Zero gets shifted during a cut

CNC Machines Shapeoko
1

So I was running a roughing pass on my Shapeoko XXL. Wood is .75in red oak, 30inx11in. I am using a $201 0.25in carbide cutter at 23000 rpm, feed rate of 100in/min and plunge rate of 25in/min. Carbide motion has 2.5hours for the estimated cut. After about 30minutes of run time, noticed the spindle moving outside of the stock area so I force shutdown the program. I check the machine zero and it had shifted by a good 3 inches on the x-axis.

Any idea what is going wrong here? Is it the machine or is it me doing something wrong with the settings?

2

Some possibilities:

  • Machine stalled trying to push through the wood while cutting, losing steps. Are there any knots, or any other peculiarities in the wood?
  • An obstruction hit the carriage / spindle / dust collection, losing steps.
  • Bad wiring on the X Axis - check for loose wires, corrosion on the pins, or signs of arcing
3

Thanks! The I attached a little zip tie to the two ends of the x-axis connector. That seems to have been the problem, and the latest cut is going fine. Fingers crossed!

4

As @mhotchin suggested you lost steps. The zeros dont move but the machine can lose its position. The machine still thinks it is on target since there is no feedback to the actual position. So reevaluate your F&S. Red Oak is very hard so you likely need to decrease DOC, speed and IPM. You want to make chips not saw dust. Take a look at why you already cut and see if it is chips or saw dust. High router RPM and fast IPM makes saw dust and not chips.

5

Thanks, that all makes sense now. I reduced the parameters, fixed the x-axis connector and also swapped out a vacuum collection hose to a better hose and now the machine seems to be working better. Btw, what wood is best for intricate 3d carving with several small elements like leaves and flowers?

6

For intricate detail, you want something with a close, closed grain - the open grain of oak makes small details very weak. Most softwoods are NOT close grain (even though they are closed grain), plus the softness itself is a problem.

So, a closed grain hardwood, like maple, birch, walnut, etc.

1 Like
7

This topic was automatically closed 30 days after the last reply. New replies are no longer allowed.