DRILLNOVA Request a quote

Zaozhuang · On-site fitting record

An existing barrel refitted with MH-3 roller bits.

DRILLNOVA · Field report · Updated

MH-3 roller bits fitted to the existing shell, with corrected mounting openings and a positioning reference made on site. Follow the people, measurements and welding sequence behind the completed fitting work in Zaozhuang.

A technician using a straightedge to mark a mounting opening
Marking the mounting opening for correction before positioning the replacement roller bits.

Fit the replacement bits to the actual barrel

The job took place at the construction site with the existing barrel retained. The preparation list included measuring tools, a welding drawing and a written and illustrated welding guide. Instead of using the prepared jig, the work used a centre jig made on site from reinforcing bar and steel strips.

After the existing roller bits were removed, the mounting openings were marked for correction. This gave the positioning work a defined starting point on the actual shell.

MH-3 roller bits fitted around the cutting end of the existing barrel
The refitted cutting end, labelled as the completed assembly in the field record. The steel bar across the opening is the site-made positioning reference.
Drilling rig and barrels at the Zaozhuang construction site
The working area at the Zaozhuang site in May 2020.

Make the reference visible, then check it

The site-made jig spanned the barrel opening. The next recorded step was to correct the jig before tack-fixing the replacement bits. The paired photographs show the whole reference and a closer measurement view.

Steel-bar positioning jig placed across the open core barrel
The centre reference made on site from reinforcing bar and steel strips.
Tape measurement between the barrel edge and the site-made jig
Checking and correcting the jig before fixing the roller-bit positions.

For a buyer planning a rebuild, this is the practical distinction between supplying a replacement roller bit and establishing how it will be fitted: the reference, the mounting opening and the bit position need to be considered together.

Keep the position through the welding sequence

The record separates tack fixing from the subsequent welding. It also explicitly notes cooling during the welding stage. These photographs show the work in progress before the completed-assembly view at the top of the report.

People positioning a yellow roller bit while it is fixed at the mounting opening
Holding the roller-bit position during the recorded tack-fixing stage.
A welder working at the roller-bit mounting area during the evening
Welding the mounting areas. The field note specifically calls for attention to cooling.

The work connects the positioning reference to the mounting welds, with the actual crew, tools and barrel visible throughout the sequence.

View the original six-step work sequence

The sequence recorded at the site

  1. Cut away the existing roller bits.
  2. Mark the openings for correction.
  3. Place the reinforcing-bar and steel-strip jig.
  4. Correct the jig.
  5. Tack-fix the roller bits.
  6. Complete the mounting welds, with attention to cooling.
A site worker removing the existing roller-bit mounting areas
Old roller-bit removal, as recorded at the start of the rebuild.

This record documents fitting and welding, rather than a drilling trial. It does not include post-refit drilling distance, service-life results or final inspection readings. For a new rebuild, confirm the current cutter drawing and welding procedure for that job.

Plan the fitting before replacement

Replacing roller bits on an existing barrel?

Send the barrel diameter, a full view of the cutting end, close-ups of the mounting openings and the roller-bit reference or drawing. Those details help us discuss the fitting scope and the positioning references for your tool.