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*Cullen, Dave
Message 1 of 11 (40 Views)

3 piont arc question

40 Views, 10 Replies
04-11-2000 04:17 AM
I want to draw an arc. I know the center point and one end (radius).

With QC 7 I can't figger out how to do this. It wants me to pick the 2 end
points first.

Umm?

drc
*Smith, Harvey
Message 2 of 11 (40 Views)

Re: 3 piont arc question

04-11-2000 01:15 PM in reply to: *Cullen, Dave
Hi, Dave.

The question is a little unclear to me.

You can draw an arc when you know three points, two points and the center, and
two points and the included angle. You don't seem to have enough information for
your arc.

However, if you know ONLY the center point and one end, then you should be able
to draw a temporary line through those two points, and extend it to double its
length (use Mirror, for instance). Then you can use the 2 Points and Center Arc
tool with the Endpoint snap. Delete the line afterwards.

Watch the Edit bar for the variables associated with the arc after you place it.

If this isn't it, then get back to the newsgroup with a little more info.
Someone will haul in with something for you.

H

Dave Cullen wrote:
>
> I want to draw an arc. I know the center point and one end (radius).
>
> With QC 7 I can't figger out how to do this. It wants me to pick the 2 end
> points first.
>
> Umm?
>
> drc
*Cullen, Dave
Message 3 of 11 (40 Views)

Re:

04-11-2000 01:55 PM in reply to: *Cullen, Dave
Well...

I'm hoping to do what used to be possible with GCADD...

I would select "3 point arc". First point is the center, next point is
the start of the arc. The software would then display an arc as I moved
the cursor, maintaining a constant radius. Click the 3rd point to end
the arc.

I guess with QC this isn't possible?

I know the center point and one end of the arc (the radius). I don't
know exactly where the other end of the arc will be, or the exact angle
I want. I wanna be able to decide that as I draw it, and see where it
falls.

I could draw a huge circle I suppose, and trim it to the end points. But
that seems like the hard way.

drc

Harvey Smith wrote:
>
> Hi, Dave.
>
> The question is a little unclear to me.
>
> You can draw an arc when you know three points, two points and the center, and
> two points and the included angle. You don't seem to have enough information for
> your arc.
>
> However, if you know ONLY the center point and one end, then you should be able
> to draw a temporary line through those two points, and extend it to double its
> length (use Mirror, for instance). Then you can use the 2 Points and Center Arc
> tool with the Endpoint snap. Delete the line afterwards.
>
> Watch the Edit bar for the variables associated with the arc after you place it.
>
> If this isn't it, then get back to the newsgroup with a little more info.
> Someone will haul in with something for you.
>
> H
>
> Dave Cullen wrote:
> >
> > I want to draw an arc. I know the center point and one end (radius).
> >
> > With QC 7 I can't figger out how to do this. It wants me to pick the 2 end
> > points first.
> >
> > Umm?
> >
> > drc
*Smith, Harvey
Message 4 of 11 (40 Views)

Re:

04-11-2000 02:10 PM in reply to: *Cullen, Dave
Duh! I'm beginning to get it.

Try this, it's a cutey:

Draw a line between the center and the end point. Choose Elliptical Arc Axes. It
should be somewhere in the Arc fly-out in the All-In-One, or get it from the
Draw>Arc in the Main Menu.

Place the first two points at the endpoints of the line. Now draw the arc as
directed on the Status bar at the bottom of the screen.

You'll run into some interesting features with that tool, especially if you hold
the [Ctrl] key (slant angle). Your arc can be half the ellipse. Wild stuff.

Fahgedaboud that circle business.

H

Dave Cullen wrote:
>
> Well...
>
> I'm hoping to do what used to be possible with GCADD...
>
> I would select "3 point arc". First point is the center, next point is
> the start of the arc. The software would then display an arc as I moved
> the cursor, maintaining a constant radius. Click the 3rd point to end
> the arc.
>
> I guess with QC this isn't possible?
>
> I know the center point and one end of the arc (the radius). I don't
> know exactly where the other end of the arc will be, or the exact angle
> I want. I wanna be able to decide that as I draw it, and see where it
> falls.
>
> I could draw a huge circle I suppose, and trim it to the end points. But
> that seems like the hard way.
>
> drc
>
> Harvey Smith wrote:
> >
> > Hi, Dave.
> >
> > The question is a little unclear to me.
> >
> > You can draw an arc when you know three points, two points and the center, and
> > two points and the included angle. You don't seem to have enough information for
> > your arc.
> >
> > However, if you know ONLY the center point and one end, then you should be able
> > to draw a temporary line through those two points, and extend it to double its
> > length (use Mirror, for instance). Then you can use the 2 Points and Center Arc
> > tool with the Endpoint snap. Delete the line afterwards.
> >
> > Watch the Edit bar for the variables associated with the arc after you place it.
> >
> > If this isn't it, then get back to the newsgroup with a little more info.
> > Someone will haul in with something for you.
> >
> > H
> >
> > Dave Cullen wrote:
> > >
> > > I want to draw an arc. I know the center point and one end (radius).
> > >
> > > With QC 7 I can't figger out how to do this. It wants me to pick the 2 end
> > > points first.
> > >
> > > Umm?
> > >
> > > drc
*Hulbert, Rod
Message 5 of 11 (40 Views)

Re: 3 piont arc question

04-11-2000 07:39 PM in reply to: *Cullen, Dave
With the Two-points-and-center tool, pick the second end point
where you want the center to be, hold down the control key and
the second end point will become the center point. Keep an eye on
the status line _after_ you pick the second point. I think the
message should show up before you pick the second point-- it is
poorly designed they way it is.

Rod

Dave Cullen wrote in message
news:eefe2ae.-1@WebX.SaUCah8kaAW...
> I want to draw an arc. I know the center point and one end
(radius).
>
> With QC 7 I can't figger out how to do this. It wants me to
pick the 2 end
> points first.
>
> Umm?
>
> drc
>
*Cullen, Dave
Message 6 of 11 (40 Views)

Re:

04-13-2000 08:56 AM in reply to: *Cullen, Dave
I tried your suggestion, Harv.
Nifty ... but an elipse isn't a circle, so the arc doesn't end up being
the correct radius. You have to kinda eyeball the elipse as you draw it,
or set extra snaps / locks to cause the elipse to become a circle.
Otherwise, this method is close to what I was looking for.

drc

Harvey Smith wrote:
>
> Duh! I'm beginning to get it.
>
> Try this, it's a cutey:
>
> Draw a line between the center and the end point. Choose Elliptical Arc Axes. It
> should be somewhere in the Arc fly-out in the All-In-One, or get it from the
> Draw>Arc in the Main Menu.
>
> Place the first two points at the endpoints of the line. Now draw the arc as
> directed on the Status bar at the bottom of the screen.
>
> You'll run into some interesting features with that tool, especially if you hold
> the [Ctrl] key (slant angle). Your arc can be half the ellipse. Wild stuff.
>
> Fahgedaboud that circle business.
>
> H
>
> Dave Cullen wrote:
> >
> > Well...
> >
> > I'm hoping to do what used to be possible with GCADD...
> >
> > I would select "3 point arc". First point is the center, next point is
> > the start of the arc. The software would then display an arc as I moved
> > the cursor, maintaining a constant radius. Click the 3rd point to end
> > the arc.
> >
> > I guess with QC this isn't possible?
> >
> > I know the center point and one end of the arc (the radius). I don't
> > know exactly where the other end of the arc will be, or the exact angle
> > I want. I wanna be able to decide that as I draw it, and see where it
> > falls.
> >
> > I could draw a huge circle I suppose, and trim it to the end points. But
> > that seems like the hard way.
> >
> > drc
> >
> > Harvey Smith wrote:
> > >
> > > Hi, Dave.
> > >
> > > The question is a little unclear to me.
> > >
> > > You can draw an arc when you know three points, two points and the center, and
> > > two points and the included angle. You don't seem to have enough information for
> > > your arc.
> > >
> > > However, if you know ONLY the center point and one end, then you should be able
> > > to draw a temporary line through those two points, and extend it to double its
> > > length (use Mirror, for instance). Then you can use the 2 Points and Center Arc
> > > tool with the Endpoint snap. Delete the line afterwards.
> > >
> > > Watch the Edit bar for the variables associated with the arc after you place it.
> > >
> > > If this isn't it, then get back to the newsgroup with a little more info.
> > > Someone will haul in with something for you.
> > >
> > > H
> > >
> > > Dave Cullen wrote:
> > > >
> > > > I want to draw an arc. I know the center point and one end (radius).
> > > >
> > > > With QC 7 I can't figger out how to do this. It wants me to pick the 2 end
> > > > points first.
> > > >
> > > > Umm?
> > > >
> > > > drc
*Cullen, Dave
Message 7 of 11 (40 Views)

Re:

04-13-2000 09:02 AM in reply to: *Cullen, Dave
Yup, that's what I wanted. But for some reason, you can only draw an arc
to the LEFT side (CCW) of the "start" point. How do you make it draw
clockwise instead?

drc

Rod Hulbert wrote:
>
> With the Two-points-and-center tool, pick the second end point
> where you want the center to be, hold down the control key and
> the second end point will become the center point.


Actually, the first point becomes your center.

drc
*Smith, Harvey
Message 8 of 11 (40 Views)

Re:

04-13-2000 01:36 PM in reply to: *Cullen, Dave
Try opposite click points. Make the "start" the other point. Does that do it?

Dave Cullen wrote:
>
> Yup, that's what I wanted. But for some reason, you can only draw an arc
> to the LEFT side (CCW) of the "start" point. How do you make it draw
> clockwise instead?
>
> drc
>
> Rod Hulbert wrote:
> >
> > With the Two-points-and-center tool, pick the second end point
> > where you want the center to be, hold down the control key and
> > the second end point will become the center point.
>
>
> Actually, the first point becomes your center.
>
> drc
*Smith, Harvey
Message 9 of 11 (40 Views)

Re:

04-13-2000 01:45 PM in reply to: *Cullen, Dave
Nope, that doesn't do it. I think you may have to mirror a CCW arc.

As a suggestion, why not place that part of your file in CF, reference it here
and describe what you want to do? It might be easier to see a workaround.

H
*Cullen, Dave
Message 10 of 11 (40 Views)

3 point arc question

04-14-2000 06:20 AM in reply to: *Cullen, Dave
Harvey Smith wrote:
>
> Nope, that doesn't do it. I think you may have to mirror a CCW arc.

I guess.

> As a suggestion, why not place that part of your file in CF, reference it here

The concept is simple enough to describe: Consider a belt tensioner - a
bracket with a pulley in the middle. The bracket pivots on a shaft at
one end, the other end has a slotted hole that would be used for an
adjustment bolt.

I'm trying to draw the slotted hole. Its centerline would be an arc that
is a fixed radius from the pivot point.

The 2-points-and-center-with-ctrl-key method works OK... it's just a
bummer that you can only go ccw with it.

Another challenge with this is drawing the rounded ends of the slot: two
half-circles connected by arcs. I can do it on paper with a compass
easily :-P

drc
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