An acute problem

[niftyprose]

Hello guys, my first post here. This is one of those occasions when it's helpful to set out a problem. If someone has a suggestion, that's a bonus. (The forum software highlighted a previous query about how to cut very acute angles accurately: that's good info but I'm past it already.)

I'm building bookshelves right up the end walls and up to the high, sloping ceiling of a lean-to extension which my wife had built 30 years ago, long before I came on the scene. All the walls are construction block so it's easy to get a strong fix for the lower shelves. The ones under the ceiling are more of a problem. The architect's drawings told me that the ceiling slopes at 22.5deg to the horizontal, so I planned to attach false dados to the joists using coach bolts, cut 22.5deg ends onto the shelves, slide them into the gaps and reinforce the joints with Kreg pocket hole screws.

To this end, I built a vertical fence and sourced a hard-to-find 204mm blade for my old Makita 2708 table saw. Everything went according to plan... until I found that the builders had gone off-spec. I reckon the ceiling angle is actually more like 18deg. The dados are a non-starter.

To my way of thinking a joint of any kind is a non-starter, given that the very sharp angle makes it very difficult to transfer load into supporting members. What are the alternatives? I remember Simpson Strong-Tie making bendable reinforcements that can be set to any required angle. I wouldn't want to use builders ironwork in this context, but I did wonder about buying heavy duty hinges from a flight case company. All suggestions gratefully recd.

NP.

 

[Diver Fred]

Could you post a picture of the area you are wishing to put the shelves.

 

[^woody^]

Yeah, the text is indecipherable in context of the issue.

 

[niftyprose]

Me again. I posted this problem back in the autumn, hoping for a solution before I left the country on an extended trip. I doubt that anyone was waiting on tenterhooks but here's a recap plus an account of my fix.

I was building floor-to-ceiling shelves in an annex with a sloping ceiling. All the timber is scaffolding board, a heavy-duty variant that's thicker and broader than I'm used to. The shelves are nearly 10" deep and carry heavy books, so need strong support.

The ceiling turned out to be built on a flattish 18deg, ruling out the obvious false dado. It's held up with wooden beams, but they're in the wrong place to hang from. How else could I fix the shelves to the slope?

I actually figured out a fix the same night I posted, but then had to wait for Ebay deliveries. I eventually completed the work a day or so before setting off. Here's a photo of what I did.

At left is one of the two side verticals, both of which are attached to the building block wall with coachbolts. There's also a central vertical (not shown) secured on chemical anchors and a heavy-duty shelf bracket.

The diagonal top board spans the verticals and is lightly bolted to them and also to the woodwork in the ceiling to keep it securely in line.

The shelves attach as you'd expect to the verticals and the rear wall. But, where they join the diagonal, their weight is borne on square U-bolts that span the shelf and the diagonal. You can see one of these near the centre of the picture. I think they're 10mm stock and 12cm long -- anyway, the biggest I could source to ensure good engagement. I had some concerns about accuracy, but with a borrowed drillstand and careful measurement I got the U-bolts exactly where I wanted them.

It's an eccentric arrangement but has worked out well. Sorry about the bad lighting! Happy New Year, everyone.

 

[freddiemercurystwin]

Wow, have you thought about starting a YouTube woodwork channel?