rebates, dadoes, and dovetails

Hello,
You may remember I was asking about making bookcases. I did look at the Ikea ones as you suggested but one of the gaps I want to fit a bookcase in is 60cm wide. The ikea ones come in 40cm and 80cm sizes. I've had a quick look around and 40 and 80 seem to be the standard sizes: is there a reason for this? They just seemed odd numbers: I would have expected either 50 and 100 if using a metric system or 30, 60, 90 if based on feet.
So I am wondering about making a 60cm wide bookcase. I got told off for suggesting I used melamine faced chip, so how about 6x1 PSE?
I could just butt it all together and use screws or plastic blocks but I'd like to learn to do it properly. Last time dadoes or rebates were suggested. I wonder whether "rabbets" is just a mispronunciation of rebates?
I suppose the easiest way is to use a router to make a square (in cross section) rebate. How do I get the width of the rebate to match the width of the wood?
What is the finished width of 1" PSE? Would it be about 20mm? I see there are 20mm straight router bits so that seems straightforward. Is it?
If the wood was say 23mm, do you search for someone selling a 23mm bit or do you thickness the wood down to the next standard size, i.e. 20mm? I would think you would try and keep the wood as thick as possible to give maximum strength and minimum sag but if no 23mm bit exists, I don't see there is any choice.
I suppose you could try to do two passes (one offset by 3mm) with a 20mm bit to make a 23mm rebate but it sounds like it would be very tricky to do accurately. Is the thickness option better?
For a beginner, would you recommend I route "straight through" rather than a blind stop before I reach the front edge of the book case?
The disadvantage with this is that I would still need to find a way of holding it all together. Would gluing the shelves and nailing the back be sufficient?
It was suggested that if I cut dovetail rebates, the shelves would hold themselves in place and hold the bookcase together. Very clever. I am confused about which dovetail bit to use though. There seem to be so many variations on width and angle. Which do I choose?
I imagine I try to get the width of the dovetail as close to the width of the shelf, so I look for one with a diameter of 20mm. If I use 6x1 for the sides, I would only be routing to a depth of say 7mm (one third), so do I look for a short length? What angle do I choose?
Routing the sides seems otherwise straightforward but I then need to do the shelf edges to match. Do I use a router table for this?
Thanks in advance, Stephen.
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On 16/12/2010 10:23, Stephen wrote:

Sliding dovetails would be the way, but you might be better off getting an 800 wide Ikea bookcase and "adjusting" it - the shelves should be easy but the top/bottom will require a bit of fiddling. Or a 400 wide bookcase and a matching CD rack thing (about 200 wide)
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wrote:

Thanks. I did think about cutting 200mm off the shelves of an 800mm bookcase but then thought if I am going to trim 95% of it, why not buy my own wood and make my own?
As it happens I have two 600mm gaps. In one room I want to store dvds, so I could use a dvd/cd rack thing but if all goes well, I may decide to repeat the project and make a bookcase in the other room and a dvd rack wouldn't be any use there. Or would it? Can the shelf heights be adjusted?
Thanks, Stephen.
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You could use MDF if its painted. No need to cut slots.. make the sides out of two layers.. One the full height on the outside.. one cut into sections that fit between the shelves and support them. Glue the two together and then fit a wooden strip to the front to make it look like one piece. You can fit the strip to the shelves too and joint the strips if you want.
The top and bottom you can just but and screw through the inner pieces before you glue the outer pieces on to to hide all the fixings.
In effect its a box glued to the outside of another box that supports all the inside bits.
All you need is to be able to saw straight lines, sorry no excuse to buy jigs and power tools.
You could do it with real wood if you want the grain showing.
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On 16/12/2010 11:32, dennis@home wrote:

That's how I'd do it, but I'd have all the bits cut to size if I didn't have a decent chopsaw. I'd also use laminated pine panels instead of 6x1 PSE, which is good enough for flooring, but not much else. Then again, I'd buy something ready made and adapt it, as already suggested, but I'm guessing the OP might be a potential tool junkie :-)
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On Thu, 16 Dec 2010 13:13:43 +0000, stuart noble

Hello,
I am a bit unsure about which wood is best for which application. I only suggested 6x1 PSE because around here there are a number of timber merchants who are geared up for the construction industries rather than joinery, so softwood is all they have. I figured if I waited until I found a decent timber merchant, nothing would ever get done!
When you say laminated pine, is this block board or is it something else all together? If you had a good timber merchant and a choice of any wood type, what would you choose for a book case? Is one wood better suited than any other or is it more about the appearance?
Thanks, Stephen.
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On 16/12/2010 20:31, Stephen wrote:

You might find that many such merchants carry a small amount of "hardwood" in the form of window boards, and cills.
Its probably worth just getting stuck in a making something - its a learning experience if nothing else, and a bit of wood stain or varnish can make even pine look respectable (from a distance anyway!) (apols to any pine furniture fans)

Appearance will govern what you chose to a fair extent. Price is another big factor.
--
Cheers,

John.

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Try these http://www.screwfix.com/prods/18371/Ironmongery/Shelving-Systems/Bookcase-Strips/Bookcase-Shelf-Support-Brassed-Pack-of-10 I made some shelves using these. For the wood, I used pine window shelf which has a round edge. It's just under 1" thick and supports books over about 600mm with no sign of sagging. I rebated the strips into the uprights for neatness but they can be surface mounted. My shelves were built in so didn't need a back but others Ive built simply used a hardboard rear panel to provide stability. These days I would probably use thin plywood. I wood use real wood for the shelves. I've found that any resin bonded product sags over a period of time.
John
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On 17/12/2010 09:54, John wrote:

http://www.screwfix.com/prods/18371/Ironmongery/Shelving-Systems/Bookcase-Strips/Bookcase-Shelf-Support-Brassed-Pack-of-10
Yup, if you make a proper case and don't need any rigidity from the shelves these make a nice job of it. No problems with seasonal movement of the shelf either.

You can always add a deep lipping at the front - looks quite "posh" and also added significant sag resistance to a cheap shelf.
--
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John.

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On Fri, 17 Dec 2010 13:24:04 +0000, John Rumm

With my dvd "bookcase", I know the height I need for the shelves (dvd height plus finger room) but for a bookcase where you don't know how big the books will be, these could be useful to allow you to change the heights, just like the Billy bookcase.
I am just a little surprised though: I thought these rail systems were not liked in this group or am I get mixed up with something else?
Thanks, Stephen.
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On 17/12/2010 20:34, Stephen wrote:

Indeed. You can use the rails, or drill / route regular peg holes for the little push in shelf supports.
(a small template fixed to a router base with an indexing peg will let you plunge 1/4" holes at an exactly regular spacing - sink the first, then locate the peg in the previous hole to sink the next etc).

You might be getting mixed up with the spur style uprights and brackets used for shelving. Some folks find that a bit utilitarian.
--
Cheers,

John.

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On Thu, 16 Dec 2010 21:13:08 +0000, John Rumm

No, the cill I bought was pine too ;)

I'm glad I'm not the only one who isn't a big fan of pine. I know some people like the rustic, knotty, look but not me. Still, with a bit of knotting solution and some paint I suppose it could be hidden away!
Thanks, Stephen.
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On 16/12/2010 20:31, Stephen wrote:

No, it's not blockboard, it's strips of pine glued together.This kind of thing

http://www.homebase.co.uk/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId 001&partNumberA5107
Available everywhere in a variety of sizes. Looks like solid wood but much more stable.
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On Fri, 17 Dec 2010 08:41:27 +0000, stuart noble

Thanks. They call it furniture board. Yes I have heard of/seen it at B&Q. Thanks I'll look into it.
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wrote:

Bad sag problems when loaded long-term. Even chipboard is better.
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On Thu, 16 Dec 2010 11:32:29 -0000, "dennis@home"
Thanks I followed the rest of your post but I wonder whether MDF would be strong enough? In my (limited) experience, I have found it very saggy but this is based on sheets <12mm thick. Are the thicker sheets more rigid?
Thanks, Stephen.
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wrote:

They are and you can double them up like the sides and top. You can also fix through the back to stiffen the rear of the shelves and fitting a wood strip to the front stiffens the front. It is still possible to put to much weight on them as it is with any shelf and you can make any shelving stronger by adding more uprights rather than relying on the two sides. Additional uprights also serve as bookends to stop stuff falling over.

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Simplest solution - buy the ikea bookcase and re-size it. Use a mitre saw to chop the shelves shorter, and the chopped-off piece as a guide for where to bore the dowel holes in the shortened end (I'm guessing they still use dowels and screws).
Next option - buy the pse - and check very carefully that it's square and uniform. An awful lot of the work/skill with timber is compensating for the irregularities/warps/damage etc.
You cut the rebate/rabbet/housing (all the same thing) to match your board/shelf. You do it in two passes against a straight edge with a cutter smaller than the rebate needed (and they need to be a *tight fit* to the board/shelf that goes into them).
Professionals would glue/screw and clamp up. If you haven't got suitably large clamps (actually sash cramps) - then you'll just have to rely on screws through the uprights and into the ends of the shelves - these need to all go in quickly as you'll have wet glue on all the shelves at once (i.e. you should dry test-assemble, before gluing).
Now - you're going to be cutting a lot of identical rebates/housings (I'd prefer the term housing, as rebates are often one-sided, whilst a housing is always a "channel"). The thing to do is to make a jig to cut them out - basically two parallel guides so you run the router down the inside of one guide, then back on the inside of the other (PS make sure you've learnt about cutting direction with routers). The jig is just two straight bits of wood that act as guides, spaced the right distance apart by two more pieces, which also act as the 90 degree guide against the edge of the timber.
If you don't have a router yet, I highly recommend the Bosch GKF 600 as a first router - not cheap, a bit small for some work, but superb quality and comes bundled with a very comprehensive set of top quality accessories. Shop around - you can probably get it for just over a 100 quid.
Another way of doing this is to use a circular saw to cut the shoulders of the housing, then the router to rough out the waste material in the middle.
Using the router alone, stopped housings are not much more difficult than through housings (you will have to finish off with a hand chisel to get the end square).
Dovetailed housings - er - leave that for a later project. (I agree that it's a quite a bit nicer solution - but there's a good bit greater potential for mis-measuring/mis-cutting - plus you need to develop a "feel" for the the right dimensions to get a fit that is just tight enough, but not too tight).
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http://www.axminster.co.uk/bosch-bosch-gkf-600-routing--package-deal-prod784588 /
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Piece of shit for that money. No speed control (OK on wood, useless as a laminate trimmer), and there's some tempering fault on the collets so they all keep breaking. Nasty fine depth adjust too.
If you want the best router around, get a De Walt 621 (the one with the fat leg) and buy a US spare 1/2" collet for it from any DW spares place (bizarrely not sold as standard in the UK).
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