with other things, the shape of the spine and blade must be in a certain configuration and each blade is different as it is ground and honed.
Read also a few threads on making a razor!
Above all, have fun!
~Richard