Why does my pocket hole joinery ?

[Larry Foster]

I've had a Kreg K4 for a number of years and only use it occasionally.
However, I can't recall one successful joint that I have ever made.

For example, my latest failure was to build a gate for my chicken fence.
I used furring strips and tried to make it sort of like a cabinet face frame.

Using the recommended size screw was too short and used the next size which sort of held but a couple of the cross pieces pulled out.
I believe I have the jig and bit set properly; read and re-read directions and watched a ton of videos to see if I can figure it out.
I clutch down when driving screws

Why this matters is that I need to build a couple cabinets for my kitchen.
It would be really nice to use pocket screws.

If anyone has thoughts I'd appreciate it.
Thanks

[Mike DeHart]

I've had a Kreg K4 for a number of years and only use it occasionally.
However, I can't recall one successful joint that I have ever made.

For example, my latest failure was to build a gate for my chicken fence.
I used furring strips and tried to make it sort of like a cabinet face frame.

Using the recommended size screw was too short and used the next size which sort of held but a couple of the cross pieces pulled out.
I believe I have the jig and bit set properly; read and re-read directions and watched a ton of videos to see if I can figure it out.
I clutch down when driving screws

Why this matters is that I need to build a couple cabinets for my kitchen.
It would be really nice to use pocket screws.

If anyone has thoughts I'd appreciate it.
Thanks
If you insert the drill bit into the jig how far from the base does it end up?

[glenn bradley]

Sounds like it could be more material choice related than pocket hole related. Soft woods will often fail due to pull out of the screws. The material just can't support the stress of use. Like any joint, pocket holes work out better if you have well formed, well fitting joints even though they are often just butt joints. I use pocket holes with 1/2" BB ply (pretty easy to get accurate with plywood) for crude drawer boxes with good success. Pocket hole face frames work well as there is little stress on the frames. How do pocket holes work for you in something like oak or maple?

[Larry Foster]

Thanks for the fast replies, Mike and Glenn.


If you insert the drill bit into the jig how far from the base does it end up?
I would have to check that and get back to you.
Don't know off the top of my head.


Sounds like it could be more material choice related than pocket hole related

I have the same issues with 3/4 plywood, Glenn.

I have never used them in hardwoods.

[Doug Garson]

Are you using the correct screws for the type of wood? Hardwood screws don't hold well in softwoods.

[Larry Foster]

I'm using the coarse thread in plywood and pine, Doug

[Rick Peek]

I only use pocket hole joinery in hardwoods and they work great. Can’t see them working well in plywood.
Would only use in softwoods where there is no stress.

[Osvaldo Cristo]

1. Carefully square the parts
2. Set up Kreg jig correctly and clamp parts firmly before screw
3. Softwoods and plywood are usually very fragile. Avoid to use impact driver. Use drill set up at minimum torque. Make final adjust by hand
4. It is a good idea to combine pocket screws and glue at some cases
5. Practice. As most skills it comes with actual use

[roger wiegand]

I don't think you should expect any significant structural strength from pocket screws. I expect they were invented as a way to hold face frames in kitchen cabinets together only long enough to get them attached to a carcase. You're relying on a short length of screw (often only an inch), close to the surface of the wood held by short end grain, in a joint that's subject to a lot of stress if not otherwise supported.

I've demoed quite a number of kitchens and have never had to reach for a tool to break up a pocket-screwed face frames-- you just grab it and twist and all the joints break. Mostly the wood gives way, in MDF or plywood the screws pull out.

For a gate I'd use full or half lap joints bolted, screwed, or nailed and glued through the faces of the overlap (with a diagonal member to resist sag). For fancier I'd use a mortise and tenon. I don't find it at all surprising that pocket screws wouldn't work in that application.

[Larry Foster]

Thanks, Osvaldo and Roger.

I may not have been clear about the gate and only used it as an example.
The "gate" was meant to be more of an obstruction to keep the goats out of my chicken coop and eating all the chicken feed.
Even during the build I had blowout and poor attachment.

Other times I had issues building a plywood box out of 3/4" plywood.

I know this isn't rocket surgery but there are 100s or thousands of YouTube videos of people building all kinds of thing with pocket screws.

Maybe I'm just inept?

[Bryan Lisowski]

I agree with having square material and clamping the piece before you screw. A lot of times plywood is slightly undersized, so even with the jig set properly you could get a screw that will poke through.

[Jim Andrew]

You can adjust your jig to use longer screws. Use coarse thread screws for softwoods, fine thread for hardwoods. Although I like coarse threads for walnut. And I drill a pilot hole when making face frames, as sometimes the threads pull out if you do not.

[Larry Foster]

Thanks, Bryan and Jim.
I did clamp the "gate" using the Kreg clamp that is flat on both sides.
For the plywood box, I tried using the clamp that has one side that fits into one of the holes.
That doesn't always work well for me

[kent wardecke]

I had a goat once. I don't think a pocket screw/furring strip fence is going to keep it out of the chicken feed ;-)
it sounds like you're doing it right, so i have to agree that maybe it's not the right joint for the job.
Make "T" with some 1" x4"s and 4 pocket screws then do your best to break the joint. Then make some 1" x4"s with plywood and try some 1" x2"s try 2 screws and 6 screws. I think you'll find that a pocket screw isnt bullet proof and that the joint is very one dimensional

Btw good luck with the goat

[Reinis Kanders]

You might be stripping the threads when driving screws. It is easy to do that in pine.

[Jon Nuckles]

I used pocket screws to build boxes for my kitchen cabinets out of 3/4” plywood. While I had a bit of a learning curve at first driving the screws without pulling the joint out of perfect alignment, the screws definitely provided a solid connection. Based on your description, the only thing that comes to mind is to be sure you use the set up block to get the collar on the drill bit set at the proper depth for the length of screw you are using. There is not a lot of wiggle room to work with. (I have the K5, but assume the K4 works the same way.)

[Larry Foster]

kent, it's working so far keeping my goats out.

Thanks, Reinis and Jon.

Should I compensate slightly since 3/4 plywood is less than 3/4?

How little torque do you use when driving screws?

[glenn bradley]

1. Carefully square the parts
2. Set up Kreg jig correctly and clamp parts firmly before screw
3. Softwoods and plywood are usually very fragile. Avoid to use impact driver. Use drill set up at minimum torque. Make final adjust by hand
4. It is a good idea to combine pocket screws and glue at some cases
5. Practice. As most skills it comes with actual use

I think Osvaldo outlines the items required for success very well. I wish I could have done it as thoroughly. I'll add that there is an expectation with pocket hole joinery. I think of it about the same as nailing or screwing butt joints. If the screw thread is you only source of strength, the stress the joint will take is decent but, limited.

[Jim Foster]

Are you creating the pocket hole on the "Right Side" of the joint. The pocket should be created along end grain, so the screw is fastened into grain that can hold the threads, and not end grain. Also, once or twice, I've used a hand driven screwdriver when the material was soft so the created threads were not stripped by power drill.

See photo below, borrowed from a Rockler Web page

Can you provide a photo of one of the failed joints?

403223

[Matthew Hills]

Pocket screws have generally been a pretty good choice for a butt joint, but you do have to look at overall design for the expected loads.

How did the joints fail? Is the head pulling through, or the threads pulling out of the wood?
What type of loads are causing the failure? Shear should be pretty good (limited by the material dimensions); tension and torsion will be weaker.

Over-driving the screws will significantly weaken the joint.
Glue is a good idea, particularly for plywood.

Matt

[David Eisenhauer]

I used to assemble lots of face frames using pocket screws and found that (as mentioned above by others) I had best success by doing the final screw tightening with a hand screwdriver rather than a powered driver to get the last 1/2 - 3/4 turn or so on the screw. I could feel the screw bringing the two parts into firm-solid-tight contact without overtightening when doing the last bit by hand. This was in a commercial environment where extra steps need to pay for themselves to be effective. The failure rate went to just about zero when doing this. Also, using two screws rather than one per joint makes a world of difference and that was the limiting factor for me when designing the width of my face frame material.

[Lee Schierer]

As others have noted, firring strips are about the poorest choice of wood for pocket hole joint strength. Firring strips are made from wood that is too poor quality to make much of anything else except maybe wood pulp. I use primarily hardwoods in the pocket hole screw joints that I have made. I have only rarely had a screw strip out and those occurred using soft wood. I generally use 1-1/4" screws with the fine threads. I tried some generic brand screws once and they were terrible, so be careful which brand screws you buy. I bought a box of 1,000 Kreg screws and they last a good long while.

[Larry Foster]

Thanks for all of the replies.
I'm in the middle of a 48 hour work/on call weekend.

If I get a break before dark I'll see if I can get a pic of the gate which is where the last failure was.

I talk about the firring strips and the gate but, I've had as much trouble with plywood.

I'll try the last little bit of tightening by hand and see if that makes a difference

[Andrew Pitonyak]

Larry, in the unlikely event that you live near Columbus Ohio, we can do one together.... I have built numerous things (such as cabinets) using pocket holes, and that have worked very well.

[Reinis Kanders]

I also find that his style of clamp helps to align joints better than flat clamp.

https://www.amazon.com/KHCRA-Automaxx-Right-Angle-Clamp/dp/B01H1WFPWM

[Nick Decker]

I also find that his style of clamp helps to align joints better than flat clamp.

https://www.amazon.com/KHCRA-Automaxx-Right-Angle-Clamp/dp/B01H1WFPWM

Agreed, those are very handy. I only have one, so I'll use it on one of the pocket holes to get things lined up and clamped down, then add another parallel or pipe clamp somewhere else along the line for insurance.

[Art Mann]

I have an entire shop filled with storage cabinets, tables and benches that were assembled with plywood and pocket screws. These were built around the same time about 15 years ago and they have been heavily used/abused. I don't have a hint of failure anywhere. They work great on plywood as well. You have to install them correctly and use enough of them to do the job. I think it is the best assembly method yet devised for cabinetry where appearance is not an issue.


I only use pocket hole joinery in hardwoods and they work great. Can’t see them working well in plywood.
Would only use in softwoods where there is no stress.

[Larry Foster]

Andrew, that is a generous offer that I wish were practical.
I'm due east about 225 miles.

Unless I get a real urge for Skyline and White Castles.

Reinis, I have that clamp and not real adept with it yet.

[Richard Coers]

I consider a pocket hole screw to just be a clamp. It's not a structural member, it's not a structural joint if the glue wouldn't hold it if you clamped it instead. Most often it's a tiny bit of end grain, butt glued to long grain. That is not a structural joint.

[Larry Foster]

Ok.
I was able to sneak out and get some pics

The first is of the stiles that pulled out

The second is is the gate with patches to replace the stiles that fell out.
The top and bottom 2 are the only ones that stayed

The last is a 3/4" plywood cabinet that had to be glued.
Not sure if the screws are holding much or not

One other thing.
The screws seat outside the holes and don't go in the pocket hole.
Like in the right hand photo

[Lisa Starr]

Larry, It appears you have your joints oriented correctly. I use pocket hole joints constantly, and, only occasionally have a problem with the joint holding. From your description, I'm 95% sure you're stripping the threads out driving the screws. I've learned that I need to drive them with my 12 Volt and not let it crank them down. The Dewalt 20 Volt will strip them almost every time. As others suggested, finish them by hand, if you use that type of driver.

On a side note, when building cabinet carcases, I always drill pairs of holes in each location. That way, if I do strip a hole, there is another available.

[Steve Jenkins]

Looking at your pics it appears that the stop on the drill bit isn’t set right. If you put a nickel on the jig the end of the bit should just touch it.

[Larry Foster]

Thanks for that tip Lisa.
I had a dickens of a time getting the proper size screw to go into the receiving piece far enough to hold.

You can see that in the pic on the right

Thanks, Steve.
I use the markings on the jig to set the jig height as well as drill stop.
But I have wondered the same thing when using it

[Nick Decker]

Larry, in your plywood shot, the hole placement is all over the place. Why is that?

Also, the plywood looks pretty rough. If it's delaminating or has voids, the screws will have nothing to grab and hold.

[Larry Foster]

It's a cheap exterior plywood.
I don't know why the holes are all over.
I clamp in the jig

[Nick Decker]

I've only used the smaller (K3?) jig, maybe someone else can help with why the drilled holes aren't consistent, but I'm guessing that's why you're having trouble with getting your screws to engage.

[Larry Foster]

I was thinking, Nick, that the holes being all over may be an illusion due to camera angle.
Possibly?

Some screws seat well, some blow through and some don't seat at all, like in the cabinet pic

[Osvaldo Cristo]

Are you creating the pocket hole on the "Right Side" of the joint. The pocket should be created along end grain, so the screw is fastened into grain that can hold the threads, and not end grain. Also, once or twice, I've used a hand driven screwdriver when the material was soft so the created threads were not stripped by power drill.

See photo below, borrowed from a Rockler Web page

Can you provide a photo of one of the failed joints?

403223

I had forgotten to include that into my important points for successful pock hole making. From my own experience you are very right!

[David Eisenhauer]

What are you using to drill the pocket holes with? I seem to remember that someone-somewhere advised against using cordless drills for the hole drilling operation and to use a corded drill for consistency of the hole. I always used a corded drill back when I was making face frames at a dedicated pocket hole area where an outlet was right there and I did not have to deal with batteries. Or, I am I having a senior moment? Those screw heads in your photos should be buried out of view if the holes are drilled to the correct depth and you are driving them to depth. The depth stop setting instructions with the jig (while somewhat exacting) are not difficult to follow and I have to believe you have the depth set correctly. This is a situation where 3 minutes with someone else familiar with pocket hole use looking over your shoulder while you drill/drive a screw could probably solve the whole mystery. Maybe find two decent (solid) pieces of 3/4" wood, reset the depth on the drill collar and try again with a fresh attempt as a test.

[Larry Foster]

Thanks, David.
I am using a cordless drill.
The only corded drill I own is a huge Bosch hammer drill.

I agree that the screws should be buried.

This isn't rocket surgery and I'd like to think I'm moderately intelligent.

If it's not too cold tomorrow, I'll take your suggestion and play around.
I have lots of scrap.

[Nick Decker]

I was thinking, Nick, that the holes being all over may be an illusion due to camera angle.
Possibly?

Some screws seat well, some blow through and some don't seat at all, like in the cabinet pic

The perspective doesn't seem to indicate that. Starting from the left, the first two holes look about the same, then the rest kind of go uphill from there. Just take a ruler and measure each hole's distance from the edge. They should be exactly the same.

[Larry Foster]

I was going to put a square on it but will try a ruler

[Jim Foster]

It looks like the gate needs a triangular element to keep it from racking, even if the pocket holes were correctly installed.

Regarding the other photos, at first blush it looks like the pocket hole bit might not be set correctly. In general the screws should be set in far enough that they are less visible than your photos show. Your pocket hole bit may need to be adjusted to drill a bit deeper. I've always just made sure the bit is set at a depth that prevents it from hitting the horizontal base of the jig when drilling a pocket hole. I know it's not quite according to directions, but I've never had a problem with a joint.

[Larry Foster]

I just did it quick and dirty on one of those real cold days a week or so ago.
You may be right about the bit not being correct but, if it's wrong, I truly have no idea what is correct.
I put the shoulder of the bit on the mark for the piece I'm drilling and tighten the collar.
Lately, I've been shorting it a fine hair to make up for the smaller thicknesses

[Zac wingert]

What are you driving the screws with? I use a 12v Milwaukee with the torque set low, for softwood and plywood. I wouldn’t even try use my 18v makita impact driver for it, it would damage most of it.

[Larry Foster]

I've used a number of different drills but I think they're all 18V
For the gate, probably a Ryobi
For that cabinet, maybe a Hercules

Usually my torque is at max for drilling and 9 or less for driving the screws.

[Lee Schierer]

The last is a 3/4" plywood cabinet that had to be glued.
Not sure if the screws are holding much or not

One other thing.
The screws seat outside the holes and don't go in the pocket hole.
Like in the right hand photo

It looks like you jig and drill are not set up right. Here is what a properly drill hole should look like in 3/4" plywood.
403271403272
Note that the hole should be oval and not squared off as your holes appear to be. You should not be able to see the heads of the screws when they are in properly drilled holes and fully seated.

[Larry Foster]

I believe you may be right, Lee.

I think I am doing everything properly but, apparently not.

I think my jig and bit are set ti the size of my material.
I clamp the wood to the jig to drill.

Drill bit?

I have a new, unopened bit here.
I can try that when I head out in a bit to test and practice

[Brian Holcombe]

Double up the rails, sandwiching the stiles between along with a diagonal brace. Run your slats across, all set. No pocket screws. Pocket screws aren’t going to remain tight in outdoor work for very long.

[Lee Schierer]

I believe you may be right, Lee.

I think I am doing everything properly but, apparently not.

I think my jig and bit are set ti the size of my material.
I clamp the wood to the jig to drill.

Note that the holes I showed were drilled in 3/4" plywood. Can you show photos of your setup before your drill a hole? Specifically show how far the tip of the drill sticks out of the jig where the wood would be if you had the drill fully inserted.

[Robert Engel]

You shouldn't be having this much trouble.

Regarding the plywood, first, be sure you're using the correct screws. I've never seen blue pocket screws. Are those Tapcons?? Second, the hole isn't deep enough. You shouldn't be seeing the head of the screw if properly seated.

I've not had many problems using Kreg coarse screws in plywood. I typically use 1 1/4" screws.

Check your setup:

I would go over the instructions for the correct screw length and drill block setup.

In sheet goods of any kind, you have to be careful how much you tighten. I prefer to use a drill rather than an impact driver because I can regulate the torque better. That said, once in a while you'll hit a pocket in the ply.

BTW, I would cover the gate with chicken wire on the outside to keep the goats from standing on it.

[Larry Foster]

I will do that, sir.

Robert, I didn't think I should be having this much trouble, either.
I am only using authentic Kreg screws.

I've not needed any fine screws yet because I've only tried to join plywood or pine.
I also use 1-1/4" screws in 3/4" material

I've never used an impact driver, only drills.

I'm thinking the problem isn't driving the screws but something in the process prior to that.

I'll get all my data in a bit and post it

Thanks, everyone, for sticking with me

[John Stankus]

You shouldn't be having this much trouble.

Regarding the plywood, first, be sure you're using the correct screws. I've never seen blue pocket screws. Are those Tapcons?? .

Those look like Kreg Blue-Kote pocket hole screws. They have extra layers of corrosion protection coating for outside use.

[Larry Foster]

BTW, I would cover the gate with chicken wire on the outside to keep the goats from standing on it.

They haven't figured it out yet

[Jim Foster]

Here's a photo that might help.


403283

[Lee Schierer]

Here is an improperly drilled hole where the drill depth is too little.
403284
compared to properly drilled holes.403285

[Larry Foster]

I may have found the problem for this last time but don't believe that has always been the case.
And not sure why this time unless the set screw came loose and I tightened it without checking.

The collar was adjusted so the tip and not the shoulder of the drill bit was at the 3/4 mark.
Waiting for the pic to download from my phone but it looks like yours, Jim

[Mike DeHart]

Are you lining up the tip or the step to the mark when setting the drill collar? https://www.kregtool.com/webres/Image/Drill-Bit-Tip.jpg

[Larry Foster]

Here's my jig after making correction

403286


I'll go back out in a little to practice

[Larry Foster]

I know to align the step or shoulder.
As mentioned above, somehow it was adjusted wrong

[Jim Foster]

Looks good!

[Larry Foster]

Warmed up enough to go out and experiment.

After triple checking that the jig and bit were set properly, I drilled 6 holes in 3/4 ply.
I set my torque to 8 on my drill and used 1-1/4" coarse screws.

At least 4 of the 6 blew through.

I don't know if you can tell from the pics.
One pic is of the pocket holes and the other the blowout403512403513

[Lee Schierer]

Warmed up enough to go out and experiment.

After triple checking that the jig and bit were set properly, I drilled 6 holes in 3/4 ply.
I set my torque to 8 on my drill and used 1-1/4" coarse screws.

At least 4 of the 6 blew through.

I don't know if you can tell from the pics.
One pic is of the pocket holes and the other the blowout403512403513

From the look of the wood in the photos, it appears that your plywood either is wet or was wet for some period of time. Most plywood and specially interior grade, doesn't respond well to getting wet. The glue in the lamination doesn't deal well with the swelling the water causes so a lot of strength is lost. I would suggest you try a couple of joints on some 1 x scrap and see how you fare.

[Larry Foster]

Lee, you are correct.
Just happened to be what I had in small enough pieces for quick and dirty.

After my errand, I'll grab some dry plywood or 1X and try again

[Larry Foster]

Operator error?

Just went back to try again, this time with firring strips.

Made 2 different joints.

One was a box type joint and the other was like a rail and stile joint.

Both joints were perfect.

Hopefully, I can continue with this because I'd hate to start ruining my cabinet grade plywood.
:(

[roger wiegand]

I've never had occasion to need a pocket screw, but reading this saga would certainly lead me to go out and buy a Domino! Congrats on getting it working.

[Larry Foster]

roger, it may be a little preliminary to say I got it working.
I'd say it worked once.

Let's see if I can keep it working.

Otherwise, I'm going to ruin a whole lot of plywood I cut today