The Loga Project

This is the most ambitious project I've started. I'll claim it's a work in progress.

I gave up early on the Thacher as a feasible home brew project, but I've held hope that I could build a really large scale cylindrical patterned after the Nestler and Loga cylindrical models.

Instead of the triangular bar cage, these have a flat bar design. It's amenable to a number of implementations, including printing the outer cage on transparent plastic. That is, you can be a bit more flexible in the build, and certainly pick your own size, since the basic design came in a large variety of lengths.

My idea was to build a scale generator that can be used by anyone to build a custom Loga style calculator. The configuration files allow the user to set the diameter, number of bars, length of bars, fonts and a few other variables, and the generator is to scale the output optimally.

Early prototype, on 4.5 inch O.D. ABS pipe

.While conversing with Bob Wolfson via email, he became interested in trying it out. With his advice and help, I began to add features we observed in the samples we could find on the web.

E.g., we can observe that the longer slide rules generate more digits in their scales and labels.

We see patterns where numbers ending in 10's, or 100's or 1000's, trailing digits aren't printed, instead the numbers are coloured and larger. The scales extend past the 'ends', which means the extensions appear in more than one bar.

We were having constant problems with bugs on this project, a failure on my part. I had re-cycled some old code that really should have been re-engineered. Each time we fixed a bug a new one cropped up. Despite the problems, the code does produce 'mostly' correct scales. Bob actually struggled through his own builds project using the scale generator and manually correcting the defects in the PostScript output. Check out his story Bob's Calculators and Slide Rules (find 'Loga' under 'my replicas').

Gift of Bob Woflson. These scales were produced from the Loga generator, the rest is all Bob.

At the time I was finding juggling my work life and the project a bit too challenging, so I took a breather. I'd been neglecting my interests, RF electronics for a couple of years, and decided to spend some time there.

I plan to start re-working the code this year (2020) and will eventually share a working version of the scale generator, but for now, I can generate scales on request, and deal with the tweaking of my generated PS files on my own.