Question about the strength of pocket hole joinery

[Upscale]

My question is about the strength of the connections made with a pocket hole kit like the Kreg.

I'm was thinking of using my rail and stile router bits to build a lightweight cabinet (approximately 6'h x 3'w x 2'd) using glued up 3/4" oak rail and stile construction with inserted 1/4" paneling.

Would the project be sufficiently strong to stand under it's own weight if I just used a 1/4" slot cutter for the paneling and joined everything instead with pocket joints?

I've seen many suggestions for using pocket joints when creating face frames, but I don't remember seeing anyone talking about full cabinet construction using pocket joints.

Thanks

[Robatoy]

I would think so. Making all the usual assumptions, like proper root depth, length of screw and plenty of proper adhesive. Using oak already gives you an advantage in creating a strong joint.

[Al]

I have used them I used to make fish tank stands and realy like the pocket hole jig from Kregg. It is strong and with a little glue works great.. I know where 3 of the stand are holding 50 gallon tanks still standing 3 years later no wiggle or jiggle :) I think it all comes down to preference.

Al

As always opinions are just that take from what you here and make an informed desicion. :)

[George]

You will use glue? Problem with fastener joints is that the fasteners work loose. Remember the recent discussion about whether a tenon should rest on the lowest portion of the mortise? As long as your fasteners maintain the end grain firmly against the face, just as the glued or pinned tenon does, you're all right. Bend the fastener, and Katie bar the door. Load to the end grain, of course, lest the fastener pull out from deflection.

I just use a few pocket hole screws to hold things together until the glue dries....

[Leon]

Essentially the joint is not a "Pocket Joint" You make what ever traditional joint you want and use "pocket hole screws" to reinforce it. Typically however pocket hole screws are used to strengthen Butt Joints. I would advise that you use glue in addition to the screws to strengthen the joint. With that said, the pocket hole screw can add tremendous strength to a joint. As far as your question about the cabinet, as long as the screw threads end up in solid wood, and the harder the better, the joint should be quite strong. Naturally the wider the material the better as this allows the use of more screws in a given joint. The screw and glue reinforced joints would most likely be strong enough for the rail and stile joints of the panels given the width of the rails and stiles are wide enough to be strong. You may give more consideration as to what kind of joints to use when attaching the sides to the tops and bottoms and front of the cabinet.

[Pat Barber]

I have built "MANY" cabinet boxes using butt joints, glue, and my Kreg jig. This a dead simple method and unless the glue fails, the cabinets will work just fine for many years.

This same method is used in "many" commercial cabinet designs.

Upscale wrote:

[RicodJour]

If the material is too wide there can be problems with crossgrain movement. More fasteners won't prevent the movement, they'll just create weaknesses in the grain and a starting point for splitting in the end grain board of the butt joint.

Another problem is related to the fastener spacing. If the spacing is too close, that will cause weakness and possibly splitting in the face grain board of the butt joint. Unless the pocket holes are staggered all of the holes will be lined up creating a line of weakness.

It's not a good idea to go too wide or too close.

R

[Leon]

Well if the pieces in the face frame are quite wide this may become a problem however the screws normally fit loosely enough as to allow some movement. The hole for the shank potion of the screw ia probably 25-30% wider than the shank. Having used literally thousands of pocket hole screws I have never had a problem of too many screws causing a problem. The glue in the joint is more likely to cause a problem.

Well normally I would agree and to an extent this is true. However "Pocket Hole" screws self drill and do not encourage splitting. There is not as much chance of splitting as with normal screws. With a #7 Pocket Hole screw you can put the screw in to an Oak board 1/8" from the end of the board and normally not see any splitting even when not using the stepped bit for a pilot hole.

[Upscale]

Well, it's another woodworking toy whose time has come. Nosing around Home Depot today and talking to two of their tools salesmen, they'd never heard of Kreg. I had to stifle a snicker. I'll be picking up a Kreg 3 kit at the opening of the new Lee Valley store in Toronto at the beginning of April.

Thanks for the information.

[cdo]

Not much surprise there - half of their people don't even know what

*wood* is...

cdo

[Leon]

If you have a Lowe's they might have them. Our local Lowe's carry Kreg products.

[Upscale]

No Lowe's that I know of up here in Canada. Besides, considering some of the customer service benefits I've received over the years from Lee Valley Tools, I sort of feel like I owe them my business. And at the very least, when I buy something from one of their salespeople and ask an opinion on a product, there's a damned good chance I'm going to get an honest opinion as well as a person that's experienced with it.

[CW]

They do around here too.