Fixtures, Guides, Jigs, and Templates – aids to accuracy and precision

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  • #637147
    Sven-Olof Jansson
    Participant

    The <Gallery> so very clearly shows the great talents and skills behind awesome results, making it quite doubtful as to whether there really is a need for contraptions aiming at aiding accuracy and precision. Hence, it is only with trepidation that I open this thread, which has been motivated primarily by the Wine Rack Project.

    Presently, two episodes of the project have been published; both displaying Mr. P. Sellers mastering woodworking skills some can hope to attain, while others, like me, will despair to ever reach: sawing to a curve isn’t easy with a bandsaw and doing it by hand, using e.g. a bow saw, is rather a lot more challenging. Likewise, achieving gap free mitred (V-shaped) joints using only a chisel and a hammer, is, and will be, beyond me. An even more ludicrous idea is that, lacking a bandsaw, I will be able to re-saw to 1/8″ (3.175 mm). But whatever, with some supporting guides, jigs, and fixtures, I might be able to achieve something; so here we go with a first one.

    The attached primitive draft is supposed to show a guide that aims to support achieving true and square(?) 45° mitre joints. It’s a theft from Mr. D. Charlesworth’s video “The Secret Dovetail”; but apart from that purpose the guide can also be used for accurate sawing very close to the lines of mitres (as in the Wine Rack Project), after which it can aid with positioning a chisel for pairing. Pieces of paper placed on the sloping surfaces can help with avoiding “diving with chisel” when pairing.

    (A few more to follow)

    Sven-Olof Jansson
    London, UK; Boston, MA

    #637164
    joemonahan
    Participant

    I use every guide, jig, fixture I can get my hands on. I may learn to work without them with time, but meanwhile I don’t want to waste years producing crap nobody wants to look at – not even me! Ive noticed Im not alone given the profusion of jigs, etc sold by the woodworking cos. For me there is no pride producing something sad “by hand” when I can eek out something quite passable with these aids.

    #637267
    Colin Scowen
    Participant

    IMHO, it depends what you are trying to do. Jigs and fixtures help you when you want repeatability or speed. They are generally best when they do only one thing and don’t need to be set up or tuned. These usually (but not always) require a deal more precision in the preceding stages of preparation though (compare how many times you have heard Paul say ‘Use a test piece’ vs. any of the jig / power tool demos you can find on the squinternet).
    If your goal is the finished piece then an off the shelf or simple fixture / jig will probably help to get you there more efficiently.
    If your goal is the skill of the use of the tools, then a jig may be more of a handicap. Really does depend on a bit of self awareness regarding why you are doing something.

    For example, I have a funky bit of tree that I am going to make in to a small table. I don’t need an extra table, but I would like to know if I can do it or not.
    If I can do it, then I will have succeeded against my objective of learning how to make that sort of table (and I will then have an un-necessary table to dispose of, but that’s another debate).
    If I fail to make a good table, then I will still be in the process of learning how to make that sort of table (and will have to wait until another suitable piece of tree comes along before I continue).

    Colin, Czech Rep.

    #637323
    Ed
    Participant

    Sven-Olof, sometimes developing the skill levels you describe as out of reach relies on insights on how to work progressively and discovering such methods as needed for yourself. Don’t give up!

    As an example, consider paring the shoulders of a tenon after sawing away the bulk. Paul shows putting his chisel into the knife line, pushing, moving across, and then having what he needs. I can get close doing this but found I was usually out of square a bit, especially on the side. What I’ve learned to do is to work progressively towards my knife line. So, that is the first step- Knifing in an acceptable layout all the way around the shoulders. Next, the waste is cut away. Now for the trick. I take a narrow chisel, about 3/8″, put it in the knife line one the narrow edges with the work horizontal in the vise (chisel vertical) and gently tap a couple times. This deepens the knife line. I aim away from the finished plane just a tad, i.e., I’m a little out of plumb, aimed into the waste. Just a hair. Next, I put a 1″ chisel into the knife line along the main shoulder, aim definitively into the waste (out of plumb/square), and remove a sliver of the fuzz about 3/8″ wide. What I’m looking for here is for the deepened knife line to appear from the side. I usually won’t see it on the first sliver, so I take another sliver, a little closer to square, again registering in the knife line, and repeat until the knife line on the side appears. The key observation here is that, because of the way knife lines work, you will see the knife line appear *before* you’ve actually cut down to it. Now that I can see it, I can carefully remove fuzz to be on it. You see what we have now? We’ve worked to two knife lines, one on the face and one on the edge, so we know have a perfectly square corner, about 3/8″ wide and the depth of the shoulder, and it is as good as our knife lines. No magic skills were required. No super-calibrated mystical eye. Now that I have this perfect little shelf, I plop the back of my chisel onto it, apply strong downward thumb pressure to stay registered, and walk a bit further into the shoulder, i.e., I register in the fuzzy knife line while registering on that perfect, square table I just made, and push. At this point, it goes quickly and looks like Paul’s motions, but I’m just extending that trued up surface across the shoulder.

    That’s meant as an example. There are other places where this property of knife lines comes in. So, please see that if you aren’t getting the results you want, there isn’t some fundamental weakness or lack in you. With some experimentation to find ways to work iteratively, you can achieve the precision you want, I’m sure.

    One of the most useful things a teacher ever said to me was, “Keep at it. You’ll get it.”

    None of this is meant to argue against jigs. It’s just meant to encourage. Keep at it. You’ll get it.

    #637511
    Sven-Olof Jansson
    Participant

    Colin,

    Your statements on the desirable properties of fixtures and jigs, are very interesting to me, as I am trying to design an adjustable guide for chopping out mortices (please see attached drawings). So, if they too aren’t your own subjective opinions, please may I ask for a direction to their background evidence.

    Sven-Olof Jansson
    London, UK; Boston, MA

    #637593
    rafi
    Participant

    I made a very effective mortising guide with scraps in january. Very easy to adjust and use for repetitive or single mortises whether simple blind or through.

    00122-024-GUÍA-DE-CAJAS-14-ENE-19

    #639257
    Sven-Olof Jansson
    Participant

    Thanks Rafi,

    The photo of your guide has saved me considerable experimentation.

    Pleasant Holiday Period

    Sven-Olof Jansson
    London, UK; Boston, MA

    #639490
    rafi
    Participant

    Glad to be of some help, Sven. All the best to you and yours.

    #639539
    Sven-Olof Jansson
    Participant

    Ditto to you and yours.

    Sven-Olof Jansson
    London, UK; Boston, MA

    #655549
    Greg Sarsons
    Participant

    Hi Rafi,
    If I understand the jig you made you can slide the square edge in and out to adjust to the position of the mortice? My assumption thing is the you hold this in place with a clamp while using
    Tks

    #655563
    rafi
    Participant

    Hi Greg,

    Yes, the square edge slides to adjust for the distance of the mortise from the edge of the material. The jig can be clamped in place for use on the workbench surface or it can be clamped in the vise together with the material to be mortised. Either way it works fine. Glad to help out.

    Stay safe and healthy. All the best

    #655576
    rafi
    Participant

    Greg, I just realized it may not be clear how the square edge or guide, the vertical part with the metal plate that guides the chisel, gets fixed in place. If you look at the bottom of the jig you can just see some threaded inserts. There are screws that go through the slots and into the bottom piece to fix the square edge where you want it. Loosen the screws, adjust the position, and tighten it in place. Then you either clamp the bottom piece to the work or place the whole jig and material in your vise. Stay safe and healthy.

    #655582
    Greg Sarsons
    Participant

    Rafi,
    Thank you. that is what I thought but wanted to make sure I wasn’t missing anything. Stay healthy.

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