The Build Along

Discussion in 'Archery' started by longcruise, Oct 1, 2018.

  1. longcruise

    longcruise Scout

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    A while back I committed to doing a build along here so here it comes. At a birthday party last week a cousin asked me to build a bow for him and that bow will be the product of this topic.

    The bow will be an old school longbow. Flat, 68" long nock to nock (NTN) and just a bit longer tip to tip (TTT). The abbreviations in parens are common to bow nomenclature and they and others will be used throughout the topic. I'm going to gear this to readers who have no experience or idea of this process so if you happen to be an experienced bowyer, please bear with me and add your comments and suggestions as we go.

    This is real time so it's going to take a while. Also, being real time, it could end in a remarkable success or a fence picket. I won't be hiding or glossing over mistakes or warts so there may occasionally be some suspense (at least for me:4:).

    Here's a pic of the beginning of the riser. Its been sauared up and the design glued to the riser block. Next step is to bandsaw along the lines of the riser layout and then to the sander for final shaping. As an analogy, the riser is like the foundation of a house. It needs to be accurate.

    The riser is Osage. Other components will be black glass on the back, maple core laminations, clear glass on the belly over bamboo veneer.

    IMG_20181001_130009636_crop_206x655.jpg
     
  2. PAcanis

    PAcanis Supporter Supporter

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    What a timely thread. Just Saturday I was watching bow build videos on the tube.

    Are you going to be boiling any frog bladders for the glue? lol
     
  3. manitoulinbound

    manitoulinbound Apple Fritter Lover Supporter

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  4. longcruise

    longcruise Scout

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    No frog bladders here.;) the glue Will be EA40 epoxy. More commonly refered to as "smooth on".

    Been to the bandsaw and rough cut the fades (the part that is like ramps).
    IMG_20181001_135123751-600x800.jpg

    Next to the oscillating sander to put the final shape to the riser. We start with 36 grit to get down to the lines. All the while keeping the piece in fairly rapid motion to prevent dips. We want a true surface for a straight riser and good glue joints. It's that ol foundation thing!

    All complete here EXCEPT for the feathering of the very tips. These need to be paper thin and should transition from paper thin to no thicker than 1/16" at one inch from the feathered tips. That's sort of a bowyer's rule. If the transition is too abrupt, the limb will be over worked at this point and likely to break. If they can be done with even less than 1/16" it's a good thing but requires slow and careful going.
    IMG_20181001_135837038-600x800.jpg
    It's essential to use a backer when feathering. This is a point where a riser can end up in the scrap box! Gotta go slow.

    This is close. This wood has a couple of interesting red streaks in it.
    IMG_20181001_141320439-600x800.jpg

    We're going to do one more step in getting these feathered just right.

    Meanwhile, I hope you aren't expecting any cool shop pictures. My shop is a tiny nook in the garage, the driveway and the patio. The shop is occasionaly closed due to snow, rain or just plain bitter cold! :)
    IMG_20181001_133723156_HDR-600x800.jpg
    IMG_20181001_133734157-600x800.jpg
     
  5. longcruise

    longcruise Scout

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    These fades needed very little work. One end had a little wave in it and it smoothed up very nicely. This last step is a bit hard to describe and the picture May not be very helpful but what it amounts to is setting the riser one a smooth flat hard surface and sanding with a flexible piece of wood with sandpaper glued to it. It's flexible enough to allow you to force it to the shape of the ramp but not flexible enough to follow the minor imperfections in the riser surface. In this case my surface is a thick mirror left over from a bathroom project.

    My suggestion to the beginning bowyer is to use more of this technique and less power tool until you have a few under your belt. I wrecked a few of my early attempts.
    IMG_20181001_150720609-600x800.jpg

    Regarding tools, you can sub a drill press with sanding drum for the oscillating sander and a skill saw or saber saw for a bandsaw. In fact, with hand tools, rasps and so forth you can do this without power tools.

    More electricity will be consumed during the rest of this project but I'll try to show other alternatives to power tools as we go along.

    Next we will start preparing the laminations. Meanwhile, store the riser in a safe secure place. The law of Gravity insists that a falling riser MUST land on one of the tips.

    Looks like rain, time to store the "shop" in the garage.
     
  6. jonathan creason

    jonathan creason Tracker

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    Osage and black glass is going to be a classy looking combo when it's all said and done. I've always wanted a classic Hill style longbow, and this thread isn't going to help that itch one bit.
     
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  7. longcruise

    longcruise Scout

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    Here is a brief update.

    Next Step here is measuring the actual thickness of the laminations and cutting them to Length to fit the form. There are a couple pictures with the form in it here but I won't be doing explanation of the form at this point. We will get into that later.

    In this particular style Bow the laminations are not physically joined together. Or I should say I don't join them. The ends of the form are blocked and the blocks keep the joints of the laminations tightly together at the Center point of the bow.

    The black back glass is a perfect fit to the end blocks of the form so no need to cut it.

    IMG_20181010_140902641-600x800.jpg

    The core Lams that fit under the riser come up about a sixteenth of an inch short on each end. that will work fine I will simply put a small spacer at the ends at the blocks. it will also require going back to the black glass and taking a very very small piece off to prevent buckling. I'll do that after putting the spacers in to be sure it's precise in the cut on the black glass.

    Next I clamp the Riser on to the Form at dead center and then measure from the end blocks to the very top of the sweeps on each side. the fit here is important. if they are too short the handle grip will have to be ground down which will make it longer than desired. If they are too long they will cause some tension and possibly some buckling up under the pressure of the the fire hose.

    IMG_20181010_142235741-600x800.jpg
    The correct measurement for the face glass and face veneer is 34 and 1/2 inches. The glass is marked and clamped to a flat piece of scrap wood and cut straight across with a hacksaw.

    Some of this probably seems unnecessarily detailed but some things like cutting glass if not done carefully can cost you a piece of glass. If you crack a piece of glass lengthwise it's no longer suitable for a bow. That's something I learned the hard way!

    IMG_20181010_142336087-800x600.jpg

    that's it for sizing the glass except for that little bitty piece we're going to take off the black glass. Next up will be some work on this form. The form is designed to use rubber bands to provide the pressure needed for the laminating process. We will be modifying this form to use an inflatable section of fire hose. Just a few minor alterations.

    IMG_20181010_141722944-800x600.jpg

    If you wish clarification for any of these things I have presented here, please go ahead and ask. I'm sure I have left out some details that some may wonder about.
     
    Last edited: Oct 10, 2018
  8. longcruise

    longcruise Scout

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    One small clarification.

    I noted measuring the thickness of the laminations but didn't explain why. There is a basic formula for calculating the end draw weight of a bow. It's based on this: "double the width of a design and you will double the draw weight." "Double the thickness of the design and you octuple the draw weight." So, every .003 of an inch of thickness equals 1# of draw weight.

    It's very easy to make a mistake in the lamination stack and miss the desired draw weight.
     
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  9. bumma

    bumma Supporter Supporter

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    I'm enjoying this!
    Thanks!
     
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  10. longcruise

    longcruise Scout

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    Thanks, I'll be adding more next week after my elk hunt.
     
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  11. Greebe

    Greebe Non ducor, duco. Supporter

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    Cool. I have a bow form that I build off of KennyM's R\D longbow. I need to order glass and lams on of these day but have been too busy to have time to work on a bow.

    i look forward to seeing how yours turns out.
     
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  12. longcruise

    longcruise Scout

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    Cool, you won't go wrong with Kennys design and he is a great source of supplies. Hope you show it off here.
     
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  13. longcruise

    longcruise Scout

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    This will be a brief update about the form. Here is our form as it is.

    IMG_20181017_154756092_HDR-800x600.jpg

    This is a rubber band form wherein the laminations are held in compression by rubber bands cut from bicycle inner tubes. We are going to convert this form to use an inflatable fire hose.

    Usually a fire hose form has two halves, a top and bottom that exactly match the bow design and are separated by about 1 1/4". What we are going to do is use the pegs to tie an inflatable hose down to the form and inflate it to compress the laminations and the riser as the glue cures.

    The advantage of the topless form is that it allows more versatility since there is no exact matching top half the shape and length of the riser can be varied without the need for a whole new top half.

    Those posts screwed to the sides of the form are to keep the laminations aligned with the edge of the form so they don't slip sideways. They work fine as they are with bands but won't do for a hose. For the hose system they cant stick up more than about 1/16" above the lamination stack. So the fix here will be to redo them so that they rotate on one screw and have a rounded top so that they can hold the lams in position without interfering with the hose. We will redo them with hardwood rather than the pine that is in the picture.

    We also have this notch at the center of the form to fit a C clamp over the top of the riser to hold it dead center while we do the lay up.
    IMG_20181017_155051017-600x800.jpg



    Once it's all layed up it will be held down by zip ties that we will deploy using these holes drilled through the form. There will be eight zip ties since this is a rather long form. Two of them will be positioned to pull the lams down one each of the ramps. when everything is lined up and tied down the hose will be gradually pressurized and the zip ties will be cut and pulled out at about 25 pounds of pressure.

    IMG_20181017_155302603-800x600.jpg

    You may be wondering what that slat of wood that is taped onto the top of the form is for. Well, the surface of the form is dead flat and has a fiberglass lamination glued to it like this.

    IMG_20181017_154837403_HDR-800x600.jpg

    The oak slats actually have a thickness taper of .002 per inch of length. The bow itself will have limb tapers of the same taper rate of .002". By putting these tapers on the top of the form in the reverse direction of the tapered limb laminations, the bow itself will still come off the form flat. We don't have to do it this way. By putting a very slight nearly imperceptible radius of .002 per inch in the riser back we can follow that taper rate and build the bow so that it is not absolutely flat and it will still be a fine bow. On this bow we will use the reverse tapers on top of the form. In fact, our riser is already built and is dead flat on the back so it would be risky to start putting a radius into it now.

    In the above photo you will notice a notch cut in the end of the form. That is simply to allow placing a clamp at each end of the form to hold it down while laying the bow up. It's particularly needed when doing a rubber band form since there is a whole lot of torquing going on as the bands are wrapped but also essential when tying the hose down with paracord.

    The last major mod to the form will be the removal and replacement of the dowels you see in the pictures. Those are made of a soft wood that works ok with rubber bands but for the hose we will replace them with oak dowels. If a dowel breaks while rubber banding its easy to just lap on over the top of the loosened bands but not so simple with a pressurized hose.

    So, we are getting a little closer to actually laying this bow up.
     
  14. longcruise

    longcruise Scout

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    Our alignment bars are in place and the hardwood dowels will go in next. Meanwhile, the finish surfaces of the glass lams need to be taped to protect from the epoxy during the glue up which will be the next step.
    IMG_20181019_132013707-600x800.jpg
    IMG_20181019_134755302-800x600.jpg
    IMG_20181019_135035265-600x800.jpg
     
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