Primitive Archer
Main Discussion Area => Bows => Topic started by: DC on November 27, 2016, 03:57:10 pm
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I'm tillering a twisty piece of yew and the back twists and turns all over. I'm finalising the front profile so I cutting the edges. Should the edges always be 90 degrees to the back or should they be, I don't know how to describe it, maybe parallel to the arrow? I'll try a drawing. Should it be like the left three or the right three or am I overthinking again?
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My opinion, not 90 degrees to the back. Different crown heights call for different shapes to a small degree, but rounded is best. Round the top edge and the bottom edge. Not into a circle, but knocking the edge off. I have heard it expressed as the shape of a pea....maybe...just knock the edge off.
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The left three.When drawn they will flatten out a bit.Depending on how long the slant is.
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I suppose once I round the corners off they would all look very similar anyway. Overthinking again. Thanks guys
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I'm rooting for you to on that wiggle worm bow DC I don't think you could over think that bow plenty to think about :o
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I do like the ones on the left. I keep the sides perpendicular to the back. sometimes I will stray from this idea like if there is a knot on the edge or just a "rollercoaster " on one edge only.
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Rounded or not, the left 3 are the way I would do it.
Jim Davis
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Don't let your logic get in the way of the simple rule of following the back.
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I'm trying real hard to get the thickness taper right and to follow all the backs lumps and twists. I've just got it to long string and decided to heat out a bit of deflex on one limb so it's resting right now. Just the little bit of pulling I've done on it feels real snappy. I said before that this has the most rings I've seen on a yew. It's really dense, hard wood. Splits along the grain very easily. It would be awesome if it was in a straight stave :D
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Always round all 4 edges. Jawge
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left side
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Left side is the only way to go ;)
When you have a bow like this try closing your eyes and use your finger calipers to determine the thickness taper. Eyes will fool you sometimes. Maybe buy a set of outside calipers too.
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All of the above!
If you make the edges semicircular, then all the diagrams are pretty much the same...
If it looks right, feels right and draws right, then it is right.
Del
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I only use the top two options. ;)
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Here is what I do; I start at the end of the fades and make a dot 1/2" from the back. I move down the limbs and make a dot every 6", 1/16" lower than the last one until I get to 1/4" and hold this measurement to the tips. I make these marks on both sides of both limbs. With my thumbnail on the back of the bow I draw lines connecting the dots from fade to tip. Your thumbnail will follow all the dips and bends to give you an accurate taper. These lines keeps you even side to side and you will very rarely have a limb that doglegs to the side when you string the bow.
I rasp the belly to my lines making a peak in the center of the limbs belly. I start out with excess wood and flatten the peak out as I floor tiller. For long, high poundage bows I may make my first dot at 5/8". Most of the time I will end up dropping my dot at the fades to 7/16" and redrawing my lines to drop poundage. I call these lines the road map of a bow, pay attention to them when you are rasping and don't violate them.
With the 1/4" line at the tips and rounded to the belly my tips will be about 1/2" thick which is plenty of wood for less than 1/2" wide tips.
On wide bows like hickory the belly will end up flat after tillering, on narrow osage bows there will be a slightly rounded belly. I call this method "Eric's goof proof method of making a bow", stay within your lines, use a gizmo, go slow and you can't goof up a bow.
Here is an old pre gizmo picture that shows my layout lines;
(http://img.photobucket.com/albums/v181/ekrewson/bow%20making/tilleringtoshortstring3.jpg) (http://smg.photobucket.com/user/ekrewson/media/bow%20making/tilleringtoshortstring3.jpg.html)
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Here is what I do; I start at the fades and make a dot 1/2" from the belly.
Did you mean from the back or do you cut your staves some uniform thickness to start? Other than that I think I'm following you :D
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OOPs, senior moment, yep from the back, at least I got the picture right.
I do the same on an osage core for a BBO. When It comes to tillering BBO I measure from the glue line instead of the back of the bow for my tapering dots. With nodes on the bamboo back the glue line is a more consistent place to measure from.
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Thanks, I was thinking I was losing it ;)