How to Guarantee the Perfect Counterbore Process

Countless companies in the manufacturing industry have came across problems with counterbores and countersinks. These problems can cause titanium and composite parts to turn to scrap after a single drill, which can become very expensive, very quickly. The depth of the counterbore is a hard thing to get right when machining composite material. This guide will help you avoid these problems and achieve the perfect counterboring process.


  1. Image titled Guarantee the Perfect Counterbore Process Step 1
    Check your machine tool. The first thing you need to do before you begin machining is to check your machine tool is actually capable of machining an accurate counterbore. To check this, you'll need to run the machine checking feature of your metrology software. If the machine benchmark report shows a pass, you can continue onto the next step. If your machine benchmark report shows a fail (see warnings) you must stop machining. If your machines not capable you must call an engineer to correct the geometry or you run the risk of creating a bad part.
  2. Image titled Guarantee the Perfect Counterbore Process Step 2

    Diagnose the problem.
    To do this you'll need to run the part location action from the controller. This will send an action to the metrology software to check the part is positioned correctly. Your metrology software will use the existing probe to locate the part and compensate for the new position.
    • Part Misalignment - This is when the fixture has not been located correctly, or the part is not sitting in the fixture correctly.
    • Surface thickness variation - The part may have minor distortion, which is a common problem with composite parts. The material's thickness has changed after the layup. This is usually variable by about 0.7mm thickness and can differ if the resin was pre-impregnated or layered.
  3. Image titled Guarantee the Perfect Counterbore Process Step 3
    The metrology software will compensate for variance. Next the metrology software quickly measures your machine tool geometry and part alignment using your existing probe. It then compensates for any variance/distortion – in fact the parts position could have changed considerably and it could still be machined perfectly.
  4. Image titled Guarantee the Perfect Counterbore Process Step 4
    Your counterbore is ready to be machined. Select proceed on the metrology software screen. This will machine the counterbores perfectly.
  5. Image titled Guarantee the Perfect Counterbore Process Step 5
    Archive the Benchmark report. Finally, you'll be presented with a benchmark report and a part location report. You can store these to guarantee your setup/counterbore is the same next time. The best system I've found is a system called NC-PerfectPart, but there may be other systems which have the same features. A good use of metrology software makes it easy to machine counterbore and other problems associated with composite parts. The auto-alignment and compensate features will also come in handy for part setup. Your metrology software product wont allow you to machine the counterbore until its accurate to your specifications. This stops you from producing bad counterbores and countersinks.


  • Never machine a counterbore when your metrology software shows a failed machine benchmark report. This will only result in a bad counterbore.

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Categories: Maintenance and Repair