Carcass construction with tongue and groove + pocket screws?

[Don Morris]

Finally getting around to building major items. At the last woodworking show I watched several demos and thought the idea combining tongue and groove + pocket screws for cabinets would also work for just about any type of carcass construction because: Some sort of edge routing joint promotes alignment ease because it forces the edges together only in one direction. Having the edges line up evenly because of the edge profile saves clamping time and sanding, plus it give more glue surface. It probably doesn't have to be too fancy a joint. Where there was no visibilty problem...pocket screws seemed quick and easy (although LOML ,a purist, and who was observing with me, didn't like the "idea" of having "screw holes" anywhere in "her furniture"). I was told that many production people are going the route of pocket screws and "tongue and groove" (although the groove/dado may be table saw created). I've got a lot of stuff (desks, tables, built-in cabinets) to build for LOML soon and am looking to settle on a system that will give me a heirlom result, not just a quick and easy way to get the job done. I dove tail drawers, but does a carcass of a cabinet or desk need to be that type of detail construction to be a quality result? Thanks for any comments.

Don M

[frank shic]

don, have you considered biscuits? they would take considerably less time!

[Don Morris]

Frank,

I've done biscuits, and their OK. But the added glue surface appealed to me with the tongue and groove. The pocket screws seemed quick too! Although the biscuits could also save time. And I've done them too. Another thought! Too many decisions....Could it be there is no "Better or even best way?"

[frank shic]

everything has trade-offs as you've noticed. a lof of the professional cabinet companies dado the face frames for ease of assembly but now you're looking at the extra time in swapping out your regular blade, adjusting the dado stack, running test pieces until you get it right and then repeating that process every time you want to run the face frames. the other possibility would be to buy a smaller benchtop/portable saw unit and leave the dado stack on there.

[Jim Holman]

Works just fine with pocket screws to hold the joints while the glue dries. Also cuts down on the number of clamps. To put it in a historical perspective many if not all of the best carcass builders in history would alter their methods given the tools we have today. As long as the screws do not show, restrain the wood across the grain and satisfy you - go for it.

[Jim Becker]

I wouldn't take the extra time for T&G if pocket screws are being used. Pocket screws with glue are pretty darn strong and if clamped propertly, everything should line up. AND...you cut everything to exact length and avoid calculating the extra materal for the tongues...

[Jeffrey Makiel]

By coincidence, I just did a little test building a carcass for a bath vanity and the two joint methods were tongue & groove versus pocket screw. The tongue & groove joint seemed considerably stronger especially when subjected to a bending moment that prys on the joint.

My little test was performed on plywood. Both joint methods used glue. If it had been solid wood, I think the pocket screws would have done much better. As far as using pocket screws on MDF or synthetic wood (Aztec, NeverRot, Trex, etc.), forget it.

I think the question is: do pocket screws provide ample strength for the task at hand? In my case, I still used pocket screws because of their convenience, but I also use biscuits in the same joint when I'm leary. Belt and suspenders, aye.

-Jeff

[Al Navas]

... At the last woodworking show I watched several demos and thought the idea combining tongue and groove + pocket screws for cabinets would also work for just about any type of carcass construction because: Some sort of edge routing joint promotes alignment ease because it forces the edges together only in one direction. Having the edges line up evenly because of the edge profile saves clamping time and sanding, plus it give more glue surface...

THAT is exactly what the Sommerfeld technique is, using their tongue & groove router bit set.

Was that the system you saw at the demos? I did, at the Kansas City show, and bought their 18-piece Signature Series immediately after their demo. It IS as easy to use as in the demos. I am pretty happy with it!

I hope others will give further insight into the t&g technique.

Please remember: Aesthetically, the pocket screws should be used only where they won't be seen; they should be avoided entirely inside cabinets with glass windows, as they would be visible on the walls. It is OK to place the screws in hidden areas, such as below floors, behind walls that face to the outside and against a wall, where they are hidden, etc.

No affiliation with the company - just a very happy customer.


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[Steve Milito]

I wouldn't take the extra time for T&G if pocket screws are being used. Pocket screws with glue are pretty darn strong and if clamped propertly, everything should line up. AND...you cut everything to exact length and avoid calculating the extra materal for the tongues...

What's the best way to clamp things up? Sometimes my face frame joints are perfect, but one out of four can be improved upon, that is the joint is slightly visible.

[Don Morris]

Yes, one of the demos I saw was the Sommerfeld demo using their "tongue and groove" system for cabinetmaking primarily, where they use both T&G + pocket screws. But I tend to agree with Al who tested them independently. I don't think I would want to rely on pocket screws alone, but the combination seemed a time saving yet not quality lessening choice. I guess my question comes in during carcass construction and you need to create grooves in the middle of a carcass. Seemingly you need a two piece Router Bit system to do it conveniently...one bit for the groove, the other for the tongue, e.g. Sommerfeld two piece system. The Whiteside tongue and groove bit only does theirs by lowering the bit to create the groove, so it couldn't be used in the middle of a carcass. Of course you could have a 1/4" dado blade set up in your TS or something else set up to create a groove/dado. Previously, I've been making mortise and tenon joints but they take a lot of time and care. I don't mind the time if the results are worth it, but I "hate" wasting time if it's not worth it. Sort of "diminishing return for the time spent" idea. So when I saw the demos, the time saving and yet not quality lessening aspect of the T & G + pocket screws...that appealed to me. Kind of still does.

[Al Navas]

What's the best way to clamp things up? Sometimes my face frame joints are perfect, but one out of four can be improved upon, that is the joint is slightly visible.

Steve,

I wonder if the stock is slipping slightly in the clamp as you start driving the pocket screw? I have noticed the same thing when I don't tighten the clamp sufficiently.


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[Al Navas]

Yes, one of the demos I saw was the Sommerfeld demo using their "tongue and groove" system for cabinetmaking primarily, where they use both T&G + pocket screws.

... So when I saw the demos, the time saving and yet not quality lessening aspect of the T & G + pocket screws...that appealed to me. Kind of still does.

Don,

I believe that t&g by itself would be sufficient, from a joint integrity and strength standpoint. But I believe that they suggest the use of pocket screws to minimize the use of clamps. In addition, the pockets are made at the 1-inch setting, rather than at the more traditional 3/4-inch setting on the pocket screw jig.


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[Steve Milito]

Steve,

I wonder if the stock is slipping slightly in the clamp as you start driving the pocket screw? I have noticed the same thing when I don't tighten the clamp sufficiently.


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I set them on my bench between dogs and a vise and crank down hard until I'm afraid I'll break something. The edges are all square. I also make the frame square with a good square. The hole sides look perfect.

[glenn bradley]

Steve, I just went through this last night. My hole side was perfect but the 'show' side had a small gap. Turned out my rip blade had been just a bit off of 90* when I ripped the rails. This meant when I clamped down nice and tight to a good flat surface the less than 90* 'long edge' showed itself clearly.

The stile ends were cut on my CMS and it turned out that was fine. Wouldn't you know I would choose to assemble in the way that showed the gap as opposed to hiding it. Anyway once discovered, a few swipes with a small plane put the angle on the stiles to make a match for the remaining joints; the first one was already glued and shows . . . bummer.

[Ted Miller]

Sometimes my face frame joints are perfect, but one out of four can be improved upon, that is the joint is slightly visible.

Steve, When doing frame assembly on its own try the Bench Klamp from kreg, your gaps will disappear...

http://www.kregtool.com/products/pht...?PRODUCT_ID=37