HSS Straight Shank Twist Drill (18.0mmx1pc)

A burr. When a drill breaks through the far side of a plate it does not leave a clean edge; it pushes up a ring of raised, sharp metal around the hole, and at 18mm in reasonably thick steel that ring is substantial. It matters for three separate reasons and each of them is real.

It cuts. A burr on the underside of a plate is razor sharp and invisible from above, and it is the commonest cause of cut hands in a fabrication shop.

It stops parts sitting flat. Bolt two plates together with a burr between them and they are held apart at that point. The joint rocks, the clamping force goes into flattening the burr rather than into the joint, and a bolted connection that should be solid never quite is. On anything that carries load or vibrates, that is a joint that will loosen.

And it interferes with the fixing itself. A burr under a bolt head or a washer means the fastener is not bearing evenly, so the torque you apply does not translate into the clamping force you think it does.

Removing it takes seconds. A larger drill bit spun by hand in the hole, a countersink, a deburring tool or a few strokes of a half round file will all do it. The habit is worth building because nobody else will see the burr and everybody will feel its consequences later.

Eighteen millimetre holes serve bolt clearance in structural and plant work, bracket and base plate fixings and heavy fabrication.

M35 cobalt high speed steel. The catalogue's references to a carbide tip and percussion drilling describe a masonry bit and do not apply to this product.

Buyers are structural and general fabricators, engineering shops, plant and heavy vehicle maintenance and industrial dealers.

We stock countersinks and deburring tools. Ask on 94 77 111 8880 and we will send them together, anywhere in the island.