Achieving accuracy

A lot of time can be saved if large custom installs can be made without setting them up in the shop first, and then taking them apart again for transportation to site and installation. Embedded in this procedure is the requirement to cut all parts twice; that is once a little oversized and finally hand-fitted to a given position within the cabinetry.

This procedure, while well-proven, comes from a time when the high degree of accuracy of machining materials now available was not available. So how then can we proceed with large custom work to be assembled once and once only where it finally belongs? A big time and labor saver!

Diving into decimals

The first step is to produce an accurate cut sheet by converting the incoming measurements from the site to millimeters. Converting say 24-3/4 inches to millimeters (24.75 x 25.4 = 628.65mm) is simple multiplication. From a practical point of view, working with whole numbers only we can say 629mm.

As the tolerances required for the purpose of our objective are plus or minus 0.4mm (1/64 inch) it makes no sense to work with decimal places. The beauty of this approach is that we can actually read whole numbers on a tape, whereas reading in 1/32-inch increments readily leads to errors. It's a digital world out there; let's get with it in custom work as well.

Visualization

I have always understood the difficulty for those of us not wanting to change, and here is the reason. The mind will visualize something 24 inches long and readily recognize a piece of material with that dimension, whereas 609.6mm results in a blank.

Here is the remedy: Simply say 12 inches = 300mm, 24 inches = 600mm and so on, so that you can readily convert in your head and thus identify the piece you are looking at.

The actual conversion from the site information to millimeters can be done in an Excel datasheet that produces the cut sheet. Our experiences with others who have taken this step to go metric are that everyone loves it after four days. Simply hand a metric cut sheet to the guys in the shop, give them metric tapes, and no one will ever look back.

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About the author
Gero Sassenberg

Gero Sassenberg has decades of experience in the woodworking industry on three continents, specialized in management and engineering consulting to cabinet and furniture manufacturers. He focuses on continuous improvement resulting in greater growth and profitability. He was a regular contributor to CabinetMaker and CabinetMakerFDM for many years.