- Common HC-SR04 1 cm accuracy sensor - Sparkfun - . Claims 3 mm resolution, which would work for CNC torch.
- Migatron - 
- Thread on the precision of the HC-SR04 sensor - 
- 2.5% is the general figure. so for 25 cm distance - get 0.6 cm off.
- Does that imply that for 5 cm distance, we are 0.1 cm off? That would work for the OSE sensor case.
- Speed of sound is about 1100 ft/sec
- It varies slightly with temperature
- Graph here shows errors around 1/100" for our desired sensing distance - 
- Thus, simply getting an ultrasonic sensor that works would be a good start.
1 mm Precision Sensors
- StackExchange - 
- Chirp - 
- Baumer - pricy at $500? - , and 
- SICK -  - cart does not show price.
- Optical - sub mm - 
- Laser - sub mm - 
- MaxBotix sonar - appears to work - [MaxBotix HRLV MaxSonar-EZ] - 
- Infrared - . Banner Engineering $35 - 
- 1-3 mm ultrasound - 
Inquiry to Migatron
- We are working on a CNC torch table for oxyfuel torching of heavy sheet metal. We need to detect distance of the cutting torch from the workpiece by measuring close to the cut line. This means a hot environment with possibility of smoke. Our accuracy of height measurement should be 1/16" (1-2 mm). Can you please suggest one of your products? What is the price?
- Response - Hi Marcin,
Our sensors will not work for your application.
Best regards, Jeff Van Valkenburg Migatron Corp.