Shelves in odd-shaped alcoves....

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Hi all.

I am planning to fit shelves into alcoves in my son's house. It's an old house and I doubt the corners will be 90 degrees, nor that the walls (at the back and either side) will be straight. I understand that I will need to scribe the wood to fit to the shape of each of the 3 walls (back and 2 sides) assuming they're not "flat", but I'm just struggling with one thing....

If, for example, the "back wall" of the alcove is narrower than the front, how do I scribe the shelf I want to fit, given that I clearly won't be able to properly scribe on to the shelf presented to the alcove as the width of the shelf at the front will be too wide, therefore there will be a sort of traingular gap on each side (between a perfectly angled, at 90 degrees, shelf and the side walls of the alcove). I hope that sentence makes sense! In other words, and for example, let's say that the "back wall" of the alcove is 900mm and the front of the alcove (at the point where I want the front of the shelf to be) is 1000mm. So, that also means that the angle of each side all is not going to be 90 degrees. The shelf itself will ultimately be shaped like a trapezium.

It's possible, when I get there, that the alcove is the other way round! So, for example, the front may be 900mm and the back may be 1000mm! That sounds like an even harder exercise in terms of getting the shelf to the correct shape and dimensions!

All advice would be very warmly received, thank you. (One answer may be "get your boy to do it, it's his house after all"! I don't disagree, but am happy to help him....)

Mike
 

Bingy man

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Two lengths of thin timber used as a storey stick or a method I’ve used is a cardboard template-cardboard is cheaper than timber should a mistake be made . Another is to use decent plywood and make the alcove square as a bedroom / kitchen fitter would .any discrepancies could be hidden with a front strip similar to architrave around a door casement -at least then all shelves would be uniform.
 

Doug71

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It's good to leave a couple of mill gap around the edges to get some caulk in, that's my excuse anyway 😉
 

Richard_C

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My first house, 1976, had an alcove in the dining room perfect for bookshelves. House built early 1920's. I didn't have much experience or money, so carefully cut cardboard templates and used them to mark out and cut some conti-board to fit, it varied with position so each one was unique.

Having done that, I marked out for some brackets and began to drill the first hole. At that point gravity conquered the plaster and it fell off , ceiling to floor all 8 feet of it, which made all my careful cutting and fitting worthless.

So, before you get too much into it tap and test the plaster :)

(I swept up the mess and bought a second hand tall bookshelf, too wide for the platstered alcove but perfect for what I ended up with. I pushed it into place - very tight fit - and left it in the house 7 years later.)
 

TheUnicorn

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assuming vaguelly flat surfaces, I would get a pair of bevel gauges (Adjustable Carpentry Square Bevel Gauge Sliding Bevel 9 Inch Hardwood Handle Stainless Steel Blade Ruler T Bevel Angle Finder Craft Bevel Tool for Craftsman Carpenter Architect Engineer Woodworking : Amazon.co.uk: DIY & Tools just a reference not a recomendation) set one for the left side, one for the right, measure length and add extra (10mm?), try for a fit, then slowly trim down one side by a few mm at a time. for a more complicated shape I'd get out some cereal box and selotape and make up a template. always been a fan of the pencil in a washer technique for scribing to a wonky wall.
 

baldkev

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Theres a tonne of ways.
I always start with an edge.... so I'll check the rear wall to see if it is flat, if so i use that edge, measure the width, mark that width on your board, then use adjustable bevels to set put the sides of the alcove, measure the depth of the 2 sides and mark, then you can check your front edge length on your board against the opening.

Templates in hardboard are good.

You can also cut some strips of anything and make a template. Scribe in your back edge on one strip, then scribe a side, cut to length and screw the corner of the that length to your back strip. Do the other side. Then do the front. Use 2 screws per corner for rigidity and you can even add a corner brace. Its fast and easy.

If the front us crucial, like a cill board, i hold a straightedge ( usually a level ) across the opening, set my reveal bevels off that straightedge, mark on the cill, taking into account the horns if required, then measure and mark the depth each side. Double check the window it buts up to is straight!

A useful double check on any shape is to measure across the corners to make sure it matches ( within a mm or 2 is fine ) this just shows the angles are accurate, this is not to check the squareness and the 2 diagonals can be different, as long as the measurement matches your template per corner. ( if that makes sense )
 

baldkev

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P.s, if wider at the back, you'll be offering it up by having one side up in the air, push imto the gap and lower down. If its too long to slot into place, you can check the lower edge is scribed well, if not, mark it, then remove and reinsert with the other side down and check that scribe ( being careful to make sure your reference face is lined up i.e back edge flat to the window or front corners equally spaced off the wall )

The next step before cutting is to check the width of your scribed lines on the board or template against the measurement of the opening, because if you cut to your scribe line, you need to make sure you dont cut it short.
 

peter-harrison

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I've done lots of these. My favourite way is to make a cabinet that will just fit in the space, with the stiles over-wide to allow for scribing. You lose a bit of width and it uses a bit more timber, but you can have adjustable shelves which I reckon is pretty high on the list of things you need in a bookcase. It also makes fitting doors much easier if you want them. And you do all the accurate work in the workshop.
 
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