I am working on a touch plate and I use harbour freight digital vernier calipers. I took my touch plate to work and took measurements with a brand new mitutoyo digital vernier caliper and also used a cmm to take measurements of the part i was surprised to see that the harbour freight calipers were only .003 mm off. That i can work with. The part was face milled on both sides with the xcarve and was .04 mm off from being true on the face.
Wow, .04 mm, great accuracy. One thing to be cautious about with inexpensive digital calipers is the repeatability. If you close them and zero out then open all the way , or partially, then close them. Do they read zero? I’ve had several pair that have had a repeatability error of more than .1 inch.
So far i have been lucky with this pair. just waiting till i can get a set of mitsutoyo’s from work they are on order but that means i have to wait 2 months because of the way they do things here but i can get them for $125 versus paying around $350 for the same set from grainger. Oops my bad knock a zero off that .003.