A twist drill is a tool that drills round holes in workpieces by rotating them with respect to a fixed axis.It is named after the spiral shape of its chip groove, which resembles a twist.The spiral groove can be 2, 3 or more grooves, but 2 grooves are the most common.Twist drill bits can be clamped in manual.Electric hand-held drilling tools or drill presses.Milling machines.Turning machines and even machining centers.The drill bit material is usually high speed tool steel or carbide.

twist drill bit price

There are many kinds of twist drill bits, and the price is different for different specifications.The price generally ranges from $1-$3.

Grinding method of twist drill bit

When grinding the drill bit, if the cutting edge of the drill bit is against the axial line part of the grinding wheel, hold the front part of the drill bit in your right hand and the back part of the drill bit in your left hand.The right hand is held stationary while the left hand holds the end of the drill bit and swings down to the left.During the whole process of grinding the bit, the end of the drill must not be higher than the axis of the grinding wheel, otherwise the bit will not be drilled.The force used in sharpening the drill bit should be from small to large, i.e. from small to large when grinding from the cutting edge area backwards.When grinding the drill, be sure to make the top angle of the two cutting edges symmetrical, generally at about 118°.After sharpening one side of the cutting edge, keep the same position, rotate the drill 180° and proceed to sharpen the other side of the cutting edge.If you want the hole to be drilled more round, you can grind the top angle smaller, i.e. sharper, so that when the drill is drilling, the centering is better and the hole is brighter.The two cutting edges should be the same length, and the angle of the two edges should be symmetrical, not one high and one low.The back angle of the cutting edge is generally between 8 and 12°, do not grind the cutting edge lower than the back angle, then the drill will not be able to drill.In addition, the cross edge of the drill should be ground narrower, which can reduce the axial resistance of the drill when drilling, so that the drill can save a lot of effort when drilling downwards.

twist drill bit specifications

The smallest size of twist drill is 3.5MM diameter, and there are also 5.6.8.10.12.14.16.18.20.22.32 and other specifications.

twist drill bit use

Suitable for steel casting.Alloy and non-alloy steel.Grey cast iron.Deep hole drilling and graphite processing of forgeable cast iron.Oxidation blackening treatment.