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Thread: Why does my pocket hole joinery ?

  1. #1

    Why does my pocket hole joinery ?

    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
    Last edited by Lee Schierer; 02-10-2019 at 2:13 PM.

  2. #2
    Join Date
    Mar 2008
    Location
    Buffalo, NY
    Posts
    52
    Quote Originally Posted by Larry Foster View Post
    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?

  3. #3
    Join Date
    Mar 2006
    Location
    SoCal
    Posts
    19,311
    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?
    She said “How many woodworking tools do you need?”
    I said “Why? Do you know someone who is selling some?”


  4. #4
    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.

  5. #5
    Are you using the correct screws for the type of wood? Hardwood screws don't hold well in softwoods.

  6. #6
    I'm using the coarse thread in plywood and pine, Doug

  7. #7
    Join Date
    Dec 2005
    Location
    Lake George NY
    Posts
    132
    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.

  8. #8
    Join Date
    Nov 2016
    Location
    Itapevi, SP - Brazil
    Posts
    294
    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
    All the best.

    Osvaldo.

  9. #9
    Join Date
    Sep 2013
    Location
    Wayland, MA
    Posts
    1,318
    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.

  10. #10
    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?

  11. #11
    Join Date
    Jan 2014
    Location
    New Jersey
    Posts
    409
    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.

  12. #12
    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.

  13. #13
    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

  14. #14
    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

  15. #15
    You might be stripping the threads when driving screws. It is easy to do that in pine.

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