Part wizard question

[ttwark]

Is there a way to measure a radius using the measure tool or by another method? If I have a series or radii drawn and think that one is wrong, how can we check it?

[paco]

Depends on where is the radius... different methods apply...

[Brady Watson]

The easiest way that I have found is to create a circle 2X what the radius is supposed to be, then drag it over the radius. If they match up, you've verified your size. If not, some trial and error using the transform function to enlarge or decrease the size of the circle to match the desired filet is is in order.

-B

[myxpykalix]

I have no experience with these but i saw somewhere there are some screen utilities like a screen measuring tape, or screen calipers to measure parts. I can't tell you where i saw the link, maybe here. Maybe others might know what i'm talking about.

[rob_bell]

If your arc is at least 1/2 circle or you can make it so you can use the geometric identity such that an inscribed right angle in which the apex touches the arc then the legs intersect the arc at a diameter.

[myxpykalix]

HUH????? You're talkin GREEK to me...(or is that GEEK)!? lol

[dvanr]

For two lines AB and CD that intersect at any angle in a circle at point E, the following is true. The distance of lines AE * EB = CE * ED

See the top two diagrams below

Modify the above for lines that intersect at right angles ONLY and must pass through the midpoint of at least ONE line.

You can measure AB easily by drawing in a line and looking at the line length. Use the tape to measure EC from the line AB midpoint. The tape will find the midpoints.

((AB/2)^2)/CE + CE )/2 = r

this gives the same radius result for the bottom 3 diagrams

This works for radius curves past 180 degrees as well.


9055

[ttwark]

Thanks for the input, The radii that we are trying to check is in the 38" range and the cord length of the arch is in the 30" range. we were machining along vector and the part wasn't comming out exactly right that was why we were looking for a easy way to check the drawing. A formula that I use every day in lay out would have worked if I would have thought about it long enough.

R = h/2 + C squared/8h
c is the cord length and h is the height of the arc at the center of the cord.

Dick, thanks for your formula as this help me think this through.