Tuning problems

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07 Dec 2011 00:57 - 07 Dec 2011 00:58 #15432 by submicro
Tuning problems was created by submicro
Hello

I'm having trouble tuning my setup. i.e. I ran stepconf loaded an example from the examples folder and tried to run it. then the comp says line xxx will exceed limit on joint 1 or 2 or 3 depending on the example. i know it's within the limits of my mill. I have an X2 mini mill. so what am I doing wrong? Also I'm not confident that when I tell it to jog 1 inch that it's moving 1 inch. HELP!


SubMicro
Last edit: 07 Dec 2011 00:58 by submicro.

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07 Dec 2011 01:29 #15433 by Harry_Y
Replied by Harry_Y on topic Re:Tuning problems
I don't know if this is much of a help but what I did was
instead of putting in 0 to +10 for travel I put in -10 to +10.

I do not use home switches so it worked for me

I have a Sherline lathe and Mill so I looked at how
they has setup their axis and used the idea from them.

As far as knowing is an inch is an inch.

A ruler will give you a quick method of checking

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07 Dec 2011 06:22 #15434 by cmorley
Replied by cmorley on topic Re:Tuning problems
Submicro did you set the origin for the working coordinate system? ( or in other words touch off)

I'm making some assumptions here and I hope I don't steer you wrong. Others with more experience will surely correct me:
setting the axis limits in stepconf is setting the MACHINE coordinates.
You should set the User coordinates origin (zero point) before running a program.
If you don't do that I believe EMC follows the machine coordinate (depends if there is an offset left from the last time)
and I'm betting you put a zero in for one of the axis limits (in stepconf) that means the origin is right on the limit edge
so if the program asks to move in that direction then it exceeds the limits.

Harry_Y :
I think what you are doing is setting the axis limits beyond what your mill can actually move. ( can it move 20 inches?)
You also have placed the origin (machine zero point) in the center of the travel. ( nothing wrong with that )
I bet you are not moving the table to center manually and pressing home.
All that is ok as long as you understand what you are giving up.
EMC has 'soft limits' which are limits calculated in software, EMC will never hit the hard limits barring electrical/mechanical failure.
But for that to work you MUST home. soft limits are calculated from the machine origin which is found from homing.
with out homing you are relying on the limit switches ( I hope ) to keep you safe.
The nice thing about soft limits is EMC will de-accelerate when getting close to them.

After all that - as I said it is fine to operate that way - I just wanted to point out why EMC prefers homing.

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07 Dec 2011 09:01 - 07 Dec 2011 09:10 #15438 by Rick G
Replied by Rick G on topic Re:Tuning problems
Like Chris said soft limits are great but EMC needs to know where they are to work.

A normal run without limit switch for me would be to start EMC jog the axis to it's home postion. If the X neg limit is 0 go there and hit the home button or if the neg limit and home is -10 go there and hit the home button.
Now EMC knows where you are if your limits and as Chris said if they are -10 and 10 you have 20" of travel if the work or a move tries to exced that EMC will prevent it.

Aftre setting that jog to where you want to work.
Now touch off this will set the 0 for the axis at your current location and all normal moves (G54) will go from there but if a move exceeds your machine size EMC will prevent it.

When you load a program you can see on the AXIS screen if the work exceeds your limits.

Take a look here

wiki.linuxcnc.org/emcinfo.pl?CoordinateSystems

Rick G
Last edit: 07 Dec 2011 09:10 by Rick G.

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07 Dec 2011 14:06 #15441 by Harry_Y
Replied by Harry_Y on topic Re:Tuning problems
cmorley wrote:

.........

Harry_Y :
I think what you are doing is setting the axis limits beyond what your mill can actually move. ( can it move 20 inches?)
You also have placed the origin (machine zero point) in the center of the travel. ( nothing wrong with that )
I bet you are not moving the table to center manually and pressing home.
All that is ok as long as you understand what you are giving up.
EMC has 'soft limits' which are limits calculated in software, EMC will never hit the hard limits barring electrical/mechanical failure.
But for that to work you MUST home. soft limits are calculated from the machine origin which is found from homing.
with out homing you are relying on the limit switches ( I hope ) to keep you safe.
The nice thing about soft limits is EMC will de-accelerate when getting close to them.

After all that - as I said it is fine to operate that way - I just wanted to point out why EMC prefers homing.



I'm new to EMC2 and the more I look at the capabilities and figure it out the more
I see that I really should be setting this up with Limit and Home switches etc.

I'm just a hobbyist for the most part, but it still would be nice to have things done right, if for
nothing other than being little more comfortable walking away when a long job is running.

Thank you for pointing out what I am missing with my way of doing it.

Now off to look for switches...

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07 Dec 2011 17:29 #15449 by BigJohnT
Replied by BigJohnT on topic Re:Tuning problems
Common micro switches work well.

For example this is how I installed limit/home micro switch on my plasma Z axis. The lower switch is the probe input.

gnipsel.com/shop/plasma/z-axis-02.xhtml

John

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07 Dec 2011 18:31 #15451 by submicro
Replied by submicro on topic Re:Tuning problems
Hello

Thanks everybody for the help. However I'm still confused. To clarify things this is what I'm doing.

In stepconf I set my limits to the following, X axis -4 to +4, Y axis -2.25 to +2.25, Z is not hooked up yet but I set it to -4 to +4.
Then in Axis I move the table to center of both axis then press home for each axis.

I'm not sure I understand the touch off but I tried it with no success. But I'm sure I'm not doing it right.:S


SubMicro
A.K.A Robert Willis

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07 Dec 2011 19:16 #15452 by Harry_Y
Replied by Harry_Y on topic Re:Tuning problems
BigJohnT wrote:

Common micro switches work well.

For example this is how I installed limit/home micro switch on my plasma Z axis. The lower switch is the probe input.

gnipsel.com/shop/plasma/z-axis-02.xhtml

John



I actually have a bunch of those with out the lever/roller arm.

I'll have to get some with the arm since they will have a Lil more give

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07 Dec 2011 19:18 #15453 by Harry_Y
Replied by Harry_Y on topic Re:Tuning problems
submicro wrote:

Hello

Thanks everybody for the help. However I'm still confused. To clarify things this is what I'm doing.

In stepconf I set my limits to the following, X axis -4 to +4, Y axis -2.25 to +2.25, Z is not hooked up yet but I set it to -4 to +4.
Then in Axis I move the table to center of both axis then press home for each axis.

I'm not sure I understand the touch off but I tried it with no success. But I'm sure I'm not doing it right.:S


SubMicro
A.K.A Robert Willis


What exactly is happening???

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07 Dec 2011 20:27 #15459 by Rick G
Replied by Rick G on topic Re:Tuning problems
Even though you do not have the z set up move in the axis display and home it anyway.

In stepconf I set my limits to the following, X axis -4 to +4, Y axis -2.25 to +2.25, Z is not hooked up yet but I set it to -4 to +4.
Then in Axis I move the table to center of both axis then press home for each axis.

O.K. you now have your work set at x0y0 and the x axis has 8" of travel, BUT you are in the middle of it so you can only go 4" to the limit.

Try this set the home position as you have before and then jog back to the negative limit (-4) and touch off there, now you have 8" of travel to the right and the sample is 7.43?" so it should now fit.
Do the same on the Y axis.

Can you run the program now?

Rick G

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