Negative template with guide bushing

[qwertyu]

I want to do something like this:
YouTube

But when cutting the B piece, instead of changing the bearing I would like to use a guide bushing. He went with 1/4" router bit with 1/4" bearing to 3/4" bearing for the second piece.

If using guide bushing and the negative template was cut using a 1/2" bit with 1/2" bearing would you get a guide bushing which is 1.5"?

[aldav]

Yes that's right. It's the offset that you need to get your head around, it can get complicated to the point of doing your head in in imperial. A 1-1/2" template guide bush is pretty close to the biggest size you can buy, I bought one from Carbitool at the Sydney show a couple of years ago. If you want to get into this type of positive and negative template routing it's generally better to use smaller diameter bits, within reason, so that the guide bushes don't get too big. It can certainly be handy at times, for instance when you want to fill a large hole and all you need is a single template to cut out the piece to be filled and the plug.

[qwertyu]

Yes that's right. It's the offset that you need to get your head around, it can get complicated to the point of doing your head in in imperial. A 1-1/2" template guide bush is pretty close to the biggest size you can buy, I bought one from Carbitool at the Sydney show a couple of years ago. If you want to get into this type of positive and negative template routing it's generally better to use smaller diameter bits, within reason, so that the guide bushes don't get too big. It can certainly be handy at times, for instance when you want to fill a large hole and all you need is a single template to cut out the piece to be filled and the plug.

Thanks. Currently 3D printing a bushing hopefully it works out. I will now know for next time to use a smaller bit!!