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Offline SMA

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Is there a real difference
« on: April 08, 2012, 04:47:43 PM »
This is probably a simple question but I am wondering this:

 There have been a few reports were small values are left in the DRO's due to rounding.  To be sure that DRO's are zeroed before moving to a position, in my case heading to home after touching off limit switches, I would like to force Mach to zero them.

Is there a difference in using a G92 Command such as G92 or DoOemButton1008,9,10.


s

Offline Hood

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Re: Is there a real difference
« Reply #1 on: April 08, 2012, 06:05:57 PM »
Homing to switches should zero the machine coords DROs unless you have a Home Off value set.
Hood

Offline SMA

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Re: Is there a real difference
« Reply #2 on: April 08, 2012, 06:20:01 PM »
Is it not possible to have small values left behind?  So VB that looks like this would be redundant I guess?

LoadMatX = GetUserDRO(1017)' read the stored values
LoadMatY = GetUserDRO(1018)
LoadMatZ = GetUserDRO(1019)


DoButton(24)
RefCombination (1 + 2)
While IsMoving()
Wend
DoOemButton(1008)
DoOemButton(1009)
DoOembutton(1010)
Sleep (2)
Code ("G53 G1 X" & LoadMatX & " Y" & LoadMatY & " F1500")
While IsMoving()
Wend
Code ("G53 G01 Z" & LoadMatZ & " F600")'
While IsMoving()
Wend
DoOemButton(1008)
DoOemButton(1009)
DoOembutton(1010)

Offline Hood

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Re: Is there a real difference
« Reply #3 on: April 08, 2012, 06:31:27 PM »
Without looking up oems etc it would see that macro is to set a work offset up, that is a totally different thing from homing alone.
Homing to a switch will set DROs zero and then if moving to a position and your steps per unit dont allow that exact position then Mach will move as close as it can. Unless your steps per unit are very course then that would not matter as it would be a very small amount, add to that the fact that Mach will keep track to I think 16 decimals then the moves are not rounded as any following moves will take into account the previous small shortfall.
Hood

Offline SMA

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Re: Is there a real difference
« Reply #4 on: April 08, 2012, 06:57:57 PM »
That is correct.  I am bad with terminology.  This sends xyz back to limits.  Touches off and runs out to what is a work offset.  I was "advised" by an old hand at CNC that I should "force" the DRO's back to Zero after touching off switches with a G92.  I thought it might be cleaner to use the OEM's 1008 1009 1010 (zero xyz) to do the same job but started to wonder if they might be different in some way.

The VB I posted previously was one you wrote for me a year ago and it has worked perfectly but sometimes the return to the offset would be maybe .5mm off.  I wondered if it could be due to small values in DRO's.  It may be due to a limit switch that is only so accurate but still thought I would try and add a command to be sure DRO's are zeroed before axis roll out to the workoffset.

Here is the script that was designed to do the same job.  Note teh G92 Commands.

Dim LoadMatX As Double
Dim LoadMatY As Double
Dim LoadMatZ As Double
Dim SafeZ As Double

LoadMatX = GetUserDRO(1017)' read the stored values
LoadMatY = GetUserDRO(1018)
LoadMatZ = GetUserDRO(1019)
   If LoadMatX > 0 And LoadMatY > 0 And LoadMatZ > 0 Then
      Code "M05"
      Code "G28.1 Z1.00"
      Code "G92 Z0.00"
      Code "G28.1 X1.00 Y1.00"
      Code "G92 X0.00 Y0.00"
      Code "G04 P2"
      Code "G01 X" & LoadMatX & " Y" & LoadMatY & " F1500"
      Code "G92 X0.00 Y0.00"
      Code "G01 Z" & LoadMatZ & " F600"
      Code "G92 Z0.00"
      While ismoving()
      Wend
   End If  
 
The G92's are to resolve the 1mm value after the G28.1 commands in this instance but are also used for resetting DRO's at the end instead of OEM callouts.  There is a pause as well before the roll out to the workoffset?   

I guess I might have answered my own question but still would like to know

Is calling up an OEM to Zero DRO's equal to using a G92 Command.

Thanks Hood.  I really appreciate you engaging in this.  I am sure my lack of knowledge makes the post confusing but I am reading like crazy trying to answer my own questions before psting them.

Offline BR549

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Re: Is there a real difference
« Reply #5 on: April 08, 2012, 07:57:48 PM »
You could just use the RefHome to reset the machine and use the G28 offsets to make Your Loadmat positons your G28 home. This is done in Gen config/ Homing page. You will see where to enter the G28 offsets.

G28.1 Z0
G28.1 X0Y0

That sets the machine to Machine Zero or G30 home. IF you had applied the offsets to that function then the G28 home X0 Y0  would be at the LoadMat positions

To go there G28 X0Y0 Z0 takes you there. JUST remember that IF you have added any more offsets or fixture changes then when you GO TO HOME the numbers may not read zero BUT you will be in the correct position. 

Just a thought, (;-) TP

« Last Edit: April 08, 2012, 08:00:57 PM by BR549 »

Offline BR549

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Re: Is there a real difference
« Reply #6 on: April 08, 2012, 08:39:46 PM »
Almost forgot to answer your question

CB calls to zero the Axis is NOT the same as G92.

The ButtonCall offsets the Active fixture offsets. The G92 does not effect the fixture offset but applies a local offset.

(;-) TP