Can't get xyzx motors to work

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17 Apr 2011 19:06 #9008 by andypugh
mmccoo wrote:

I still need to adjust my base period and try to get a better step speed. Since I'm using a g540, I need 200*10*20 steps per inch (200 for the motor, 10 step microstepping that the gecko does, and 20 TPI on the screw.). 40000 steps/inch. If I set my base period at 30k (given the latency I saw), I should be able to do half that many steps/sec right? I could max out at 40k/15k. inch every 3 sec and 20IPM

You can get 1 step every base period (with "reset" turned on on the relevant pins)
10x microstepping is a bit of a drawback in this context. Can it be turned down to 4x?

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17 Apr 2011 19:36 #9009 by BigJohnT
Andy,

The 540 is a pint sized 203v and both are fixed at 10x.

John

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20 Apr 2011 04:48 #9155 by mmccoo
ok, things are moving along but the confusion continues.

So, I'm able to move the gantry as a unit if:
1) I go to each axis and click on home. I don't have limit switches set yet (more on that in a sec)
2) I switch to world view. or go to MDI view. both require #1

ie, no homie, no movie.

fine. feels a bit clunky but whatever.


So now I've connected my limit switches I do this partially to keep my machine from breaking itself, but honestly, I don't know that it's strong enough to do that.

Now when I tell it to home, it wants to only move the one axis. now, my gantry has a fair amount of flexibility; one side can be off the other by an inch or two. (this is why I added the second motor)

But what if the gantry is a foot away from the limits. Am I supposed to let one side move that foot followed by the other?

To make things worse, I can't even use manual mode to get it close enough (see 1 and 2 above)



Surely this is not a unique situation. how do I tell it to home joint 0 and 1 together and make the appropriate adjustments to each. how do I manually move the gantry to "pretty close" so I don't have to wait forever for it to creep up on the limits?

What's the special sauce?


Miles

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20 Apr 2011 09:40 #9159 by andypugh
mmccoo wrote:

Now when I tell it to home, it wants to only move the one axis. now, my gantry has a fair amount of flexibility; one side can be off the other by an inch or two
...
But what if the gantry is a foot away from the limits. Am I supposed to let one side move that foot followed by the other?


The trick is to give the same homing sequence number to both "joints"
Look at HOME_SEQUENCE= at
www.linuxcnc.org/docview/html/config_ini...b:%5BAXIS%5D-section
and you might also want to read
www.linuxcnc.org/docview/html/config_ini_homing.html

Assuming
X1 = 0
Y = 1
Z = 2
X2 = 3

Then you would typically have in the relevant parts of the INI file

[AXIS_0]
...
HOME_SEQUENCE=1
...
[AXIS_1]
...
HOME_SEQUENCE=1
...
[AXIS_2]
...
HOME_SEQUENCE=0
...
[AXIS_3]
...
HOME_SEQUENCE=1

That will first home Z (presumably upwards, out of the way) and then home both X joints and the Y joint simultaneously.

Once you have a home sequence defined you should find that the "home axis" button becomes a "home all" button.

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20 Apr 2011 09:42 #9160 by andypugh
I forgot to say:
It would be really neat to have the machine automatically switch to World mode once homed. There are ways to do that with logic in the HAL file (though I can see good arguments for it being an INI file option)

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22 Apr 2011 02:12 #9245 by mmccoo
Ok, The homing sequence thing worked.

Still leaves me short of where I want to be though it's starting to be workable.

1) Andy: you mention that through logic in HAL one can get it to switch to world mode. Is this something you wish for or something you have. If the latter, please do share. ;-)

Honestly, I see the world view as a more logical default state.

I still have the issue that until I'm homed, I can really do anything.

2) is there a way to tell emc2 to just consider everything homed? something like setp axis.0.homed true (homed is on output unfortunately). This was I can manually guide the machine to close to homed followed by hitting the home button.

I guess I would ask why I must be homed before I'm "allowed" to use world view? I'm standing right in front of the machine. I know where each axis is. I would understand an override, perhaps, but as it is it just says, "nope"

Rather annoying behavior, so I'd appreciate any advice on this.


Either way I thank all those who have replied to this thread. I'm trying to avoid installing windows on this machine and using mach3. mach3 does work with this machine and is rather easy to configure. It's unfortunate that it's sucking up so much time making it this far. Assuming I arrive at a satisfactory configuration, I plan on taking some time to add a bunch of comments to the ini and hal files and posting them for the benefit of other newbies.

Miles

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22 Apr 2011 04:08 - 22 Apr 2011 04:09 #9248 by andypugh
mmccoo wrote:

1) Andy: you mention that through logic in HAL one can get it to switch to world mode. Is this something you wish for or something you have. If the latter, please do share. ;-)

It was rather speculative, though I think that the pins exist in HAL.

Honestly, I see the world view as a more logical default state.

Yes, definitely. To be honest custom kinematics isn't the best fit for gantries. Much of the time you are probably better off just sending the same step pulses to 2 drives in a conventional config. You lose auto-square bit get back incremental and jog-wheel jogging.
It's one of those "known issues" which is likely to get improved when the hard-link between motor-0 == joint0 == X-axis is removed

2) is there a way to tell emc2 to just consider everything homed?

Luckily, yes :-)
www.linuxcnc.org/docview/html/config_ini...b:%5BTRAJ%5D-section
(NO_FORCE_HOMING in the [TRAJ] section of your machine INI file
Last edit: 22 Apr 2011 04:09 by andypugh.

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