.drill-tip-calculator-wrapper {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 0 auto;
padding: 20px;
background-color: #f9f9f9;
border: 1px solid #e0e0e0;
border-radius: 8px;
}
.dtc-header {
text-align: center;
margin-bottom: 30px;
}
.dtc-header h2 {
color: #2c3e50;
margin-bottom: 10px;
}
.dtc-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 600px) {
.dtc-grid {
grid-template-columns: 1fr;
}
}
.dtc-input-group {
margin-bottom: 15px;
}
.dtc-input-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
color: #333;
}
.dtc-input-group input, .dtc-input-group select {
width: 100%;
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
}
.dtc-input-group .hint {
font-size: 12px;
color: #666;
margin-top: 4px;
}
.dtc-btn {
background-color: #0073aa;
color: white;
border: none;
padding: 12px 24px;
font-size: 16px;
border-radius: 4px;
cursor: pointer;
width: 100%;
margin-top: 10px;
transition: background-color 0.3s;
}
.dtc-btn:hover {
background-color: #005177;
}
.dtc-results {
margin-top: 30px;
background-color: #fff;
padding: 20px;
border-radius: 4px;
border-left: 5px solid #0073aa;
box-shadow: 0 2px 5px rgba(0,0,0,0.05);
display: none;
}
.dtc-result-row {
display: flex;
justify-content: space-between;
align-items: center;
padding: 10px 0;
border-bottom: 1px solid #eee;
}
.dtc-result-row:last-child {
border-bottom: none;
}
.dtc-result-value {
font-weight: 700;
font-size: 18px;
color: #2c3e50;
}
.dtc-content-section {
margin-top: 40px;
padding-top: 20px;
border-top: 1px solid #ddd;
line-height: 1.6;
color: #444;
}
.dtc-content-section h3 {
color: #2c3e50;
margin-top: 20px;
}
.dtc-formula-box {
background: #eee;
padding: 15px;
font-family: monospace;
border-radius: 4px;
margin: 10px 0;
text-align: center;
}
function calculateDrillTip() {
// Get inputs by exact ID
var diameterInput = document.getElementById('drillDiameter').value;
var angleInput = document.getElementById('pointAngle').value;
var resultBox = document.getElementById('dtcResults');
var resultLengthSpan = document.getElementById('resultLength');
var displayDiameterSpan = document.getElementById('displayDiameter');
var displayAngleSpan = document.getElementById('displayAngle');
// Parse floats
var diameter = parseFloat(diameterInput);
var angle = parseFloat(angleInput);
// Validation logic
if (isNaN(diameter) || diameter <= 0) {
alert("Please enter a valid positive number for Drill Diameter.");
return;
}
if (isNaN(angle) || angle = 180) {
alert("Please enter a valid Point Angle between 1 and 179 degrees.");
return;
}
// Calculation Logic
// Formula: L = (D / 2) / tan(Angle / 2)
// Javascript Math.tan uses Radians. Convert degrees to radians.
var angleInRadians = (angle / 2) * (Math.PI / 180);
var radius = diameter / 2;
var tipLength = radius / Math.tan(angleInRadians);
// Display Results
// We use .toFixed(4) because machining usually requires high precision (4 decimal places for inches)
resultLengthSpan.innerHTML = tipLength.toFixed(4);
displayDiameterSpan.innerHTML = diameter;
displayAngleSpan.innerHTML = angle + "°";
// Show result container
resultBox.style.display = "block";
}
What is Drill Point Length?
The drill point length is the distance from the tip of the drill bit to the point where the full diameter of the drill begins. In CNC programming and machining, this value is critical when drilling blind holes (holes that do not go all the way through the material).
Because standard twist drills have a conical tip, the programmed depth ($Z$-depth) usually refers to the very tip of the drill. If you need a specific "full diameter" depth, you must drill deeper by an amount equal to the drill point length.
Drill Tip Formula
To calculate the length of the drill tip ($L$), you use the drill diameter ($D$) and the included point angle ($\theta$).
L = (D / 2) / tan(θ / 2)
Where:
D = Drill Diameter
θ = Point Angle (e.g., 118 or 135 degrees)
tan = Tangent function
Common Standard Drill Angles
- 118°: The standard angle for General Purpose High-Speed Steel (HSS) drills. Suitable for soft steels, aluminum, and wood.
- 135°: Common for Cobalt and Carbide drills. Used for harder materials like stainless steel to reduce walking and heat generation.
- 90°: Typically used for Spot Drills and Chamfering tools.
Calculation Example
Let's say you are using a 0.500 inch diameter drill with a standard 118° point angle.
- Divide the diameter by 2: 0.500 / 2 = 0.250.
- Divide the angle by 2: 118 / 2 = 59°.
- Calculate the tangent of 59°: tan(59) ≈ 1.6643.
- Divide the radius by the tangent: 0.250 / 1.6643 ≈ 0.1502 inches.
Therefore, to achieve a full diameter depth of 1.0 inch, you would need to program a Z-depth of -1.1502 inches.