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 (http://www.sommerfeldtools.com/) technique is, using their tongue & groove router bit set. (http://www.sommerfeldtools.com/item.asp?n=03004&d=79&b=1)

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.php?PRODUCT_ID=37

[frank shic]

steve, even with good clamping including the kreg right angle clamp, you will still get joint creep which is inherent to the kreg's 11 degree drill angle. i recently sold off my kreg jig and purchased steve clardy's pocket hole machinie because it cuts a lower angle 6 degree pocket hole. so far i've discovered that it does indeed eliminate the joint creep in face frame joints. i'll be testing it for right angle joints in the very near future - as soon as i can get down to rockler to purchase another RAC (right angle clamp).

[Bruce Benjamin]

I agree with Jim Becker that using both T&G and pocket screws might be a little overkill as far as strength goes. But there is an advantage to using them both. The T&G assures speedy and perfect alignment, (assuming accurate milling) and the pocket screws eliminate the need for clamping as well as adding a little extra strength.

One question I have is regarding whether or not pocket screws make a strong enough carcass or not. If this is going to be a stationary cabinet just how strong does that joint have to be? Once the top is screwed on and all of the glue sets I doubt that any flex allowed by the pocket screws is going to be an issue. And any glue added to the pocket screw joints is going to set up pretty good adding to the joint strength.

In a production environment where minutes cost $$, T&G might take more time than it's worth, maybe. But whether I'm made the T&G on my TS with a dado blade or on my router table, once you have it set up it doesn't take too much time. I've done this method on quite a few drawers as well as a few cabinets. One set up for the tongues. Run everything through the machine. One for the grooves. With a cabinet it sure does save clamping time as well as cussing time if something slips out of alignment without the T&G. But using the pocket screws can be tricky sometimes if the goal is to not see them in the finished product.

Bruce

[Don Morris]

OK, that does it. There were enough positive responses for T&G plus pocket screws for me to go out and get a T&G set. I have an older Kreg system. Have used the Kreg system several times and been pretty happy with the results. But every time I go to the annual wood show Kreg has something new and "improved". Well that'll be for next year. I'll probably end up with the Sommerfeld two piece T&G set unless someone knows of a better one. The only reason I'll get the T&G set is convenience, and it's a good excuse for another tool! I could always break out my dado set and set that up but that's a PITA because I can see the changes I will have to make between it and swapping the saw blade. Or...going over to the router table, where if I had the Sommerfeld T&G set I could be ever more time efficient and productive. No more of a quality result, but the Law of Parsimony applies: "If two things get the same result...go with the simpler way". Again, many thanks people for the wise inputs to save me creating more sawdust than I otherwise would.

[Ted Miller]

Bruce has a good point. That is why I mentioned frames only. I will use pockets on carcasses only if they are stand alone screwed to the wall next to a stove or something and the size is not very large. Especially if the client wants some serious pullout for something heavy next to the stove. Otherwise its T&Gs on all my carcasses...

[frank shic]

as far as exposed ends go, you could still use pocket screws and screw on a plywood panel or a five piece solid wood panel from the inside of the cabinet or even glue on sheet veneer.

[Peter Kuhlman]

I purchased the Sommerfeld T&G set and used it to build a very large router table. It does work as advertised but I found one issue - at least with my set. I "assumed" that it cut a 1/4" by 1/4" tongue to fit in a 1/4" by 1/4" or deeper groove. Wrong. It cut a tongue slightly shorter than 1/4" and the groove was precisely 1/4" deep. I sure would have thought it would have been the other way around - a little deeper groove and a precise tongue so that measurements would be super easy. This really messed up my assembly as I had several internal panels. Each shorter tongue added a little more than 1/32 inch (X 2 - 1 each side = 1/16") to the panel width. The concept is great. I did email Marc Sommerfeld about this and he said he would look into it but never heard back from him.
Pete

[Al Navas]

I purchased the Sommerfeld T&G set and used it to build a very large router table. It does work as advertised but I found one issue - at least with my set. I "assumed" that it cut a 1/4" by 1/4" tongue to fit in a 1/4" by 1/4" or deeper groove. Wrong. It cut a tongue slightly shorter than 1/4" and the groove was precisely 1/4" deep. I sure would have thought it would have been the other way around - a little deeper groove and a precise tongue so that measurements would be super easy. This really messed up my assembly as I had several internal panels. Each shorter tongue added a little more than 1/32 inch (X 2 - 1 each side = 1/16") to the panel width. The concept is great. I did email Marc Sommerfeld about this and he said he would look into it but never heard back from him.
Pete
Peter,

The set I bought recently is right on the money. Please look at the latest comments and photos in an older post, in this part of that thread (http://www.sawmillcreek.org/showthread.php?p=534180&highlight=sommerfeld+dimensions#post534180):

http://i4.photobucket.com/albums/y136/Sandal_Woods/Shop%20Tools/Tgjoint-sommerfeld.jpg

I believe that the tongue length issue has been resolved, as of late 2006. The real issue now is: HOW do buyers of older t&g sets get them to work properly? You may want to read several posts above mine in that same thread. Mark told me that he is committed to making new bearings, and distributing them to those who call in.

What I truly like about the Sommerfeld t&g set: Using a rubber grommet in the router bit cavity of the router, you can pull out one of the bits and drop the other in, tighten, and continue work. No additional setup is required when changing bits, other than the initial setup.


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[Barry Anderson]

I received the Sommerfeld T&G set just a few weeks ago and it is spot on. I chatted with the demo guy at a wood show this past weekend. He told me that the bearing is the same and they fixed the cutter!!

Barry in WV

[Al Navas]

I received the Sommerfeld T&G set just a few weeks ago and it is spot on. I chatted with the demo guy at a wood show this past weekend. He told me that the bearing is the same and they fixed the cutter!!

Barry in WV
You are correct, Barry. Since late 2006, that is the case. My understanding is that the new bearings will be sent (for free) to users of the t&g sets before the fix, which are the ones that have been problematic and resulted in some undesirable work-around, as explained in the thread that I linked above.


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[Pete Brown]

Peter,
What I truly like about the Sommerfeld t&g set: Using a rubber grommet in the router bit cavity of the router, you can pull out one of the bits and drop the other in, tighten, and continue work. No additional setup is required when changing bits, other than the initial setup.
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I would love that feature...except my Milwaukee has a much deeper hole there and even using the grommet, I can't bottom out the bit.

Pete

[Al Navas]

I would love that feature...except my Milwaukee has a much deeper hole there and even using the grommet, I can't bottom out the bit.

Pete
I remember your comment, from the face frame thread some weeks ago (I think...), Pete.

I wonder if you could use a 1/2-inch diameter dowel sanded down to a diameter slightly smaller than the router bit, cut to proper length, insert it in the cavity, place the grommet above the dowel, and then insert your bit in the collet? For that matter, some other soft, solid material, that could replace the grommet, but still give you the correct height?

Just wondering... :)


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[Peter Kuhlman]

Al's idea of the 1/2" dowel was recommended to me by Marc Sommerfeld for my PC 7518 due to it's deep socket. Works fine.
Thank you Al for informing me about the fix. I will contact Marc or maybe he will be there at the Houston show next weekend so I can ask him.
Pete

[Al Navas]

Al's idea of the 1/2" dowel was recommended to me by Marc Sommerfeld for my PC 7518 due to it's deep socket. Works fine...
It hit me tonight, as soon as I re-read Pete's post, Peter. Maybe it was in the back of my head and I was unable to fully visualize it - I think that the current job I am designing got in the way...



Thank you Al for informing me about the fix. I will contact Marc or maybe he will be there at the Houston show next weekend so I can ask him...
I am glad you read about the fix, Peter! Marc Sommerfeld asked me to post about it here, so that exposure would be wide. You may want to read at least some parts of this thread, (http://www.sawmillcreek.org/showthread.php?p=525894&highlight=Sommerfeld+face+frame+dimensional#post52 5894).

In particular, in this post (http://www.sawmillcreek.org/showthread.php?p=528071&highlight=Hang+LATEST+information+Marc#post528071) I first mentioned one of my early conversations with Marc about him making the new bearings available to users of the older sets (pre-November 2006 t&g sets).

Other posts in that thread simply re-iterated the same message. Good luck, Peter, and please let us know hot it turns out.


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