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Author Topic: 4th axis question, possibly configuration ?  (Read 9996 times)

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Offline Sage

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Re: 4th axis question, possibly configuration ?
« Reply #10 on: May 15, 2011, 12:44:16 PM »
Derek:
The program was written for inches (G20). Therefore 1300 in/min. A crazy speed of 21 inches per second. (or in metric 550mm /sec)
I suspect for the A axis that might be interpreted as DEG per minute which is 21 deg per second a (somewhat) manageable number. My A axis has no problem with it (surprisingly since my motor is small) so it must be deg/min.

also

The moves in X,Y and Z as you mention, are locked together is speed only if the commands are on the same line. In the example programs the Z moves are on a separate line from the A moves with a G0 in front which should revert the Z moves to whatever the config says for maximum speed for the Z axis. (as far as I understand it anyway). It works fine single stepped.

Sage



Re: 4th axis question, possibly configuration ?
« Reply #11 on: May 15, 2011, 02:34:57 PM »
Derek:
The program was written for inches (G20). Therefore 1300 in/min. A crazy speed of 21 inches per second. (or in metric 550mm /sec)
I suspect for the A axis that might be interpreted as DEG per minute which is 21 deg per second a (somewhat) manageable number. My A axis has no problem with it (surprisingly since my motor is small) so it must be deg/min.

also

The moves in X,Y and Z as you mention, are locked together is speed only if the commands are on the same line. In the example programs the Z moves are on a separate line from the A moves with a G0 in front which should revert the Z moves to whatever the config says for maximum speed for the Z axis. (as far as I understand it anyway). It works fine single stepped.

Sage


Hi Sage,

Yes, 21"/ sec is a bit fast :-)





You can "chop it off" but can't "chop it on"
Re: 4th axis question, possibly configuration ?
« Reply #12 on: May 15, 2011, 03:59:21 PM »
Right now we are machining wood as a test piece. But the final material will be aluminum and stainless , with possibly a carbon steel thrown in. Most likely the Stainless is 410-417 and the aluminum I would assume is around 6061. Carbon steel would probably be 1045. We are using single point 1/8 45* engraving carbide tool.

This is for a checker pattern on a radius surface of .812 diameter, with only 1/3 roughly of the surface being checkered.

I ll have to check with my programmer who is working with the program, as I didn't path this out myself. But Mastercam is what we use, so I am going to take a look at it myself here shortly.

I am going to try slowing down the A axis and see what happens. But nothing makes weird noises or acts funny. Its runs smooth and as it should, other than the z losing its position.

Which would make me question, why would it just be z that loses its place, why not A or X ?

Thanks
Todd

Offline Sage

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Re: 4th axis question, possibly configuration ?
« Reply #13 on: May 15, 2011, 04:42:16 PM »
I haven't looked at the whole program carefully but, at first glance the Z commands are the ones immediatly after the crazy F feedrates.
The G0 in front of them does take effect eventually I guess (proven by single step) and apparently makes it ok for the following X move.

N280 A62.222 F1357.7
N290 G0 Z.542    <---------- G0 doesn't seem to take affect for this Z move.
N300 X-.16 A-62.222

I don't have time at the moment but try putting an X move where the Z is and see what happens. Perhaps like this.

N280 A62.222 F1357.7
N290 G0 X.1.5
N300 X-.16 A-62.222

See what happens. I suspect the X will screw up instead.

Obviously the Z IS being affected because it isn't resonding to the fast step pulses and not positioning properly. You probably don't hear anyting (like I do) perhpas because they are so fast the motors don't even respond. I have NEMA 42 sized steppers and Geko drives at full power 7Amps so they see sometihng but can resppond.

I'll try it myself in a while.


You might also try putting the G0 on a separate line for each of the offending commands and see if it helps - like this:

N280 A62.222 F1357.7
N290 G0
N295 Z.542
N300 X-.16 A-62.222

You might also try removing the F commands altogether becasue I don't see why you need them. G0 should be full speed set in configuration. So try removing them or subbing them for a G0 like these examples.

N280 A62.222
N290 G0 Z.542
N300 X-.16 A-62.222

or

N280 G0 A62.222
N290 G0 Z.542
N300 X-.16 A-62.222


Let me know what happens
Its a Mach bug as far as I can tell.



Sage
« Last Edit: May 15, 2011, 04:44:04 PM by Sage »
Re: 4th axis question, possibly configuration ?
« Reply #14 on: May 15, 2011, 04:49:37 PM »
I am going to try this tomorrow when I am back in the shop.

I am just curious as to my little machine ( the one I am using that has problems with this program , is a Novakon NM 200 with Nema 34's and Gecko drivers as well ). The little machine didn't seem to have a problem running the program, but I didn't plug a stepper to the a axis, I just ran it as is. So I am not sure , but think it would have the same problem of missing the z steps, but it doesn't.

I am going to try a few things suggested here and see what happens.

I am hoping to figure something out and get this running asap.

I appreciate everyone's help so far.

Todd

Offline Sage

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Re: 4th axis question, possibly configuration ?
« Reply #15 on: May 15, 2011, 04:55:27 PM »
Perhaps it has someting to do with how the different configs of MAch deal with such a high feedrate command.
I don't no the congif pages so well as to have an idea what might be adjusted to fix it.

I'm surprised none of the "experts" have chimed in here.

Definitely a problem here though.

Sage

Offline BR549

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Re: 4th axis question, possibly configuration ?
« Reply #16 on: May 15, 2011, 06:19:07 PM »
Just a thought, BUT do you have the A axis set to use radius for feedrate??

Config,toolpath, check box
Settings page, A radius = xx.xx

I recall there was a bug at one time that allowed the Z feedrate to be effected by the A feedrate when synced to radius.

What is the gear ratio of your fouth axis?

Just a thought, (;-) TP

Offline Sage

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Re: 4th axis question, possibly configuration ?
« Reply #17 on: May 15, 2011, 06:33:23 PM »
For me:
Box un-checked
A axis radius 0.0
My A axis is a standard rotary table at 90:1

Sage
Re: 4th axis question, possibly configuration ?
« Reply #18 on: May 15, 2011, 08:01:56 PM »
Sherline Rotary table , I believe its 72 to 1.

I ll check the config tomorrow and report back.

Thanks
Todd

Offline BR549

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Re: 4th axis question, possibly configuration ?
« Reply #19 on: May 15, 2011, 08:29:25 PM »
HUM tested here and I don't see any problem. The A feedrate is only about 11 ipm at the surface.

The feeds are also switching back and forth between feed and rapid.

Are you gaining in the z or loosing in the z?   

Is this a new machine ? Has this code ran on another machine ok?

Just some thoughts, (;-) TP