pocket joinery and dadoes

[Greg Muller]

I am a newbie to SMC although I have been a frequent reader and relied on many of your experts, uh expertise. Now I have a question that I haven't found previously addressed anywhere. I have been shown the strength of the pocket hole joinery and I am wanting to implement it in the building of mobile cabinets and tables, but have always relied on dadoes, biscuits, tenons, and through screws. I became interested in the pocket joinery since I would then have no screw heads showing or to plug and the mechanical join of the pocket screw seems very strong.

Here's the question; Has anyone tried using the two methods together? In other words, built the cabinet with dadoes and reinforcing with pocket holes in the same joints? I know I would have to use slightly shorter screws and be VERY careful that I didn't drive them through the backside of the "T", but is it worth it? Would the connection be any stronger, or am I just continuing my usual tendency to try to over-engineer everything?

Secondly, what pocket hole kit is best? So far, I am leaning towards the Kreg.

[frank shic]

ditch the rabbets unless you're really hard up for alignment. the pocket screws will hold fine in 3/4" material. i like the old aluminum kreg jig without all the fancy doodads that the newer versions come with - you can find them on craigslist and ebay every once in a while. you do not need to buy the entire kit although i'm sure others will disagree. i had the kreg 2000 kit and almost never used the rocket or the minikreg. the vacuum attachment on the k3 is clever but i don't find it necessary unless you're going be boring A LOT of pocket holes like for a kitchen cabinet project in which case i'd rather use a router-driven pocket cutter like steve clardy's machine or the porter cable pocket cutter. you get less joint creep with the latter two options on face frames BTW.

[Bruce Benjamin]

Combining pocket hole screws with dados and glue will of course be stronger. You get the best of both worlds that way. As you mentioned, you will have to use a shorter screw but that's no big deal. You'll get slightly less mechanical strength with the shorter screws though.

The only pocket hole jig I've ever used is the Kreg Rocket. The resulting holes are the same as with any other Kreg jig and for most of what I've used it for it's been more than adequate. But it would be nice to have the fancier version with all of the bells and whistles. I just don't need it or really want to store it most of the time so what I have will do fine. There are other brands of pocket hole jigs out there but Kreg is certainly the most popular. Is it the best? As I said, it's the only brand I've ever used but I don't really see how another brand is going to work any better. The Rocket jig is pretty basic but the deluxe version looks very versatile and the ability to easily switch the jig for different stock thicknesses is a must-have option. Combined with the built in clamp and the dust collection port and it looks pretty hard to beat. The Kreg brand of clamps also work very well.

Bruce

[Randal Stevenson]

If they weren't deep dados, they would help align your joints and I would think that would be a better design for any cabinet, that may have to be disassembled and reassembled. (like large shop cabinets, if your thinking of moving). Keeping the same depth would be critical, which may be a problem with shop (borg) plywood, as its depth can vary.

My experience with the jigs, is with the K2000 and the new K3. They changed the depth setting adjustment between the two, but if this were for speed, a production shop is going to use one of the machines instead. The dust collector is nice, but can be made for the old one, with some scrap and vac parts (my father did it). He had a cheapy pockethole jig, and it was OK at best, but the bits sucked.

[Bruce Benjamin]

you do not need to buy the entire kit although i'm sure others will disagree. i had the kreg 2000 kit and almost never used the rocket or the minikreg. the vacuum attachment on the k3 is clever but i don't find it necessary unless you're going be boring A LOT of pocket holes like for a kitchen cabinet project in which case i'd rather use a router-driven pocket cutter like steve clardy's machine or the porter cable pocket cutter. you get less joint creep with the latter two options on face frames BTW.

I have found that using the Rocket has allowed me to make pocket holes in quite a few situations where I wouldn't be able to use the larger version that has the built in clamp. The Rocket allows me to take the tool to the work instead of the other way around. The larger bench mounted version is possibly more convenient for face frames but when I have a panel of plywood to drill I don't think it would be as convenient to have to pick up the, (frequently heavy) panel and clamp it upright into the larger jig versus the simplicity of just clamping the Rocket onto the edge of the panel while it is sitting flat on my bench. I guess it boils down to the size of the work you're drilling. Bear in mind that I haven't used anything other than the Rocket jig but my reasoning seems logical to me. For what the OP was talking about with dados in panels I can't see how lifting them upright into a bench-mounted jig would be as easy as the Rocket.

Bruce

[frank shic]

you could always turn the jig and clamp it sideways to the panel to avoid the understandable pain of having to position it vertically and of having to build that plywood jig with the extension arms flanking the kreg jig.

[Cary Swoveland]

I avoid dados like the plague. On the other hand, I use pocket hole joinery whenever I can. If you need greater strength than is provided by pocket hole screws alone, you can combine them with biscuits or loose tenons, or use sliding dovetails. Often I use a few pocket holes just to avoid the need for clamps.

Not only is pocket hole joinery super-fast, it's got to be the best bang-for-the-buck among joinery jigs.

I have been very impressed with Kreg's pocket hole products. Some competitors may put out equally-good products, but I can't see how they could be superior, so I take the easy road and stay with Kreg. Comparing old and new Kreg products, the differences are really minor, but the cost of upgrading is so small that I don't hestitate to do so if I think the upgrade truly represents an improvement.

Also, have a look at Kreg's Klamp Table. It's a great idea, and has uses far beyond the assembly of pocket hole joints. If you don't want to spring for the cost of the full setup (stand, top, rails, clamps and other bits--about $400), consider buying just two rails, two clamps and a "klamp box set" (about $160), and build your own.

Cary

[Gary Keedwell]

Just a little tidbit....Those Kreg clamps that you mortise into your bench are great.
Gary K.

[Cary Swoveland]

Just a little tidbit....Those Kreg clamps that you mortise into your bench are great.
Gary K.
Yes, and they can be used interchangably between the fixed plates and the Klamp Table rails. Moreover, the thickness of the plates is the same as the depth of the rail slot (1/4"), so the clamp screw does not have to be re-adjusted when moving between the plate and rail.

The clamps shipped with the Klamp Table include a small piece of acetate (or some-such) at the base to make it easier to slide in the rail. Kreg was happy to send me a few of those gratis.

Cary

[Greg Muller]

Thanks for the opinions!

Have any of you actually tried the combination dado/pocket joint?

Remember, this is for mobile benches that will sometimes ride over uneven surfaces, so I really want them to be rigid, strong and last forever!

[Jim Becker]

If they weren't deep dados, they would help align your joints

I agree with this...a slight, perhaps 1/8" groove, rabbit or dado could help lock things together relative to alignment and provide a little increase in strength, but it also adds a lot of work. I've been using pocket screws a lot these days and don't miss creating all the "lines" one bit. That said, I'd do it if I felt I needed a lot of extra strength from "locking things together" for a particular project. But by the time you use glue and the screws and then apply things like a cabinet back and/or face frames, you have a mighty strong structure already. (The same can be said for butt joints that are glued and then screwed from the outside after drilling and countersinking for the fasteners)

I'm definitely a fan of the Kreg pocket screw systems.

[Allen Bookout]

Greg,

This is a really great video about combining tongue and groove with pockethole joinery for cabinets to make them accurate and strong. http://www.sommerfeldtools.com/item.asp?n=dvd4&d=118&b=1

[Jerry Olexa]

The bookcases I finished this week were built using that method. I made the gooves fairly shallow (about 1/8"deep) versus the usual 3/8" and then did the pocket holes in the normal manner (w/o adjustment for the 1/8"). The Kreg screws are 1 1/4 inch long and installed on a slight angle. I glued in the grooves as usual and installed the screws. Worked like a charm and strong IMHO!! I favor the Kreg system and keep finding new uses for it...Great tool!!

[Anchor Sarslow]

I recently built an Oak 2x2 framed cart for a friend.. Used lap joint and 1 Kreg pocket screw per lap .. It turned out incredibly solid. I would do it again on my own stufdf eventually. he asked the same thing. He wanted solid construction for this cart.

[glenn bradley]

Thanks for the opinions!

Have any of you actually tried the combination dado/pocket joint?

Remember, this is for mobile benches that will sometimes ride over uneven surfaces, so I really want them to be rigid, strong and last forever!

This goes in the opposite direction. I built my rolling worktable with the anticipation of some racking. If your cabinet does not flex, your wheels will not all stay on the ground over uneven flooring. This makes locking your casters a challenge.

I used a locking rabbet/dado to capture the back. Regular rabbets or dados for the other joints. The front is full of drawers. The inset drawers have 1/8" clearance instead of the usual 1/16" or less. This allows them to keep moving freely if I lock the casters on a particularly uneven spot on the floor.

I've rolled this thing around for almost three years and worked it very hard with no problems.

[Greg Muller]

Yeah, Glenn, but I will be parking on level and even surfaces, so my castors will lock fine. I have to occasionally roll over some rough areas (rough concrete, close grating, etc) that has shaken loose the joints on some rolling workbenches that the other guys have. I really want this to be firm in order to keep the top surface as flat as possible and last forever. Later, when this job is complete, I want to bring it home.

Good thinking, though. I hadn't considered that as you may have surmised.

[Suanne Lippman]

I have used dadoes and pocket screws together, but mainly because I didn't have clamps big enough and used the pocket screws to draw them together.

I seriously doubt the pocket screws will add much strength; they won't enter into the equation until your dadoes start to fail.

OTOH a few years ago one of my first WW projects was a TV stand made with dadoes reinforced with nails. Last year I scrapped it, but tested it first by putting 300 pounds of weights on top. Desperate to make it fail, I hit it from the side with a sledgehammer. That made the dadoes fail, but the the nails kept it from actually collapsing.
If you application calls for something like that, pocket screws should work also.

[Gary Keedwell]

I have used dadoes and pocket screws together, but mainly because I didn't have clamps big enough and used the pocket screws to draw them together.

I seriously doubt the pocket screws will add much strength; they won't enter into the equation until your dadoes start to fail.

OTOH a few years ago one of my first WW projects was a TV stand made with dadoes reinforced with nails. Last year I scrapped it, but tested it first by putting 300 pounds of weights on top. Desperate to make it fail, I hit it from the side with a sledgehammer. That made the dadoes fail, but the the nails kept it from actually collapsing.
If you application calls for something like that, pocket screws should work also.
http://i182.photobucket.com/albums/x286/jc623/cigar.gif http://www.woodworkslive.com/Smileys/default/evil.gif It is late and I'm a little punchy but I thought that was a good post. :)

Gary

[Jim Becker]

OTOH a few years ago one of my first WW projects was a TV stand made with dadoes reinforced with nails. Last year I scrapped it, but tested it first by putting 300 pounds of weights on top. Desperate to make it fail, I hit it from the side with a sledgehammer. That made the dadoes fail, but the the nails kept it from actually collapsing.

Sounds like a fun way to let off a little steam! LOL:D

[John Schreiber]

I'm planning a cabinet style workbench, kind of a Shaker style. As workbenches are supposed to be overbuilt, I'm planning 3/8 dados and screws with their heads on the other side. That will require covering the screws, but it seems to me that it will be as strong as can be and will save on clamps.

[JayStPeter]

I have used pocket holes in combination with a shallow dado and biscuits. In the case of a dodo, I usually use the pocket screws as a clamping mechanism. But, I'm guessing they add some strength as well. I use the biscuits to maintain alignment while driving the pocket screws with butt joints. But I only use that mechanism on shop cabinets. They have held up well though.
The pocket screws are especially helpful on large carcasses which would require lots of clamps and/or cauls to get proper clamping force all around. Especially shop cabinets using low cost ply that will tend to warp out of shape. If you make the dadoes normal 1/4" depth in ply, the shorter screws will just strip out. It works fine in hardwood. I actually use the full setup for 1/2" in the case of a 1/4" dado in 3/4" material. It is possible to use the 3/4" setup so the screw will be centered, but I've had screws punch through occasionally doing that. Since it's not ultimate strength I'm looking for in that case, the 1/2" setup is good enough. In ply, I either use biscuits or don't use pocket screws as I haven't found a reliable setup in combo with a dado. The less than 3/4" depth leads to problems with screws either punching through or stripping out with too little material. Quick butt-joint drawers with 1/2" BB ply do work, but cheaper ply will have a tendency to strip out. Even 3/4" cheap ply will have a tendency to strip out occasionally, so have a backup plan.

My only tool related purchase at the woodworking show yesterday was one of the Kreg bench clamps. I'll probably pick up more mounting plates for it at some point as I can think of a few places around the shop it would be useful for different things.

[Richard Magbanua]

Personally, I think that if you use pocket screws you need the full plywood thickness for maximum strength. As far as alignment issues, with pocket screws if you can clamp the two pieces tight with a right angle clamp or bar clamp you should be right-on. The real strength comes from your carcass back and your face frame. This is what guards against wracking forces. Your shelves and bottom should have strength against downward forces from heavy items. I built 5 rolling cabinets for a state fair food stand and I tested pocket screwed joints on plywood shelves vs 2" deck screws driven in through sides. I pulled downward on these "t" joints I made and the ones with screws placed through the sides were, by far, much stronger. Not very scientific, but good enough for me. I dressed these screw heads up with decorative brass washers and it looked pretty nice.

[Byron Trantham]

A few months ago one of the wood mags did a review of various joint methods that included dowel, butt, dado, rabbit, and pocket hole. The winner was doweling. They pointed out that the doweled joint was marginally better than the pocket hole! That sold me. Of course you can't use them everywhere for aesthetic reasons if for no other.

[Greg Muller]

Okay, thanks for all the feedback, guys (and ladies)!!

I am going to pick up a pockethole jig tomorrow (monday), now I just want to know which setup to get. I think I like the Kreg system, and being that I'm a toolaholic :rolleyes: , the master kit version will probably be the one I end up with.

Does anyone know where I can get one for less than $139.00???

Does anyone have any objections to that choice? Perhaps try to talk me into a smaller kit size for less cost?

[frank shic]

greg, the kreg jig will work. i bought the older k2000 master kit and then sold it on craigslist and purchased the older aluminum version since i usually only use pocket holes in 3/4" material. i didn't like how the body of the plastic successors would flex ever so slightly whenever i applied the clamp and i never really used the rocket or the minijig.

my pocket hole tool of choice, however, is the porter cable pocket cutter (steve clardy's router jig will also work) since it virtually eliminates joint creep which gets rid of all that annoying sanding that you have to do - at least on face frames. i used it last night to build the skeleton of a rolling four router station and the joints were almost perfectly flush on the majority.

[Greg Muller]

DONE!!!!!

I went to Woodcraft today and, just as I knew I would, caved in and got the Master kit of the Kreg pocket hole jig. Darn, I am weak!!! Not only that, but I also bought about $60 worth of Incra "T' tracks, and zebra wood for a couple panels I have planned. Fortunately, I left the Amex at home, or I'm sure I would have walked out with a new Sjoberg top.

Thanks to you all who helped me with my decision!!! Now I am going to run a couple tests of my own with the dado/pocket hole ideas. I have a tensionometer I'll hook up to some various joints (with/without glue, with/without dado's, etc). The stronger joint wins my undying use.