break arc

[rickt23]

Basically I have a 20 inch circle and 1 line thru the circle offset from the center by 1 inch.

I am trying to break the circle at 1 place only, but it always breaks the arc in half instead of just 1 place. Is there an command that I'm missing?

[Andy]

Try Edit/Break at intersect. It may break it in 2 places so you may have to Edit/join to get rid of the undesired break.

[rickt23]

When I try Break at intersect it breaks in 2 places and then I tried join entities and it joined both places, so I ended up right where I started.

[Andy]

I was wrong!

Seems strange, doesn't it?

[rickt23]

I've been messing with it on and off all day, I am stumped.

[John Summers]

Try trimming, and put 2 different arcs together.

[Andy]

John,

He has a circle, so if he makes it 2 different arcs he will have 2 break points.

[Matt Berube at Ferron Mold]

enter TRIM, select "trim to point" AND "break", then allow the auto-cursor to "snap" to the intersection you desire to break at.

 

This is the result I got. Click the pic for a better view.

 

Is this not what you want ?

 

You need to realize that circles in Mastercam are already "broken" when they are created. Usually at 3:00 position. That is why you get 2 arc segments when you make a single break.

 

Hope this helps.

[rickt23]

I'm assuming that you are referring to trim 1 entity. If you that is it, I tried it and it doesn't join the break together.

[rickt23]

Matt,

I tried that and I got the same result that I have been getting. Your picture shows what I am trying to do. I use contour pass to go around the circle, and then across the line. The program will work just fine, but when it adds the break in there the program post's with the arc broke into 2 lines of code and it makes it harder for the machinist to edit if the stock comes in differant than I programmed.

[rickt23]

Matt,

I tried that and I got the same result that I have been getting. Your picture shows what I am trying to do. I use contour pass to go around the circle, and then across the line. The program will work just fine, but when it adds the break in there the program post's with the arc broke into 2 lines of code and it makes it harder for the machinist to edit if the stock comes in differant than I programmed.

[Andy]

Rick,

If a circle has a breakpoint at 3:00 then you could rotate the circle until the 3:00 poin is where you desire and you will have 1 breakpoint.

I tried this in 9.1 just now and it worked.

I tried this in X2 just now and it worked.

[rickt23]

I'm going to have to try that one tomorrow.

What is the formula for figuring out what degree to rotate?

[Andy]

I assume you want to start 1" up on the circle and then cut a full 360 degree cut. Is that correct. Or are you only cutting part of the full circle?

[Matt Berube at Ferron Mold]

You are right that this is tricky... I did it once and got the result you are looking for (joined in an alternate location) but then couldn't repeat it.

 

I do have a bulletproof way to do it though...

 

After you break as in my picture above, create a gap where you want the break to occur by using Trim and pressing the length button and type "-.1"

 

Then click on either arc where you want the break to end up.

 

Then join at 3:00

 

Then enter trim again, press the length button, and this time type ".1" which will extend the arc back to a full circle and leave your arc "endpoint" in the modified location of 1 inch away from center.

 

It shouldn't be this hard...

I was just doing this on X demo version. I wonder if it's better in X2. I'll try tomorrow if I remember...

[within a thou]

break the chain how you have been doing it creating the 2 arcs. Go to Analyze, 2d area click chain partial then the small arc this will tell you the perimeter record that number delete the small arc then click on edit trim use the extend function punch in the perimeter value and click on the arc on the opposite end of the chain you want the break.

[Span]

in X...

 

transform rotate pick circle

pick center of circle as rotate point

right click in angle box

from angle menu pick pts (2 or 3)

pick center of circle

pick intersection of line and circle

done

[rickt23]

Thanks for all the help.

[doyleg]

simple way - draw line from center of circle to the intersection point that you wanted to start at. this will give you the angle to rotate the beginning of the circle to. now you can do this 2 ways. pick circle and rotate it the amount needed or analyze the circle and adjust the start point to the angle needed making sure it is still revolving 360 deg.

[Rick Curtis EastechInc.]

Create arc polar will give you the option of putting your start and stop point in the place you want it . The rub on this is you will have to have the other geometry to construct your work from.

[Rick Curtis EastechInc.]

Create arc < circle center point> 20

creat line - origin <> past dia on right

------------(auto curser set to horizontal/vert)

------------(type in 1 in the field for y dim)

change level

create arc polar (snap to center)

-----------------(initial angle - snap to)

-----------------(final angle - snap to)

once you do this a couple of times you should be able to do it in about 20-30 sec.

But who is counting