G540 + EMC2 = missing steps

With the spindle off and the axes not moving, how much can you pull and push the spindle in each direction by hand? This will give you some idea of how much of the problem might be machine flex.

Andy,

Good morning. I took all 3 spindles out and push and pull x ,y and z no slack or movement at all. I even check all the coupling between spindle and the lead screws.

Thanks

Andy,
problem with circles

I finally solved my problem by just adding Lead in and Lead out . ( I called the K2cnc and advised me to add lead in and lead out.)

Thank you very much for all your help.

If adding lead in and lead out fixed your problem. Then it almost certainly proves that your machine has to much flex (not stiff enough) and or back lash. Probably most likely in the Z axis. Lash and loose ways in the Z can be difficult to detect because the weight of the axis masks it until you try to plunge into some material.

Hello Everyone, tagging on to an older thread with a similar issue...

I am running a small 3-axis gantry router, G540 10 microstep driver, LinuxCNC 2.6.something. I am having troubles with the Z axis becoming lower and lower as I run. X and Y are generally fine.

Last weekend I ran a 3D program and a feature that should have been .165" deep from the top of stock ended up more like .230" deep. Program was 22k lines of code and much of that is parallel finishing a convex curved form so X-Y-Z are all moving at the same time. The longer the program the more I notice the issues. And some of my stuff is two-sided so I get hit double with errors.

My stepper motors are NEMA 23: Max Torque 282 oz-in, 3A
Power supply is 12.5A 48VDC

Normally I am cutting wood with 1/8" end mills, 12krpm and 60-75 IPM. I tried some FR4 too and the cutter seemed to pull into the material until it broke.

The motor and coupler on Z seem tight but the machine as a whole is not as rigid as could be desired, Y is the worst and allows Z to flex as well.

Currently X and Y are set to 3 inches per sec max velocity and 30 inches acceleration. Z is 1 and 10 respectively.

If I run the Z axis test alone things seem good but real world performance is not.

I have the G540 Stepconfg set up as X-Y-Z-A. Could I be wasting power supply headroom maintaining the A axis position?

Would slowing down acceleration even more on the axes help? Disable the microstepping?

Or do I need to stiffen the machine first?

Thanks!

this is a common problem , slow down your z axis speeds will help enormously , your simply running at higher rates than the stepper motor can cope with , ideally you dont want a 10 microstep driver on the z .
as a start i'd lower them by 50% , or untill you have them running fine and then increase slowly untill they fail and then drop back about 10%

the faster a stepper goes the less torque it has
( and why you find z axis tend to have a 2:1 reduction pulley incorporated )

running 4 steppers could be dragging the system down , i'd tend to run the Z axis on a seperate supply ,
if the machine is not ridgid , then thats the first port of call to fix, electronics can only do so much , it cant make a machine better than it's frame can support

dont forget a stepper uses more current when holding a stationary position ,