[slawsonb]

I am doing an outside offset contour on part with 90 degree corners. The problem is that the corners are being rounded off instead of being sharp as the drawing defines. Is there a setting I am missing somewhere?

Bruce

[HuFlungDung]

Are you sure? An offset path around a square will have rounded corners because the tool swings around the corner point in an arc.

If your machine rounds the corners off, it may be some kind of motor tuning issue, meaning the motors are not responding 'tight enough' to follow the contour commands.

[Geof]

What kind of machine? How round are the corners? If you are dealing with a commercial CNC some do have a Setting that can affect corner rounding.

[slawsonb]

Actually it looks like sheetcam is displaying the correct tool path but when exported to mach 3 the corners get rounded off. I have not completed my CNC mill so no real results yet.

Bruce

[ger21]

Mach3's screen display is not necessarily the actual cut path. The screen isn't updated constantly and at higher feedrates you may see rounding in the display, when there isn't any in the actual toolpath. Post the g-code here and we'll take a look.

[ger21]

My previous posts assumed the rounding was during a cutting simulation. Is this correct?

[slawsonb]

My previous posts assumed the rounding was during a cutting simulation. Is this correct?

Correct.

[Konrad]

Your offset will make a arc around a square corner....but the part should remain square.
Konrad

[ynneb]

I know your problem, You need to use the exact stop setting in Mach. This is not a sheetcam issue.

[slawsonb]

Here's the G code.

[slawsonb]

I know your problem, You need to use the exact stop setting in Mach.

How do I do this?

Bruce

[ynneb]

In mach select at the top /config/state and see this picture.

This mode is good for doing hard angles, bit painfully slow when cutting curves.

[ger21]

I know your problem, You need to use the exact stop setting in Mach. This is not a sheetcam issue.

Incorrect.

SheetCAM is rounding the corners of the toolpath, but the part should have sharp corners. No need to use exact stop mode.

[trevorhinze]

As Ger21 stated there is nothing wrong at all with the toolpaths that Sheetcam has generated. It is moving your bit along a nice continuos path in order to keep the cutter moving at as constant a speed as possible. This helps to avoid having the feed of your machine start and stop at every corner. Remember that when you look at the toolpaths they represent the center point of your round cutter, not the geometry of your finished part. This is something I got used to after awhile, but it can be a bit confusing at first. If you are working with some cheap material the best thing I can suggest is to simply let your machine cut out the part ans watch it carefully as it moves. I think that watching your machine move around following the paths that Sheetcam has generated is the best way to learn and understand what is actually going on. Good luck to you, I have had excellent results with Sheetcam!

[slawsonb]

Yes, sheetcam shows an arched tool path that still results in a square corner. The simulation in mach 3 looks like it is hacking the corner off.

Bruce

[ger21]

It's just the simulation. Use the FRO to slow it way down and it should look correct.