Rule Making

Graduating, Engraving & Etching, 60p, $6.95 *LINK*

David Barnett - SW Florida

>You can do it by hand with simple equipment (gravers, routers, etc.), photo-etching, build a linear engraving engine or even a barebones ruling engine and make x-ray or difraction gratings, too (well, you could), or get this book and learn how to make all manner of precision dials, rulers, whatever. I've done simple stuff with boxwood, ivory, brass, aluminum. Helps to have good magnifying optics and lighting, 'specially if your eyes aren't what they used to be.


Graduating, Engraving & Etching

Re: Rule Making

Don McConnell

>Hi Wayne,

I'm not familiar with the book which David recommends, but it looks as if it could be quite useful.

While I've done a little research into early rule making, I'm far from an expert on the practical aspects of the trade. But, I thought I'd pass on what little I've gleaned in the hopes it may help in further discussions or development of your thoughts.

If you are wanting/needing to reproduce only a couple of steel rules in a manner consistent with those produced before mechanization of the process, then I think some form of engraving will the most appropriate. Along those lines, I've run across evidence that, as early as 1556, carpenter's rules were being engraved in London, and some were being made by the best mathematical instrument makers of the day. And, I believe that the divisions and numerals were both being engraved. I've not done the research into when the numerals began being stamped.

In any event, as late as 1892, John Rabone and Sons were still dividing their boxwood carpenter's rules by hand. John Rabone, Jr., briefly discussed this:

" ... Since the invention of the dividing engine by Ramsden ..., all the most accurately and finely graduated astronomical and other instruments have been divided and marked by means of it; but the process is much too slow and costly to be employed upon the rules in general use by mechanics. Straight scales and rules are usually divided by placing the article to be divided and the original pattern side by side, then passing a straight-edge with a shoulder fixed at right angles to serve as a guide along the original, and pausing at each division; then a corresponding line is made on the copy by the dividing knife. Segments of circles are also graduated in the same way ... . ..." [ as quoted in Roberts, _Some 19th Century English Woodworking Tools_, c. 1980.]

While the above pertains to wooden rules, I believe a similar approach would have been used with metal rules. I'm including a small illustration of a dividing knife as it would have been used in graduating a segment of a circle, as found in an online article by Jeffrey Lock. As he describes it, the dividing knife is used somewhat differently from a regular engraver's burin, in that it is used to "plow a furrow" in the metal, by pushing material aside rather than removing it. The resulting raised "lips" are then removed with a fine whetstone, "leaving an extremely accurate straight line."

Not much, but hope it is of some interest.

Don McConnell

Eureka Springs, AR

Re: Rule Making

Patrick Gibbons, Houston, TX

>Astragal Press puts out Philip Stanley's A Source For Rule Collectors. He refers to and quotes many sources concerning wooden rule making. It is surprising how quickly the lines can be inscribed manually. Afterward the piece was polished and then lamp black was rubbed into the lines and numbers. The coat of shellac kept the black from discoloring the body of the rule. A little sanding, some more polishing and voila.

A few more resources... *LINK*

David Barnett - SW Florida

>Another must-have Lindsay booklet, "Precision Lead Screws, Gears, and Pantographs", 48p, $5.95 (link below).

For the full article (more pictures) referenced by Don McConnell (good stuff, Don):

http://www.colonialinstruments.com/im/pdf/Dividing_Ring_Article.pdf

"Dividing Engine - linear by Hicks" (w/pics, from auction catalogue):

http://www.earlytech.com/common/show_item.phtml?Id=231713861

Photos of two early line-dividing engines:

http://brunelleschi.imss.fi.it/museum/esim.asp?c=413014

http://brunelleschi.imss.fi.it/museum/esim.asp?c=413016

It's probably easier to purchase an off-the-shelf lead screw, Acme or otherwise, than to make your own, but if you know a good machinist, the persnickety old-fashioned type, they might be persuaded to cut what you need. There is, of course, no shortage of inch or metric precision lead screw manufacturers/distributers, with prices from reasonable to ridiculous. Check the usual suspects first, I'd say; MSC, McM-Carr, Enco, and so on.

http://www.nookindustries.com/acme/AcmeHome.cfm

http://www.abssac.com/product.asp?productnum=16&catnum=1

http://www.smallparts.com/products/descriptions/lsx.cfm

Acetal/Delrin screws and anti-backlash nuts are okay, but not nearly so pretty as metal.


Precision Lead Screws, Gears, and Pantographs

MSC - Nook precision acme lead rods/components  *LINK*

David Barnett - SW Florida

>


MSC catalog, page 3853

Thank You

wayne anderson

>Thank you all very much for the great info. I think I will cobble together a rudementary dividing engine with what I have on hand. If it works ok, maybe I'll have to make one with more precision components. Yet another "after-hours" project. -wayne

Re: Rule Making

CJ McLaughlin

>MAKE magazine had an article recently about how to photo etch face plates for different stuff (the project was an art piece made to look like an old time radio). The process involves making the design (in this case the ruled markings) and printing it on a transparency (I cannot recall if it is positive or negative). Next, you apply photoresist to your workpiece, cure it, and expose the workpiece to bright light shone through the mask that you made (transparency). After removing the mask, acid is used to etch the workpiece and once the prescribed period of time has passed, the photo resist is removed and your piece is done. You can blacken the etching to make it darker.

CJ

Re: Rule Making

wayne anderson

>I am aware of that etching process. I think that these rules were probably scored and the numerals stamped, rather than etched. I have observed the overrun on a few lines. That would likely not happen (IMHO) with etched graduations.

Re: Rule Making

Paul Kierstead

>Also, etching doesn't leave the lovely v-groove that makes a sort of faceted look that catches the light so nicely. It sure is easier I expect though :)