I have a door with a transom that I need to fabricate a divider for, which consists of two differently sized pieces of wood, each with a bevelled groove. One is 2-1/4" x 3/4" and the other is 1-7/8" x 1-1/4". I do have a Bosch router and am skilled at using it (I made really nice window stool edges) but I don't know where to find bits that can make these grooves.

Pictures are attached (from another door that is identical and for which I was able to restore the old ones but for this one the old ones are too rotten). The good picture is the thinner and wider, the bad one is the fatter and narrower. The grooves are similar shape but different width, which is why I suspect they would require different router bits. Which router bit(s) I should get?

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    If all edges are straight then you can just make multiple passes with a tilted table saw or router to get the profile hollowed out. – ratchet freak Jun 29 '16 at 8:39
  • If you have (or get) a profile gauge use it to more clearly show the profile you're looking to reproduce then take a picture of that against a nice, high-contrast background, people may be able to help identify bits or blades that will help you out. – FreeMan Jun 29 '16 at 20:40

It's a bit difficult to tell from your photos (2D pictures just don't do 3D very well), but the bottom one looks like a simple dado cut would do it. I have a feeling that some significant amount of detail is missing from the picture in the greenish area, thought.

The top picture looks like you could cut the profile on the edges of a piece of wood, then cut the profile off at the required width and add it to a piece of flat stock to create the final profile. I think building it up that way would be much easier than trying to hog out all that wood from the middle.

If you really want to build it out of one piece of wood, use a dado to clear enough room in the center that you can cut the two profiles with the router. By leaving some wood down the middle, you'll have something to support your free-hand router. Then, once you've profiled it, use the dado to clear out the rest of the middle. Of course, if the router is table mounted, that's not as important since you can rest both narrow edges on the table top, but it would make the piece more stable while routing with a center ridge.

You may not be able to find a single bit to cut your entire profile, though. You can either get a custom bit ground (cabinet shops often do this, but $$$$$...), or use a combination of several bits to cut small portions of the profile at a time. Identify a bit that will cut a piece, then figure out which order to use them in to safely make the final profile without damaging previously cut areas.

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  • Two pieces is fine – amphibient Jun 29 '16 at 20:31

This is not something you would cut out of one piece, but is almost certainly a piece of flat stock with a back band, or combination of mouldings simulating a backband on either side.

Instead of thinking strictly reductive, think about breaking down the moulding into multiple profile that can be built up to what you see.

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I found that the type of router bits that do this is called plunging bits.

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  • A plunging bit is not required for these kinds of profiles. A plunge bit is just a bit that can make a plunge cut without getting stopped by a part of the bit that doesn't cut. For example, any straight bit that has flutes that don't extend across the full diameter of the bit are NOT plunge bits, but a straight bit with a flutes that extend to the center of the bit ARE plunge bits. (The latter are commonly known as mortising bits for their usefulness in cutting a mortise with a plunge cut.) – Katie Kilian Jan 5 '17 at 21:00
  • I am confused by "can make a plunge cut without getting stopped by a part of the bit that doesn't cut". Can you please elaborate? – amphibient Jan 5 '17 at 21:30
  • A router bit such as this one has flutes that do not extend across the entire bottom of the bit. As such, if you attempt a plunge cut with this bit, the work piece will hit against the center part of the bits where there are no flutes. The bit itself stops you from making a plunge cut. – Katie Kilian Jan 5 '17 at 22:00

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