We turned the calculations we redo on every project into five browser tools, and published them

Why we took it on

Design work means redoing the same calculations over and over. Beam deflection, bolt preload, spring stress, the speed and torque of a linkage. All of them are in the textbooks, but what the work needs is not the formula — it is an answer on the spot, with the verdict attached.

We had been doing it in spreadsheets. The trouble with a spreadsheet is that it becomes a different thing the moment somebody edits a cell. The formulas are out of sight, nobody can say which version is correct, and it cannot be handed to another department or to a supplier. Those three problems stayed unsolved.

There is a second problem. A company outsourcing design work has little way of judging the engineering behind it beforehand, and we cannot publish the content of our projects. So we decided to show, in working form, what kind of calculation actually goes into the design.

What we did

We sorted the calculations we use into five tools and rebuilt them to run entirely in a browser.

• Beam deflection and bending stress — six sections, four support conditions, the section drawn as you change it, with a bending moment diagram
• Bolted joints — torque coefficient from the friction coefficients, how the external load divides, bearing pressure, margins against slip and shear
• Compression coil springs — torsional stress with the Wahl correction, spring index and solid length
• Slider-crank mechanism — run the crank continuously and see the behaviour near the dead points with your own eyes
• Toggle mechanism — force ratio and clamping force for a production clamp, with the buckling of the links on the same screen

Three decisions shaped the design.

Nothing typed in is sent to a server. Every calculation finishes in the viewer's browser. Design values are not something you can show to other people, so the tools do not receive them in the first place.

Give the verdict, not just the number. A number on its own does not answer “so, is this all right?”. Each result is compared with a safety factor or an allowable and comes back as OK, caution or NG, with the reasoning written out.

Say why. Each tool carries an explanation — why the force rises at a dead point, why the l/r ratio matters. Handing over answers alone does not leave the user any better able to judge.

The outcome

All five are published and in service. We use them in our own design work.

What this project shows

With an in-house tool, the hardest step is deciding whether it is worth building. We limited ourselves to work that was already being done by hand, and could be counted. Once you have a figure for how many times a month and how many minutes each time, whether the effort pays for itself is settled on the spot.

The things that started from “this would be handy” were built and then not used. That is the first thing we check with a client, too.