# Thread: intersection of arcs 90 degrees apart

1. Login to Give a bone

## intersection of arcs 90 degrees apart

I'm trying to figure out how to draw this arc at the 45 with only 2d. I tried point/point/direction, but it's not right as you can see by the extrusion.
My lines are the intersections of top point, mid point, and end point.

What is the correct math/method to use to find the intersection of two arcs that are 90 degrees apart?

ARCINTERSECTION.PNG

2. Login to Give a bone

## Re: intersection of arcs 90 degrees apart

As you can see by this one, it is closer to correct. But I didn't draw it and I can't reproduce what was done. My arc never lands on the same point.
The only way I can manage it is to draw it in 3d and flatten it. And even then it still seems off.
ARCINTERSECTION2.PNG

3. Login to Give a bone

## Re: intersection of arcs 90 degrees apart

Are you changing your work plane to match the 45 on it's side?

4. Login to Give a bone

## Re: intersection of arcs 90 degrees apart

I had to do that to draw it in 3D. What I'm trying to figure out is how to get an arc that looks the same but not draw it in 3D.

In the first pic the midline is going across the X/X plane and meets with the midline of the X/Z plane. That shows me my correct intersection of midpoints. I turned the UCS 45 and drew my arc. That is the blue arc in the first pic.

But when I take the top distance from the plan view at the 45 and turn it to 0, take the bottom distance on the plane view at the 45 and turn it to 0, separate their Y by the height, and draw a point/point/direction arc it is wrong. (pictured in the first pic). Nothing I do by working with just the plan view and the elevations makes the correct arc, I had to draw it in 3D, rotate it 45, and then cut the part to get one that actually worked. The guy who did this before me never had to draw it in 3D and his worked, but no one knows what how he did it (not their job anyway). But now that I'm the one doing it and he's no longer around...I've got to figure out how he was doing it in only 2D and it work right. I thought the point/point/direction would have done it or a 3-point, but neither are right.

5. Login to Give a bone

## Re: intersection of arcs 90 degrees apart

Other than drawing it in the horizontal plane and rotating or aligning in 3d, I have no idea at this point.

I'm curious what you are trying to create, but I do not believe it is material to getting you a solution.

6. Login to Give a bone

## Re: intersection of arcs 90 degrees apart

It's a Custom Range Hood
rangehood.PNG

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•