# Snapping circles together.

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A Silver Surfer, brand new to Autocad and only three lessons under my hat, so please forgive niave question:

If I draw a couple of circles of different size, a little apart....

Lets say for sake of example, a 100 diameter circle with another 150 diameter circle offset centre 150 to the right side. ie, with a spacing of 25.,

I then draw another circle (say 200 dia) somewhere above, and wish to move it down to snap to touch exactly to the first two. ie. sit on top of them like some badly made cannon-balls.

Is there a way to move the 3rd circle so that it snaps to the first two?

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An easy method would be to use the circle TTR (tangent- tangent-radius) method to construct the third circle rather than moving the circle after creation.

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Perhaps your exercise could be approached from another angle.

If you have two circles, then instead of drawing a third circle separately and then moving it, you could use the inbuilt functions for drawing a circle which is tangential to the first two, namely the option TTR (Tangent, Tangent, Radius).

However, if you were really determined that your first choice was the way to go, you could offset each of the original two circles by 100, and then move the third circle so that its centre was at the intersection of the two offsets.

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Superb, thank you Gentlefolk.

Most grateful.

BarryD

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Sorry, being a Muppet here.

How do I select / enter the commands for that crafty create the circle move?

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You have Dynamic input on, right? If not, just type any or all of the following into the command line, otherwise just type it anywhere. Watch the prompts in the command line and/or in the dynamic input window. they will keep you in the proper order.

Type CIrcle, ENTER > hit your down arrow on the keyboard, select TAN TAN RADIUS, or simply type TTR, select one existing circle, select the other existing circle, type in the new circle radius, and bob's yer uncle.

OR - Click the down arrow below the CIRCLE button, select TAN TAN RADIUS - you know the rest.

When you select the existing circles, it's best to click them somewhere to the side of their center points where you want the new circle to be tangent. If one or both of your existing circles could possibly fit inside the diameter of your new circle, AutoCad can draw the new circle tangent to the existing circles with one or both inside the new circle, geometry allowing.

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Thank you all very much.

I suspect that we may "Meet again" before too long.

Barry D:D

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I updated my post. I got a phone call while I was editing.

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Sorry, being a Muppet here.

How do I select / enter the commands for that crafty create the circle move?

If you have the Ribbon up, then from the Home tab go to Draw panel, use the pull down for the circle, pick Tan, Tan, Radius

Edited by rkent
minor edit
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Or 1st principles how to work out the center of the 3rd circle offset the two existing circles by the radius of the new circle where they cross is the center point.

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