Cutter Compensation

[Southbend Sam]

I recently acquired a Hurco MHP-3K mill with a Dynapath 20 control. I have the manual and am learning to program it. For CAD/Cam I am currently using Dolphin CAD CAM and it has a post processor for Dynapath. I was recently, as a test, trying to program the cutting of a circle, normal milling, with a G42 cutter compensation using the program mode and EIA programming, I ran into problems. First the control in that mode only allows one G code per line. So my first question concerns where to place the G42 code.
I tried something like:

N20G00X0Y1.255 (for a 2"circle with a .5" endmilland .005 offset for finish)
N25G01Z-.125F5
N30G42
N40G03I0J0
etc with multiple cuts for depth.

and that gave me a circle without compensation and then multiple circles (as the circle was deepened) with compensation.
So my question is how does one use cutter compensation?

And as long as I'm asking, my post processor gives multiple G codes on one line in certain cases. My manual says you can't do this when programming . My next step will be to start downloading programs via the RS232 port. Am I going to have to fix my post processor or will the controller accept this type of program when downloaded?

I am relatively new to CNC so I thought I'd seek some counsel before bumbling along. By the way, I realize I can program a circle conversationally pretty easily. My goal is to get to the point where I can download programs via RS 232.

[CNCRim]

cutter comp only go/start with G1 or G0...... as your sample program show cutter comp with G3.

[BobWarfield]

Related to what CNCRim says, there are 2 things to keep in mind about cutter comp:

First, you can't transition into comp mode unless you're in G0 or G1 as CNCRim says. Your program is okay there as the G3 comes after the G42 and you were in G1.

Second, you need an initial G0 or G1 move that allows the cutter to transition to a comp'd move. That move has to be at least the radius of the cutter in length so that there is enough room to smoothly go from no comp at the beginning of the line to fully comped at the end of the line.

Ideally that move is done in air and not while cutting, though the control has no way of knowing or enforcing that. It's just a good practice.

Cheers,

BW

[Southbend Sam]

Thanks for the replies. I did overlook the topic on cutter comp in the appendix of the manual. That addresses lead in events. I'll go back and experiment some more.