Easy way to find the radius?

[turboboy]

Is there a easy way to figure out the radius on a part. I need to figure out the radius to transfer in to CAD program to cut the part.I dont have radius guages but wondered if theres a simple formula?. thanks for any help

[quadbob]

I don't know how big the part in question is but I have found that I use an edge finder. I start as close to one end of radius as possible and zero out the x axis. then I move the edge finder in y axis until it touches part. Lift up the z axis, and move 1/2 the diameter of edge finder toward part. Then zero out the y axis. Then I move a standard distance in x, say .500 and repeat the step for y. Basically you are looking for three points on a curve. When you input the 3 x and y values into a cam, assuming your cam can generate an arc from 3 points, it will give you the radius. I hope this is clear enough.

[ctate2000]

Don't know what the part looks like. Guess, then print to scale from CAD/CAM and use as an overlay for comparison. Keep changing until it fits. Crude but effective.

[miljnor]

if you have end mills and a machine you can make radius gauges.

[dertsap]

if its small enough ,drill bits work well

[ChrisJ]

Along the lines of Quadbob, here is a spreadsheet that I made a while ago. If you have three points on the arc, just input them in the spreadsheet and it will determine the center. Of course if you have a CAD program you can just draw a 3 point arc like Quadbob said.

Chris

[ajl6549]

Do you have access to a cmm? If so...you know the rest.

[widgitmaster]

Finding the center of a radius is the 1st task, just use a dial indicator and sweep the radius until the dial stays at zero.

Next move over to the adjacent flat surface and get that distance!

Or use an edge finder to start from the flat surface, and then use the dial indicator to find center of the radius, thus the distance from center to the flat surface!

Eric