Step Drill Bit (4-20)

Twenty millimetres reaches the common cable gland and conduit sizes, so between its smallest and largest steps this one bit covers the great majority of holes in a consumer unit, a control panel, a trunking run, an enclosure or a piece of ducting. That is the real appeal: instead of a case of twist drills and hole saws, one bit in the pouch does the job, and it does it without the grabbing and tearing a twist drill produces in thin steel.

The technique that gets the best from it is worth stating because it is not obvious. Run slow. Step drills are frequently ruined by high speed, since only one narrow cutting edge is engaged at a time and it concentrates all the heat. Use a drop of cutting fluid on steel. Apply steady moderate pressure and let each step cut through fully before pressing on to the next. And watch the step you are on, because it is easy to go one further than you meant and end up with a hole that is too large, which in sheet cannot be undone.

Support the material as well. Thin sheet flexes and drums under a drill, and a panel that is oscillating gives a poor hole and shortens the bit's life. Clamp it or back it with timber.

The steps and their spacing are given inconsistently between this bit and the three piece set that contains the same sizes, so rather than quote a figure we cannot stand behind, ask us and we will read the actual steps off the bit in stock.

HSS, heat treated, titanium coated.

Buyers are electricians and panel builders, air conditioning and ducting installers, sheet metal fabricators, signage trades and hardware shops.

Message 94 77 111 8880 with your gland sizes and we will confirm the range. We deliver island-wide.