How many clamps?

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Dave wrote:

Given the usefulness of plywood and the ugliness of the edges, the ability to glue solid wood to the edges should be cultivated. It isn't hard either; all you need is...
1. smooth, square edges on both ply and wood
2. sufficient glue
3. sufficient pressure to hold them together until the glue dries.
Your previous failure may have been due to any or all of the above but I'm thinking the most likely is insufficient glue. You don't want so much that gobs squeeze out but enough to get a line of roughly pin head sized globules.
All in all, much easier to apply than to trim flush.
--

dadiOH
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"dadiOH" wrote:

-------------------------------------------------------------- IMHO, exposed raw plywood edges are like ugly on an ape.
I prefer to band plywood visible edges with an interlocked tongue and groove glued joint as follows:
(Think of tongue and groove construction used with wooden siding of years ago.)
Assume a 3/4" plywood and a visible 3/4" solid wood edge.
Run a 1/4" x 9/32" deep dado centered on the 3/4" plywood edge.
Starting with a 1" x 3/4" solid wood piece, cut a 1/4" thick x 1/4" long tenon centered on the 3/4" solid wood piece.
(This yields a 3/4" x 3/4" solid wood band when assembled.)
The assembled edge banding yield a 33% increase in the gluing area of the final joint (3/4"^2 vs, 1"^2) as well as creating a 3/4" vertical interlock of solid wood.
Quick, low cost, and strong like bull.
The biggest PITA of the whole process is making sure the wood is flush with the plywood after assembly, IMHO.
BTW, have used rubber bands and a dowel pin as clamps while the glue dries. Surgical tubing also works.
Lew
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On 3/27/13 11:06 AM, Lew Hodgett wrote:

I gave up spending the time and effort to even try to make them flush when gluing and setting up. Now I simply make install them a bit proud on purpose and then trim them flush with a pattern bit in the router.
I have a jig for running them vertically. I can do that in less time than it would take to try to glue them flush.... plus, I never get it perfect and end up going to the router, anyway, so why not cut to the chase.
--

-MIKE-

"Playing is not something I do at night, it's my function in life"
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"-MIKE-" wrote:

------------------------------------------ Be carefull.
I've used this technique and had a bit that cleaned up the wood but also left cutter marks on the plywood.
After that ran test cuts with a different bit.
No problems.
Lew
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On 3/27/13 1:48 PM, Lew Hodgett wrote:

You are correct, not all bits are the same. I prefer a to start with a quality bit that is more likely to have an exact match between the cutter and the bearing.
This isn't to say that a cheap bit will be off, but testing on some scrap is recommended. We talking thou's here, so it's not something you can see by looking at the edge of the bit or even using a straight edge to check.
ALSO... if you're not perfectly square to the table, meaning there will be a slight angle to the pattern bit, you can end up cutting into the plywood surface. DAMHIKT. :-)
You can also guard against this by raising your bit *only* high enough to cut the solid wood and not the plywood. It's tricky, but I've gotten pretty good and fast at it.
--

-MIKE-

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-MIKE- wrote:

For those less experienced, one can also leave a sliver of wood which is then easily removed with a chisel. Or file.
It can also be done other ways; by hand, eg. I've also done it with planer blades in a molding head on a radial arm saw.
--

dadiOH
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aner

I used a rabbet plane to trim down the solid oak edging around a desktop I made. The picture quality is lacking, but these photos illustrate the concept:
http://www.flickr.com/photos/gdguarino/6248117874/lightbox/
http://www.flickr.com/photos/gdguarino/6247597691/lightbox/
It was easy to set the plane's fence to cut only the edging. I think I may even have set the depth stop to be flush with the bottom of the plane iron at first, but I may have been afraid it would leave scratches; I don't see it in the pictures I took.
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Lew Hodgett wrote:

------------------------------------------------------- "-MIKE-" wrote:

-------------------------------------------------------------- The "Tongue and Groove" technique minimizes this problem.
Start by measuring the thickness of the plywood using a dial caliper.
Plane the wood equal to the thickness of the plywood + 0.020".
Center cut the "tongue" and "groove" cuts on the respective parts.
Glue the assembly together.
The result will be a joint that leaves the solid wood 0,010" proud on both top and bottom surfaces, well within the scope of a scraper for final finish.
The scraper can easily be positioned to clear the plywood surface.
Just another way to skin a cat,
Lew
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On 3/31/13 3:06 PM, Lew Hodgett wrote:

It is another way and I realize the strength of that joint. But by the time I measure and cut the tongue and grooves with the set-up involved, I can have them glued on and trimmed with the flush bit. (glue drying time being subtracted from both equations.)
--

-MIKE-

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On 3/27/13 6:30 AM, dadiOH wrote:

I'm not saying the OP did this, but it bears mentioning, because who knows what might have happened or what he may have been told to do, technique wise....
I was sort of mentoring a young man in the shop who was building a gift for his wife. When we were in the process of gluing something, he asked why I didn't let the glue "set-up" first before joining the parts.
Apparently, at some point in his life, he was building something with someone else and from what I could surmise, they were using contact cement. Well, he obviously had taken what he learned about contact cement and falsely applied it to all gluing, in general.
It makes me wonder about the current condition of anything this young man has ever glued before. :-)
There *are* techniques many of us have used where you apply glue to a surfaces, especially porous ones like plywood, let it soak in a little, then join together... or even add a bit more glue to the surface, and join and clamp.
But that's not what I got from my experience with this gentleman. This was more waiting so long that the glue was setting already. In any case, those things always make me wonder what's "not' being said when subjects like this come up.
--

-MIKE-

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On 3/25/13 1:31 AM, Dave wrote:

I can't speak to your experience or process, but I glue thick, solid edge banding/reinforcement to plywood all the time and get very strong results. I routinely test small sections of the joint from where I've cut a shelf to length and end up with a cut-off piece of shelf that is 1/4" to 1" wide. It is very difficult to break this joint and it rarely fails at the glue line. I stopped using fasteners (screws or nails) for this joint, several projects ago, as they proved to be unnecessary overkill.
As to strong.... well, strong is relative, isn't it. In the case of the OP's bookcase, the shelves look to be about 18" wide in my estimation. Not only does he not need any reinforcement on those shelves, he could probably store electric motors on them with no deflection. :-)
The face frames in the OP's bookshelf are just that, face frames. Face frames in cabinetry *do* add rigidity and strength, but in modern cabinetry are much more cosmetic/esthetic. I know of designs in which the face frames of a cabinet is intended to provide critical strength to the construction. This is certainly not the case in the OP's bookcase. The OP's face frame, IMO, is purely cosmetic and could be attached with 18ga trim nails and it would be stronger than needed for the intended purpose. Gluing it on now means it would likely hold up in a circus elephant act. :-)
Moving on to a broader discussion of solid edge support.... If I get to the point where I want the edge banding on a plywood shelf to act as reinforcement against deflection, I will often cut a rabbet in the solid wood banding to add strength, like this...
http://www.mikedrums.com/shelf_edge_top.jpg
http://www.mikedrums.com/shelf_edge_bot.jpg
This is generally for shelves that are very wide, like 3feet and more. This adds a great deal of strength and gives the shelves a thinker front profile, which I think looks better. So, it serves a dual purpose. I would never think (any longer) to have any fasteners in this joint. But I can assure you, even without the rabbet, I would use only glue.
--

-MIKE-

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On 3/25/13 5:51 AM, Mike Marlow wrote:

I addressed this in my previous post, but from the OP's pictures, that face frame could be more than adequately attached with trim nails. Those shelves are very narrow and are glued/dadoed in as integral segments of the case. IMO, they need no reinforcement at all. The frame certainly will add some strength, especially if glued. But glue AND fasteners is beyond overkill and simply a waste.
--

-MIKE-

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Possibly. Much of what we build is dependent on how we've built things through the years. For quite a few years, I used a blind nailer on my face frames, something I bought a long, long time ago from Lee Valley Tools.
Essentially, it's a mini-plane that raises a thin shaving of wood. I'd then drill a slightly undersized hole in that space and drive in a countersunk finishing nail. The raised shaving would then be glued back down and clamped in place for about ten minutes. I produced an invisible method of joining my face frames.
That method worked really well for a long time. Then I bought a Domino and just like the biscuit joiner, I haven't used the blind nailer since.
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On 3/26/13 3:50 AM, Dave wrote:

I love the blind nailing technique. I don't know who invented it or when, but I think it's brilliant.
In the case of gluing *and* finish-nailing a face frame, I still contend that the purpose of the nails is to act as clamps until the glue dries. Norm used to mention this a lot on his show.
--

-MIKE-

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I always thought, maybe mistakenly that the glue was just to add some extra holding power. And yes, I've read the articles stating that a properly glued wood connection is superior strength to the wood surrounding the joint.
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On 3/26/13 4:30 PM, Dave wrote:

Those articles are correct. And honestly, if the wood breaks before the glue joint, isn't that stronger than it ever needs to be?
--

-MIKE-

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Greg Guarino wrote:

Two would be enough, three won't hurt.
Why no clamps on top & bottom rails?

No.

Faster to eschew clamps and use countersunk screws and face grain bpugs.
--

dadiOH
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Greg Guarino wrote:
I find that the more simpleminded the question, the more likely people here will argue about it. This should be interesting.
I'm finally getting ready to attach the face frames to my first two bookcase units. Apart from some pocket screws for the top and bottom rails (whose holes will never be seen), I plan to just glue and clamp. I took a first stab at laying out where the clamps should go. I find that it's a little less nerve wracking if I have all of the clamps at hand and set to something like the right opening before I apply any glue.
http://www.flickr.com/photos/gdguarino/8583909737/in/photostream/lightbox/
and
http://www.flickr.com/photos/gdguarino/8585009670/in/photostream/lightbox/
I have two questions:
Do I need three clamps for each rail, as shown in the photos? Or would two (plus the clamps at the ends of the rails) be enough? The units are 21" wide.
I have shown five pipe-style clamps on each side (one at each T intersection) plus some cheap bar clamps in between the shelves that are further apart. Do I also need clamps between the shelves that are closer together? Those are 11.25" apart on center.
I feel I'm going to get a lesson on cauls, which, if quick and simple, I could consider. But my spare time has become very spare indeed lately. -------------------------------------------------- Other than use biscuits to maintain registration between carcass and F/F, what does your gut tell you?
Lew
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I have a few ideas on the subject of "gut". What we call "gut" or "feel" is a mental association built up over multiple repetitions of some observation or activity. It's what allows people to accomplish tasks that are too complex for conscious calculation, like hitting a curve ball, or playing music without a written score. (In my case, that would be "yes" for the latter, "no" for the former)
I think I have developed a reasonable mechanical sense over the years, and what "gut" I have tells me that it will probably work fine, even with fewer clamps than I show. But I am always willing to learn from people with better-developed "guts".
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wrote:

.

.

Well, they could be seen, if one were to look under the shelves. This will be easy to do for the upper shelves, as these units will rest on existing boxes that raise them up about 30". The top shelf will be above eye height, at least for height-challenged folks like me.
The better question is why I shouldn't use pocket screws for the stiles, drilled in from the outside of the boxes. These two bookcase units will be flanked on one side by another bookcase and on the other by the side walls of the room. The answer is that I did consider it, and haven't entirely rejected the idea. I just wonder if I'll regret it someday. By Murphy's Law, putting pocket holes in the outside walls of the cabinets will guarantee that we'll need to re-purpose them at some point; the new configuration exposing the sides.
Now this is a pretty minor concern, and I could be convinced otherwise if I thought it was structurally necessary to reinforce the glue. Is it?
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