Drill and Tap Reference for CNC Machined Parts

Do you have a question about tapped holes on your part?  You’re not alone, luckily this guide should answer all of the questions you have about how to add tapped holes to your part.

How do I add threads to my 3D part?

The short answer is, you don’t have to.  In most 3D CAD applications adding threading is a time consuming task that isn’t needed to add 3D taps to your part.  If you want to add threads to certain holes on your part, just follow these steps

  1. Make sure the holes match the pilot drill size required for the tap.
  2. Reference in your order notes or a reference document which holes are tapped and the thread type and pitch.
  3. Add any notes if a custom thread depth is needed.

Can my part be made with custom threads?

Usually, but it depends on the diameter.  Tapped holes can be made with a traditional tap which is a tool made for a standard thread size, or a thread cutter, which is a small disk that cuts threads through the XYZ movement of the CNC.  The thread cutter is limited to diameters greater than 1/2″.  Custom threads can be made with a thread cutter, but this may result in a additional charge.

What size should I make the pilot hole?

We’ve added a simple chart for the most common Standard and Metric tap sizes below.