BIT GRINDING

Whatever you do, safety is always the number one concern. So let's get that one out of the way immediately.

When using grinding equipment, always wear a safety mask and breathing apparatus as necessary.

BUTTON GRINDING - DIAMOND CUP

The best results are achieved by rotating the grinder in a cylindrical manner to provide a nicely finished shape with the grinding tool.

GRINDING STEEL BASE - DIAMOND CUP GRINDER

The grinding tool must be kept in direct line with the button axis at all times. If the tool is rocked from side to side, the button could be damaged.

BUTTON GRINDING METHOD - DIE GRINDER

Draw a pencil line across the flats, thereby dividing the button into two symmetrical halves. Gently grind on each side of the pencil flat, leaving the pencil line untouched. Finally, gently blend the pencil line, removing as little carbide as possible from this area. The aim of the technique is to remove as little carbide as necessary so that when grinding is completed the re-sharpened button will be spherical and slightly smaller than new.

RE-FACING THE DRILL BIT GAUGE

Particularly in abrasive drilling conditions, not only will the peripheral buttons wear, but also the body of the bit just below the buttons. Excessive wear can result in the diameter across the buttons being the same as the diameter of the steel body (gauge). This causes ‘binding’ or tightness of the bit in the hole. This is remedied as follows –

GAUGE GRINDING

Grind a flat 4.5 mm (0.18”) in length, around the drill bit head, and at 90 degrees to the drill bit face.

TAPER RELIEF GRINDING

Grind the taper relief, if necessary, at a 4-degree angle from the bit axis.

Ensure that the depth of flushing grooves is adequate and re-grind them regularly to allow free evacuation of the drilling debris.

Ensure that the flushing holes are not deformed and grind them if necessary.

And there you have it! These are the basics of button bit maintenance by regrinding.

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