Machining Performance issues

Owned by Erica Santos (Unlicensed)
Last updated: Mar 19, 2020
2 min read

Problem 1: My tool chatters during the cut.

Explanation: Vibration causes the cutter to not cut smoothly. This vibration is due to the natural frequency of the tool/spindle.

Possible Solutions:

  1. The feed and speed, and/or step-down and step-over need to be adjusted. See the feeds and speeds tutorial for more information.

  2. Turn the spindle speed up.

  3. Adjust the feedrate, usually moving slower will be smoother, but this is not always the case.

  4. Increase the step-down, taking a deeper cut into the material.

  5. Increase or decrease the step-over, the width of the cut. Typically the ideal step-over is about 60% of tool diameter.

Problem 2: Spindle sounds like it is slowing down during the cut.

Explanation: The spindle power is insufficient for the amount of material being removed.

Possible Solutions:

  1. Decrease the feed rate in 5% steps until the spindle stops bogging down 

  2. Decrease the step-down and step over in your toolpaths.

  3. Switch to a tool with more cutting flutes.

Problem 3: The Pocket NC is not cutting in the location that I expected.

Explanation: The stock may not be located in the same position relative to the origin point that it was in the CAM software used to create the toolpaths.

Possible Solutions:

  1. Make sure that the origin for your toolpaths is the B table offset/machine origin point of the Pocket NC. This is a point in space about 0.839 inches above the center of B table.

  2. Check if the coordinate system of your machining setup in CAM is set up so that the positive Z axis points at the spindle of the Pocket NC, the positive X axis points at the A table, and the positive Y axis points straight up from the B table.

  3. Check if the toolpath origin is also the B table offset/machine origin point and that the toolpath coordinate system is appropriate. Remember that the Z axis is always the Pocket NC spindle.

  4. Make sure that your stock is located in the same place on your machine as it was relative to the origin point in your CAM program.

Problem 4: The drive/lead screws squeak.

Explanation: The end of the lead screw is touching the frame of the machine when it turns. 

Possible Solutions:

  1. Make sure that the screw and the hole are free of debris.

  2. If the noise it minor is is best to let it wear into position. The noise should decrease with time.

  3. To re-grease:

  • Use a very small amount of general purpose synthetic grease to lubricate the tip of the screw.

  • Do not grease the whole screw.

  • Do not put grease where it will contact the anti-backlash nuts.

  • Grease will collect debris and may cause increased wear on your machine.