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Post by craigmarshall on Feb 2, 2008 21:40:13 GMT
Hi, In a month or so my boss and I are going to build an oak and MDF bookcase for a customer. This is the first phase - agreeing on the design. This is the first draft, there are already changes to make to this, e.g. upgrade from 18mm MDF to 25mm. Make the top centre shelf line up with the outer shelves and lose the centre divider at the same time. Beef up the oak thickness slightly, etc. I'll post revised drawings and work in progress pics as they happen (and of course lists of lessons learned!) It's about 3m long and 1.8 high for reference. The hole in the middle is the size of the TV + 10mm all round for breathing space. Yes - the MDF will be sprayed gray, at the customers request (Wouldn't want that myself!). It matches some other furniture in the house and will hopefully fit right in when it's installed. Any comments (improvements) on the design gratefully received! Cheers, Craig
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Post by engineerone on Feb 2, 2008 22:01:46 GMT
certainly you will not be able to make the centre upper shelf without someway of supporting and stopping it sagging in the middle. i would guess it will be about 1000 or so wide. for sure in mdf of single thickness it will move. that's a no brainer. i would suggest either making it a torsion box, or using supports top and bottom. otherwise it looks interesting. remember the cable paths. paul
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Post by engineerone on Feb 2, 2008 22:03:30 GMT
basically in my experience any bookshelf in mdf, especially 18mm cannot be any wider than about 600mm otherwise the sag will be visible. there is a thing called the sagulator, which is a web site, someone will know where, and that gives a better idea of widths and loading. paul
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Post by craigmarshall on Feb 2, 2008 22:08:42 GMT
certainly you will not be able to make the centre upper shelf without someway of supporting and stopping it sagging in the middle. i would guess it will be about 1000 or so wide. for sure in mdf of single thickness it will move. that's a no brainer. i would suggest either making it a torsion box, or using supports top and bottom. otherwise it looks interesting. remember the cable paths. paul Well - the back (no it's not drawn in yet) should provide enough support, it's only 150mm or so deep, and the thickness will be upgraded to 25mm which will stiffen it up. It it is a problem, we can lip it with a piece of oak or something to give even more stiffness. I have seen the sagulator, I will look it up again. Do you (or anyone else) know if the normally superior green moisture resistant MDF is better than the standard weetabix MDF you can get? It's certainly nicer to cut, drill, rout, plane (!), sand, etc. just wondering if it was less sag-prone too? Cheers, Craig
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Post by engineerone on Feb 2, 2008 22:16:01 GMT
not sure if the green stuff is less saggy, but i agree, better to paint and work with. as for 150 mm deep at the top, you are there talking about small books which people tend to stuff everywhere, so that is why i mention the concern about sagging, i just pass on my experience. as for the weetabix, maybe go for a brand name rather than just the shed product. paul
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Post by craigmarshall on Feb 2, 2008 22:19:08 GMT
I have seen the sagulator, I will look it up again. Found it: www.woodbin.com/calcs/sagulator.htm - What an awesome website. It gives options for MDF- LD, MD and HD. I'm guessing these are low, medium and high density? I'm guessing the green stuff we use (Moisture resistant) is HD, it's definitely higher quality, let's hope it's higher density too. The page also says the eye will detect a sag of 1/32" per running foot, that's 2.56mm in my 1000mm. I selected MDF-HD - and I used a shelf length of 1000mm, 150mm deep and 18mm thick. A uniform loading of 10kg (yet another guess!) gives a deflection of 5.08mm. Upgrade it to 25mm MDF and the deflection reduces to 1.90mm. Now - this doesn't take into account being secured at the back edge, but still it's very close for comfort, I'll have to keep an eye on it. Especially with this many guesses in my workings! Thanks, Craig
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Post by engineerone on Feb 2, 2008 23:17:41 GMT
craig remember two important things. your design involves a tv under the middle shelves, so it will be the most important part of the whole device, and it will be REALLY visible. secondly the other shelves lower down will probably take bigger ie taller books, and divert the eye too. so they must be checked for sagging. i assume the top shelf will be solid oak so will deflect less. paul
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Post by dom on Feb 3, 2008 8:56:07 GMT
Well here's something I've been doing of late, it may be old hat to some but others may find it useful. When making adjustable shelving I cut a stopped groove in the sides of the shelf so that rather than the shelf sitting on the pins the groove slides into the pins and so hides them. With deep shelves I route a couple of 18mm grooves across the width of the shelf. So if the shelf is say 300mm deep one groove is at CD depth and the next at paperback depth from the front. I then make a strip of wood to fit the length and width of the groove and about 30mm tall, when installed this stops books or cd's sliding to far back from the front of the shelf. Hope this makes sense.
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Post by craigmarshall on Feb 5, 2008 19:40:33 GMT
Well here's something I've been doing of late, it may be old hat to some but others may find it useful. When making adjustable shelving I cut a stopped groove in the sides of the shelf so that rather than the shelf sitting on the pins the groove slides into the pins and so hides them. With deep shelves I route a couple of 18mm grooves across the width of the shelf. So if the shelf is say 300mm deep one groove is at CD depth and the next at paperback depth from the front. I then make a strip of wood to fit the length and width of the groove and about 30mm tall, when installed this stops books or cd's sliding to far back from the front of the shelf. Hope this makes sense. Those both sound like good ideas. I'd be worried that reducing the effective thickness of the shelf would weaken that part of the shelf, all the weight is concentrated in a smallish area as it is... I suppose you could upgrade to three or four pins per side, given that they're hidden anyway. Craig
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Post by mrgrimsdale on Feb 6, 2008 7:35:26 GMT
It'll weigh a ton and be difficult to move without some structural support i.e. if you lift it at each end it will bend in the middle. Needs some sort of bearers or plinth to hold it together. I'd use real wood as far as possible, especially for the shelves, which look very likely to sag. MDF, cardboard etc are convenient but basically crap, and highly obsolescent.
cheers Jacob PS and perhaps the top ought to be a separate unit - just to make the whole thing portable, or is the whole thing built in?
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Post by jfc on Feb 6, 2008 8:36:10 GMT
From the drawing it looks like you can make the units in seperate parts and hide all the face frame fixings with biccies and pocket hole screws to hold them while the glue dries . In effect you can flat pack the whole frame .
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Post by craigmarshall on Feb 6, 2008 21:10:23 GMT
Yes - you're both right each MDF box will be made individually and we'll join them up later. I don't know how we're going to fix the front on yet, but the pocket holes idea is worth following. We don't have a pocket hole jig, but I reckon we could make a temporary one with a bit of greenheart/ipe and the pillar drill...
Craig
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Roger
Junior Member
Posts: 59
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Post by Roger on Feb 6, 2008 22:08:10 GMT
Sorry - but I'm not a big believer for MDF of whatver quality in this type of unit! As Jacob says: It'll weigh a ton and be difficult to move without some structural support i.e. if you lift it at each end it will bend in the middle. Needs some sort of bearers or plinth to hold it together. I'd use real wood as far as possible, especially for the shelves, which look very likely to sag. MDF, cardboard etc are convenient but basically crap, and highly obsolescent. Plywood would be my choice for flexibility, strength and ease of use. I tend to think you have an accident waiting to happen here
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Post by craigmarshall on Feb 6, 2008 22:19:45 GMT
Sorry - but I'm not a big believer for MDF of whatver quality in this type of unit! Hi Roger, You're probably right - I don't like MDF myself either and don't quite trust it for finished furniture projects, but it's what we're using and I don't have much say in that.. I know I asked for input on the design, but I'm not going to have much luck suggesting that we change the main material I'd personally be very happy making one-off free-standing stuff out of real wood only*. And not idigbo, sapele (and friends) or iroko! If and when I run my own workshop, I will try and do just that! Cheers, Craig * Perhaps that should be my future furniture company name, "Realwoodonly". Hmm.
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Post by jfc on Feb 6, 2008 22:39:14 GMT
Using solid timber will be ten times the work as you will have to join everything so it reduces the amount of movement . Im assuming this will be at least 400mm wide maybe 600mm as i didnt see a depth for the unit . That makes the job ten times labour plus materials . Nice idea wanting to build it all out of solid timber but not practical and you will be going back every time the central heating goes on . I also want to build things out of solid timber for a man with millions of pounds that lives in a draughty old castle but it aint gonna happen .
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Post by jfc on Feb 7, 2008 9:49:38 GMT
P.S you dont need a pocket hole jig , a 10mm flat bit does the job on its own .
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Post by craigmarshall on Jun 11, 2008 23:48:38 GMT
Hi, Thought I'd dig this old one up as well. The unit is now finished and installed in the customers home. Here's a pic: Cheers, Craig
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Post by wizer on Jun 12, 2008 9:06:02 GMT
hehe I like that, but isn't it a shame when the customer messes it up with their clutter?
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Post by craigmarshall on Jun 12, 2008 19:56:12 GMT
Yes - there's some kind of dissonance or irony with all the clutter and then the sign that says "simplify" :-)
Craig
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