4 Axes Machine Questions

I have not realy set up anything specific to the mahcine yet. All I did was add gantrykins to the sim inch setup (that ouputs steps to the pc speaker) with Z and A slaved. I have to get a simulation I feel works before I try it on one of our machines that are currently running production.

someone mentioned writing a script to adjust the G code files. This might be my best option, but something tells me this might be harder than it sounds.

I'd need something that could take code like this:

G1 X7.286672 Y10.920909 Z-0.165422
G1 X7.290075 Y10.882176 Z-0.162863
G1 X7.289496 Y0.985702 Z-0.161858
G1 X7.286561 Y0.942836 Z-0.161923
G1 X7.280504 Y0.912766 Z-0.166510
G1 X7.256354 Y0.833603 Z-0.159223
G00 Z0.25
G00 X7.006710 Y0.939417 Z0.25
G00 Z0.0
G1 X7.006710 Y0.939417 Z-0.079312
G1 X6.995858 Y0.916412 Z-0.086247
G1 X6.980558 Y0.899274 Z-0.080125
G1 X6.937673 Y0.867952 Z-0.085329
G1 X6.918087 Y0.863142 Z-0.087211
G1 X6.889543 Y0.859730 Z-0.086135

and turn it into code like this:
(the axis letter W would need to be what ever the 4th axis is)

G1 X7.286672 Y10.920909 Z-0.165422 W-0.165422
G1 X7.290075 Y10.882176 Z-0.162863 W-0.162863
G1 X7.289496 Y0.985702 Z-0.161858 W-0.161858
G1 X7.286561 Y0.942836 Z-0.161923 W-0.161923
G1 X7.280504 Y0.912766 Z-0.166510 W-0.166510
G1 X7.256354 Y0.833603 Z-0.159223 W-0.159223
G00 Z0.25 W0.25
G00 X7.006710 Y0.939417 Z0.25 W0.25
G00 Z0.0 W0.0
G1 X7.006710 Y0.939417 Z-0.079312 W-0.079312
G1 X6.995858 Y0.916412 Z-0.086247 W-0.086247
G1 X6.980558 Y0.899274 Z-0.080125 W-0.080125
G1 X6.937673 Y0.867952 Z-0.085329 W-0.085329
G1 X6.918087 Y0.863142 Z-0.087211 W-0.087211
G1 X6.889543 Y0.859730 Z-0.086135 W-0.086135

The simplest solution in this case is probably to short-circuit the W axis feedback[1], then use user-defined M-codes to connect the W stepgen to either joint.2.motor-pos-cmd or to joint.8.motor-pos-cmd.

[1] ie net fb-loop axis.8.motor-pos-cmd => axis.8.motor-pos-fb

Are you refering to fixing my problem with gantrykins, or an alternate solution using trivkins?

So what could the M code look like (using A instead of W, using W as a 4th axis will be a topic of another discussion)

for ZZ

---

#!/bin/sh
halcmd net Apos-cmd axis.2.motor-pos-cmd => stepgen.3.position-cmd

---

and for ZA

---

#!/bin/sh
halcmd net Apos-cmd axis.3.motor-pos-cmd => stepgen.3.position-cmd

---

Todd Zuercher wrote:

for ZZ

---

#!/bin/sh
halcmd net Apos-cmd axis.2.motor-pos-cmd => stepgen.3.position-cmd

---

Yes, that is pretty much it (using, as you said, trivkins).
However, you need to remove the old link before creating the new one, which you should be able to do with halcmd delsig Apos-cmd (you can try these commands out in a terminal window to see if they work)

I tried it and received the error

Debug file information:
core_stepper.hal:32: Pin 'axis.2.motor-pos-cmd' was already linked to signal 'Zpos-cmd'
7643

I changed it to

Zpos-cmd axis.2.motor-pos-cmd => stepgen.3.position-cmd

Then when I try to jog z I get a joint 3 following error