Question about Pocket Hole "Creep"

[Joe Vincent]

I understand one of the issues that some have had with using pocket hole screws, particularly for face frames where flush faces are needed, is misalignment due to what has been described as shifting or creeping.

Is this creeping something that gradually happens over time or is it just an issue of the screws pulling the faces out of alignment at the time they are inserted?

I'm just wondering if I should be concerned that joints that look fine now may "creep" out of alignment in the future?

[Joe Vee]

Joe,

I am by no means a pocket hole expert but have used my Kreg kit multiple time. I have found, if you have the 2 pieces of wood clamped and drill the pocket hole at the angle of the jig, then when the screw is inserted and tightened you don't get much creep. Also, if you are using hardwood, don't over tighten the screws. I have snapped a lot of screw heads off. Hope this helps

Joe

[Anthony Whitesell]

I have noticed if both pieces are not clamped when the screw is driven then the face opposite the screw may not be flush. The effect has been instant and I attribute it to the fact that screw is on an angle and being driven on an angle in a way that pushes the faces out of being flush.

[Jim Becker]

Effective clamping is absolutely essential to avoid this in my experience.

[Ray Schafer]

I have been considering using a couple of dowels in some cases to avoid the creep. I have also used hand-screw clamps to hold the joint in alignment -- this works well for face frames. When doing 90 degree joints, I just use a couple of bar clamps to hold the joint very tight.

[Chris Padilla]

http://www.sawmillcreek.org/showthread.php?t=8119

(Edit: sorry for the broken links but unfortunately Todd didn't load up pics to SMC)

[Josiah Bartlett]

Clamping the parts together and pre-drilling the holes helps even more. I wish Kreg would make a bit with the shoulder further up the shank (giving a longer tip) so you could clamp the mating parts together, drill the holes with the jig, and have pre-drilled starter holes in the mating side all in one swell foop. Maybe I'll customize on of the dull bits I have with a grinder and see if it works.

[Jim Becker]

Josiah, I suspect that it's intentional that the bit doesn't penetrate the second piece, because it would be larger in diameter than you want on that piece. Hence, the reason that the pocket screws are self-tapping. The tip of the step bit is a clearance hole that keeps the screw from binding on the host piece.

[Chris Padilla]

Josiah,

That could work but you need to be careful of the depth of the hole in the mating piece...don't wanna drill out all the wood such that the threads have nothing to bite on. :)

[Brian Dormer]

For pocket hole joinery (I'm speaking from experience with Kreg) to work - you MUST securely clamp the parts being joined. For most joints, this isn't a problem. For a few types of joints - you have to get creative in holding everything together while the screw goes in. Once the screw is in - the pieces shouldn't move relative to each other.

As for driving the screws - if you are snapping the heads off - you need to back off the torque on your drill/driver. The best solution is to use a driver with a slip clutch and set it so that the clutch slips at the point where the screw just bottoms out (start out a low torque and adjust up until you find the sweet spot). Overdriving the screw (especially in composite materials or softwoods) will strip out the hole and leave you with a loose joint.

[Larry James]

I agree with the comment about being securely clamped. That is a must, but not always easy.

I use a drill/driver just to drive the screw most of the way in and finish with a screwdriver, this is extra work but I have found it is worth it.

I use glue on most joints. I've been using the Kreg jig and clamps for several years and have never noticed "creep" after the joint is properly made.

Amazing how many pocket hole screws I use - Kreg must make their money from selling screws!

Larry

[Karl Brogger]

Glue is a must. I run 2 screws in anything over an 1 1/4". Over 4" I add a third screw.

Kreg has a really sharp angle but work well enough, especially if you can't justify spending $2500 for a Castle Machine.

[glenn bradley]

The following is, of course, JMHO: Guess I'll chime in. Unless I missed it, someone should mention the proper screws are critical. Clamping is important but you only need a snug grip if you are using appropriate screws. I fought creep and clamped tight enough to dent my material till I switched screws.

The threads should not cross the joint line where the two pieces meet. By this I mean the non-threaded shaft crosses the joint once the screw is tight. If they do, clamp the pee-wad out of it or it will want to creep (and probably will once you unclamp). I find it easier to just use the right screws.

This pretty well covers it: http://www.mcfeelys.com/tech/pocket-hole.htm

[Steve Mellott]

I clamp both pieces of wood to the surface of my workbench and then insert the self-tapping screws. I have never had a problem with "creep." I also glue all surfaces and have never had one fail.

Steve

[Joe Vincent]

Lot's of great tips. Thanks, everyone.

[jack mazzuchelli]

Regarding proper screws;
with hardwoods you must use FINE threaded screws

softwoods ( ply,poplar etc ) use coarse threaded

[frank shic]

this is one of the reasons to get a porter cable pocket cutter or steve clardy's version: a routed pocket has less creep than the kreg.

[Bruce Benjamin]

this is one of the reasons to get a porter cable pocket cutter or steve clardy's version: a routed pocket has less creep than the kreg.

A properly executed pocket hole joint made with the Kreg doesn't have any creep at all. You can't get less than none. The suggestions of proper clamping technique and using the proper screws mentioned by other posters will eliminate any and all creeping of the wood.

Regarding the predrilling of the hole in the, "Other piece", what Jim Becker said is true. You wouldn't want the drill bit to put a pilot hole in the other piece that big because the screw wouldn't bite into the wood properly. Just follow the proper clamping procedure, use good quality screws designed for pocket holes and it's easy.

Bruce

[Matt Meiser]

Using the Kreg drill bit, set with the Kreg depth stop, in the Kreg jig, with Kreg screws recommended by Kreg for the material, I've seen creep with the Kreg clamp. What I've noticed is that the pieces will sometimes push apart slightly as you drive in the screws. Because of the angle, that puts the entry point in the second piece slightly closer to the front than it should be. I suspect that Todd's method makes up for this slight misalignment. I've also had luck clamping the face frame parts to prevent that type of movement, which the Kreg clamp doesn't really prevent since its faces are smooth.

[Joe Chritz]

100% avoid creep with this method.

Glue and align the two pieces. Use a clamp (kreg clamp or anything solid) to clamp both pieces down the the work bench. Use a parrellel clamp (I have K-bodies) to clamp the joint together length wise. One clamp keeps them from spreading one keeps them from lifting.

Once you get going it doesn't add much in time. More now that I can't use the kreg clamps with the thicker table (torsion box).

If the stock is square and milled correctly I get joints that are as close to perfect as I could ask for.

Once they are tightened they aren't going anywhere.

Joe

[Michael Lutz]

Proper clamping may help, but sometimes the screw seems to have a mind of its own. I was clamping two panels together 90 degrees from each other. I was using 90 degree clamps to hold the panels together and I still had creep. I think dowels would be easier than clamping the panels at least in my application.

Mike

[Bryan Berguson]

In my experience, the harder the wood is the more likely it is to creep. I use alot of shag bark hickory and have found the only way to prevent creep is to use the Kreg vise grip clamp for alignment and then clamp it parallel to the screws with a bar or bessey clamp. I use Kreg fine thread screws and haven't had any break.

Bryan

[Roland Chung]

With my Kreg jig, the only times that I've noticed creep is when I was using pocket screws to hold cabinet panels together. If I didn't use that special clamp that has a post for fitting into a pocket hole and just tried to hold one panel over another and then run the screw, the vertical panel would shift on the flat panel and be just the slightest bit off.

For assembling faceframes, the double disk type clamp seems to hold the faceframe parts adequately and I have noticed no creep.

I also have the Porter Cable Production Pocket Hole Cutter. When I was considering the Kreg electric pocket hole cutter, I did some research and found out that the PC cuts a hole very much like the Castle Pocket Hole machines. It uses two routers, one to cut a pocket with a sweeping motion and another to drill a hole. The thing about the PC and Castle machines is that there seems to be almost no angle and that when you run the screw, it is about 90 degrees to the piece that you are fastening to. The result is no noticable creep. If you do a search on this forum and others, you will find that much has been discussed about the difference in pocket hole cutters.

Bottom line is that adequate clamping will go a long way in dealing with any creep. Getting the PC does not mean that you no longer need to clamp.

I've now started using Dominos and screws when assembling Euro cabs - no creep!

[Al Willits]

Clamping helps greatly, but on 90 degree joints I found I'd still get a bit of creep, so I made a simple jig and use a thin shim to offset the joint, when screwed together it creeps just enough to be flush.
Takes a couple of times to get the shim thickness, but once ya do, cut a few extra for next time.

Same thickness shim worked for white oak and cherry, not sure about other woods though.

Al

[Jim Kaczmark]

Similar to Bryan, I've taken to making sure the boards you are joining do not slide apart slightly while screwing in the screw.

I made my own version of Kreg's clamping table. When making face frames, I'll put the back side of the stock I'm screwing into against the side of the table. With the board the screw starts in, I'll clamp it with two Kreg Klamps to ensure it does not slide at all. My theory is if the board begins to slide at all as the screw begins to self-tap into the 2nd piece of wood, then it will many times create slight misalignment in the face frames. I'll use this 2nd Kreg Klamp instead of a bar clamp to achieve this like Bryan does. A 3rd Klamp is obviously right over the joint in all cases.
Jim

[Phil Thien]

It would seem the most important clamping direction wouldn't be to clamp the pieces down to a flat surface, but to clamp them tight (with a bar clamp, for example). If the screw pushes the two pieces apart at all before being cranked down, then the geometry is going to cause creep (the screw acts like an elevator as it pulls the other piece snug).

[David Parker]

I agree with Josiah.

From a theoretical perspective, it seems that there is a critical point when the screw first contacts the second piece of wood. For a fraction of a screw turn, the screw tip is pushing against the second piece of wood. Once the threads of the screw bite into the wood, then the screw will pull the second piece of wood toward the first.

The goal should be to minimize the time that the screw tip is pushing against the wood before the threads bite. It seems to me that a small eighth or quarter inch starter hole about half the diameter of the screw shaft would encourage the threads to bite more quickly while minimizing the amount of "push" that the screw tip would exert against the second piece of wood. This would help eliminate any creep.

Just theoretical of course.

[J.R. Rutter]

I've done hundreds of frames with the Kreg system. The other posters have pretty much covered everything, but here are a couple of things that I didn't see mentioned.

First, I use a big C-clamp to hold the joint firmly against the table and tightly together. The screw force is very strong. It is true that snugging the joint with a bar clamp works, but I find the C-clamp faster and easier, which is what pocket screws are all about.

Second, in very hard woods, I use a long "aircraft" drill bit to drill a properly sized pilot hole in the stile right through the glued and clamped pocket hole. Before I started doing this, I was snapping screw heads regularly in Jatoba (often before the screw was fully tight).

[Michael Stanley]

I sometimes use one of these in addition to the Kreg clamp.

http://www.woodcraft.com/family.aspx?FamilyID=3793

[Greg Sznajdruk]

In my experience, the harder the wood is the more likely it is to creep. I use alot of shag bark hickory and have found the only way to prevent creep is to use the Kreg vise grip clamp for alignment and then clamp it parallel to the screws with a bar or bessey clamp. I use Kreg fine thread screws and haven't had any break.

Bryan

Bryan:

I had never seen Shagbark Hickory until I moved to Kingston. I have about 2 acres of this stuff; I find it a royal pain when the nuts fall off in the fall. It never occurred to me that this wood could be used for woodworking. I've been cutting it up for firewood.

What are the characteristics of this wood for furniture?

Greg

[John Gornall]

On one job I wanted to be sure of no creep at all so I designed using a rabbet only 1/16th deep to give a shoulder to locate the joint - worked well.