Product Description
The 35 mm seven-button cold-pressed bit is intended for tunnel development, mining rounds, and compact construction holes in competent rock. Its 1.38-inch gauge and stated seven-button face provide a defined small-hole option, while the source number 253 is retained as a model reference rather than a dimension. Review the job under the construction drilling application archive and the rock under the medium formation archive. The bit is not intended for loose-ground stabilization or core recovery.
The source identifies cold pressing, a 35 mm gauge, seven buttons, tunneling and mining use, and the number 253. The engineering record uses an alloy-steel body with seven fixed carbide contacts and model 253, without claiming that 253 is a material grade or size. Connection, face profile, button distribution, skirt, and flushing arrangement are not supplied. Cold-pressed wording is not a retention guarantee. Confirm the rod fit and inspect a face drawing before the bit is introduced into a production pattern.
Use 1,000–3,000 lbf/in of diameter and 25–60 RPM. Medium and hard formations are suitable; abrasive rock requires closer checks of the seven contacts and gauge edge. Start conservatively during collaring so the compact face seats evenly. Document the physical connection, verified face layout, and model meaning together so future replacements do not rely on the image alone. Flow is blank because rod bore and port geometry are unknown. The explicit limitation is the absent connection and undefined meaning of model 253 beyond identification. Rock-mechanics background can be reviewed through the ScienceDirect engineering topics.