A cantilevered bookcase.

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A cantilevered bookcase.

This topic has 11 replies, 10 voices, and was last updated 25 December 2017 at 23:01 by Robin Graham.

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23 December 2017 at 00:13 #333492
Robin Graham
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@robingraham42208
After about two months of stalling the plasterers have finally arrived and started work on my living room. This has motivated me to think in more detail about a problematical feature of the room -the first step into the stairwell down to the cellars intrudes into the room, so if I were fit a door flush with the living room wall it would leave a big hole (about 3' by 1' ) in the floor.

I'd like to cover this with a bookcase (about 3' wide by 1' deep by 6' high) hinged so that it would double as a door. I've been advised that given the loading (around 250kg of books), and that it would need to be cantilevered from a single upright, this would be difficult to do in wood so I should think of a steel frame.

So to my question – if I go for a welded box steel frame, can anyone advise what sort of section I should be looking at? I could calculate (tedious and subject to error) , but don't have any gut instinct for this sort of thing.

Rob.

Edited By Robin Graham on 23/12/2017 00:15:27
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23 December 2017 at 00:13 #35072
Robin Graham
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@robingraham42208
23 December 2017 at 00:36 #333494
vintagengineer
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@vintagengineer
25mm box section x 1.6mm should do it.
23 December 2017 at 01:29 #333497
Bazyle
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@bazyle
Wheel on the outer end to take the weight?
23 December 2017 at 09:53 #333525
Steve Pavey
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@stevepavey65865
A timber frame for a heavy door would probably be machined from something like 100×75. In steel box section you could easily halve that and more – so 25×50 for example. It’s the fixings to the masonry that will fail before the frame, followed by the hinges.

I would go for resin anchor fixings – probably 4 or 5 on the hinge stile. I would also support the (presumably timber) bookcase in a steel frame, which is in turn hinged to the main frame. Make up some decent hinges (probably 3 or 4) with 10 or 12mm dia pins rather than just welding on some steel butts from B and Q. And a wheel or non-swivel castor on the latch stile as Baz suggests is a good idea.
23 December 2017 at 10:46 #333538
Nick Hughes
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@nickhughes97026
A quick Google search would help you, with sites such as **LINK**

Nick.
23 December 2017 at 11:03 #333543
Farmboy
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@farmboy
I would suggest that the steel frame of the bookcase need not be massive if it is suitably braced with diagonals, but the hanging post will need to be substantial. How it is fixed will depend on the condition and construction of the wall.

A wheel (or possibly two) would be good if the floor is level, and might even allow the existing door frame to be used if it supports the weight adequately.

Sounds like an interesting project.

Mike.
23 December 2017 at 11:04 #333544
Clive Foster
Participant
@clivefoster55965
If fixed shelf positions with relatively deep frontal appearance are acceptable a "speed frame" unit using 1" square tube and knock together joints is much easier than welding and will be amply strong. Especially if you fix thin sheet to the back and sides. A similar pivoting shelf assembly was done in that manner years back where I used to work. As I recall it no support wheel but hefty hinges.

Don't recall where I got my last lot from but one source here **LINK**, probably cheaper than official Dexion version. Its a pity the 3/4" square system appears to be no longer made as the smaller tube is far less visually intrusive. These folk **LINK** sell 20 mm connectors intended for their stainless steel tube so maybe an ordinary steel or anodised alloy tube could be found to fit.

If you are going to cantilever with no support wheel best to use hinges with internal bushes or bearings rather than the common type. Much stronger but very intolerant of mis-alignment and somewhat spendy. Consider sitting a a couple or three small plastic (nylon?) wedge-front flats on the floor to support it in the normal closed position, possibly with a roller let into the tube so it runs on easily. Drop down foot to hold it stable when open and provide a bit more support would be good idea. Letting it close on you when down in cellar sound less than fun.

Clive.
23 December 2017 at 14:28 #333568
Georgineer
Participant
@georgineer
How much grunt would it take to start 1/4 tonne of books moving when opening the door?

George
23 December 2017 at 18:04 #333631
Michael Gilligan
Participant
@michaelgilligan61133
Posted by Georgineer on 23/12/2017 14:28:26:

How much grunt would it take to start 1/4 tonne of books moving when opening the door?

.

Depends mostly on the bearings !!

MichaelG.
23 December 2017 at 18:41 #333637
An Other
Participant
@another21905
Just a suggestion – If a bookcase is problematical, could you use a hinged panel at the bottom of the door, with a linkage so that as the door is opened, the panel is raised against the door, and drops down to fill the hole as the door is shut? I don't think I have explained this too clearly, but a similar idea was used on some railway carriages once. The steps intruded into the carriage, so as the door closed, the panel hinged down to cover the top step.

I don't think it would be too difficult to think up a suitable mechanism to do the lifting.
25 December 2017 at 23:01 #333933
Robin Graham
Participant
@robingraham42208
Thanks for replies, all helpful.

vintagengineer, thanks for suggesting dimensions, that was what I was hoping for in my original post.

Bazyle – sadly castors on the outboard end are not an option as the living room floor is flagged with well worn stones, so far from flat..

Nick – many thanks for the link, I had in fact Googled but one man's 'simple Google' is another's maze of irrelevant links. It's a matter of getting the search terms right. You did, I didn't. My bad. The project in your link is very similar to what I want to do.

It's clearly doable – given the info I've had I'll go for either a welded frame or the 'knock in' fittings Clive suggests.. I think I'll try a thrust bearing for the bottom pivot and a ball race at the top.

An Other – My wife is opposed to the bookcase idea and if she saw your alternative solution it might undermine my strategy!! It's a good plan B though – thanks.

Rob

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Edited By Robin Graham on 25/12/2017 23:14:40
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