Workspace

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21 Sep 2010 00:54 #4263 by occesar_0
Workspace was created by occesar_0
Does somebody knows if there is some way to calibrate automatically my workspace?

I was thinking something like "scan" the space between my maximum limit switch and my minimun limit switch and therefore achieve a good accuracy or on the other hand, can you tell me how did you do your calibration to define exactly your workspace?

One more question...

When there's soft limits, who is first? I mean, inside the space of my soft limits should stay also my limit and home switches?

I was imagining that in first place there's a soft limit, after it, a limit switch and then a hard stop switch or am I wrong?

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21 Sep 2010 11:34 #4270 by andypugh
Replied by andypugh on topic Re:Workspace
occesar_0 wrote:

I was thinking something like "scan" the space between my maximum limit switch and my minimun limit switch and therefore achieve a good accuracy or on the other hand, can you tell me how did you do your calibration to define exactly your workspace?

I am not sure what you would use as your calibration reference.
You could use a set of glass scales (or a laser interferometer, or similar) to define a screw compensation file. That is not automatic though.
wiki.linuxcnc.org/emcinfo.pl?Screw_Compensation

I was imagining that in first place there's a soft limit, after it, a limit switch and then a hard stop switch or am I wrong?

There is normally only a limit switch. The soft limit needs to be fractionally inside the limit switch.

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23 Sep 2010 16:02 #4302 by jmelson
Replied by jmelson on topic Re:Workspace
occesar_0 wrote:

Does somebody knows if there is some way to calibrate automatically my workspace?

I was thinking something like "scan" the space between my maximum limit switch and my minimun limit switch and therefore achieve a good accuracy or on the other hand, can you tell me how did you do your calibration to define exactly your workspace?

If you have switches, then you can home the machine to those switches, establishing a repeatable coordinate reference system. Once homed, you only need to find the limits once, and enter that into your .ini file. Why automate a procedure that only needs to be done one time? Just hold down the jog keys until it hits the limit,
then observe the position in the machine coordinate system. Write these down for all axes and then enter slightly smaller numbers for MAX_LIMIT and MIN_LIMIT for each axis, and you are done. This will only take
5 minutes.

One more question...

When there's soft limits, who is first? I mean, inside the space of my soft limits should stay also my limit and home switches?

I was imagining that in first place there's a soft limit, after it, a limit switch and then a hard stop switch or am I wrong?

You can rig up all that extra complexity, but except in the case of $100,000 machine or those that move at extremely high velocities and therefore could be unusually dangerous, it may not be necessary to have so many levels of safety. I only have home switches and soft limits on my machinem no hardware limits at
all.

Yes, the innermost safety margin should be the soft limits. If your G-code commands a move exceeding these limits, you will get an error message when LOADING the G-code file, BEFORE you even hit Run! If you jog to the end of the soft limits, the machine will decelerate smoothly and stop right at the limit. The other hardware limits are only there in case the computer or servo drives go haywire.

The proper way to use this is to touch off your coordinate system on the workpiece before loading the G-code program, so the coordinate alignment is correct when you load the program. Otherwise, you can get false "X-axis move exceeds machine limits" type messages, because the program assumes the workpiece zero is at the left edge, but the last touch-off had the zero at the right edge. If you do this, you then just have to cancel the message, and touch off the coordinate system, then when you hit Run it will check it again.

Jon

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24 Sep 2010 17:21 #4316 by occesar_0
Replied by occesar_0 on topic Re:Workspace
Andypugh
Well! I think that a laser interferometer is a great idea, I like that advice.

Jmelson
That's exactly what I expected to read, so, there's no doubt.

I did it just like you did it, and now is working with big accuracy.

By the way , you're right I was adding extra complexity and I'm quiet now. Thank you for your time

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