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View Full Version : Divider in carcase - glue/fasten or not?



Jessica Pierce-LaRose
06-16-2012, 12:23 PM
Sorry for the stupid question, but I've never really worked on largish casework before.

Anyway, I'm working on the tool cabinet project, and staring to fit the dividing sections of the carcase to main box. These are all fit into dados in the main carcase or the other dividers.

I know if I had a perpendicular grain situation, I'd want to pay attention to wood movement, and if anything was glued or fastened, I'd want to only glue/fasten it a bit in one area to allow one piece of wood to expand/contract along it's width and slide past the long grain of the other piece.

In this case, however, all the case pieces are made out of the same poplar. I've tried to illustrate at least an example of what I'm doing in this picture - it's not quite the layout I'm working with (and there are a few more dividers, and drawers as well to be added) but as I hope shows up in the picture (never used the texture thing in sketchup before) the grain in the dividers runs in the same direction as the main carcase pieces parallel to it. So the horizontal divider still has the grain running in the same direction as the top and bottom, the vertical divider still has the grain running in the same direction as the sides, etc.

Can I secure these along their length? I'm not sure glue is going to do too much give the lack of long grain to long grain surfaces, but if I did something like put a couple screws or nails into the edges of the horizontal divider from the outside, do I risk the piece tearing itself apart from wood movement? There's just a hair of cupping on the interior of the vertical boards to the main carcase - it's so little that I can push it in with light hand pressure, and things would work fine just letting them sit in their dadoes. I'm not even sure you'd see more than a hair of shadow if I left it as is, but I was thinking of putting a hidden fastener or two in the middle of the horizontal divider from the outside to pull this in.

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I know the correct answer would have been to have payed more attention to my stock prep so this didn't happen - I obviously neglected to do this, or my clamping of the tails made things a little worse, I don't know. I'd hate to start over at this point, and I'm not sure how to plane out this slight cupping of the boards with carcase assembled. I suppose I could take a shaving or two off each end of the horizontal dividers to try and make it match the slight cup to the vertical carcase boards.

I suppose sliding dovetails could help, but I don't think I really have a way to cut those given the tools I have. Part of the plan was to put a dovetailed piece in front of the shelf as was recommended to me by Karl in in my previous question about this (http://www.sawmillcreek.org/showthread.php?186988-Dado-tenon-or-both) and while that will add some rigidity to the cabinet, that's not going to help with the slight cupping in the middle of the exterior vertical boards.

Greg Wease
06-16-2012, 3:23 PM
As shown, there are no cross-grain joints so you can glue all joints. Fasteners from the outside will go into end grain and won't hold very well. Since you can flatten the sides by hand, just use curved cauls across the joint when gluing to pull everything flat.

Correy Smith
06-16-2012, 11:39 PM
Joshua, Glue will certainly help and not bother with the grain orientation you have designed. Be it all poplar or not, the next "?" would be "are all my pieces flat or quarter sawn". I feel all glued dadoed joints will fail eventually. I try to design joinery so there is not long spans of carcass sides without some form of mechanical connection. For instance, if your were to build a 4 foot book case with shelves every 12" you might only use a sliding dovetail joint on the middle shelf. It will keep the sides from spreading just fine and the other shelves could just use a 3/16 dado.
Depending on the overall look you are hoping to acquire screws and bungs may ( or may not) be a tadd coarse. Though in this application they should treat you right. I build mostly case work these days. Mostly Tansu. In the old days they would use a couple wooden nails thru the sides at the front edge with animal glue. There are plenty of 150 year old+ examples that are still going strong. The peg would preferably be tapered and about 2" long, planed flush on the outside. Alas this will look pretty much like the bunged screwed but you will have plenty of long grain surfaces. The trick being that you tap in the peg, cut just shy of flush then tap flush and the head will mushroom over expanding the head in the hole. Sliding dovetails work great but your joinery has to be spot on or your just relying on the glue. I also enjoy using thru twin tenons that you may wedge about 1" back from the front edge.
I routinely use drawer partitions with the show wood just on the first three inches of the partition. I use a less expensive species for the remainder of the shelf. These I tenon the front edge and float the rest with out glue.
Here are a couple pics that show what I am explaining but with a sword tip miter added. The shelf edge will later receive a slight radius. This particular partition is of like grain orientation and specie, I added a rear tenon but also gave the mortise room to move if need be. I plan to glue the whole edge.
Best to you and your project. Please post a pic when completed.
Correy Smith234683234684

Jessica Pierce-LaRose
06-17-2012, 12:13 AM
Thanks for the input guys.

With all the dividers in place (http://www.sawmillcreek.org/showthread.php?187992-Today-was-a-good-day) things are pretty darned sturdy at this point. It also occurred to me since I'm using a plywood back, I could screw things to the back of the ply.

Corey - that looks terrific. I aspire to do that kind of work some day; right now I'm still figuring my way around casework - most of my woodworking up to this point has been electric guitars; (or poorly done things with plywood and screws and much further into the carpentry than cabinetry spectrum) for the longest time I only had to do one kind of joint, and only one surface actually needed to be truly flat, so larger pieces like this are interesting.

It's interesting you mention wooden nails, that was something I was thinking of - wooden nails/pegs from the outside, perhaps angling them slightly against each other so something couldn't pull straight out.

All of my pieces are flatsawn, but being as wide as they are, most of them run out to riftsawn as they get to the edges.

Turns out because of my dado method (alternating marking with a knife, followed by a router plane) my dados got a little wider at the bottom - not quite a dovetail, but a little tilt with the rabbet plane I was able to match it - my dados slide from the front, but won't pull out, although I'm sure they would eventually if you tried.

The curve I thought I saw was quite minimal - certainly less than the other couple of gaps. I took an extra pass at the end of the board when shooting it, and a little finesse with fillester planer when making the rabbets and it's matched pretty darn well.

Ultimately, this piece isn't destined to be fine furniture, or fine work, but a quick and dirty place for me to store some tools and gain the confidence and experience to work on larger pieces. I have enough guitars and small boxes.

Bob Jones
06-19-2012, 12:45 AM
I;m no expert, but Glue all the way. If it was a corner, you would have no hesitation to dovetail all the way. If the boards are still long enough, you may consider adding 2 or 3 through tenons. It is overkill, but I like overkill for strength.

More importantly, how are you going to keep the clamshell doors closed? I'm building a similar cabinet now, and I am looking for hour hardware options.

Correy Smith
06-19-2012, 3:21 AM
Hey Joshua, If it's a quick and dirty tool chest ( I feel they all should be, plenty of more important stuff to make) I would nail it together. Probably still dovetail the corners with big utilitarian pins and tails. But nails are just fine in this case.

Jim Neeley
06-19-2012, 12:15 PM
Joshua,

If you are concerned about glue strength you could orient the divider with the grain running horizontally. You might need to consider appearance, depending on scale and spacing but that way the top and bottom would be glued flat grain with the bottom of the dado..