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Big glue-up, screw-up, pocket-hole-up approaches?

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Jeffo

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I've got a big floor-to-ceiling/wall-to-wall bookcase to piece together in the coming days. I've designed it in 5 sections that can be attached to one another.

In practice this means that I've got five 2m x 0.75m caracsses to construct. Relatively straightforward construction, in a normal 'ladder' type structure with a backing comprising:

1 x 18mm MRMDF back
2 x 18mm MRMDF sides
5 x 25mm MRMDF shelves (lipped front and back with hardwood)
2 x 18mm MRMDF tops and bottoms

I intend to spray paint it when finished.

Does anyone have any recommendations on the approach I should take to construction? I've got access to a Domino, Pocket Hole jig, 4 x Bessey K-Revo 1200mm clamps, 4 x Kreg 90 degree clamps and a few homemade 90 angle blocks with some small claps that can be used with them. I've also go lots of Titebond 2, pocket screws and regular screws.

I tend to make things is a bit of an over-engineered way, but really want this to be square and conscious that they'll have some pretty heavy books on eventually...

I was planning on doing the following, constructing the outer carcass first, then installing the shelves later. I'd be really grateful for any advice as to the merits of my approach:

Carcass
- Construct the outer carcass using pocket holes and a little glue. I'd drill pocket holes along the edges of the two 'sides' and two 'tops/bottoms' to that they can be screwed to each other and the 18mm bookcase 'back'. I'd put a pocket hole every 12" or so

- Against for the outer carcass, I wonder whether pocket holes are enough and whether I should use glue for strength and/or dominos for alignment. I figure that I can clamp the outer carcass pretty well and can even dry fit some of the internal shelves to avoid the pocket holes 'pulling in' as they tighten. I'm worried about this, as I have it happen quite frequently when using pocket holes, but in this case, the carcass really needs to be millimetre perfect. Glue adds a further complication... I'd have the time pressure to deal with, and the challenge of clamping/positioning everything without spreading glue all over the place. Any thoughts?

Shelves
- Using glue and dominos for the shelf sides would have needed to have been done when I constructed the carcass. But I think gluing the carcass, shelves, dominos, assembling it all, clamping, dealing with squeeze out etc all is too much for me working on my own (and not very experienced). I also don't want to use pocket holes on the shelves as would like to avoid all the hole filling that would be required.

- I'm wondering whether screws alone (drilled from the outside of the carcass, that will eventually be hidden) into the sides and rear of each shelf will be sufficient? Or should I use dominos/glue across the back edge of the shelf?

- If I just use screws, things seem simple - I'd lie the carcass on its back, make spacers from scrap to define my shelf heights, dry fit the shelves, use my kreg 90 degree clamps to hold them in place, and start adding screws along each side and the rear.

- Alternatively, I could use dominos and glue across the back of the shelf. For this, I figure I'd need to make my spacers from scrap, drill domino holes in the rear carcass and rear edge of the shelf. Apply glue, position shelf, clamp and screw as above. Not sure if the domino/glue along the back of the shelf is necessary - it certainly adds complication.

I guess the significant thing in this approach is that I'm not trying to glue my shelves in as I construct the main carcass. In my head that 'feels' like a better/higher quality/stronger approach, but I'm not sure I've got the skills to do so much gluing, positioning, clamping, screwing etc without either the glue drying or creating a massive mess.

Thanks
 

petermillard

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Fun project. 18mm back is a bit OTT, and if the shelves are fixed then lipping the back edge won’t add much, as you can fix through from the back. If the carcasses are in a run, then only the outer two faces will be visible, so easy to screw the shelves in position as the fixings will be hidden.

I’ve made lots of these types of shelves. I domino, screw & glue the carcass together, glue and fix the back on then glue & screw the shelves in, positioning them with spacers; fix through from the back as well. Once fitted, use an 18mm end panel on the two outer-facing carcasses to cover the screws, and make all the carcass uprights consistent.

Your design would have the carcass uprights at 36mm, the top & bases at 18mm and the shelves at 25mm. Personally, for a run like this, I’d make all the shelves, carcass tops and bases from 25mm, the two outer carcasses from a combination of 25mm and 12mm uprights, and the three middle carcasses with 12mm uprights. When they’re butted together, I lip the front of the carcasses to cover the join; this way when they’re all together in a run, the carcass and shelf thicknesses are much more consistent.

HTH P
 
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