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Help with Mach 3
« on: August 27, 2013, 08:43:25 PM »
Hello, I'm having a problem with milling a circuit from within Mach3.

I have created a basic circuit in EagleCAD 6.5 and exported it using PCB-GCODE for use with Mach3. The problem I'm running into is the circuit is being milled at about 70% of it's original size -- the overall circuit is being reduced in size.

I have Mach3 setup in millimeters and the exported GCode is also set in millimeters. I have checked over all my setting within Mach3 and everything is set to what the manufacturer of the milling machines suggests it to be for Mach 3.

I'm not sure what I'm doing wrong and any help would be appreciated.

Thanks, Chris
Re: Help with Mach 3
« Reply #1 on: August 27, 2013, 09:32:30 PM »
Hi Chris,

Check the Gcode to see if it is cutting the PCB smaller. If so then it is a problem in Eagle.

Cheers,

Peter

----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com

Offline Tweakie.CNC

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Re: Help with Mach 3
« Reply #2 on: August 28, 2013, 03:36:40 AM »
Hi Chris,

Not sure if this is any help to you or not…

I machine many circuit boards and often use different CAD/CAM software to create the layouts. As the problem of scale is always a possibility I now include in the layout an outside border, of known dimension, around the pcb (or two outside markers of known distance).
Once the GCode has been loaded into Mach3 the Toolpath tab shows the Program Limits (size of my border or distance between markers) I then, if necessary, adjust the X and Y Scale DRO’s (main screen) to get the size correct (just a simple calculation required here).

Tweakie.
KEEP SAFE !
Re: Help with Mach 3
« Reply #3 on: August 28, 2013, 10:35:00 AM »
Once the GCode has been loaded into Mach3 the Toolpath tab shows the Program Limits (size of my border or distance between markers) I then, if necessary, adjust the X and Y Scale DRO’s (main screen) to get the size correct (just a simple calculation required here).

Tweakie.


Thank you for the reply, the original circuit board in Eagle is 38mm x 38mm and when it's loaded into Mach3, it also shows 38mm x 38mm as the program limits (unless I'm looking at something wrong), Either way, I added 4 drill holes at each of the corners of the board and ran just the drill file to show what's happening (please see the screenshots in the links below). When finished, the circuit is only 28mm x 28mm.

Also, If Mach3 is properly seeing the program limits of 38mm x 38mm, does that mean the GCODE file is correct, as peter suggested it might not be?

Thanks again,

Chris

http://i1056.photobucket.com/albums/t369/jess_dawson310/Limits.jpg

http://i1056.photobucket.com/albums/t369/jess_dawson310/20130828_090315.jpg
« Last Edit: August 28, 2013, 10:37:09 AM by ckapus »

Offline Tweakie.CNC

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Re: Help with Mach 3
« Reply #4 on: August 28, 2013, 11:31:33 AM »
Hi Chris,

My guess is that your GCode is OK and that your Steps per Unit have been set incorrectly in Motor Tuning.

It is perhaps best to calculate the steps as per your equipment and Al's calculator can help http://www.machsupport.com/forum/index.php/topic,16315.0.html
Alternately, you could use the Mach3 Axis calibration feature (Settings page).

Tweakie.
KEEP SAFE !
Re: Help with Mach 3
« Reply #5 on: August 28, 2013, 12:14:32 PM »
Thank you, Tweakie.

The Motor Tuning definitely seems to be the problem.   :)

- Chirs