You are tasked with fabricating a precise, large-diameter hole in a thick carbon steel bracket using a drill press. To ensure exact location, prevent bit wandering, and maintain tool life, arrange the following hole-making steps in the correct chronological order.
- 1Apply layout fluid and scribe intersecting lines to establish the hole's exact location.
- 2Strike the intersection with a center punch to create a precise seat for the drill bit.
- 3Chuck a small twist drill bit and configure the machine for a high spindle speed (RPM).
- 4Drill a pilot hole that is slightly larger than the web thickness of the final drill bit.
- 5Chuck the large final twist drill bit and significantly decrease the machine's spindle speed (RPM).
- 6Drill to the final hole diameter while continuously applying appropriate cutting fluid.
Answer
The correct chronological sequence is: layout and scribing, center punching, setting up and drilling the pilot hole at high speed, then setting up and drilling the final hole at a lower speed with cutting fluid.
A precise hole requires layout lines and a center punch mark to ensure the bit starts accurately. Drilling a pilot hole (at high speed) clears material for the non-cutting web of the final bit. The final bit (run at low speed with fluid) can then accurately bore to the final dimension without wandering or overheating.
Step-by-Step Solution
Key Concept
Precision Hole-Making Sequence and Speed Optimization