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Tips/Techniques Intermixing metric and imperial on a CNC machine

Tips/Techniques

jcdammeyer

John
Premium Member
I would like to say I've gone totally metric but in fact I still have the the CAM program generate imperial movement commands. If I type in the MDI window G1 X2 F3 I know it goes 3 inches per minute and I have a feel for that speed. If I was running the machine in metric mode then the feed is 76.2 mm per minute which is a value I can't get my head around. Plus I have to remember that the machine would be in metric mode especially since an F76.3 in imperial mode is quite fast.

The problem is so many of the drawings for say the robot arm are in mm not inches or dual dimensions from the drawing. So if I've done a project using say a 1/4" two flute cutter as Tool #3 the dimensions in the dialog are in inches.

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But the software hasn't got a parameter in the tool table definitions to flag it as metric or imperial so if I bring in a drawing which is done in metric dimensions the G-Code generation now assumes that the tool diameter is 0.25mm not 0.25".

If I say well just change the global parameter for the document to be imperial rather than metric no problem. Except all the work done to set up tool path programss for each tool etc. vanish.
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With the list above wiped out I have to start over again for example all the center drill points first.
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And so on. So what I thought might be the easiest solution is to create two tool tables and load the appropriate one depending on metric or imperial drawings.

The table would still have a Tool#3 but instead of 0.25 diameter the value would be 6.35 and feeds and speeds would change from 11 IPM to 280 mm/min.

None of this would be needed if the MECSOFT AlibreCAM was able to switch units without destroying all the tool path programs.

And just as an aside, when MECSOFT stopped supporting Alibre they offered the identical MECSOFT VISUAL CAM software except now it imports a STEP file where often a circle is two half circles. Again more tedious to work with.

Want to make one tiny change to make machining easier, change the drawing, export the new STEP file and import back into MECSOFT CAM with the total loss of all the pre-programmed motions. In other words start over.

Sorry for the ramble.
 
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