Aligning Pocket Screw Joints

[John Maeda]

This might just be newb craftsmanship or process errors, but

I find that when making a frame for a table top or similar, using pocket screws ,the short ends (with 2 screws per side total of 4 per board) find themselves twisted counter-clockwise anywhere from 1/16 to an 1/8th of an inch resulting an a less then FLAT frame.

I use clamps during the glue and assembly of the joints. Is this just the nature of the beast? or am I skipping an all important step?

I was thinking that if I glued the joint up first, and then put the screws in after drying it would twist out.

[Joe Vincent]

This might just be newb craftsmanship or process errors, but

I find that when making a frame for a table top or similar, using pocket screws ,the short ends (with 2 screws per side total of 4 per board) find themselves twisted counter-clockwise anywhere from 1/16 to an 1/8th of an inch resulting an a less then FLAT frame.

I use clamps during the glue and assembly of the joints. Is this just the nature of the beast? or am I skipping an all important step?

I was thinking that if I glued the joint up first, and then put the screws in after drying it would twist out.

There was a recent thread about pocket screw "creep" that you should be able to find using the "search" feature. A good discussion about such issues.

[Steve Rozmiarek]

John, are you using a jig? Kreg or...?

[glenn bradley]

With the right screws you don't need a whole lot of clamp pressure to keep things aligned. I have good success when following these guidelines:
1. - clamp the pieces to a solid flat surface not just to each other.
2. - use the proper screw type.
3. - use the proper hole depth.

Items 2 and 3 are done in combination. The screw should be a pocket hole screw. That is, one with a shaft that is a smaller diameter than the threads. The threads should end up in one of the pieces being attached but not across the joint where they meet.
http://www.mcfeelys.com/images/pages/penguide.png

As you see in the diagram, the threads do not cross the joint. This is the most common cause of 'joint creep'. Once I learned to select my screws and my hole positions to assure this occurred, all my joint problems went away.

[Joe Chritz]

Are you talking about a face frame joint or edge banding plywood?

For face frames I clamp both pieces to the table with a clamp. I used to use a kreg vise grip style clamp but now with a torsion box I use a small bessey k body. I then use a bessey across the frame to hold them together. Just clamping them together gets 99% perfect the last clamp gives a perfect joint every time.

If it isn't joint creep and the board is no longer flat that is usually a problem with one of the faces not being square.

Joe

[tim mathis]

john ,
kreg offers a right angle clamp that fits into a drilled pocket hole and pulls the wood together it's about $ 25.00.
i use these and clamp the wood down with a large face clamp and the joint always comes out great. you might want to get 1 or 2 of the right angle clamps.
tim m.

[Dave Falkenstein]

It is important when assembling a pocket screw joint to clamp the pieces being joined vertically, DOWN onto a flat surface. Or use the Kreg flat faced clamps to hold the two pieces together vertically. This vertical clamping helps hold the pieces in the correct position so they will not twist during assembly. The screws will pull the joint together (horizontally), although a little clamping pressure to pull the joint together helps also.

[Lee Schierer]

I find that when making a frame for a table top or similar, using pocket screws ,the short ends (with 2 screws per side total of 4 per board) find themselves twisted counter-clockwise anywhere from 1/16 to an 1/8th of an inch resulting an a less then FLAT frame.

Back off the tightening torque setting on your screw driver. You don't need a ton of torque to get a tight joint. I usually put the screw 95% in with my cordless drill and then hand tighten the final turn on narrow pieces. On longer pieces with multiple screws I get on in on each end and work towad the center.

[Matt P]

I had a jig alignment problem where the screw hole was not in the exact center of the board edge. The resulting joint wasn't aligned properly. I adjusted the jig so that the hole was in the center, and problem was fixed.

[James Suzda]

Also make sure that your pocket hole drill bit is set so the point does NOT drill through or even make a dimple in your lumber.
Plus only use pocket screws for assembly. They will drill their own pilot hole.
Clamp the pieces down to a flat surface and drive the screws in. BTW, the best thing about using pocket screw joinery is you don't have to clamp the project. The screws hold the material until the glue dries.

[Jim Becker]

Clamp them more securely...any misalignment of pocket screw joints is generally due to that. And clamping on a flat surface and to that surface is the most effective...the vice-clamp alone is prone to flex.

[John Maeda]

Thanks guys, I totally forgot about this thread!

I think I got the problem licked with using
A) A better work surface
B) More clamps
C) clamping this to the work surface and not just to itself

Now on to getting/making square-r stock. o.O

[Per Swenson]

I add a extra 1/8th or so to the collar of the step drill

and clean the tear out thoroughly.

Besides all the clamping stuff.

Per