How is countersink calculated?
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How is countersink calculated?
> A simple rule of thumb is to choose a countersink which is 50% larger than the diameter of the hole > Countersink diameter = 1.5 x bolt size (hole) diameter > Ex: For a 1/4-20 bolt, multiply the diameter (. 250) x 1.5 = . 375. This equates to a 3/8” countersink.
How do you measure a countersink angle?
Since the countersink has a 90° included angle, bisect that angle with the centerline of the hole to create two equal 45° angles. Subtract the existing hole diameter from the countersink diameter. Then divide the answer by two because ½ the difference is on each side of the hole.
How do you measure the depth of a countersink?
The depth of a countersink depends don’t the diameter of the countersink and the angle. The depth is typically considered as the vertical distance from the opening of the countersink to the “tip”. This tip is the point at which the countersink comes together.
How do you calculate the depth of a spot drill?
A spot drill has a 90-degree point angle, which makes it easy to calculate the depth of a hole to be spot-drilled. You simply divide the diameter of the spot-drilled hole. If you have drilled a 0.25″ diameter hole and want a 0.031″ chamfer on the hole, the diameter to be spot drilled will be 0.312″.
How are countersunk screws measured?
Shank Length For fasteners where the head usually sits above the surface, the measurement is from directly under the head to the end of the fastener. For fasteners that are designed to be countersunk, the measurement is made from the point on the head where the surface of the material is, to the end of the fastener.
How deep should holes be spotted?
A long drill can deflect when it initially contacts a flat surface, making spot drilling necessary. Some drill makers agree that for holes more than 5 diameters deep, spotting is needed. Others say that threshold is 7 or 8 diameters deep or more.
What is the rpm formula for drilling?
R.P.M. = (3.8197 / Drill Diameter) x S.F.M.
What size is a #12 countersink?
1/2″ diameter
If you are using a #12 countersink you would need to use a 1/2″ diameter plug.
