Primitive Archer
Main Discussion Area => Bows => Topic started by: bootboy on May 12, 2009, 09:21:33 pm
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I've asked a few times here and a few times i've gotten some answers, however Im still pretty puzzled.
When making a character bow, I understand that you follow the grain and whatever, But what im really lost at is, how do you keep the taper constant. With a board board you are using straight lines usually. Its simple to take a ruler at a 2" fade mark, then trace a line to the 3/8" pin pin nock or whatever have you and there by being sure of the tape. How do you do it on a character bow?
Any help is appreciated.
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I assume that you're talking about laying out the width profile (back of the bow?) You need to just follow the grain and forget the idea of stright lines. When I'm laying out a bow on a crooked stave, I lay out a centerline first. Measure the width of the stave and find the center at the handle and fades (or you can sometimes follow the crown.) Then do the same thing everywhere the stave changes direction, and connect the dots. You can lay out the width at any point then by measuring out half the width on each side of the centerline. Also remember that the taper may not always be even and straight-if there's a knot or something, you may have to follow the grain out around it to let the bow swell a bit at that point to avoid cutting through the grain. With some practice, you can grab a pencil between your thumb and first finger and let your ring finger run along the side of the stave and act as a guide as you slide your hand down the stave-follows the grain automatically. It's not as hard as it sounds laying out a snaky bow, you just have to fool with it and you'll figure it out. Do away with your notions of straight lines, because they usually don't exist on a stave, and when in doubt, follow the grain.
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bootboy, I like to run a chalk line first. Then I try to lay out the bow, watching for runoffs as Steve does. Leaving the stave wide also gives you room to change if you hit a not that you have to leave some "meat" on. Oop's, guess we said the same thing :).
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how do you chalk a line on a snakey stave, :-\
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i leave the stave as wide as i think will allow for all the curves. then i make a center line following the crown and the vertical grain lines. i say that because a stave from a big log may not have much of a crown to follow. then i mark it every 3" or so and gradually narrow my taper along the marks then connect the dots. dont be afraid to just eyeball a little if you just follow marks you may miss something. Twisted limbs does most of his bows by eye and feel. does fine work too!! remember your looking for a consistent taper from fade to tips. if it doesn't look right, measure and check again. You'll do fine!!
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I found out a little trick. I use a piece of cardboard or thick paper. First follow the grain faithfully and mark your center line.
Now, decide your layout. I don't have many bow made but I have laid out one that was 1.75" (1 3/4") wide at the fades, and stays 1.75" for 10", then tapers to 0.375" (3/8") tips.
So for the first 10" measure 1/2 of the 1.75" on each side of the centerline. Connect the dots.
Now for the pyramid taper. Ok, not sure how to explain this on a forum. But you know you want to go from 1.75" to .375". So you know in the middle of that pyamid, its going to be 1/2 as wide as 1 3/4" minus 3/8"= 11/16". So measure half way between the tips and where it was 1.75". Mark a point 11/16" wide.
You keep doing it until you get enough points to connect the dots. I section off the pyamid or taper to 8 equal lengths. With the cardboard, you can keep folding it over and over but not sure how to explain that here.
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I do about like bigcountry except for the cardboard,The firstpart of the limbwhere there is no tapper I lay out the center line and measure off each side 1/2 the limb with.Depending on how snaky will determine how many marks I will dots I will make along the length.Then on the taper I will mark it off in 2 or 3 inch sections,then figure how much I need to drop at each point to get to what I want for the tip end.Measure off the center line all the way down and connect the dots.Buy the way you can cheat a little on the profile as long as you don't violate the longitudinal grain much.
easier to show than tell. ;) ;D Clear as mud. ???
Pappy
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Ferret (Mickey Lotz) even made up and gave away a bunch of rulers where you can mark off 1/2 the width from the center line on each side. I use this method, to the degree I measure at all, on all staves even straight ones. Although I'm see very few completely straight staves.
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I can't add much beyond the excellant directions already given. Like Hill Billy said...forget straight lines and remember you may have to tweak around potential problem area's when laying out the bow. I like to start off by running a center line full length of the stave by following the linear grain. Then decide what length and style of bow you want to make, and decide where on your stave that your future bow can best be laid out. Remember that the handle area is nonbending and if need be you can cheat to one side or the other if it can help you avoid a bad spot on one of the limbs.
When determining the taper, I draw lines ACROSS the staves width 90 degrees perpendicular to the snakey centerline...on 2" increments. If you were figuring the taper for a straight bow, wouldn't you have your taper lines 90 degrees to your centerline? Have to do the same thing on a snakey bow, although I'm eyeballing the 90 degrees...not exact by no means. Then if for instance you're 1-1/2" at the fades going down to 1/2" at the tips...you start with 3/4" on either side of the centerline dropping in length how ever much you need to for the number of 2" fade lines you have down the limbs length in order to end up with 1/4" either side at the tips.
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I use this method on straight and snaky bows. I make round belly bows so I make a mark at the fade, depending on what my target poundage is, usually 1/2" from the back. I make a mark every 6" down the limb dropping a 1/16" every 6" until I get to 1/4" near the tip then I keep the same measurement to the tip.
I use the my fingernail on the back of the stave as a guide and connect my marks with a pencil line. I shape the belly wood in a tall arch never cutting below my reference lines on the side. The belly will flatten during the tillering process except for the last 6" of the limb which will be rounded. If I have too much poundage when I have my bow almost tillered I will lower my side guide lines another 1/16" and evenly remove wood side to side and the full length of the limb.
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Pardon the Interruption:
Regarding Ferret's Floppy Ruler: I"ve got it in a pdf file if anyone wants it just get me an email address. If your printer can handle the transparent plastic then it will print three on a sheet.
Back to regular programming.
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Its not a bad idea to to leave them 13/4in wide for the full length thin then down some before any straighting or reflexing, because if you have missed the grain it will crack for sure when you heat and clamp,if you do get a crack take a screwdriver and work the sliver of wood completely off the limb,if you just sand it smooth and blend it in it will crack later,,better to ruin a bow at the beginning than put 90 hours in one then crack it, I made 15 character, snakey and holey osage blanks this week I will post some photos tomorrow