Cutting a template with a router...

[Sinner]

I was wondering what type of bit you would use in a router to follow a template to cut another piece of wood...for example,  if I cut out once side of my cabinet, and I want to use it as a template for the other, I clamp the cut piece to a new sheet of MDF, then use some sort of bit to route around...sounds simple, and I'm sure it is, but what kind of bit do I use??  I have these plastic discs that came with my router...they screw into the bottom, and are supposed to be guides...
Do I use these to follow the template??  Is there a special bit, or do these "guides" and a regular straight bit allow me to cut the pattern?

[AlanS17]

Actually, those are trimming bits. They work in reverse. It's made for things like cutting laminate. It's the same concept, though.

When in position, the router bit will have the bearing on top and the straight bit on bottom. The bearing runs along the edge of the wood on top and prevents you from cutting into it. As a result, you follow along the outside edge.

[pcb]

AlanS17's got it right.  The bits with the bearing on the top are what you want.  FYI they are called Pattern Bits.

[nostrebor]

Of course you are right although, I have used both kinds for pattern work. You just put the pattern on the bottom instead.

The correct bit is a pattern bit...

http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/bt_flush.html#pattern_flush_anchor

I removed the previous post to avoid confusion...

[Sinner]

That's awesome guys...thanks for the information...I think I'm going to go this route for the sides...I think the cost of the bit will be worth the savings in frustration in the long run...
Does anyone know how the plastic discs that came with my router work?  I read the manual, but I'm still unsure...BTW it's a Ryobi with the 3 bases...

[Voodooray]

Hi sinner.
The plastic bits you mention should have a piece sticking proud of the rest of the disk. These bolt on to the bottom of the router and are for following an internal pattern. They are very useful but not for what you want at the moment. The blade goes through the whole in the middle and there is a gap between the guide and the blade so the second piece you cut would be slightly bigger. To use these correctly you would need a template slightly larger than the actual shape you wanted to cut and you would run the router around the inside of the template instead of the out side.
Unfortunately this is a terrible explanation, i'll try to photoshop something tommorrow.