Product Description
The 30–50 mm cross drag-bit family spans 1.18–1.97 in and is intended for soft tunnel or mining ground where a fixed carbide cross can cut without a button array. The source filename specifically lists a 50 mm cross bit and a 30 mm hollow-bit reference, so both endpoints are retained in the reviewed size field. See the mining exploration archive and the soft formation archive for the allowed pairing.
The head uses an alloy-steel body and four intersecting carbide edges. Its fixed profile has no cones, bearing, or IADC code. Inspect the outer corners for equal gauge and the center for cracks or lost carbide before each run. The word “hollow” in the filename does not define the actual rod interface. Confirm the taper, socket, or thread from the physical product instead of assuming that the 30 mm reference is a connection size. Record which endpoint model is installed, because a 30 mm and a 50 mm face create different cleaning space and cannot share one assumed setup.
Use low WOB and 100–250 RPM. Stable torque and even chips indicate that the cross is cutting; bouncing, sharp torque pulses, or rapid edge rounding indicate a mismatch or hard inclusion. The design is limited in hard and abrasive rock, including material with quartz above 20%. Geological descriptions can be reviewed through the U.S. Geological Survey. Stop forcing the bit when granite, basalt, or quartzite appears, and move to a button system suited to 15,000–30,000 psi rock.
