Glue Up Question

[Bill Waller]

I am working on a small shelf unit for storing CDs, DVDs, and video tapes.

The unit that is presently sitting in clamps is 32' high and 23" wide. The shelves are 6 ¼" deep. The wood is ash. The shelves are set in dados across the uprights.

The question: I am using Titebond II, applied to the inside of the dados and the ends of the shelf boards. Each of the four shelves fit well and I used four bar or pipe clamps per shelf on the outside of the uprights to keep everything together while the glue set. There was a small amount of "cup" in the uprights that I was able to draw in with the clamps. The joints are tight enough that I got a little ooze on each of them. After curing for 24 hours, can I expect the bond to hold, or will I get a nasty surprise when I remove the clamps?

I have not used any mechanical fasteners.

Thanks for any illumination into what to expect when I pull the clamps. ____________________ Bill Waller New Eagle, PA

[e-mail]

[Leon]

You should be just fine. You may hear a few pops as you loosen the clamps.

[dnoyeB]

Im about to do the same thing tomorrow. Ill be using Titebond original wood Glue. When should you use fasteners in addition? My shelf will be in the basement, in-wall.

[David]

A day is MORE than enough time for TB is harden. I take clamps off between 45 minutes to 2 hours, unless I forget or it's nighttime and then of course I leave the project clamped until the next day. The shorter clamping time I mentioned is for smaller projects. I'd leave furniture bonds alone for more than 90 minutes, just to be certain there's no glue failure.

Dave

[Swingman]

Normally there is no need to use fasteners when you glue shelves into dadoes in a casework side, although I will do it from time to time. Sometimes in lieu of clamps, but mostly on a frameless cabinet and when I feel that it will benefit because of an extraordinary load, or the design calls for it, or just out of an abundance of precaution ... and then so grandma's priceless Ming vase won't need krazy glue now that my cabinet shelf pulled out when the clients teenage gorilla used it for chin-ups.

[wood_newbie]

Swingman,

I've always wondered if a glued dado adds a ton of strength to a piece. I figure on all sides it's an end-grain to face-grain joint. Say...on a bookcase...if you were only going to glue the shelves into dadoes, do you have to add a lot of "structural integrity" elsewhere to keep the case from racking? (Or even pulling apart...)

In other words, does the glue serve basically to keep the shelf from sliding out, or does it add some integrity to the piece?

Any thoughts appreciated.

[CW]

32 feet high? Your definition of small is a bit different then mine.

[Chris Friesen]

Given that end-to-face glue joints don't have *zero* strength, it will add something--just not a lot.

Also, you have a certain amount of resistance against racking from the shelf top and bottom pressing against the dado. However, given that the dados are usually shallow this will not resist a large amount of stress.

Chris

[Leon]

Well, yes the glue adds a lot of strength to the joint provided the joint is a correct fit to start with. Even with out glue a correctly fitted dado should not allow a shelf to slide out easily. Racking is going to be the problem, however a thin plywood back and or face frame on the front adds considerably also.

[David]

a bottom and top shelf will NOT reduce racking enough to be the final solution, Chris. A back will solve the problem; even a partial back.

Dave

[Swingman]

What Leon said ... also, if you should happen to dado the top and floor into the sides, along with the shelf, you may be surprised at how much the combination can add "integrity" and resist racking, which is what this thread seems most concerned with.

Cabinets are boxes, and boxes are almost always stronger with at least five sides, so _attaching_ a back is the key.

Of course, and as a far as racking is concerned, add a faceframe and you're into elephant seating territory.

[Chris Friesen]

I may not have been clear. I was discussing the top and bottom of each shelf pressing against the sides of the dadoes.

If you had (for example) 2" deep dadoes this could contribute a fair bit of racking strength. However with your basic 3/4" thick uprights you can't get enough dado depth to contribute any serious amount of mechanical strength.

Chris

[Josh]

You'll need a back or faceframe to prevent racking, but otherwise the glue should be more than strong enough since the dado will be bearing all of the load.

Whenever I do shelves like this, I cut the dados with my router and run them from the back of the uprights up to within about 1/2" of the front. Then the shelf can slide in from the back, but not fall out the front. You just have to "nip" off the corners of the first 1/2" of the shelf so that it can slide all the way forward. This also makes the dados invisible once the shelf is in place.

Josh

[Josh]

I put some pictures on line showing what I mean. This is moot to the OP, of course, but for dnoyeB who's doing this tomorrow, it's something to consider.

973 and 974 at the bottom of the page show the detail of the dado.

Josh

[David]

I've never seen a 2" dado, so I don't see the relevance, but yes, a deeper dado would provide additional resistance to racking. Having actually built cabinets, I know that until the back goes on, they have little stability, even with multiple dadoed shelves.

dave

[wood_newbie]

Nice stuff! Thanks for the photos...I wasn't quite sure what you had meant by stopping the dadoes...these 'splain it nicely.

And that's a technique I'm definitely going to copy.

[Bill Waller]

Okay, the clamps have come off and nothing moved. I am happy. The second section is sitting in the clamps,, even as I type.

Thanks for all of the input, including pointing out my 32' typo.

The design does include a back which will be set in a rabbet on the back of the uprights. The back piece will probably get attached with my little HF brad nailer.

Considering the anticipated loading for the shelf (see above) I do not anticipate any problem with overloading. The second section will also be attached at a 90º angle forming a corner shelf unit configuration. Racking should not be a problem, once everything is assembled.

I have used this construction method before with softer woods than ash which was my primary concern.

Thanks for the help. ____________________ Bill Waller New Eagle, PA

[e-mail]

[dnoyeB]

Hmm. This would seem to imply that while my box is curing after glueing, I should get to work on the back. Then I should glue the back on before I even move the box too much?

im forseeing sitting this thing on its corner in order to get clamps all around the back. Is that how folks put backs on boxen?

[David]

I put the back on to help ensure the box is squared up. others don't like spraying finish into a cabinet that has a back (because of annoying blow back), so they build without the back, do the finishing, and finally, install the back. There really isn't a right and wrong way to assembly as long as the results are ok. If the cabinet is melamine, of course there's no interior spraying to be done, so the back could during final assembly to assist in keeping it square. Of course that only works well if the back is a tight fit in the rabbets.

I use a crown stapler to install the back unless it might need to come off in the future.

Dave

[Swingman]

Make, or buy, some 90 degree angle clamp assists. You can make them easily of the factory edges of sheets of plywood. Clamp two to opposite corners of your casework during glue-up and they'll keep your assembly square. Leave them on while you put the back on.

Rockler sells some like this called Clampits:

but they are very easy to make by cutting a factory corner at a 45 degree angle, then notching the sides for clamps. Clamp them in the right place and you can keep them there until you get the back on.