Copeing / fishmouth pipe

I’m trying to use sheetcam to do a simple milling operation.

I have basically a “D” shaped contour to mill and I’d like to use the side of an end mill and not do any plunge cuts.

Trying to start on the inside of the straight of a “D” shapped contour which is off the end of the pipe.

Seems like SC wants to start close to center with the operation and plunge to start.

I’m not doing something correctly. What is the best way to approach a job like this?

Here’s the code that I wrote to do the operation. It’s a long process to plot the points and write the code. There has to better / faster way to do this same type of operation.

I know I’m not seeing the big picture…

Thanks for the suggestions.


If you want to start on teh straight edge you can just move the start point. Make sure you have your operation selected then select Mode->Edit start points. Now click on teh contour where you want to place the start point. If that doesn’t work you probabaly have a break in your contour.


The problem with a inside contour, the machine is cutting the full diameter of the tool as it goes around the contour.

There is no step over as in a pocket operation. And when I use a “pocket” there is a plunge cut near the center and it steps over from there and no finish contour. I find it best to avoid plunge cuts if possible.

I guess I’m trying to do something between the contour & pocket operation as my post shows.

A roughing out to remove the bulk of the material and then a finish contour pass.

I’m just spoiled by how good sheetcam works for my plasma cutting so I’m trying to use it here to save time.

Thanks for all the help.


A zigzag pocket may work. If you set the start point and pocket angle correctly it should start from the flat side and work it’s way across. However I would have thought it would be better to simply cut it using the full width of a slot drill. It would be quicker and with less tool wear.

I thought I had this figured out on how write the code for a circle. But I’m at a loss.

Can someone share some documentation on how to lay out an arc and a circle with I & J G-code.

Been on it most of the day and I’m brain locked…

Thanks, AJ

I think I got it…

The I & J is the X & Y location for the center of the arc relative to where the arc starts at.

another way to put it…

The arc start location is a temporary new origin from where the center of the arc is measured from.

I read my G-code guide a lot today and it finally sunk in a little…

Please speak up if I’m off track. This is something we all should have a taste of…