In a recent thread on brad nailers, the discussion moved to attaching the customary 1/4 inch plywood to the back of cabinets such as bookcases. What is the “best” or the “right” technique?
I strongly prefer to finish the back before attaching it to the cabinet. This makes the finishing easy (thus better quality) for both the back itself and the back part of the sides and fixed shelves. But there is no longer bare wood to form a simple glue joint when the back is attached. So what are the options?
- I have been using brads to attach the finished plywood back into the usual rabbet. The rabbet and brads provide plenty of support from racking. But I have had someone lean on (or fall into) adjustable shelves, and push the plywood back loose.
- I have considered changing to screws or construction staples rather than brads, to keep the plywood back from pulling “through” the brad.
- Someone on the nailer thread suggested that the back should really be glued (of course if the wood is already finished, special glue will be required). Brads would then be adequate support until the glue dried.
- I could mask the glue area before finishing, so the back could be glued in “normally” but this seems like a lot of work to simplify or strengthen the gluing.
- I have considered sliding the back into a dado rather than a rabbet, more like a drawer bottom.
- etc.
I am concerned with what is considered “good practice” or “right” as well as what works. I haven’t given up my day job (yet), but I still want friends, family, and customers to feel that what I make is professional quality.
________________________
Charlie Plesums Austin, Texas
www.plesums.com/wood
Replies
I glue and brad nail(staple) the backs. If the shelves are adjustable, then they won't be there when applying a finish. If fixed, masking the glue area shouldn't take more than 5-10 minutes. I think it best to glue and fasten the back because without glue, the nails can work loose when the bookcase is relocated or when pressure is applied to the sides or shelves.
I have to differ from most of the replies so far. I have glued a few backs but most of the time just nail in place as part of the construction. Most of the time I use wall paneling nails (for lack of the exact name), they contain ridges that provide a great grip, have some head to them and come in different colors. I nail well, corners and every 4 to 6 inches all the way around, and most of the time predrill because of the beefer nail I'm using. Almost always use rabbit joints for the back.
Enjoy, Roy
I have never attached my backs with a rabbet, for fear of what you discribe.
i cut a dado in the sides for the back to slide into, much like a drawer bottom.
i then install 3/4 x 2 or 3 strips across the back for added support, and to allow the cabinet to be screwed to the wall (if required).
Custom Cabinetry and Furniture
http://www.BartlettWoodworking.com
I like your approach!!! That sounds like it would be really sturdy. For shelves that are just used for display the loading isn't too bad - but for someone like me, who is a book hound - I really load the bookcases full - this sounds like a terrific approach. Not only is it good from a racking standpoint - it is good from a safety standpoint...little ones playing cannot pull a bookshelf full of books over on themselves if it can be easily (and is!) screwed to the wall. Thanks!
-Martha
Friends,
Would say it'd be glue and brads. Shoot the brads at a slight angle away from the rabbet, and use the right brad length. That'd be the brad protrudes about the same thickness as that which it attaches, or slightly more, not less.
If staples are used and no glue, they'd loosen too. Most cabinets are p.w. sides and p.w. has no holding power hardly when brads or staples are shoot at the edges. Staples don't look good even in the back of cabinets.
Brads usually always used with glue, except if they hold real light pieces.
For large back covers, some clamping might be called-for, too, while the glue dries.
-mbl-
Edited 5/7/2004 11:41 am ET by mbl
"Staples don't look good in the back of cabinets"
Who looks at the back of cabinets? I am assuming this cabinet/bookcase is against a wall. Who on earth would have it freestanding, like an island kitchen? 1/4" crown staples hold remarkably well, and better than finish nails, and are hidden in the rabbet. The rabbet is also useful when scribing the piece to an uneven wall.
With respect to Squian Dubh, "maintaining" the back is known as a callback. It means the job wasn't done properly the first time, which is why I use glue on plywood backs.
Edited 5/7/2004 3:38 pm ET by JACKPLANE
I said nothing about maintaining the back, jackplane. I did say something about getting the back off to maintain working parts inside, such as tambors, drawers, runners/kickers, pocket doors and the like. This sort of cabinetry might reasonably have a lifespan of between 50 to 250 years.
Other types of cabinetry has a life expectancy of between 5 and 15 years. Most built in furniture such as kitchens, wardrobes, closets, offices, commercial cabinetry, etc., falls into this category. It's ripped out and replaced on a whim, and I'd agree that a call back to fix a bog standard plywood or melamine faced back would be embarrasing. Neither extreme is right or wrong. It just is the way it is. Slainte.RJFurniture
Who looks at the back of cabinets?
The people that buy furniture, at which time the unit may not be against the wall.
They might not buy it if they see staples are so visible.
Have moved cabinets that have been against the wall for years, and the staples are already loose from no-glue and resulting stresses of things bumping into the covers.
If the item is of solid wood, the staples would hold well. But if it is of solid wood, then staples don't look well as solid wood relates to a workmanship of no-visible fasteners.
But it's not a crime nor a sin to do wood anyway any one can, or wishes to do. But if it is for sale, the view of others has to be considered.
-mbl-
"customary 1/4 inch plywood to the back of cabinets"
Huh, what customary plywood is that Charlie, ha, ha?
Certainly in some types of construction economical backs such as plywood are used, but I'm not aware that it's customary for all cabinets. Traditional cabinetry might include anything from a high quality solid wood M&T'd frame and panel job to solid boards nailed onto the back, to hardboard nailed into a rebate, or hardboard simply nailed onto the back edge of the unit in extremely economical furniture, e.g., Ikea type furniture and a lot of kitchen cabinetry.
Take a for instance-- a display cabinet. Glass shelving, solid wood bevelled glazed doors, lighting, visible back panels behind the displayed items. Would a bit of white painted hardboard nailed on be appropriate, or perhaps a complex and visually stunning solid wood framed and veneered back panel job be better?
For small cabinets where economy of construction and a low price point is a major factor, just nail some ply or hardboard on. If we're talking $10,000 or $15,000 for a single cabinet, I suspect a nailed on bit of ply might be out of place.
Anyway, on small enough cabinets backs can be slipped up from the bottom in a groove and a few screws driven through the bottom of the back into the back edge of the bottom shelf of the cabinet. The back can be a frame and panel job, a ply or hardboard item, dependant upon the quality of the piece.
On large pieces it's common to work a rebate and the back dropped into place and screwed along all four edges into the rebate-- this is because it's extremely difficult to slide a large panel up from the bottom. Sometimes the rebate is not square, but tapered from the back edge towards the inside corner, and the edge of the panel is bevelled to match. Nails might be used as a substitute, but that would be unusual in a cabinet with working parts that might need maintenance in a few years, e.g., cabinets with tambors, drawers, pocket doors, etc.. Easy access from the back is always helpful to the restorer or repairer.
If you want to glue and screw (or nail) the back on, and also want to pre-polish the back prior to assembly simply mask off the area that's to be glued prior to polishing. However, a glued and screwed back indicates a fairly economically made item for a particular market, and there's nothing wrong with that, but it wouldn't be a piece expected to last more than a few years either. Slainte.
Richard - I need to take your course, even though the commute just got harder (I am closer to Houston than to Haddenham) - I never got $10,000 to $15,000 for a single cabinet, but would love to produce work worthy of that price level!
Seriously though, my technique is to use 1/4 inch or 3/8 inch furniture grade plywood, with full furniture finish (most often rubbed lacquer over whatever filler or (don't say it) stain/dye as required. That has seemed to be a good compromise between hardboard and a full finished back of solid shiplap or tongue and groove wood or raised panels, especially for bookcases, entertainment centers, and other pieces where the back is on limited display. (I have never resorted to a painted hardboard back..... even I have standards.)
So looking at that intermediate level between particle board paneling and an exotic veneer in a finished frame <grin>, I am still struggling with the best way to attach my furniture grade plywood. Note several suggestions for glue, but I am concerned with access for repairs, as well as whether glue is necessary/appropriate. I am not familiar with a "rebate" as you mention, and when I try to look it up, only find links to cheap metal furniture where I can get a cash rebate - are there other terms for rebate (particularly on the western side of the pond?). And sliding a plywood panel into a groove doesn't seem impossible, while the cabinet is lying down in the shop (my cabinets are at least straight and square). ________________________Charlie Plesums Austin, Texashttp://www.plesums.com/wood
Sorry Charlie. Rebate is the same as a rabbet in the US. Your question there was tongue in cheek wasn't it?
At what you're doing I'd say a decent plywood back is adequate. Tall bookcases, 6'-- 10' tall are probably dealt with most neatly by fitting the plywood back into a rebate (rabbet) worked on the two sides and across the top. Cut the bottom shelf narrower than the sides by the depth of the rebate and allow the back to extend to the bottom edge of this bottom shelf.
I prefer to screw the back in, and if you've got a fixed intermediate shelf or two, screw into the back of those too. It adds rigidity. I've never glued a back in to any cabinet I've built-- that's one of the oddest suggestions I've ever come across. It's impossible to get the back off for maintenance without damaging the back, and probably the carcase sides too and as far as I'm concerned the idea is a non starter, even in the most economical furniture I've ever built. Slainte. RJFurniture
Hey charlie,
Just to finish up your question. I use screws and a rabbit(rebate) ...put it on for the glue up (to help make sure everything is square), take it off for the finishing process. It just makes it easier to finish without a back in most situations.....and a hell of a lot easier to move around with no back on....
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