Hi, I use Mach3 to mill pcbs. My software chain is DipTrace -> CopperCam -> Mach3. I'm a happy user, but I've got problems when the holes I want are bigger than my drill piece. I'm pretty sure my gcode files are OK, because everything looks OK when I load the drill files into my dummy Mach3 installation on the laptop. However when I load the files into my main work machine it seems like the hole centers are replaced by the file origin. All circular boring holes become ridiculously big and inside each other, not side by side.

I suppose my problem is easily solved with a simple check button tick somewhere, but I haven't been able to find it. Can anyone here please help a newbie in need?

Perhaps your I J mode is set incorrectly on your machine PC.
Config/General Config/ mid screen.

Russ

Thanks for replying, that sounds like a reasonable solution. I'm not able to check it, though, because my mill is out in the woods in offline-land. I've got CopperCam set up to export G-Code ISO standard, and the next option is to export G-Code Num version(I/J absolute). My laptop Mach3 that shows things right has IJ mode set to incremental, and I'll bet my machine PC has it set to absolute.

Problem hopefully solved, thank you, Russ!

Yup, I can confirm that this solved the problem. So now I've got a GREAT way to break my 1mm drills... any advice on this?

You can, or can't confirm ?
IJ might not be your problem. Circular boring holes ? ? ? ? with a drill bit ? or an endmill ?
Post the file so we might see the issue.
Russ

My initial problem with Mach3 showing the circles wrong was fixed with the I/J mode setting. But as I said, I'm new to this, and I've found out that circular boring with a drill bit is a bad idea. I also tried with a 10 degree V-shaped bit, but didn't like the results. So I suppose I'll have to find some other bit that'll work somehow, or I'll have to start putting small (<1mm) and big holes (>1mm) in separate drill files, but I'd rather not.

I've attached the file that broke my 1mm drill bit. Thank you for any advice.

Drill bits can't cut sideways, they have wide lands and no relief. You need an end mill for mill boring a hole. If you are only doing circuit boards look for a stub length mill, with the depth of cut only slightly greater than the board thickness. Doubling the length of a tool reduces the stiffness by a factor of 4!

Thanks. So this means if I'm milling a circuit board with some of the holes bigger than 1mm I shouldn't be using a drill at all but an endmill, because drilling holes with endmills is OK too.... ?

End mills technically can not be used for drilling as they are meant for side cutting. You do however get "end mills" that are centre cutting and most 3 and 4 flute ones nowadays are, but not all so be aware of that. You could use them for drilling although the ideal tool for drilling is, not surprisingly , a drill.
Hood

There are also Mill-Drills that can drill, mill, chamfer and countersink, but I have not seen them as small as what you are probably requiring.
You might be better off to do a tool change and use the proper size drill bits for the various holes. (at a glance, 2 in the case of your attached code)
Adjust your CAM output to Drill Points instead of circles for the larger ones.

Variations on cat skinnin',
Russ