A Raspberry Pi-Powered Screw Jack Puts Matthias Wandel's Glue Collection Through Its Paces
Designed to apply a force and measure it at the same time, this clever contraption tests glued joints to failure.
Woodworker Matthias Wandel has decided to find out which of the various brands of wood glue prove the strongest, and has turned to a familiar gadget to collect empirical data: a Raspberry Pi single-board computer.
"I made several samples where I glued one of these pieces onto this piece and these all came from the same piece of 2x4 so they should be consistent," Wandel explains of the samples for testing, put together with his usual brand of glue and ten others for good measure, "and I'll be testing them with the screw jack which is on top of some load cells to measure the force."
The idea behind the experiment: The wooden samples, with both construction lumber and maple hardwood used to see if the type of wood affects glue performance, are clamped down and the screw jack, driven by a stepper motor under programmatic control, used to apply increasing pressure until the glued joint — or the wood itself — breaks.
The load cells are connected to a Raspberry Pi single-board computer through a suitable interface, with a clever text-based program offering data gathering and visualization: A simple graph shows the increasing force, measured in kilograms, then reports the force at which the sample broke — and captures a picture for posterity, using a Raspberry Pi Camera Module.
The conclusions drawn from Wandel's testing may surprise, though they come with some heavy caveats — including the note that some glues that perform well are hard to apply, or go off far too quickly resulting in a wasted bottle.
The full video is now available on Wandel's YouTube channel.
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