Re: I need help defining cutter compensation (Offset?) in Dolphin CAD/CAM

Eric,

In the long run you'll be much better off letting the CNC controller
do the offsetting rather than doing it in CAM. Of course this only
works if your controller supports CRC (cutter radius compensation), I
think Ahha does.

To have your controller handle the CRC, requires the CAM software to
insert the correct offset commands, G40,G41,G42, in the appropriate
places in your Gcode file. I don't know anything about Dolphin so I
have no idea whether it will do this for you automatically, or
whether you have to manually edit the Gcode file and insert the
commands yourself.

The best reason to let the controller handle the CRC is at any time
you can cut the same profile using the same Gcode file with whatever
diameter end mill you have handy. You could just as well cut with a
1/8" or a 3/16" and so on. The end result would be the same. All
without having to re-generate a new Gcode file to reflect the cutter
diameter.

Another important reason for controller CRC, you can easily adjust
part size by varying the actual tool's diameter in the control's tool
offsst table. For instance, if because of cutter deflection, your
milled square profile comes out too large, just re-run the same
Gcode, but change the tool offset table so the cutter is shown as
smaller than it actually is.

In summary, tool offsetting in CAM is a bad habit. In theory, it may
sound good, in practice it isn't. Unfortunately, some controllers
don't support CRC so you have no other option.

Doug

--- In CAD_CAM_EDM_DRO@y..., glee@i... wrote:
>
> First off, I am a newbie so please forgive the question as I am
sure this
> is basic stuff..
>
> I have recently started using Dolphin and I am very pleased with
what I
> have been able to do and the ease of use. So far, most of the
problems I
> have faced, I have been able to resolve myself either through the
manual,
> help file or trial and error. This one stumps me but largely
because I
> don;t fully understand the concept. I suppose I would have this
problem
> with any product until I get the concepts down.
>
> Here goes:
>
> I am using Dolphin CAD/CAM and I have defined a pay (say it is a 1"
square)
> that I want to cut to .125"
>
> I have drawn my square in the CAD Module and then I defined my
contour.
>
> Next I went into CAM and defined a tool (1/8" End Mill) and
selected the
> tool to apply to the cut.
>
> I generate the G-Code effortlessly and put it onto a floppy to take
to the
> shop.
>
> In the shop (I'm using an AhHa controller with a Sherline Mill) I
load the
> file from the diskette onto the hard drive and run the part.
>
> The part came out just fine. When I go to measure it I find that
the part
> was cut on centerline. (I hope I described this with the right
words) In
> other words, if I asked for a 1" square and I am using a 1/8"
cutter, what
> I get is a square that is actually 1/16" smaller on all sides.
>
> I assume that somewhere, I missed a step either in setup of my
system or in
> defining the contour. I imagine that I am supposed to somehow tell
the
> system if I want the cut to be to the right, left or on centerline??
>
> In terms of vocabulary, I am not sure if this is called offset or
> compensation of if those mean the same...
>
> Again, I may not be asking this question properly but hopefully I
have
> revealed enough that some of you with more experience can help me
out.
>
> Thanks in advance,
>
> Eric Mack