ELIPSES

[Tom Dorgan from American Precision]

OK, time for a newbie question from someone who has used Mcam for 3 years although mostly self taught.

When I create an Elipse it looks ok on the screen but when I cut it on my routers is is all straight lines. I have been making my elipses in another program and bringing them into Mcam for all this time. How do I improve my Mcam elipses?

[kinglouie V]

good question Tommy. to investigate I drew a box and an ellipse. I extruded the box and was going to 'cut' the body (box) but it prompted for a planar chain set when I picked the ellipse. what's up with that??

[kinglouie V]

ok, after restart ellipse no problem. but I see some lines in the ellipse after verify. what method are you using contour, pocket or what?

[Tom Dorgan from American Precision]

I have tried both and get the lines every time.

[PBpaul]

Tommy:

 

We've had similar issues with ellipses that were originally drawn in Autocad and in Rhino. I think there is another thread that covers some of the things we found. For instance, be careful of anytime you do an offset. An offset of an arc might no longer be an arc but rather a spline. I believe 99% of our trouble comes from thinking an arc is an arc or an ellipse is an ellipse only to find that we did something back down the line that converted it into long line segments.

 

HTH- PBPaul

[Tom Dorgan from American Precision]

I am creating the elipse in mastercam and it is making lines instead of arcs. I cannot find a setting to correct this.

[Snaglpuss]

In 9 try modify-break-splines to arcs.

You can keep or delete the original elipse/spline.

I have done this a lot on elipses for our router.

For the life of me I can't figure it out in X.

I don't know if they got rid of the function.

Anybody else know?

[kinglouie V]

I never could get that function to work for me. I think since v7 I've had trouble with it.

[ToolMan184]

If you create it using Create-Rectangle-Options-Ellipse it will create using lines. If you create it using Create-Next Menu-Ellipse it should use arcs. This is what I have run into anyways.

 

I cut alot of ellipse pockets using Create-Next Menu-Ellipse and dont have trouble.

[Tom Dorgan from American Precision]

That is how I did it Toolman but mine is still lines. You can actually see it on the screen.

[Tom Dorgan from American Precision]

Snaglpuss's trick seems to have worked, at least on the screen.

 

In X it is simplify but it does not seem to smooth the elipse any at all. I will have to cut some when I get time to test both methods.

[kinglouie V]

yes, for me too, but what's this modify-convert splines to arcs. how do I get that to work in v9. or better yet simplify in X ??

[Kannon]

for it to output arcs in the post for a elipse, I do it the way Snaglpuss suggested.

But I am dealing with 9.1, not sure what X has/or dosent have when workin with elipses.

[Snaglpuss]

Make an elipe, then modify-break-spline to arc,

click on the elipse-done-do it. You can toggle in the dialog box to keep the original elipse and the new elipse made of arcs or delete the original elipse.

You can set the chordal deviation of the elipse in the dialog box too. This will control the size of the new arc pcs.

This works great in 9 BUT HOW IN X!!!!!

Anybody?

[Guest]

trim. break many pieces, pick the cordial deviation, and the line or arcs button.

[Guest]

For some reason that command is not covered in the V9 to X function map.

[JDowe]

In V9 create toolpath contour

set cutter to off

then filter to toolpath to get arcs and tangent

lines - experiment with settings - to see what you have backplot using static endpoints

when you have one that looks good

backplot and save as geometry to another

level

 

In X backplot create geometry does not work

for me

[Storkman]

JDowe, in backplot extend the options with the blue arrow in the top left corner, highlight the operation and select save as geometry. Works fine. You don't even have to run the backplot.

[Snaglpuss]

Marc,

Thanks, thats it for X.

[P_Scott]

Tommy Dorgan,

 

The best way to smooth out the toolpath from lines to arcs is to change the geometry into arcs. One way this can be done is to follow Marc Lindsey's suggestion. If the geometry cannot be modified into arcs, the next best thing is to apply the Filter to the toolpath. Perform a Search on this forum for Filter topics and I'm sure you will find loads of great information. This has been discussed many times in the past. HTH

[LaszloK]

Call me old fashioned, but I ALWAYS manually recreate elipses into arcs. Usually requires 3 arcs per quadrant or 8 for a full ellipse, but geometry is bulletproof after that.

[Guest]

Man. You guys do stuff the hard way. Just break to arcs or filter.

[George_Gerhard]

Tommy

I always use the filter. But when I cut high speeds, grater than 900 ipm, I draw the ellipse in autocad. In autocad at the command prompt type pellipse set this variable to 1, then draw the ellipse. It will be 12 arcs.

And will cut the way you want

 

rgds

George

[Chris Flint Two Ft Pty Ltd]

I use V9 and use "create next menu elipse"

When machined, does not matter what I "filter" or change the tool path is G1 which tells me it is not an arc ( or am I crazy) I would expect to see G2 and G3, and I also get tiny lines as opposed to arcs, again it does not matter what I alter.

I would also like an explanation from CNC Systems as my reseller says I should see G2 and G3

chris f

[Gary]

Tiny arcs will usually come out worse than just leaving it a spline. This way at least you can set a linerization tolerance on the toolpath itself. Makes for big program though.