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Author Topic: Mach4 y coordinates are wrong when machining  (Read 355 times)

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Mach4 y coordinates are wrong when machining
« on: August 07, 2019, 09:26:02 AM »
Dear people,

Iam trying to mill a large pocket in a piece of wood which need to be the same distance between the upper outside stock and the lower outisde stock. The gcode is correct in fusion360 but when I machined the part the lower dimension is 9,5cm and the upper is 10,5 mm. When I try a smaller part with the same feature it is correct. So looks like mach4 shifts the y coordinates when it starts the program. The x values are the same as my drawing but the Y value is shifted.

It is strange because when I try a smaller part, with the same feature and adjust the feature dimensions to the stock size, the problem does not occure

I use g54 to define my work coordinates. Could someone please help me. Iam really lost what it could be

Offline Chaoticone

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Re: Mach4 y coordinates are wrong when machining
« Reply #1 on: August 07, 2019, 11:01:18 AM »
If your steps per are not right the further you go the worse it gets out. Check you backlash and calibrate your motor tuning. These 3 links will help. They are very short and very relevant.

https://www.machsupport.com/forum/index.php?topic=12513.0

https://www.machsupport.com/forum/index.php?topic=12512.0

https://www.machsupport.com/forum/index.php?topic=16315.0
;D If you could see the things I have in my head, you would be laughing too. ;D

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Re: Mach4 y coordinates are wrong when machining
« Reply #2 on: August 07, 2019, 01:20:41 PM »
I don't think that is the problem.  Ok let's say that I have a rectangle(A) which is 200mm x 200mm and I want it on the center of a plate which is 400mm x 400mm(B). So on all sides between rectangle A and B is the distance 100mm if it is correct. But the problem I now have is that the A is 200mm x 200mm and the distance between A and B is in the x direction 100mm on both sides. But the distance between A and B in the Y direction is 99,5mm in the upper part and 100,5mm in the lower part.

So if the counts would be wrong rectangle A would not be 100mm x 100mm am I right? And the strangest thing is that when I try to run a small part the problem never occurs. And then when I enlarge the part with the parameters in fusion360 this problem occurs. I only need to change the stock size, because I have constraint the sketches to the stock so it adapts.

Hope this explanation is clear. Thanks in advance and for the former reply

Jelle