Machsupport Forum
G-Code, CAD, and CAM => G-Code, CAD, and CAM discussions => Topic started by: lokey on March 30, 2009, 09:12:25 AM
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Hi, What does G73 do? On the mill options tab on the ports and pins configuration page there is a general option selection for G73 and pull back for when no switches used. Mach 3 will not let me apply this option. Is there away to set option? Thanks in advance for any feedback received.
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G73 is a peck drilling cycle, the pull back is the amount the tool jumps up to break the cuttings.
Graham
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Hi Graham, Thanks for the feedback. I am using a Zenbot with Mach3. I am trying to cut a rotor for a wind turbine. The image file is attached. Every time a circle is cut the the center point shifts positive by 0.001 of a inch on the machine but is not shown in the position DRO. When the last circle is cut the center point of the project is off by about 1/8 of an inch. I need to write a macro that will solve this problem. I am new to Mach3. I watched the videos on VB script. If anyone has any ideas or can point me in the right direction please let me know. Best Regards
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If the position is changing then you are loosing steps, you need to fix this by retuning the motors or slowing the rapids or reducing the cut size, a macro will not fix this.
Graham
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OR possibly the steps per unit setting is not correct????
Just a thought (;-) TP
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Hi, I tried the suggestions and the machine still has the same problems. I tried the axis calibration and the circles where cut as ovals. The problem remains the same, after a circle is cut, the next circle that is cut is not centered on the last. There is a shift positive of 0.001. The affect accumulates and the last circle cut is off by about a 1/8 th of an inch. The same problem occurs in other projects with many chains contained within many layers. Thanks again for the feedback and if anyone has a idea how to solve this problem please let me know. Best Regards
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DOes MAch show the correct position values?? and the machine NOT cut where it is suppose to? IS your code correct. Has it always done this or just started?
(;-) TP
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Hi, after each chain cut of a circle the DRO shows the correct value but the machine shifts to the positive.
A simple G code test of
G1 X 0.5
G1 X 0
The DRO reads 0
The Dial Test Indicator reads 0.003 and if I run the code more than once the problem adds up and the machine shifts to the positive and the DRO reads still reads 0. This is causing each circle to be off center a little more after the last. The last circle in the project is of center by about a 1/8 th of and inch.
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IF you have confirmed that the steps per unit are CORRECT(measured) then it is either missed steps ( too fast accel rate) or gained steps( noise) or something loose on the machine. Couplers or pulleys not rigidly mounted tightly to screws and slip under load.
(;-) TP
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Hi, Lokey
Post your xml file if you can.
Some axis driver boards are sensitive to LowActive settings in ports & pins, Motor Outputs.
Are all your Low Actives set the same for X, Y & Z, "They should Be". If an axis runs backwards use "Reversed" in Home & Limits page to reverse It.
This can cause lost Step's.
Chip
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Hi, I loaded a copy of .xml file. It does not appear to be loosing steps, it moves the same distance every time, there is just a .0025 shift to the positive after each chain is cut. Would installing home switches solve the problem or maybe write a macro for a software solution?
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Hi, Lokey
I don't think so, Try setting your LowActives as shone in the first pic below, If that doesn't help, Set it up as shone in the sec & third pic's.
All of your Axis LowActives should be the same for Step & Direction State, All "Check" or "X", The only exception to this is if the axis controls are not the same type.
Edit: Also try the Sherline 1/2 step mode 4'th pic, It will increase the Pulse width and give your axis cont. more time to see the pulse's.
It's strange that it's only the X axis, Can you swap the axis cont. boards around to trouble-shoot it ?
Give us a better description of your setup.
Post your G code file.
Chip
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Hi, I the problem occurs on all the axis x,y,and z. I was hoping to find a fix for x and then repeat for y and z. I get overwhelmed if problems become to complex. One question, does it matter what Cycle Jog Step is set to when running a project? I will try your suggestion and report finding. Thanks again and best regards.
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Are you running G90 or G91 mode? Is it possible that your system is experiencing rounding errors? In G91 if your code has X.0015 and your machine only moves .001 this could add up.
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Hi, here is copy of the G code. I am still testing other suggestion. Thanks again for all help being received. Best Regards
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Hi, I found a solution without having to write a macro. I replaced G28 with G28.1 X-0.0015 and I was able to perform the repeatability test with a great degree of accuracy. I had to set the Home software limit to less than zero. When I cut a project I will have to Home the machine after each chain is cut. Thank you very much for all support.