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  1. #1
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    Default What exactly is a 2 x 2 and what do you think of pocket holes?

    Hi, I'm a newbie at wood work and I thought building stuff with a pocket hole jig would be a good start; I can use a drop saw no probs, but I'm not ready to use the more dangerous stuff like table saws and routers.

    I found a nice day bed project which has some general instructions like use 2 x 2's for the base and legs. I had a look at a Kreg jig and saw that it basically goes to a max depth of 1-1/2 inches. Then I found an American chart which seems to show that 2 x 2 is physically 1-1/2 x 1-1/2 inches or 38 x 38 mm. Next looking at my local wood supplier I see that the nearest common lengths to 38 mm are 35 and 45.

    So when the Kreg jig says it supports up to 1-1/2 is it actually referring to what is know as an American 2, as in 2 x 4? And what is the equivalent in Australia; is 45mm x 90mm a 2 x4? Would the Kreg jig be OK with 45 mm, given that 1-1/2 is actually 38 mm?

    Sorry if this is obvious, but its doing my head in

    Cheers,

    Gerry

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  3. #2
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    Hi Gerry and welcome to the forums.

    Americans are a bit weird with their timber dimensions; but the size limitation on the Kreg jig refers to finished timber. So it's only designed for timber up to 38mm. I find that rough sawn timber is usually only approximate in its claimed sizes and always expect to lose about 1\2" in all dimensions once the jointer and thicknesses have had a go. DAR (dressed all round) is already finished and supplied in exact sizes.

    You can make the Kreg jig work on thicker materials than 1-1\2", what you have to do is move the body of the jig further away from the edge. And use a longer stepped drill bit. And longer screws! Other than that it's simple

    As a thought though you could use thick dowels in conjunction with the Kreg; the dowels provide the strength and the screws enable the assembly to be dismantled. The screws wouldn't be going straight through the center of the timber but by using dowels the loss of strength would be negligible.

    One more thing; avoid those Sachy Robertson square drive Kreg copy screws in hardwoods. They WILL snap. If you are using anything harder than Cypress Pine use the proper Kreg fine threaded screws. SR screws are OK for softwoods but that's about it.

  4. #3
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    Default Thanks

    I think it get it now. The jig is setup to drill holes at the optimum width apart and depth in the various 'common' thicknesses of American standard sized wood, up to 38mm. If I used a piece of wood 35 mm wide on the 1-1/2 inch setting the holes would be slightly wider apart and a little deeper than the optimum, so a little less strong, but they would still be OK. And what you are saying, is that if it was a problem I could add a dowel as well, not glued in, that way it could actually be dissembled if necessary. If I where to get this pocket hole guide that doesn't come with a jig I could manually determine the correct width apart and distance away from the the end of any sized wood to get the optimum strength pocket hole, as long as the drill was long enough. The jigs are actually designed for speed and convenience.

  5. #4
    rrich Guest

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    Quote Originally Posted by Chief Tiff View Post
    Americans are a bit weird with their timber dimensions;

    I had to laugh over that comment.

    I am one of the Imperial persuasion. While I understand the metric system, it is not one with me.

    I've encountered houses (100-150 years old) where a 2 x 4 is really a 2 x 4 and not 1½ x 3½. This makes it difficult if not impossible to use modern sized building materials.

    The ultimate was from those of metric persuasion. I don't remember the company but it was a European company, might have been Hammer or one similar. I was looking for a combination jointer / thicknesseser machine. I was reading the installation instructions on the Internet. The object was to move the tables into position for assembly. The instruction was, "Use a meter 2 x 4. . . . "

    The thing is that I couldn't resolve, "Who was corrupting whom" (Imperial vs. Metric or Metric vs. Imperial.) That comment has provided a smirk when discussing the advantages of either system.

  6. #5
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    Default

    I was brought up using the imperial system but quite happy to use both.
    If I designed a piece of furniture then I would work out the proportions in feet and inchess but us metric millimeters when making the joints etc.

    Have not used the pocket hole system gut suspect it might not really be that suitable for your daybed project as it need to benvery rigid and able to carry a reasonable load.Buying and using a dowel jig might be more suitable.I think the pocket hole system is better suited to cabinet and door framework and other applications where high strength is not vital.

    If you can upload a photo of your design or something similar it will be easier for forum members to advise you on construction etc.

  7. #6
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    Pocket holes are, in my not-so-humble opinion, THE WORST thing to happen to furniture and wood work since people started using biscuits for structural applications.
    As far as I'm concerned, the only acceptable use for pocket holes is to hold a cabinet- or table-top down.

  8. #7
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    There's a good article over at woodgears.ca on the strength of pocket hole joinst vs mortise and tenon.

    http://woodgears.ca/joint_strength/pockethole.html

  9. #8
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    Quote Originally Posted by Gerry_K View Post
    I think it get it now. The jig is setup to drill holes at the optimum width apart and depth in the various 'common' thicknesses of American standard sized wood, up to 38mm. If I used a piece of wood 35 mm wide on the 1-1/2 inch setting the holes would be slightly wider apart and a little deeper than the optimum, so a little less strong, but they would still be OK.
    I have the Kreg 3 Master kit and a standalone (clamp in position) jig. Both have 3 guide holes in the jig body with the centre one offset to one side. When you see how the system works, it quickly becomes obvious that it is not smart to use a single screw per joint as there is not much to stop the part rotating under load and splitting around the drilled pocket. So at least two screws per joint becomes a more logical choice. The three guide holes in the jig give you preset spacings for:
    Narrow material (centre guide and nearest edge guide)
    Medium width material (centre guide and furtherest edge guide)
    Wider material (both outer guides)
    The screw spacing is therefore a user choice of 3 fixed settings. Long time since I read the manual, but I think they recommend screws being at least 1/2" in from the edge.

    As for material thickness and its relationship to the system, the screws are set at an angle to the face of the material and screws are available in lengths to about 2 1/2". The system has a table relating screw length to material thickness, recommending longer screws for thicker material. The full jig kit has a guide block and a guide block holder that will position the guide block in a number of different positions depending on material thickness. These positions move the guide block position relative to the the edge/end being drilled, so for thin stock, the pocket is positioned near the edge/end, while for thicker stock it is further away. The whole setup of the guide and screw length is configured to have the screw pass near the thickness centre at the joint, but not have the end of the screw emerge from the material that it is attaching.

    The standalone unit uses the same style of guide block and a clamp to lock it in position, you determine how far it is offset from the edge/end with a rule or setup block, place it and then clamp it on position to drill the pockets.

    I am in North Croydon and home most of the time. If you wish, send me a message with a phone number and I will call you to arrange for you to come around and have a play with my kit to clarify the above ramblings. Might also loan you the kit for a while for your project, then you only have to pay exorbitant prices for screws instead of screws and jigs.

    The Kreg system is OK provided that you do not require invisible fasteners and pockets. You can get plugs in a variety of timbers to plug the pockets, but they never match the original timber to the point of merging into the grain because they are endgrain in a surface of face grain. They can be an issue for getting small fingers caught if left unplugged where young children can explore.

    With regard to timber sizes, there tends to be two distinct ways that it is labelled. For rough sawn material, 2x2 or 50x50 would indicate that when the material went through the mill, the saw was set to cut 2" or 50mm. In drying etc the material may shrink and each dimension may be smaller than the nominal size.
    For surfaced all round material, the quoted sizes would normally be nominal finished size, although their is some scope for shrinkage if moisture content changes. To get to 2x2 surfaced all round, the raw stock was probably cut at least 2 1/4" square, part of the difference being shrinkage during drying, and the rest being machined off to obtain straight surfaced all round stock. Buying surfaced all round is expensive because you are paying for additional material, then paying wages, machinery time and overheads to machine the stock to finished size.

    Hope all of this makes sense for you.
    I used to be an engineer, I'm not an engineer any more, but on the really good days I can remember when I was.

  10. #9
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    Quote Originally Posted by Chief Tiff View Post
    One more thing; avoid those Sachy Robertson square drive Kreg copy screws in hardwoods. They WILL snap. If you are using anything harder than Cypress Pine use the proper Kreg fine threaded screws. SR screws are OK for softwoods but that's about it.
    After reading this I contacted Screw-It-Screws to see what their take on this was. Below is the reply I got
    Our pocket hole screws forhardwood are sold mostly to industry (Caravan manufacturers cabinet makers etc)They are designed for use with kiln dried hardwood.
    I you are using heavy woodsuch as Red gum Black buck etc you would need to use our 7 gauge face framescrews which are designed for this purpose and are equal to the Kreg system. Iwill put this information in the next newsletter.
    http://www.screwit.com.au/Shop/wood-screws/face-frame-screws/face-frame-screws-7gx-31mm

  11. #10
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    Default Thanks

    There is a lot of info here, I appreciate it. I'm taking the family to Thailand today for a holiday, so I it will be a while before I start the project. But I feel a bit more confident now. Thanks malb for the kind offer re the Kreg jig. I think a Kreg jig will be my next bday present. A day bed probably isn't the best use for pocket holes, but I can add extra support afterwards. That wood gears link was VERY interesting.

    Cheers!

  12. #11
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    Quote Originally Posted by Gerry_K View Post
    .... I'm taking the family to Thailand today for a holiday,....

    Enjoy your holiday.

  13. #12
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    Quote Originally Posted by Treecycle View Post
    I you are using heavy woodsuch as Red gum Black buck etc you would need to use our 7 gauge face framescrews which are designed for this purpose and are equal to the Kreg system.
    http://www.screwit.com.au/Shop/wood-screws/face-frame-screws/face-frame-screws-7gx-31mm
    Saw them, bought them, snapped them, cursed them. Yes they are equal to the Kreg system SOFTWOOD screws and like those if you throw them into Jarrah they'll break. The Kreg hardwood screws have a fine thread, Screw-it screws don't.

    The beauty of these forums is that everybody has their own opinions and experiences that can be used as an aid in decision making, generally experience trumps opinion. My opinion of Screw-its claim that they are suitable for hardwoods is that they either only tested them in balsa or pawlonia, or they are just selling snake oil. My experience in using their screws in jarrah, karri and Tas oak is that they are useful for expanding your vocabulary in profanity.

    Maybe someone has had the opposite experience?

  14. #13
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    Happy to go with experience so I will keep that in mind if using the really hard woods.
    It's amazing how the formatting changed in the quote I posted. It looks like there was a poor grasp of the English language now when I go back and read it. That is not the way it was originally written.

  15. #14
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    I'd assumed the quote was exactly as it appeared in your post; the poor grasp of their English would appear to mirror their screws performance

    Seriously though; I once purchased a load of Screw-it screws once because of the high cost of the proper Kreg ones and was fully taken by the hype. At the time they actually mocked a "well known brand" of pocket hole screws for having fine threads when clearly that was a marketing gimmick. When they arrived I was a bit nonplussed to see that they didn't copy the self-drilling cut out on the screw tip either.

    Well, every screw I put in hardwoods snapped. Even in softwoods they made an awful squealing noise and were harder to drive. The only way I could feel comfortable using them was to actually use a Kreg screw first to cut the thread, and then replace it with one of these pieces of junk. Took me a while but eventually I got through them. Now I just only buy the Kreg ones and curse the expense.

    Maybe I got a bad batch, I don't know. Perhaps they've addressed the problems now and can make a screw worthy of the name but unless I see other forum members stating that they work in Aussie hardwoods no different than that "well known brand" I shall avoid them like the plague.

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