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Author Topic: Coordinate Shift When Thread Milling  (Read 8499 times)

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Offline AJA

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Coordinate Shift When Thread Milling
« on: December 07, 2010, 05:31:21 PM »
Thread Milling Problems

When I attempt to run an old threading program (Mach 3 Wizards) my y-axis shifts about 4 inches.  When I returned to the center (eyeball) of the 6 mm shaft both the machine coordinates center, and the dro centers are off by approximately 4 inches.
I also lose the ability to jog, unless the shift key is used.
If I reload the program, using the machine coordinates I can return to the center of the shaft.

I have generated a new g code using Mach 3 Wizards with the same effect.

If I run an old circle g code, everything seems to work normally.

Any ideas as to what's going on?
AJ

Offline Hood

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Re: Coordinate Shift When Thread Milling
« Reply #1 on: December 07, 2010, 05:48:59 PM »
Can you attach the code and your xml.

Hood

Offline AJA

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Re: Coordinate Shift When Thread Milling
« Reply #2 on: December 07, 2010, 07:40:20 PM »
See attached file

Offline BR549

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Re: Coordinate Shift When Thread Milling
« Reply #3 on: December 07, 2010, 09:05:13 PM »
Ran your code here it is fine. One note T0 is technically a reference point for the tool table and in general not a good idea to use it for actual use.

Please check your fixture offsets to make sure there is not a number in there that would represent the shift value.

Just a thought, (;-) TP
« Last Edit: December 07, 2010, 09:07:00 PM by BR549 »
Re: Coordinate Shift When Thread Milling
« Reply #4 on: December 08, 2010, 03:04:55 AM »
Hi,

I often use T0 when the program uses only one tool - never had a problem.
Only difference I can see is that when using T0, I never use G43. I dnot think an offset can be applied to T0 - maybe Mach is getting confused by that ????
I maybe way off, but you never know.

Also I always apply the tool length offset on the next line of the tool change...i.e
T1 M06
G43 H1

ATB
Derek
You can "chop it off" but can't "chop it on"

Offline AJA

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Re: Coordinate Shift When Thread Milling
« Reply #5 on: December 08, 2010, 11:06:38 AM »
Any ideas why the machine coordinates do not repeat when I return to the center shaft.  My understanding is that the machine coordinates in Mach are always repeatable as a reference to table position.  After I run this code, the machine coordinates change!

Offline BR549

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Re: Coordinate Shift When Thread Milling
« Reply #6 on: December 08, 2010, 11:27:10 AM »
THis is a problem for Brian to addresss. It seems there is a random coord shift occuring in several areas that I cannot get to to verify.

HUM?  now when you say the machine coords have changed do you mean the user Coords or the actual machine coords?? There is a difference.

I see where you wrote when you returned to the 6mm stub the values were different that would be users corrds unless you changed over to veiw the machine coords.

Every small tip may lead to the answer(;-)

Just a thought, (;-) TP
« Last Edit: December 08, 2010, 11:31:17 AM by BR549 »

Offline Hood

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Re: Coordinate Shift When Thread Milling
« Reply #7 on: December 08, 2010, 01:56:58 PM »
I am not sure if you saw it before but I will ask again,  please attach your xml and I will try and simulate here.

Hood

Offline AJA

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Re: Coordinate Shift When Thread Milling
« Reply #8 on: December 08, 2010, 02:36:14 PM »
The actual machine coordinates change.  

Operation:

When I center spindle over shaft:  MC x=17.9441, y=6.6080.   Zero user coordinates, x=0 y=0

Load code:  MC x=455.7804, y=167.8425  User coordinates x=437.8363, y=161.2346.  This change occurred without running the code.

If Mach 3 is shut down and restarted the shaft zero is again x=17.9441 and y=6.6080.  

Offline AJA

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Re: Coordinate Shift When Thread Milling
« Reply #9 on: December 08, 2010, 02:39:34 PM »
Hood,
I saw it but I don't know what the xml is.