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Author Topic: mach3 and the cartesian coordinate grid  (Read 3530 times)

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Offline kosmo

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mach3 and the cartesian coordinate grid
« on: May 16, 2012, 05:53:56 PM »
When I test run the roadrunner program mach seems to run in the wrong coordinate. All X & Y values are positive in the program yet according to the cartesian grid it runs in the X- & Y- grid (roman numeral 3 on the picture). I am a former cnc machinist and am use to the X+ & Y+ being in the number 1 section of the grid. The machine behaves like it should, when I hit the left arrow key the x axis moves to the left. When I hit the up arrow key the Y moves away from me, same with the Z. Machine homes correctly. What do I do to change this feature ? Thank You

Offline Hood

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Re: mach3 and the cartesian coordinate grid
« Reply #1 on: May 16, 2012, 06:18:15 PM »
How are you determining that it is running in X and Y negative?
Are the X and Y DROs showing negative values?
Are you possibly looking at machine coordinates?
When you are saying press left key and X moves to left and press Up arrow and Y moves away are you taking about the tool direction in relation to the work or the table direction if a knee mill?
Hood

Offline kosmo

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Re: mach3 and the cartesian coordinate grid
« Reply #2 on: May 17, 2012, 12:09:39 AM »
The arrow keys move the TABLE in the desired direction. I have a retrofit Bridgeport boss 4. When standing in front of the machine and homing, the machine zero is on the left front side of the table. Bridgeports have a half circle cut out on the table that shows machine zero. When jogging away from machine zero point X & Y DRO read minus values. This is normal in cnc machining.
 When it comes to setting the work zero (G54) it should follow the cartesian grid. If I move the tool to the center of the table and place the grid under the tool at X0,Y0 (red dot on grid) and call this G54, then any positive XY values in the program should move the tool in quadrant 1, regardless of where machine zero is. All my movement is in quadrant 3 of the grid which would be all XY negative values in the program.
Its like a reverse mirror image.
And to top it all off, I now have my z axis stuck. Traveled beyond the limit switch and jammed.
Sometimes I think its better to kick yourself in the nuts and stay in bed all day than to take on the headache of cnc troubleshooting ! ;D  

Offline BR549

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Re: mach3 and the cartesian coordinate grid
« Reply #3 on: May 17, 2012, 12:24:48 AM »
WITH a bridegy the table itself should move backwards to the jog controls. The quadrants are based on tool tip movement not table movements.

From a front left Zero/Zero  IF you push the X pos jog key the "table" moves left. IF you push the Y pos jog key the "table" moves towards you

Just a thought, (;-) TP

Offline BR549

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Re: mach3 and the cartesian coordinate grid
« Reply #4 on: May 17, 2012, 12:48:39 AM »
Remove the Z belt cover (2 screws) then use a large straight screwdriver to back the belt sprocket(spindle side not motor side)  up to unstick the Z axis. (;-)

A wise fellow would wire the first switch  to limit/home and the top switch as ESTOP it is really hard on them to jamb the z all the way up. ASLO very agrevating.

Benn there many times before the Estop conversion as MACH is not always keen on stopping on home switches EVERY time. (;-)

(;-) TP

Offline Hood

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Re: mach3 and the cartesian coordinate grid
« Reply #5 on: May 17, 2012, 02:22:32 AM »
As Terry has said and I alluded to in my post you have the X and Y motion reversed by the sounds of it. Table should move right with left arrow and towards you with the up arrow. If you look at the tool in relation to a work piece on the table it will then make sense.
Hood

Offline kosmo

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Re: mach3 and the cartesian coordinate grid
« Reply #6 on: May 17, 2012, 11:41:03 PM »
Want to Thank You both for the input, it all works now! ;D When it came to freeing up the Z, I would only recommend using a hard wood punch type tool. I used a piece of osage orange tree branch shaved down to fit against the pulley to knock it free. A screw driver or metal object will damage the internal pulley. Great tip about the top switch being used for an E-stop. Will do   Thanks again for the help