hole size cutting smaller than program

[Danno]

I just finished converting a router table and this is my first test piece.
Everything works great, and all dimensions but one are right on size except the 2 1/2" diameter hole in the center.
For some odd reason, it measures 2.420" ??
I really have no clue why just that one hole would have machined smaller.
Hopefully someone has an idea.

I'm using OnShape for my .DXF drawings, and Dolphin CAD/CAM to generate the G-code.
Machine is running on Mach4 with ESS.

I've enclosed the drawing, but I'm unable to post the complete .TAP file used to cut the part, so I posted the first part of the program because the 2 1/2" hole gets machined first.
I will also ask on the Dolphin Cad forum.
Thanks for any help.
Dan

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[awerby]

I'm not familiar with Dolphin, but it sounds like the sort of error you get when you intend to have the tool run on your circle, but instead it runs inside it. There's usually a setting that specifies whether the cut is inside the line, on the line, or outside the line.

[Danno]

That's not the problem. If it ran "on" the line, the hole would be .250" smaller ( it's only .080" smaller)
The odd thing is that the other contours are dead on size including the four .375" dia holes that were programmed the exact same way as I programmed the 2 1/2" hole. (pocket clear cycle)

[the_gentlegiant]

Any way to post the code for the center hole bigger? Can't see a thing. Also include what size tool you're using.

[joeavaerage]

Hi,
in most CAM softwares there is a setting <Stock to Leave>. It is usually set to 0.1mm or similar on a roughing toolpath
and is intended to be cut in the final finishing pass. Is it possible that this operation has inadvertently got <Stok to Leave> set?

Craig

[ger21]

My guess would be a mechanical issue.