Digital calipers are excellent for precise readings. But I am expert at getting imprecise readings from them. Maybe I measure the wrong area of a corrugated board, or tilt them slightly when I use them or stick my thumb inside their jaws. I don’t know. Plus I often misplace the calipers by burying them beneath Glowforge detritus.
I am no luddite, but I find assurance in this set of wooden slots, even if the original design was off by .007 inch. What I like is that if I create a slot in Inkscape based on the values printed on the gauge, I know exactly how the Glowforge will cut it. JamesDHatch is quite correct to remind me about kerf. So I should regard the numerical labels as pointers, not as actual values.
After designing a two-part hook that slotted together I decided to make the Thickness Gauge. The slots were quite loose because I lazily assumed a plywood thickness of 0.12 inches and the calipers were hiding beneath some 2mm EVA foam pieces.
If the Thickness Gauge disappears as swiftly as the calipers, I’ll cut another, repeating as necessary. My next challenge may be to find things covered by layers of Thickness Gauges.