# Struggling with Boolean Subtraction

I am having so much trouble trying to wrap my mind around boolean subtraction. I’m trying to remove the top and bottom parts my letters. I successfully did with the letter R but cannot seem to replicate it for the others. I believe that I have make copies of each vector but for some reason this is not intuitive.

Any suggestions?

Please post the file and we will do our best to walk through this with you.

Thanks Will appreciate that. Here’s the file.

I was able to get it to work in certain areas but not in others. When I get it to work, it’s more a stumble upon a success versus knowing exactly how I did it.

The big thing to consider is the interaction of the two geometries. Note that if you get the wrong key object, you can undo, which will change which object is the key object, then re-do with a different effect, so Boolean Subtraction with:

results in:

which is the opposite of what is desired, so we undo:

which toggles the key object to the E and repeat the operation:

which works and is what is desired, once the un-removed E is removed:

Just repeat that for each letter:

until one arrives at:

Hang on while I finish the outer circle.

So do you start with multiple copies of the E before doing the subtraction?

Playing around with it here. So I didn’t realize the undo switches the key object, that’s a great tip that’s not obvious in the UI. It looks like I have to start with 2 copies of both vectors to get it to function like I want.

Since the outer circles are not yet joined, the most expedient thing to do is to select all the geometry which crosses from one circle to the other:

(note that all of the counters (inner areas) have been removed from the selection)

and Boolean Union them with the inner circle:

resulting in:

Then select only the crossing geometry:

and simply add the outer circle to the selection so that the inner geometry is the key object:

and do Boolean Subtraction:

and delete the crossing geometry:

Attached.

Fixing the geometry which wasn’t crossing is left as an exercise for the reader:

Circle Sign with First Last Est Date.c2d (464.3 KB)

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Thanks Will for your help! I’m sure that you’ve been doing this for so long it is second nature. I’m still trying to figure out when to use union and/or subtraction.

Am I thinking correctly when I need 2 copies or layers of each vector? Then I take the vectors and do the Boolean subtraction.

Here’s my final version. I’m not so sure the letters at the top are centered over the R but I may do this again to practice.

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When you use which depends on the geometry you are interacting with.

Duplication is only necessary if you will need to re-use geometry for some reason.

I had to delete a lot of geometry to arrive at the file which is posted above and it looks like your current version has a lot of duplicate geometry which should be deleted so as to make toolpath creation more straight-forward.

You might be able to rotate the words around the edge now to make them centred… they should descend equally on both side of the circle but at the moment they are lopsided

Thanks Will! It’s starting to click now or at least I know what to look for when I’m doing the boolean operations. The undo and flipping of the key obj is really handy. I realized that you don’t always need the 2nd copies of vectors to make it happen.

@Gerry, yep. I had to start over but it gave me another go at it to work with the boolean ops. Things went much smoother the 2nd time around. I realized that I had the date wrong as well.

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