Drawing an arc in OrCAD (solved)

[Zero999]

I'm having problems with creating an arc shaped PCB in OrCAD. It's for an optical speed sensor and needs to fit round a shaft.

I've managed to create a semicircle but removing a semicircle from the middle to create an arc is proving difficult.

Is it just me or is OrCAD a pig to use? I can draw arcs in most drawing programs easily.

See bottom of the attached, for what I'm trying to achieve.


This was drawn using OpenOffice.org in a couple of minutes. I've spent several hours trying this with OrCAD and not had any luck!

[Alex Eisenhut]

I'm having problems with creating an arc shaped PCB in OrCAD. It's for an optical speed sensor and needs to fit round a shaft.

I've managed to create a semicircle but removing a semicircle from the middle to create an arc is proving difficult.

Is it just me or is OrCAD a pig to use? I can draw arcs in most drawing programs easily.

See bottom of the attached, for what I'm trying to achieve.


This was drawn using OpenOffice.org in a couple of minutes. I've spent several hours trying this with OrCAD and not had any luck!

What do you mean OrCAD? What they call "OrCAD PCB editor" that is actually Allegro?

[Zero999]

Yes, sorry should've been more clear.

[nctnico]

In Orcad Layout you have to force 3 line sections by extending the ends of the circular part. Once the inner circle has been drawn you can drag the extentions back to the intended size. Easy if you know what you are doing.

[Neilm]

I admit I haven't had to draw PCB outlines in Allegro (they get imported from Solidworks) but can't you just draw a circle void on the PCB outline? Then merge the shapes and job done.

[Zero999]

Thanks but I got there in the end, although it's probably a slow method.

To create the semicircle, I drew a circle and cut a piece off it. What's annoying is OrCAD always keeps the larger piece of the shape so I had to perform the cut in two operations.

To make the arc, I drew two semicircles, decomposed the shapes, dragged the lines about to make the arc, used the compose shape command to join them back together and had to do a z copy to put transfer them to the correct layer.

[Alex Eisenhut]

Thanks but I got there in the end, although it's probably a slow method.

To create the semicircle, I drew a circle and cut a piece off it. What's annoying is OrCAD always keeps the larger piece of the shape so I had to perform the cut in two operations.

To make the arc, I drew two semicircles, decomposed the shapes, dragged the lines about to make the arc, used the compose shape command to join them back together and had to do a z copy to put transfer them to the correct layer.

Board outline should be on the board geometry/outline layer, you just create a polygon shape and use the arc mode. You do see the option panel, right? Sometimes on dual monitor systems the windows go off-screen.

Cadence also enjoys slicing functions very finely when they create licenses. Maybe arc mode is disabled...

[Neilm]

Board outline should be on the board geometry/outline layer, you just create a polygon shape and use the arc mode. You do see the option panel, right? Sometimes on dual monitor systems the windows go off-screen.

Cadence also enjoys slicing functions very finely when they create licenses. Maybe arc mode is disabled...

By default, those option panels are not shown so it can be easy to miss. On my system at work, it selects the line 45 degree option by default. I can't imagine Cadence would disable something so basic.

[Alex Eisenhut]

Board outline should be on the board geometry/outline layer, you just create a polygon shape and use the arc mode. You do see the option panel, right? Sometimes on dual monitor systems the windows go off-screen.

Cadence also enjoys slicing functions very finely when they create licenses. Maybe arc mode is disabled...

By default, those option panels are not shown so it can be easy to miss. On my system at work, it selects the line 45 degree option by default. I can't imagine Cadence would disable something so basic.

By default, they're all there usually. If not, go to view -> windows and click them back on. If they're off the screen as can happen with laptops when docking to another monitor configuration, go to view-> reset UI to Cadence default, that'll marshal all the windows back to being docked to the main window.

If still no go, just draw a shape rectangle and use the shape editor edit boundary, you should see arc in the pop menu.

[Zero999]

Yes I did have problems with the options window not showing but sorted it out long before I encountered this issue.

Anyway I think drawing the semicircles separately, before joining them up is probably the easiest way to do this. I need to accurately control the size of the arc and it needs 0.5mm chopped off the flat sides as the two arcs will be fitted round a collar and I need 1mm clearance.

[Alex Eisenhut]

Yes I did have problems with the options window not showing but sorted it out long before I encountered this issue.

Anyway I think drawing the semicircles separately, before joining them up is probably the easiest way to do this. I need to accurately control the size of the arc and it needs 0.5mm chopped off the flat sides as the two arcs will be fitted round a collar and I need 1mm clearance.

The little arrow to show if the window is maximized is quite small. But I can draw a perfect circle without ever using circle or arcs.

"But how can you do this Alex!?" you ask excitedly. 

Look at the manufacture -> dimension -> fillet command. Enter the radius you want, click on two intersecting line segments. There you go. 

Only valid for line segments, not shapes.