I am constructing a bookcase with sides about 4 ft x 11 inches, and 3/4 dados cut in the sides to accommodate shelves. The back edge is rabetted to accept the back, whcih is made up of ship lapped boards. After assembly of the basic case, I see there is some outward bow of one side in particular. (About 3/16 over the 4 feet) If I had made the shelves with sliding dovetails, that would hold the sides of the case parallel. In this case, with just dadoes, the bow of the side could pull the side away from the endgrain of the shelves. What would be the best way to keep the sides parallel? If I use a faceframe held on with biscuits, that would force the front edge parallel, but could induce twist, since the back edge mught still flare out. Any ideal/advice welcome. Thanks.
Jay
Replies
Jayst,
What do you suspect is causing the bow on the side?...is it fair to assume these are solid wood panels...what kinda wood?...did the bow happen with the cutting of the dado...or are the dados too tight? The only success I've had with this issue is to use cauls at glue-up....and plane afterwards if needed. I like to dovetail the corners to help maintain the boards flatness...not sure it does...
Yes, they are 7/8 inch thick, solid walnut, with 3/8 deep x 3/4 inch dados. The top and bottom are joined to the sides with half blind dovetails. The shelves have not yet been installed. I don't know if the bow developed in one board while sitting around my shop for a month after jointing and thicknessing or if it occurred after cutting the dados.
Jay
Jayst,
Do you think it's fair to assume that if the bow were there before the dado was cut you would have had a hell of a time on the TS...or did you use a router? Either way perhaps it'll flatten out after the moisture equalizes. I had a bit of the same issue recently while trying to finish a solid poplar cabinet...the darn back would warp 1/4" between putting paint on the front and then warp back when I painted the back side...
Clamp it up and see if you can impose your will on the bookcase...
I used a router, so the bow could have been there before the dados were cut. Even if I had found it, the only solution would have been to throw out the board and start again. I probably wouldn't have done that anyway, due to grain match between the two sides.
In general, I have found that imposing my will with clamps is at best, a short term solution. If there is not a mechanical solution the stresses will cause glue joints to fail eventually.
Jayst..
assuming the dado's are identical in depth and the shelves are identical in length, the only stress to deal with are in the bent side. A face frame will stiffen the sides, letting you use the "good" side to pull the other true. Once the glue dries it'll be fine.Mike Wallace
Stay safe....Have fun
I'd get that bow out with glue or fasteners or both.A couple well placed ...... dare I say ......... nails........ would do the trick. Fill them, and no one will know the difference. Or use dowels which could be invisible if done from the inside.Finally, I'd use epoxy and clamp the bejesus out of it, which should bring it into line.I agree that a face frame will probably get rid of a sixteenth or maybe even an eigth of the bow.Regards,
Boris"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
If you think that the face frame will be strong enough to remove the bow from the front then maybe give it a shot at the back too. Either attatch a frame at the back if design allows or attatch your one outside edge ship lap board solidly to act as a face frame.
I've run into this when I've made my dados different depths - or cut the shelves slightly longer (or shorter) than intended. Sometimes, the shelf (or shelves) aren't fully seated in the dados.
If you can, you really should take it apart and fix the problem. Otherwise, you'll be fighting with it all the way.
One way to avoid this is to dry fit everything before you reach for the glue bottle. It takes a little longer, but it can save a lot of aggravation.
A couple of things I've observed about casework construction (cabinets, bookcases, etc.) is that while not as "romantic" cabinet grade veneered plywood is generally an easier way to build boxes because it is less likely to bow than solid lumber. Solid lumber construction makes for a better piece of furniture but requires a thought out process prior to cutting and construction in order to avoid issues such as what you mentioned.
A couple of solutions: Don't assume that when your piece of furniture acclimates it will reduce the bowing, it may get worse. Try fastening your center shelf to the end panels so this shelf pulls the bowed panels in (pocket screws from underneath). Normally when you attach the back to the cabinet you should always try to fasten the back to the endpanels. This helps with the bowing. I will assume that you do not wish to fasten through the endpanels so as not to have visible nail holes which have been filled. Maybe try a few pocket screws along the back where it meets each endpanel. You may have pry your sides from the back a little to get more glue in, then clamp and screw. Your back attaching process should eliminate most of your bowing. Follow this by fasten one or more shelves to the endpanels and you should correct the problem and have a strong sturdy cabinet that should endure years of ambient conditions.
JAYST,
3/16" over 4' isn't too drastic. I'd count on the face frame to help hold things at the front. Clamp things tight, on assembly, of course. Then toenail the shelves, at least the middle one in place. Then nail (or screw) the last piece of shiplap backing to the end, and the shelves.
Regards,
Ray
3/16" can be a real pain. - lol
I'm modifying a customers existing TV cabinet and adding some raised panel doors - including flipper doors. The cabinet had been built by the previous homeowner and looked like a decent job. I installed most of the stuff yesterday and spent almost two hours getting the flipper doors dialed in. Nothing was grossly off, but nothing was really square either. I was mumbling to myself by the time it was done - lol
Moral of the story is to make it as square and true as you can because "tweaks" get harder and harder.
Amen,Brother,
Flipper doors are a pain when everything goes RIGHT!
I meant 3/16 wasn't too drastic to make right. An old timer told me once that the measure of a good craftsman was not that he never made a mistake; but that he knew how to cover his mistakes so no-one could find them!
Cheers,
Ray
The Accuride 1234 flipper door hardware has worked pretty well most of the time - but that's when I also do the carcass. The real hassle with a retrofit job is that I can't check the fit as I go along. The carcass is across town. - lol
Dave,
I understand; you have my sympathy--hope the job is cost-plus!
Regards,
Ray
Unfortunately, it isn't cost plus but I bid it with some fat in it. (My parents didn't raise any stupid children - lol) and the customer has some other projects planned for next year.
Dave,
That's good--make it up on the next ones. Just don't be like the ol' boy who was buying watermelons from the farmer for 2.50, and selling them in town for 1.75; he figured if he had a bigger truck, he could make up the difference in volumn.
Merry Christmannukwanza,
Ray
Jay:
Last book case I built, I used ¾-inch oak, cut the dadoes with a router, ½-inch deep. Dry fit it, then drilled for screws (3 to a shelf), assembled and then doweled the screw heads. I used #8 screws, 2½ inches long.
You may find that the "mammoth" type clamps work better, I find them a great help with that sort of case work.
Jorgenson and Harbor Freight both make them.
Regards,
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