# making concave indentation into end of piece of wood

I need to reinforce a railing, above a stairwell, that is completely un-supported at one end (other than flimsy metal vertical stiles, which are nowhere near strong enough to keep the end of the wooden rail from being secure). Here is a picture (sorry it's not clearer) which shows the situation; it's the left-hand end of the rail that is the issue.

I plan to do it by running a 2-3/8" diameter aluminum tube from floor to ceiling, and screwing it into the end of the wooden rail.

To make this look decent, I therefore need to cut a concave indentation into the end of the wooden rail (so that the tube fits into it). The rail is roughly 2-2.5" wide also. How can I do this ?

Here is another photo, showing the situation better ...

• As far as whether the tube is strong enough ... The formula for maximum deflection with a point load on a simple-supported beam is F*L^3/48EI (I believe this works for me, even though my beam is vertical). So the height is about 100", and I'll imagine someone leans on the thing with 100lb of force. E = 1e7 for aluminum, and I = 0.63 for a hollow round tube with OD/ID = 2.35"/2.05". The deflection is about 1/3". (These are imperial units - inches, pounds, etc). Commented Aug 22, 2022 at 19:17
• TBH, I'm rather shocked that this flimsy end of the railing ever passed an inspection. I'd guess that it was put in DIY without any inspection at all. Commented Aug 29, 2022 at 14:30
• @FreeMan No, I don't think so. There needed to be a railing of SOME kind, or it certainly wouldn't have passed inspection, because there would have been a dangerous dropoff. Maybe someone replaced the original railing, but why ?!? There's actually a number of these houses, built by the same builder and with the same floor plan, in this area. I'm curious how the railing looks in those places; I may get a chance to look at one of our new neighbor's places soon, so I'll find out. Commented Aug 30, 2022 at 17:04

When I need to use a hole saw to make a partial hole, here is what I do.

Clamp a few pieces of scrap lumber to sandwich the work like this (side/cutaway view):

Then drill your hole straight down through the sandwich. The scrap pieces will allow the pilot bit to hold onto something and keep the hole saw from going off course. Remove your scrap pieces and you're left with a nice partial hole.

When choosing your hole location, make sure that your hole saw is biting into as much solid wood as possible in order to keep the stability highest. If needed, cut a little further back into the railing to achieve that stability. The most important thing is to keep the density as close as possible around the entire circumference of the hole saw to keep it from wandering or binding.

• Neat idea, but the sides of the wooden rail aren't just vertical edges - they have a sort of serpentine shape to them (as is very normal, if you imagine wooden railings you've seen). So clamping the side pieces might be tricky. Commented Aug 21, 2022 at 5:47
• @RustyShackleford True, the shape of the railing is generally not perfectly rectangular. However, if you can get the "sandwich" piece the same vertical thickness as the railing, it should still be stable enough to do what you need. You can also use those adhesive rubber pads for furniture legs on the top and bottom piece to both cushion the railing and keep the piece from moving around. Commented Aug 22, 2022 at 16:41
• Whatever the shape of the railing, this is exactly the way I'd do it, too. You may need some shims to hold the top/bottom blocks nice and square so you can get clean cuts. Note that the bottom block will help significantly reduce the tear out when the hole saw exits the bottom of the railing so that it will look nice instead of having chunks taken out of it. Additionally, the side block is only to hold the top/bottom blocks square to each other - with this in there, you might not need the shims if you can clamp securely enough. Commented Aug 23, 2022 at 14:52
• @RustyShackleford Yes, that's a side view - edited my post to make that clearer. :) Commented Aug 23, 2022 at 17:43
• @RustyShackleford A forstner should be OK as long as there isn't any empty space in the center where the pilot screw bit is. Commented Aug 23, 2022 at 17:44

That's a tough one. Have you considered how bendy the middle of an 8-foot long aluminum tube may be? The whole deal may wobble.

Consider instead a simple brace running from the hand rail at the last stile to the floor, with the floor end of the brace about 6" away from the stile. This makes a triangle, which should give excellent rigidity to the rail. It looks like the sofa is right there, so the brace should not be a trip hazard.

• Could you put a second handrail on the inside (to mirror the one on the wall) and use that as your brace? Maybe with an augmented but only rail high final vertical element. Commented Aug 20, 2022 at 19:31
• Assuming decent wall thickness, 2-1/2” aluminum pipe will be spectacularly stiff. Commented Aug 20, 2022 at 23:54
• Yeah, I ran the numbers - it will be plenty stiff. Commented Aug 21, 2022 at 5:48
• @RustyShackleford, yes, a "frame challenge" is a Stack Exchange expression for "try this a different way". Commented Aug 21, 2022 at 13:14
• @RustyShackleford He meant to make a small(2 or 3 foot) railing that would be along the side end of the sofa, at right angle to the long railing. Would match better than having a post at the end of the railing. Commented Aug 21, 2022 at 17:45

Probably a jig/scroll saw(power or hand) would be the best. Might want/need to remove the end stile while cutting.

Imagine it will only be a half diameter cut(only half of the tube), so a drill hole saw would be difficult.

A router would also be difficult to control.

Will probably want to sand the cut so the tube fits right, there are small drum/tube type type drill sanders.

• Yeah, I was thinking about a sanding drum I could put on a drill, such as leevalley.com/en-us/shop/tools/supplies/sanding/drums/… I wonder how much time, and how many changes of sandpaper, it would require though ? The railing piece is oak, of course. Commented Aug 21, 2022 at 5:53
• a router could work, start by making a template to guide the foot of the router then clamp the template in place and use the longest straight cutter you have, the may be some splintering on the right side of the cut. Commented Aug 21, 2022 at 9:34
• a sandpaper drum in a drill is going to be hard to control. sandpaper can generally move more than its thickness in wood. Commented Aug 21, 2022 at 9:38
• Sorry, what does "move more than its thickness in wood" mean ? You mean instability, or the amount of wood it removes ? Commented Aug 21, 2022 at 17:22
• @RustyShackleford I'd focus on the "sandpaper drum in a drill is going to be hard to control" part of that statement. You may well end up sanding off more than you want. I've used a wire wheel in a drill to clean up car parts and the wheel is more than happy to catch on any little thing and scoot around. It takes both hands to control it, and if the wheel moves, it just removes grease & grime from another place on the part. In your case, if the drum moves, it may remove wood from someplace that you don't want it to remove wood from. Commented Aug 24, 2022 at 13:40

A coping saw can do this. you'll need to attach guides top and bottom with the half circle you want to cut marked on them then just saw along the marked curves keeping the blade vertical. sawing vertically is tiring, and coping saws have short blades with tiny teeth, so this will be unpleasant work.

If you only have basic tools start with the hungriest and work your way down, start with a saw, then use chisels, a rasp, file, and finally sandpaper.

A holesaw might work. but it'll need to be sharp. and the drill is going to need to be fed at a steady rate, and held securely even when it kicks. a guide plate above and below the work, and alone the path of the pilot drill will help somewhat. Maybe worth a try if you can borrow a drill press, I wouldn't attempt this free-hand. I've never done partial holes in oak, so I don't know how much risk there is of the hole saw taking chips off the right side of the bite.

• Would the guides be solid material that the coping saw bears against, or just marks ? Commented Aug 21, 2022 at 17:30
• it's a lot easier to draw a an accurate circle on a flat surface, so I would use something solid, eg: 1/8" MDF Commented Aug 21, 2022 at 22:10