Project Description

The customer had recently purchased a new gear box which needed to be spot faced approximately 1” with ¼” NPT holes drilled and tapped at 45 degrees for instrumentation to be added.

Mactech’s Role in the Project

Mactech proposed designing, fabricating, and mounting a custom fixture to properly position equipment to drill, counterbore, and tap.

Alternative Methods

Disassemble the gear box and send the necessary components out for machining.

Challenges & Mactech’s Value Added to the Project

There was no off-the-shelf fixture to perform the work. Mactech designed a bolt-on fixture to locate the drill spindles on the centerline and different tooling was purchased to meet clearance issues. Mactech was able to mount the fixturing using an existing bolt pattern on the gearbox. The custom fixture was manufactured in-house at Mactech.

Steps Taken to Complete the Job

  1. Engineer and fabricate custom fixture to mount on existing bolt patterns and accommodate compound cross slides
  2. Mount and align fixture to the gearbox in place
  3. Drill and tap instrumentation holes

Equipment Used

Custom fixture Compound cross slides

Useful Job Statistics

  • Holes drilled at 45 degrees and 131mm depth with ¼” NPT threads


The customer was very satisfied with the final result. All work was completed as quoted and under budget.