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I'm essentially restoring a bathroom in a 1920s house and I'm trying to be as true to the original woodwork as I can (as a novice).

I'm using my dad's old router for the first time ever and so far it's been going OK (not perfect, but OK).

One edge that I haven't been able to figure out is the edge of the window sill. It's got sort of an "S" shape (if you cut off the bottom third and the top right downward curve).

The convex portion of the curve at the top goes 180° around and is definitely a 1/4" radius curve and I think maybe that the concave lower portion is perhaps a 1/2" radius curve.

I went to Home Depot and lowes to try and find a bit (or bits) that I could use to do this. The closest thing I found was a 1/4" radius Roman bit that could do the bottom of the sill (though the radius isn't right for that) and I thought maybe I could find a 1/2" radius one, but when I thought about it, I realized that in doing the top 1/4" curve (if I've already done the bottom curve), there would be nothing for the bearing to guide the second cut. I'd have the reverse issue if I did the top curve first.

So how do I do this?

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Edit:

Someone suggested that I mount the router underneath a plywood table. However, I do not immediately see a way to mount it. There are screws underneath the rods that I could use, but they are metal screws, not wood screws. Could I use the holes on the guide attached to the rods to screw it into the side of a table?

enter image description here

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    If you can't find the exact bit, you'll need to play around with a few different bits, and for this, you probably need a router table. Lucky for you, that can be a hunk of plywood suspended between milk crates with a router bolted onto the underside and a stick clamped on top. Jun 20, 2022 at 14:47
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    Google ‘stool router bit’. The bad thing is that these tend to be big, so might not be suited to your router. And attaching a router to a table usually involves removing the baseplate and using longer screws through those holes. Jun 20, 2022 at 16:50
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    OMG, there's a "sill router bit" that looks exactly right and I found it when googling "stool router bit" as you suggested.
    – hepcat72
    Jun 20, 2022 at 16:55
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    Regarding the machine screws holding the router to the “table”… the head is on the top surface of the table, then threading into the router base. So all you need on the top of the table is a countersunk clearance hole. (And probably longer machine screws.) Jun 21, 2022 at 13:43
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    Incidentally, one idea I had last night after my trip to the stores, was to use my tablesaw to "route" the sill. My tablesaw blade will rotate 45° and I realize that with maybe a dozen passes or so (and some sanding), I could reproduce the curve without a router. I'm sure you guys would think that's insane but I think it's cool as a "thinking outside the box" solution.
    – hepcat72
    Jun 21, 2022 at 13:54

2 Answers 2

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I might try an Ogee bit with a board upside down and then use a 1/4 radius after that 'on the top'. Should be able to get this pretty close with the right Ogee bit, probably a bigger one.

I'm sure I've seen single bits close to that, I have this finger pull door pull that is 'close' but a bit more aggressive on the 'bottom'. https://www.google.com/shopping/product/13986480099114392013?q=router+bits+door+pull+freud&prds=eto:13639532660545370309_0,pid:9685896006746805321,rsk:PC_10815388883686490806. I'll keep looking to see if I can find another. The finger pull might be pushing a full 1" board.

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  • I just found this bit, but I only have the image. I don't know what it's called or what it's dimensions are, but the middle of the bit looks extremely close to what my sills are... images.app.goo.gl/3eYddNF6orfBxXU4A
    – hepcat72
    Jun 20, 2022 at 14:40
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    @hepcat72, yeah have to say the very first thing I thought here was "two passes, with two different bits" on a router table (or the cheapest stand-in for one, which costs nothing). You could maybe find something very similar, as you have in fact, but specialist single-purpose bits are for me only worth it it there's a requirement for very long lengths of the needed profile. Much preferable IMO to get might-use-many-times bits, even if it does take a bit of time and a test piece or two to dial in the multi-bit profile.
    – Graphus
    Jun 20, 2022 at 14:58
  • @hepcat72 the one you linked to can be found in most hardware stores that sell any router bits if you want to go look at one and take a few measurements.
    – bowlturner
    Jun 20, 2022 at 16:07
  • @hepcat72 After seeing which router you have, pretty sure that is a 1/4" shank, all the bigger bits that could do the whole shape are going to be 1/2" shank, so you are back to using 2 passes to get your shape.
    – bowlturner
    Jun 21, 2022 at 20:40
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  • Create accurate profile of edge using gauge or playing cards held by rubber band.

enter image description here

  • Draw profile on both ends of short test board.
  • Remove most excess wood on table saw, stay outside lines.
  • Round off top edge with plane or by sanding, start with 60 or 80.
  • Make scratch stock from scraps of hardwood.
  • Draw bottom of profile on steel with Sharpie, file to shape, hone
  • Scrape bottom curve using scratch stock

After checking new work matches old:

  • Cut new sill board slightly long.
  • Repeat all steps on new sill.
  • Complete by sanding profile to same grit as used on top surface.
  • Trim both ends.
  • Drink to celebrate spending $0?

Make Your Own Scratch Stocks by Garrett Hack
How to Make & Use a Scratch Stock for Woodworking by Joshua Farnsworth
Posts tagged 'scratch stock' by Peter Follansbee

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