Elegant way to jack two materials apart, applying spreading pressure to pin them in place?

Question

I have a tall cabinet acting as a room divider. Since it's not against a wall, it could fall. Screwing into the floor or the wall is not feasible, but the top of the cabinet is 5 inches from a concrete beam. If I could apply "reverse clamping" pressure between the top of the cabinet and the ceiling beam, that would push the cabinet against the floor, tacking it in place.

The solution needs to be permanent, so I won't be using woodworking clamps set to spreading. I'm considering wedging some wood in place with a hammer, but I'm having a flashback (or is it a dream?) to some kind of bolt with plates at each end that can be spread apart by rotating a nut in the middle.

Does anyone know any such device and what it might be called? Regardless, I'll take any and all ideas about how to engineer some spreading pressure. If it's ugly, I could box it in.

Thanks in advance!

@FreshCodemonger Ha, hadn't seen comment but just posted this exact same idea for a situation where there would be more space — we has the same thought. — zx81, Dec 04 '21 at 13:50

score 7 · Answer 1 · answered Dec 04 '21 at 21:42

Power Wedge with Wing Nut

Build a power wedge from some wooden wedges, a bolt and a wing nut.

It will be strong, simple to tighten, and seismically safe when the bottom wedge is fastened to the top of the cabinet.

Tightening the nut will pull the wedges together, and you have leverage (e.g. 3:1) from the angle of the wedge.

Drill the through hole before cutting the wedge diagonal, and choose a hole diameter that is perhaps 2x the diameter of the bolt shaft to accommodate angling of the bolt. Simply cover the oversized hole with large enough washer on both ends.

Power Wedge with Power Tool

You could also replace the wing nut with a T-nut and drive the bolt with a power tool and a hex bit.

https://www.youtube.com/watch?v=nq8RM-E4THk

r13 · Answer 2 · 2021-12-03T21:51:38.797

I know you are thinking of using a turnbuckle on two threaded rods to push the beam and the cabinet, while it is doable but not reliable because the rod exerts a point load and the ends are similar to the pinned condition - they can move that causes the rod to bend and rotate. I prefer the wood wedge block method, you should wedge at least two locations (along the length of the cabinet) on both sides (front and back faces of the cabinet) and ensure the wedges will stay in place with the cabinet, maybe through nailing from inside of the cabinet onto the wood wedge. The large contact surface between the concrete beam and the cabinet will prevent outright fall over even when some shrinkage takes place.

Note that you can then conceal the wedges by using decorative edge trims or cover boards nailed to them.

isherwood · Accepted Answer · 2021-12-03T21:24:06.440

3

Don't wedge wood. Houses (and wood) move a lot with the seasons. That likely won't be reliable over the long term. You also risk damaging your furniture.

You can easily make such a device at your local hardware store. Some 1/2" bolts and a sleeve nut get you any post height you need. Add a couple wood plates with dimples in them and you're all set.

_____________________________________________________
      |                _______                 |
      |______________||__   __|| ______________|<-- wooden plate
                         | |
                         | |<-- hex or carriage bolt
                         | |
                        |   |
                        |   |<-- sleeve nut or turnbuckle
                        |   |
                        |   |
                        |   |
                         | |
                         | |
                         | |

With this strategy you'll need to turn the bolt(s) to adjust tension (turning the sleeve just moves the sleeve). You could also use a heavy (3/8" or better) turnbuckle and adjust with the connecting nut, which will have opposing threads on each end. You'd want the type with the solid sleeve, though. The hollow ones may not be rigid enough for compression duty.

In either case, a simple wooden surround of 1x4 boards finished to match your furniture could be installed to conceal it all between the top and bottom plates.

edited Dec 03 '21 at 21:24

answered Dec 03 '21 at 21:12

isherwood

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This sounds like just what I was looking for. Will look for turnbuckles. Just so I understand, since the pressure is obtained by turning the bolts, if I make a dimple in the wooden plate I don't think I'll be able to turn them. Am I missing something, or would you like to remove the dimple idea from the answer? Just wanting to check with you before hitting accept. Big thanks. – zx81 Dec 03 '21 at 21:32
That's to keep things in place and aligned. You can clamp a Vice-Grip pliers on the bolts to turn them. You aren't lifting a truck here. :) – isherwood Dec 03 '21 at 21:33
I was thinking you'd countersink with say a 3/4" spade or Forstner bit for the dimple. Just a slight depression a bit wider than the bolt head. – isherwood Dec 03 '21 at 21:35
Yes, Forstners are some of my best friends. Just trying to visualize turning the bolts inside the dimple. Accepted your answer, thank you again. – zx81 Dec 03 '21 at 21:48
Just thought of another solution, riffing on yours: two sleeve nuts (at each end) instead of one in the middle, and a threaded rod in the middle. That way there would be space to grab the nuts outside the dimples. – zx81 Dec 03 '21 at 22:00
1

I'm guessing you meant "one sleeve nut at each end", but sure. Good enhancement. Just use parts robust enough to be laterally stable. You don't want them flexing around. Go oversize if price isn't crazy. – isherwood Dec 03 '21 at 22:01
Extra point (well sorry that's not possible) for pointing out a normal turnbuckle might buckle if used for compression. – jay613 Dec 09 '21 at 00:39
Feel free to change your answer selection. There are others that align better, I think. – isherwood Dec 09 '21 at 21:31

zx81 · Answer 4 · 2021-12-08T22:12:33.480

1

Car Jacks

Another possibility occurred to me which could help someone in a similar situation. If there were a tad more space between the top of the shelves and the ceiling, it wouldn't be that crazy to place two cheap car jacks there — boxed in for esthetics of course.

edited Dec 08 '21 at 22:12

answered Dec 04 '21 at 13:48

zx81

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score 1 · Answer 5 · answered Dec 04 '21 at 15:44

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Frame challenge:

A wire will work equally well. The point is to stop the cabinet from overturning. A taut wire between the beam and top of the cabinet will achieve the same thing, and may be easier to install.

The wire should be short enough that the cabinet can't turn so much that the center of gravity is outside the base. It should be strong enough to handle relevant loads that may be applied.

answered Dec 04 '21 at 15:44

vidarlo

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While you'll accomplish _safety_ with this method, you won't get stability. It'll still have a fair amount of wobble when being manipulated (loading books, etc.). – isherwood Dec 09 '21 at 13:41
It need not have any wobble if it's standing on the floor. – vidarlo Dec 09 '21 at 18:50

score 1 · Answer 6 · answered Dec 09 '21 at 21:09

1

Here is what I did in the end

Another idea that occurred to me: adjustable feet, placing them at the top of the furniture rather than the bottom. Found some at the hardware store.

Thanks for everyone's contributions, I learned heaps of ideas for next time.

answered Dec 09 '21 at 21:09