I just finished building my mpcnc ( Burly version ) and the crown test was a success.
I even printed it twice .A4 size and also A2 size .All went very well .
Next step was to make a waste board with some holes to put some tubtara in them .
So I made spherical hole diam 8mm and a second pocket with diameter 12 mm/depth 2 mm.
I copied that hole 4x8 times .
The first hole is ok ,but then the second hole is a little bit deeper ( the 2 mm pocket is 2.1 mm ) ,the third hole is again a little bit deeper ( 2.2 ) .
Hole number 20 is allready 2mm deeper .
When the tool was again at the origin ,the z-azis was 2 mm below the original level .
I’m using estlcam + cncjs to send the data.
Question is : what can be the possible cause of this .
Marc
Warped spoil board and unequal leg length are two common reasons. If you are using Fusion 360, recent changes have caused some z issues as well. As a quick test, put a small bit in your router and move it around the spoil board. At each test location, raise or lower the router until it is just scraping. How much you have to raise or lower the router will give you an idea of differences in your spoil board. I’m assuming that your spoil board is MDF. I’ve found that relatively quickly MDF assumes the shape of the surface below the MDF, even two layers of MDF. So if you have an uneven spoil board, check the surface the CNC is resting on.
Hi Robert,
Thanks for the info .I will do the test this evening .
My mpcnc is mounted on an mdf board which is then mounted on an old table .The plate is about 40 mm thick in multiplex which seems flat .
regards
Marc
Reading back over your question more carefully, I did you a disservice with my answer. If your z axis was 2mm below the original level at the end of your run, then this is not a spoil board issue…or at least only a spoil board issue. The most likely cause of this problem is loose grub screws on the connector between the lead screw and the z axis stepper motor. If the grub screws are tight, next twist the lead screw by hand both up and down the full range to check for any binding. Make sure you’ve lubed the lead screw. Three less common reasons I’ve seen on the forum for lost z steps:
Router mounting issues where the router is brushing against something on the core.
Stepper motor issues typically with having the current set correctly on the driver
Rapid settings too high. Make sure that “Rapid Feed Z” setting is set correctly in estlcam. Ryan recommends 480.