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Main Boards => The Bowyer's Bench => Topic started by: EwokArcher on September 27, 2018, 04:16:28 PM
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Let's assume my form Is off and I want to use a string to get everything aligned on a recurve. If I draw a centerline through my riser that is about 14 inches or so. I can see right away that a string from center of one tip to the center of the other tip does not line up with my center line I drew. Should I just adjust the tips however I need to to get the string from tip to tip to be parallel dead centered on that line I drew through the handle? That's what I'm thinking. What do you think?
Thanks for your time,
Ty
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Yup.
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Even if my tip looks like this? The far tip pictured is adjusted about 1/4 to the right of the pic and the close tip is adjusted about 1/8 to the left.
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I've never drew a line along riser. Just a mark in center and both nock locations, , then move both tips the same way to get the string over mark at center.
You may have a better way there on a recurve. Mine are all longbows.
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I really have had a time getting these recurves lined up. I'm ready to pull back out my Kennym form after this really.
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Damn those are off a ways that way.
Probably look better if you didn't have the tips drawn out at ends.
Kenny has a better idea.
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That’s 3/8” difference from end to end. Laying a straight edge on your form should show that.
I’ve never had to correct one that much. But have done similar. I will put a mark center and end of both fades. Then adjust accordingly.
Moving 1/4” is going to require quite a bit of profiling to both limbs to get things squared up and even.
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Just by looking at the fine line, assuming that is the string and ignoring the thick sharpie tip lines it looks ok, the form can be perfect and still the the alignment of components can be off for variable reasons, a slid or slip side to side at ends, the pressure from the hose can do that,if alot, could be form, check the glass before lay up, I've had glass that was not straight, did'nt know till I checked the other pieces I had,was still able to make a good bow but was a pain to do so.
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You can get away with a form being off a little, more with long bow,or highbred LB but on a recurve from the start of the hook to the end can be 5" and more, if its off a little will show up alot. not only does the form have to be good horizontally but also vertically and a perfect 90 degree edge. That being said nothing is perfect, as long as you can find a center tip to center to tip and can adjust accordingly it should workout.
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I clean the sides up and run mine thru the drum sander. Now the sides a parallel . Find the center with a square. mark from both sides in case you are a bit off. Very few times have I worked off a center line and not been able to get them to pull straight. On curves start out with tips a bit wide if have to deepen the string grooves.
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Exactly what Crooked said. Square up the blank and finding center is easy.
Alternatively, create a center line either with a string or, better yet, a laser and work outwards rom that. Make your marks with an extra fine tip marker, or a sharp pencil (if you can still see pencil lines). The thick Sharpie lines will cause you alignment problems.
With a recurve, you want to be as close to perfect as you can get with your tip alignment. If you're off too far, it can cause the limbs to twist as you draw, particularly if the tips are flat and wide.
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I file the edges of each limb on both sides of the blank right at the end of the fades. Filed just to the point where all the lams including the riser fade have been touched by the file.
Next I mark the exact center of the limb at the fades at each end of the riser and line a straight metal yardstick up with one end of the yardstick matched to one Center mark. The yardstick is extended through the other Centermark and clamped down. Next a line is drawn along using the yardstick as a guide. then the yardstick is moved to draw a straight line on the opposite limb. it probably won't reach the tips but it's easily laid down on the line reclamped and the line extended out. Now are you have a straight Center Line. You have also established the max width that your bow can be built at.
This has worked for me on asl and RD design bows. No one have ever been a problem getting string alignment. in fact I have fully shaped limb tips, filed in nocks and strung the bow up many times and had perfectly centered string alignment.
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I redrew everything using a fine tip sharpie and it looks much better. Only one tip was about 1/8 inch off. I'm still working on th wife to let me get that drum sander crooked it's high on my priority list :thumbsup:
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A trick I learned from composite horn bowyers is square up at least one edge of the blank find the center of the riser put the squared edge on a dead flat surface like a table saw and make a shim to hold a pencil at the half way mark and draw the line , it works on forms too , and it's easy to follow high reflexed curves !
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Good idea Ritchie.
:thumbsup:
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No matter what you do, you will never be able to rely completely on a center line or straight edge on a recurve.
Now if all of your lamb's and glass are perfect! yeah, whatever.
The most ideal way I have found to center everything with relative ease is to true one side, then true the other so it is basically parallel. Trim tips to final length and apply a cabling devise. You then draw the bow back and forth while hooked on a peg at the riser throat.
If one tip is off, you tap the block to one side on that limb. Flip it over and draw and watch the other limb... do the same.
Continue to do this back and forth until both limbs draw straight back. Mark the side of the blocks and once removed, use this to find dynamic center of the limbs. Put your pattern on and trace, or however you do it form there.
This method has made a bid difference in my "Recurve" building.
Not affective on longbows.
At this time you will have to look it up in the history here as I have seen some made by others.
I have had mine professionally done and have talked with him about making more so I could sell them, but I'm sure he has more important things to do.
BigJim
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Jim you have pics of that device?
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Jim you have pics of that device?
X'S 2 on pictures..
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Try as I might, I can't get the picture to post.. Sorry
BigJim
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Email it to me I will post it here if you want.
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I've been using something similar to what Big Jim described. I'm sure they aren't as fancy but they work for me. I took a piece of flat bar 3/16 thick and use a short string to brace the bow. I start out on center line of the limb and work from there. I made them so they fit the hook of my the limbs.
(http://i.imgur.com/HT8gcUh.jpg)
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Jim, any chance you could do a YouTube video of this process?
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Yes Roy, but it may be a few days. crooked stic, I don't have your email.
Thanks, BigJim
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Jim PM sent
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I use these to find the strong limb and be sure things are gonna hold together before tapering. Just termed tillering blocks.
(https://i.imgur.com/Au76bnk.jpg)
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Ok here is the fixture pic Jim sent me to post. This one is neater because it is adjustable so you dont need several strings for different length bows' I suppose you should be able to post pics out of your own files. I just use Imgur.
(https://i.imgur.com/UsHaeU7.jpg)
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That is basically how I line my boo and lams up prior to glue up.
My bamboo backing is cut to the exact shape of the bow before glue up.
I lay the boo on top of the core and belly lam.
I run a weighted string from tip to tip and get everything lined up straight with the center of the handle grip.
Then clamp it down and drill the pilot holes for the toothpicks to hold things in line while glueing and clamping up.