what type of router bit is commonly used to profile trim board for use as a window stool?

The only bits I currently own are a 1/8" radius roundover bit and whatever this bit is (came with the secondhand router I purchased).

the bit you show is probably a 1/2" round-over. it would really be to your advantage to start off with Carbide Cutters on some new bits with the bearings on the ends.
some nice inexpensive small sets are available on Ebay.
I have a lot of the "Yoniko" brand and have been quite satisfied with them. (you will need 1/4" shank bits) this is an example of "Round-Over" bit profiles.

we would have to see the video in question to understand what they mean by "beading bit".
the term means different things in different parts of the country. (or if you can draw a sketch).
this is one example of a Beading Profile Bit - they also come in different sizes.

Not quite clear what you mean by window stool. Is it a freestanding stool, or is it more like a bench below a window or in a bay, or recess in the wall with a window in it, and a space for a bench?

If it's a bench a simple roundover is all you need to just soften the edge. You can do the same for a freestanding stool. The roundover keeps the sharp edge from digging into your leg, and reduces the chances of dents, or at least minimizes their appearances.

I am concerned about your bit. It is obviously quite old and it has rust on the shaft, which makes it dangerous to use. I URGE you to buy a new bit and toss the one in the picture. I also suspect that your collet is rusty as well, in which case it should be replaced. You can try removing the rust from the collet if you can't find a replacement, but do it chemically, dry it thoroughly after a final rinse with spirits or denatured alcohol. Here's a picture of a collet that's in working condition. Compare this to your collet:


Collets are extremely precise devices. As you tightening the nut, it presses the collet into the spindle at the end of the motor shaft, which contracts the collet slightly. The difference between a loose vs tight collet is a matter of a few thousandths of an inch. If they are rusty or even pitted, you can't count on their holding the bit. Believe me, you Never want to be anywhere near a loose bit that's spinning at 20,000 rpm.

If there are collets available for your machine, check with the manufacturer if they are still in business first, then try ereplacementparts.com. If it's not there, then you have an orphan, with parts that increase your risk of serious injury. Although it seems expensive, this is one reason most of us wind up buying new routers, and in my case they've multiplied over time like bunnies. Two Bosch 1617s, a Bosch colt trim router (great for small roundovers cut in place), and a Triton TRA001 in my table (3.25 hp!).

Bosch has a superb reputation for customer service and quality products in the U.S. They continue to produce small parts long after a model is discontinued, and the parts are easily found. The problem with some of the off brands is they are made in factories that only seem to produce just enough for the run of the tool. It's all about price so when another maker gives a lower price, there's no incentive to continue making spare parts.

Finally, if you're talking about the trim around the window, you can find that stuff pre milled at any big box store. They have trim in all varieties, from plain to very doggone fancy.

This has gone long but I was very concerned for your safety when I saw the picture of your bit and what looks like the collet. A new roundover bit is not very expensive, but please don't use that collet if it's rusty or pitted.

DesertRatTom said:

Not quite clear what you mean by window stool.

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From what I've seen, these are usually not just a simple roundover.

gn86 said:

I need to trim out a window and have some trim board to make a stool. What would a simple traditional profile be for a window stool?

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You say you want a traditional profile so I suggest you look at different stool caps in your area. Different regions of the country have different traditional edge shapes and even those shapes change through time so you will have more than one option even for your location. Another thing to consider is whether it will be painted or stained and how thick your material will be. The thicker the material means that if you want a more detailed profile you will not have to stick with a simple roundover on the upper and lower edges. For myself, I prefer a simple 1/4 inch on the upper and lower surfaces. Stool caps can often be subject to abuse and the more detail the more the damage will be noticed. I have noticed that in some areas the ends of the caps are mitered so they return to the wall. I do not believe this was ever traditional and having worked as an itinerant carpenter in New Hampshire, Massachusetts, Texas, Hawaii, Maine, Oregon and Alaska I have only seen stool caps returned to the wall in newer houses. If you are going to use stain and return the caps the miter will have a conspicuous line.but the ends will stain nicely because no end grain will be showing. If you are going to stain endgrain sand it very smooth and I believe there are products to apply to the endgrain before the stain that will prevent the stain from being considerably darker than the rest--but a painter will be able to tell you more about that. If you paint it then just sand the endgrain smooth.

Your sample was probably made from two pieces, the top piece's edges are roundovers top, bottom and edges. The seconpiece is a cove cut. The combination makes a kind of S shaped profile when glued together.

You could get a similar look with one thick piece on top, and on a thinner piece below with multiple passes with a cove cutter.

The simplist method would be to do the top, then use some commercial coved trim underneath. The trim is fairly thin and easily damaged, but you could apply it to the edge and ends of a same-thickness board, and glue that to the bottom of the bench. The trim option looks great painted, is very easy to do, and will save you buying a cove bit and working out the multiple passes.

Another really simple option would be to purchase some edge material such as this bar front trim, and glue it to a squared off board. Voila, done. There are many of these available at a wood supply or even from Home Depot. This is how I'd do it, but it requires cutting very accurate 45 degree miters at the corners.



Here's a cove bit. It isn't cheap. You can also get one with a bottom mounted bearing on the tip that's a little easier to use, but won't allow for cutting a cove in the middle of your workpiece. FYI, bottom/top is based on the the assumption you're using the router freehand. In that case, the bit is pointing down, so that the bearing is on the tip, or bottom. If the bearing is closest to the collet, it is a top mounted bearing.