Measuring and Layout — FAQ
What's the difference between ultrasonic and mechanical thickness gauges?
Ultrasonic gauges use sound waves to measure through materials without contact, ideal for painted or corroded surfaces. Mechanical gauges require direct physical contact and only work on clean, accessible metal. Ultrasonic models cost more but offer greater versatility and non-destructive testing.
Can I measure painted metal surfaces accurately?
Yes, but only with ultrasonic gauges. They measure total thickness including paint, then subtract the paint layer to give the base metal reading. Mechanical gauges compress paint and give false readings. Always specify if you need paint compensation when buying.
How accurate do I need for automotive paint inspection?
Automotive paint inspection requires ±0.01 mil accuracy to detect subtle variations indicating bodywork. Our top automotive pick delivers this precision. For general metal fabrication, ±0.001 inch (1 mil) accuracy suffices, while precision manufacturing may need ±0.0005 inch.
Do digital thickness gauges require calibration?
Most digital gauges include auto-calibration on startup or calibration blocks. Ultrasonic models need periodic calibration with reference standards, especially after drops or temperature swings. Mechanical gauges rarely need calibration but should be verified annually against known thicknesses.
Which gauge works best for plastic and composite materials?
Ultrasonic gauges are the only reliable option for plastics, fiberglass, and composites. Mechanical gauges can't grip these materials, and digital micrometers only work on flat, firm sections. Ensure your ultrasonic model includes a plastic material setting for accurate sound velocity compensation.
Are budget mechanical gauges reliable for professional welding?
Yes, quality stainless steel mechanical gauges like our budget pick provide reliable measurements for welding prep and inspection. They lack digital convenience but offer durability and zero maintenance. Professional welders often keep one as backup even when owning digital units.
