Hi All,

I have a PRS Standard 5x12.

Things run great X,Y,Z in a straight line. I've made some intricate cassette tape cabinets and the math on those all checked out when I was done.

Today I went to make some large arcs connected with flat ends and the two identical shapes came out different.

The shapes were drawn in Rhino and imported into Aspire 9. I drew a bounding box 48x96 so i could stay within the plywood area. I carefully rotated the shapes in Rhino so they were nested. Once I was done I exported the geometry as a DXF and opened it in Aspire where I made the tool paths.

So even though the two shapes are copies of each other, they come out not matching. There are flat ends connecting the arcs and they aren't the same length, even the curves of the arcs are slightly off when you put the pieces face to face. The pieces are about 90" long.

What is also strange is that the pieces are otherwise flawless. I used a downcut .375 roughing bit and only took .120" passes at 40ipm. There doesn't seem to be any play in the gantry and all the passes seem to be lining up with each other, so my thinking is that it's not slipping somewhere if it keeps making the same (wrong) shape over and over.

My inclination is that it's software, but I'm wondering if anyone out there has any ideas.

Also, is there a verifiable way to do the Circle test? Like, after you run a circle ( say 6") and let's say it's off.. then what? Asking for future me. (I'll test tomorrow morning)

thanks in advance to everyone who has any ideas.

all my best,
JAMES