Hey guys! Im using mach 3 and a chinese CNC we brought off ebay, however things are cutting either too small or too big. any tips or ideas how I can adjust the machine to cut at the right size?
Im using HSMXpress to generate the Mach 3 code from solidworks.
Is it just a case of playing with the motor and tuning settings or is there something a lot more obvious that I am missing?
Tool compensation comes to my mind. How is your CAM software dealing with it?
Looking at the software befor ei process it, it seems to be hitting the edge as expected really. So if i have a 240mm sqaure, the milling bit hits the edge of the piece at 240, unless thats not being carried across durin gpost processing.
You might measure the threads per inch on your lead screws, make sure that matches your configuration. Then look at step rate. If you get those gimped up, then sizes can be way off.
I went through mach 3’s own axis calibration wizard, it has improved it however it isn’t spot on, I’ll do the lead screw calculation to see if that h elps. Thanks!
Sounds like an axis calibration issue… There’s a manual way and an automated way that might work… http://m.instructables.com/id/Automatic-Axis-Calibration-Using-Mach-3/
@Chris_Kendall I am assuming your machine moves exactly 100mm when you tell it so, on each axis. But if at any time your motors are loosing steps then you can be in CNC hell. Steppers will lose steps if they cannot overcome the cutting forces (though they may move the machine happily and accurately when there is no load).
Question is to know how off you are from the real size. First most common issue is that you may have your machine set in metric or in imperial and/or MACH3 set differently. I heard of an option to calibrate eventual variation on motions with some controllers (mostly the DSP controller found on CNC Router from China) but depending on the one you have you may not have that option. You can have a look at this video if the controller is the same you can correct the axis variations with your own reading from a simple square size: https://www.youtube.com/watch?v=bWRqECq9HA8
With ARTCLIP3D we can also set the post-processor according to the value of your variation, but if your machine is completely off the screw dimensions information then you are going to have a long trouble shoot session to correct any offset detected.
Thanks for the input guys! really appreciate it! I did a cut piece and measure how much it was off and converted it to a % of the final dimensions, from here I could work out what % i needed to increase the steps per value in Mach 3 for it to equal 100%, we are now on track!