Z Axis Depth Changes


(Mark Singleton) #1

I have a XXL and I have had the z axis depth change during a project.It was cutting a pocket and when it was time for the next toolpath it went back and started the old toolpath again but really deep .I had it happen 3 times on 3 different Gcodes


(Neil Ferreri) #2

Can you give a little more detail and share the gcode?

Sounds like you might be losing steps on your z axis.


(William Adams) #3

Usually when this happens it’s one of the following:

EDIT: if none of the above pans out, contact us at support@carbide3d.com and let us know what you’ve tried and we’ll do our best to help.


(Mark Singleton) #4

Think I found the problem.The z axis belt was loose.


(Dan Nelson) #5

Can also happen if your retract height is higher than the machines physical max height. The Z will hit the top of its limit, try to keep going, slip some belt teeth, then think it’s higher than it is and plunge down too far and destroy your work. Ask me how I know this(hint, there’s a very nice piece of curly maple scrap in a trash heap somewhere with a big gouge in it).

Dan


(Gerald Mackelburg) #6

Even if everything is properly setup, the Z axis stepper motor will slip (which also sounds like gears slipping) when you jog it up past the limit switch. IMO the software should prevent that from happening.


(William Adams) #7

It should prevent that from happening when jogging — CM4 implements soft limits for that.


(Gerald Mackelburg) #8

Thanks! I guess I (we?) experienced it on an earlier version of CM!


(Mark Singleton) #9

I am still running CM 3.My laptop will not run CM 4.


(Gerald Mackelburg) #10

Will,

Will the X and Y axis steppers also slip before something gets damaged on the machine?

Gerald


(William Adams) #11

Yes. That’s one advantage of using belt drive all around.


(Gerald Mackelburg) #12

How does belt drive help? Is the maximum of 19 lbf per stepper correct? Is that set by the controllers’ current limits or by the stall torques of the motors?


(Neil Ferreri) #13

If your axis is screw driven and you drive it past the limits, it won’t just skip. It’ll tear itself apart.


(Gerald Mackelburg) #14

Does that apply to the HDZ?!


(Luke) #15

Good question. In short no. The HDZ is strong enough to withstand the pressure of a ball screw driving into it. The coupler or motor will slip before damage is caused but it will make a loud noise. I did test a HDZ to destruction but you need a 1600oz nema 34 with glued couplers.


(Gerald Mackelburg) #16

That’s good to hear! IMO it would be a rather poor design if it was that easy to break!

I still don’t understand how belt drives are supposed to help (unless something slips before the motors).

I assume that you didn’t use the S3 for your destructive testing, right? What was the corresponding force on the Z axis?


(Luke) #17

Correct, there isn’t even a way to fit a nema 34 to a HDZ.

I didn’t measure the forces but the motor is over 10x more powerful than that on a shapoko to cause damage and required a 60v power supply traveling at 10,000 mm a min.


(William Adams) #18

Usually what happens is the belt starts skipping before something gives way — when it does it’s usually the Delrin V wheels. There’ve been some crashes where inertia was sufficient to keep things moving, so the V wheels gave way, in a couple of instances the rails have gotten gouged as well, but that’s not as common.


(Gerald Mackelburg) #19

The Z axis stepper motor slips before the belt skips. Is that not the case on the other axes?


(William Adams) #20

Good question. I haven’t tried to track that or differentiate. If anything, you’d think it would be the other way around since there’s less surface area engaged on the 6mm belts and the two 90 degree angles.