Primitive Archer
Main Discussion Area => Bows => Topic started by: WilltheArcher on May 31, 2015, 04:31:44 pm
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Hi guys - I'm making my first bow, a 3-piece takedown longbow. Limbs are an ash/ipe laminate. I've strung it and pulled it back (just a little bit for a while as the limbs got used to stretching, then to full draw) many times. Unfortunately today during the first big test at a range, one of the laminate limbs broke as I was stringing the bow. Here are a couple pictures of the breakage.
(http://imgur.com/cOvBzaO.jpg)
(http://i.imgur.com/3TMFxIx.jpg)
(http://i.imgur.com/wJqfNNN.jpg)
checking the tiller the day before.
It looks like only the ash laminate broke but I haven't had a chance to unbolt to check. The hole pattern is .75" from the bottom of the limb, then 1" between the two bolt holes. Bolts are quarter inch.
I laminated it together using titebond III wood glue and a ton of clamps. Here's a picture of the lamination: http://i.imgur.com/hmYdKiO.jpg
Anyone have any idea what I did wrong and what I can do better next time? I've got 5 days till I lose access to my woodshop so I'm kinda in a crisis crunch. All advice appreciated, THANKS!
Edit: The limbs are 28.5 inches long. They're 1-1/4" wide at the riser and taper to 5/8" at the end. The riser bed is 3" long. I checked and only the ash lam broke. The ipe below is relatively unscathed, except for an edge splinter about 8" up.
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Are you certain you made all the surfaces perfectly flat before gluing them? When you use TB for laminating there is no room for error.
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Now that's a frankenstein! What is that on the tips? There was just a thread posted by Fiddler 49 about field wrapping a bow that dealt with having wedges in the limb area that contacts the riser. That may help. I've never made one but I'd say something funky is going on with the fit to the riser, and depending on the unbraced shape your tiller may be a touch stiff in the outers?
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The bolts should bear down onto a plate the full width of the limb.
Those two washers are concentrating the stress, which would be ok on a woven material like carbon or glass fabric... but it's just going to make wood split along the grain.
Mechanically it was an accident waiting to happen.
Hope that makes sense.
Here's a pic of how I joined a limb to a riser... it was glued, but it dovetailed in along the whole width of the limb, and that's the key.
Del
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The bolts should bear down onto a plate the full width of the limb.
Those two washers are concentrating the stress, which would be ok on a woven material like carbon or glass fabric... but it's just going to make wood split along the grain.
Mechanically it was an accident waiting to happen.
Hope that makes sense.
Here's a pic of how I joined a limb to a riser... it was glued, but it dovetailed in along the whole width of the limb, and that's the key.
Del
Del - thank you, and yes that makes perfect sense. Ironically I was already planning on replacing those washers with a much larger washer plate that spanned very nearly the width of the limb. Picture below. Do you think this will be adequate to relieve the stress concentration?
My friend and I were debating whether it delaminated then split or split and that caused the delam. You think it was the split at the fastener, right? I'm worried I did something wrong with my lamination process, so that'd be bit of a relief.
(http://i.imgur.com/xLqzkmx.png)
Are you certain you made all the surfaces perfectly flat before gluing them? When you use TB for laminating there is no room for error.
Gordon, I am planning on making another laminate. Is there a better material than TB? Maybe some sort of epoxy? I am certain the limb surfaces were flat. I used a wood planar to get the lams to thickness and then lightly sanded both.
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Just make it full width, don't mess with anything less.
The plate can be glued to the limb or left loose and clamped by the bolts.
I'd suggest something like 3/16" inch plate.... there is a lot of leverage...
The limb is effectively trying to pivot along the riser edge where I put the yellow arrow on the right of the pic so that's only about 3" from the lower bolt... the rest of the limb is say 24" long... so that's 8:1 leverage ...
Say 40# pull on the end of the limb, that gives 320# on that bolt !!! ... and you wonder why the wood split? >:D
That's why they don't make pry bars out of wood ;)
Del
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Look at this post I hope it helps..
http://www.primitivearcher.com/smf/index.php/topic,52745.0.html
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Just make it full width, don't mess with anything less.
The plate can be glued to the limb or left loose and clamped by the bolts.
I'd suggest something like 3/16" inch plate.... there is a lot of leverage...
The limb is effectively trying to pivot along the riser edge where I put the yellow arrow on the right of the pic so that's only about 3" from the lower bolt... the rest of the limb is say 24" long... so that's 8:1 leverage ...
Say 40# pull on the end of the limb, that gives 320# on that bolt !!! ... and you wonder why the wood split? >:D
That's why they don't make pry bars out of wood ;)
Del
Del - really appreciate the speedy responses. I've got five days to make a bow that works! Doesn't have to be perfect, or last for super long, just needs to work (for a class).
Ok, I'll make plates that are the full width of the limb (1.25") and the height of the riser bed (3"). I'll let the 1/4-20 bolts clamp them down. I've got 1/8" steel plate - don't have 3/16 but this stuff is really solid so I'll hope it's enough.
Bow101 - I checked out that link, and I see how for 3pc bows they have that wedge that gives you a bit more support along the high-stress pivot area. It's smart, and unfortunately not something I'll be able to pull off in my time remaining. I hope this steel plate does enough to distribute and reduce stress concentrations in the riser bed.
Would like opinion on the lam though. I've got another 6' piece of laminated ash and ipe that I'm planning on cutting a new set of limbs out of. Friend of mine recommended I try splitting it with a chisel and redoing it with some sort of epoxy that might be stronger. Seems a little extreme to me, but we're both worried that maybe my TBIII lam wasn't strong enough. Think that can be improved, or should I focus on the steel plate?
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More likely to be glue failure first and then the Ash failed in shear at the bolt when it was essentially reduced to a cable.
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More likely to be glue failure first and then the Ash failed in shear at the bolt when it was essentially reduced to a cable.
Hey Pat - yea that's what I'm worried about. Problem is I've got no idea how to improve the lam. Planed the wood, lightly roughed up the surface with sandpaper, then TBIII and a ton of clamps and 36 hours of dry time. Should I try to get my hands on more ipe and then lam with epoxy?
My school's woodshop closes on Friday so I've got until then to make this work. If I can't get my hands on more ipe in time I may try to make a set of limbs out of red oak, provided I can find a piece with a good grain at my local woodstore. If so, what thickness do y'all recommend? Still planning on keeping the ~30" height and 5/8" taper.
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Just make it full width, don't mess with anything less.
The plate can be glued to the limb or left loose and clamped by the bolts.
I'd suggest something like 3/16" inch plate.... there is a lot of leverage...
The limb is effectively trying to pivot along the riser edge where I put the yellow arrow on the right of the pic so that's only about 3" from the lower bolt... the rest of the limb is say 24" long... so that's 8:1 leverage ...
Say 40# pull on the end of the limb, that gives 320# on that bolt !!! ... and you wonder why the wood split? >:D
That's why they don't make pry bars out of wood ;)
Del
Del - really appreciate the speedy responses. I've got five days to make a bow that works! Doesn't have to be perfect, or last for super long, just needs to work (for a class).
Ok, I'll make plates that are the full width of the limb (1.25") and the height of the riser bed (3"). I'll let the 1/4-20 bolts clamp them down. I've got 1/8" steel plate - don't have 3/16 but this stuff is really solid so I'll hope it's enough.
Bow101 - I checked out that link, and I see how for 3pc bows they have that wedge that gives you a bit more support along the high-stress pivot area. It's smart, and unfortunately not something I'll be able to pull off in my time remaining. I hope this steel plate does enough to distribute and reduce stress concentrations in the riser bed.
Would like opinion on the lam though. I've got another 6' piece of laminated ash and ipe that I'm planning on cutting a new set of limbs out of. Friend of mine recommended I try splitting it with a chisel and redoing it with some sort of epoxy that might be stronger. Seems a little extreme to me, but we're both worried that maybe my TBIII lam wasn't strong enough. Think that can be improved, or should I focus on the steel plate?
I dont know other than right it off and start again, today as I type this message I'm trying to fix a a mistake !....will it work...? I will find out in a couple days and post it if the bow lives....... :-X This bow is a repair beyond repairs like 3 times.
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Looks like you squeezed all of the glue out and left a dry glue line.
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Looks like you squeezed all of the glue out and left a dry glue line.
Hey Pat - does that mean I clamped too much? I didn't realize that was possible, but that could explain it. It's got to be either the stress concentration like Del said, or the lamination itself. Just wish I knew which...
What is that on the tips? There was just a thread posted by Fiddler 49 about field wrapping a bow that dealt with having wedges in the limb area that contacts the riser. That may help. I've never made one but I'd say something funky is going on with the fit to the riser, and depending on the unbraced shape your tiller may be a touch stiff in the outers?
Cast aluminum bowstring nocks are bolted to the tips with 6-32 screws. Maybe it's a bit fantastic, but it's pretty fun. It's funny because that's the area I was most worried about - holes, even that small, near the end of the tips. But it's slotted on so the stress is probably pretty well distributed.
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I usually use an overlay on the attachment area to help to distribute the stress that full size washer might do the trick
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Did you rough sand the ipe, if you put it through a planer it might not be pourous enough.
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I usually use an overlay on the attachment area to help to distribute the stress that full size washer might do the trick
Bubby you have any pictures of that? Might try to glue an overlay on to this new pair of limbs I'm cutting out. How thick is it?
Did you rough sand the ipe, if you put it through a planer it might not be pourous enough.
I sanded it to rough it up then wiped it off with acetone to make sure it wasn't oily, but maybe I didn't rough it up enough.
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I'll have to take a look see if i have a pic
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Bubby I think I get the idea from this thread you linked me to a while back:
http://www.primitivearcher.com/smf/index.php/topic,24354.30.html
That brown diamond shaped piece at the riser ends of the limbs right, looks to do about 1/8 inch thk? Do you think that and Del's washer plate would be too much?
Del - machined two of these today. Going to round the corners tomorrow.
(http://i.imgur.com/CyloNoQ.jpg)
(http://i.imgur.com/zyY3B6z.png)
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That looks much better :)
What material is the plate made of ?...
Oh , I see you said steel...
Yeah 1/8 steel should do it... I just said 3/16 to err on the side of caution :laugh:
Still use a decent thick washer (especially on the lower bolt to spread a good clamp action across the whole lower edge of the limb)
Looking at the pic of the break again, I can see it's actually pulled the limb away from the end stop in the riser. So it's effectively just split out that narrow strip the width of the bolt.
Maybe a thin rubber sheet between the faces (increase the friction/grip and spread the load evenly onto the wood fibres?)... dunno?
What do they do on commercial bows?
If you glue the plate to the limb you can call it an 'overlay' like Bubby suggested :) ;)
Del
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That looks much better :)
What material is the plate made of ?...
Oh , I see you said steel...
Yeah 1/8 steel should do it... I just said 3/16 to err on the side of caution :laugh:
Still use a decent thick washer (especially on the lower bolt to spread a good clamp action across the whole lower edge of the limb)
Looking at the pic of the break again, I can see it's actually pulled the limb away from the end stop in the riser. So it's effectively just split out that narrow strip the width of the bolt.
Maybe a thin rubber sheet between the faces (increase the friction/grip and spread the load evenly onto the wood fibres?)... dunno?
What do they do on commercial bows?
If you glue the plate to the limb you can call it an 'overlay' like Bubby suggested :) ;)
Del
Glad to hear it. The rubber sheet to spread the load out sounds like a good idea. And I'll remember to still use a washer.
Del, the funny thing is the ipe didn't break, just the ash lam. I'm using that same piece of ipe and gluing a new piece of ash lam on top. Once it's finished drying I'll sand it to match and make sure it's the same thickness as the other limb. I still don't know whether it was the stress concentration at the bolt that did it or whether it delaminated. I'm hoping it's the stress concentration. If it was the lam, I don't know what to do :(
Ok I'm not gonna do the wood overlay for now. Tomorrow I'm going to remake that limb once its finished drying, then remount it with the plate washer and some 1/16 rubber sheet underneath. I'll warm it up, do some light tillering, and hope for the best. Speaking of tillering I took a few photos yesterday and wonder what you guys recommend.
(http://i.imgur.com/L9OVv2Q.jpg)
(http://i.imgur.com/zmd06CJ.jpg)
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The failure was due to the bolt!... else why did it happen exactly there?
Occams razor... the obvious is the most likely.
Del
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The failure was due to the bolt!... else why did it happen exactly there?
Occams razor... the obvious is the most likely.
Del
A cat that knows of Occam's Razor...the wonders never cease ;)
Hoping you're right!
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S'pose if I was being picky, I'd probably do an overlay on the belly (underlay?) with a fade incorporated so there isn't a hard transition where it meets the riser.
Del
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The failure was due to the bolt!... else why did it happen exactly there?
Occams razor... the obvious is the most likely.
Del
Why would it delam after the limb was no longer supported? I still think it was the delam first. The rubber gasket is not a good idea. A soft surface in a structure that you're trying to make rigid is a poor recipe.
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The failure was due to the bolt!... else why did it happen exactly there?
Occams razor... the obvious is the most likely.
Del
Why would it delam after the limb was no longer supported? I still think it was the delam first. The rubber gasket is not a good idea. A soft surface in a structure that you're trying to make rigid is a poor recipe.
It would delam because the spilt has then allowed the part which is still held by the bolts to bend on a tight radius and delaminate... once it starts to delaminate it continues along the limb.
I'd suggest if the delamination started mid limb, the limb would loose all it's rigidity and no longer have the strength to cause the split.
There is no actual way of telling which came first.
I'm quite happy to be wrong, I'm just saying what I'd do*.
Note I said thin rubber. I agree you don't want it to be able to move, but on the other hand you don't want it flexing up against a sharp edge.
Is any part of any bow is ever trully rigid...? (Answers of 500 words to "philosophy and bow design" department WPB... Del the Cat, Harlow UK.... ;) )
Del
*As the old Irish joke goes:-
A driver pulls up at the road side to ask an old guy the way to Balally...
The old Irish guy looks at him, strokes his chin and replies.
"Ah, to be sure, If I was you I would start from here... " :laugh:
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For it to delam like that you had a shoddy bond. Fact ;)
The best way to prepare surfaces for TB3 is with a drum sander. Failing a drum sander then a planer thicknesser will work but you must roughen the surfaces up for a good bond. Planer thicknessers will compress the fibers and TB is a water based glue that won't get 'into' the ipe. They also leave the surface washboarded (if you look closely enough!).
The best glue is probably Smooth On EA40 expensive but it real is very good. Cure it with heat for a better bond.
Your design is in my eyes destined to failure...maybe not today, maybe not tomorrow but someday! Look at Fiddler's thread the advice there is solid and you should follow it. After all why do 'normal' bows have fades and why is it critical to get them right.
Also your bow is on the edge of hinging at the inner limbs. You need to remove more material on the mid to outer limbs - this will also help to stop it failing where it did again.
Good luck and don't try to rush it ;)
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So many wooden takedowns have this problem, you need a wedge where the limbs and riser meet! Every laminated takedown has wedges or they'd blow out at the bolts too. compounded by the grain structure of wood it makes it even more important.
(http://i.imgur.com/geTWkFx.png?1)
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First of all guys thanks a ton for taking the time to help me troubleshoot, really appreciate it.
So many wooden takedowns have this problem, you need a wedge where the limbs and riser meet! Every laminated takedown has wedges or they'd blow out at the bolts too. compounded by the grain structure of wood it makes it even more important.
(http://i.imgur.com/geTWkFx.png?1)
David, this is really useful. I have another pair of limbs and I'm going to try to make wedges like this for them today and glue them on. Can you help me out with dimensions and materials? Looks like it's flat along the riser bed then slopes in for about an inch or two? Maybe quarter inch thick? What kind of wood should I make it from?
For it to delam like that you had a shoddy bond. Fact ;)
The best way to prepare surfaces for TB3 is with a drum sander. Failing a drum sander then a planer thicknesser will work but you must roughen the surfaces up for a good bond. Planer thicknessers will compress the fibers and TB is a water based glue that won't get 'into' the ipe. They also leave the surface washboarded (if you look closely enough!).
The best glue is probably Smooth On EA40 expensive but it real is very good. Cure it with heat for a better bond.
Your design is in my eyes destined to failure...maybe not today, maybe not tomorrow but someday! Look at Fiddler's thread the advice there is solid and you should follow it. After all why do 'normal' bows have fades and why is it critical to get them right.
Also your bow is on the edge of hinging at the inner limbs. You need to remove more material on the mid to outer limbs - this will also help to stop it failing where it did again.
Good luck and don't try to rush it ;)
Good advice. I hate to rush but sometimes you don't have much of a choice. School project and the woodshop closes end of day Thursday so I'm workin' round the clock. I'm not sure I'll be able to get my hands on smooth on in time - can you buy it in a store (not online)? If not - is there an epoxy that's better than TBIII that I can get at an Ace Hardware/Home Depot? If I can, I'll try to get that and some more Ipe/Ash and do a better laminate. I don't have a drum sander but I roughed up the Ipe pretty good with some 80 grit sandpaper so I was pretty surprised with the delam.
There is no actual way of telling which came first.
I'm quite happy to be wrong, I'm just saying what I'd do*.
Note I said thin rubber. I agree you don't want it to be able to move, but on the other hand you don't want it flexing up against a sharp edge.
Is any part of any bow is ever trully rigid...? (Answers of 500 words to "philosophy and bow design" department WPB... Del the Cat, Harlow UK.... ;) )
Del
Del, you're right it's hard to say. I actually woke up this morning thinking what PatM about why it would delam after the bolt failure. But at least I have some ways to troubleshoot. The rubber sheet I have is only 1/16 thk so I'll go with it for now. That and the plate washer and the bolt shouldn't fail. If it delams again at least I'll know it's the lam and not the bolt. Hurray troubleshooting haha!
One thing though - do you think that rubber sheet should go between the riser bed and the limb, or between the washer plate and the limb?
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Q. Rubber sheet between bed limb or plate and limb?
A. Either neither or both.
I'd actually be tempted to epoxy the plate onto the back of the limb* and then have rubber between riser and limb.
Other opinions my vary. Contestants must be 18 years or over. Terms and conditions apply :laugh:
Del
*This is good on several counts.
1. It helps make the root of the limb more rigid.
2. The epoxy will fill any imperfections.
3. It will prevent any movement between plate and limb due to vibration, slight flexing etc.
4. You won't loose the plate.
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I think my problem now is there are so many possibilities I don't know what order to try them in.
1. Plate washer/rubber sheet like you (Del) say.
2. Wedge like David says.
3. Try to relaminate.
Number three is hard because the guy I bought the Ipe from hasn't gotten back to me, and I don't think I can get my hands on the Smooth On epoxy in time.
I'm tempted to try the plate washer, rubber sheet, and David's wedge. But the fact that Bubby and even the guy in Fiddler's post made takedown longbows without wedges that lasted 1000+ shots without incident makes me think that it's not the critical problem right now (though it'd definitely make the bow better in the long run).
think once the new ash lam is done drying on the broken limb I'll try those with the plate washer/rubber. I'd epoxy it on like you said but it'd be hell to get it off if the limbs end up breaking again, and it takes a while to machine em on the mill.
if I can figure out dimensions on the wedge I'll try to make that and glue em on to my second pair of limbs.
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It doesn't need much wedge... remember stiffness is proportional to the cube of thickness, so even and extra 1/8"-1/4" will make a big difference to stiffness.
If it's relatively thin, the fade becomes easier and less critical as there is some flex in the wedge itself.
Embrace the problems... if it's a project, then learning and experimentation is part of the process.
That's why we do it... :) (that and a tiny bit of insanity ::) )
Del
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Ok folks it's 3AM and I've got 3 days till the school shop closes. Here's where we're at.
Waited 24 hrs after gluing on the new ash lam to the broken limb. Who knows whether it was the lam or the stress at the bolt, hoping it was the latter. I made sure to rough up the ipe with 80 grit sandpaper, and the ash for good measure. Wiped the ipe down with acetone and glued it up, and tried not to squeeze too much glue out. Cut off the excess ash and sanded down to size, then sanded down to thickness - hurray new limb. I machined two washer plates and used gasket rubber to make two (you guessed it) rubber gaskets, one between riser bed and limb, other between the washer plate and limb.
(http://i.imgur.com/4xyVf9N.jpg)
Hoping beyond hoping this does it.
Now some more tillering advice would be great. Got my long tillering string, pulled it back a few times and snapped some pictures.
(http://i.imgur.com/jXaTPt7.jpg)
(http://i.imgur.com/1KooBH6.jpg)
Think a couple people mentioned before it looks like it's not bending much in the outer limbs, especially on the right limb. I'm thinking start with fifteen strokes of a card scraper on the outer 12" of the right limb and ten on the left..but I've never done this before so advice appreciated.
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Give us some info.
What is the width taper on the limbs and what is the thickness taper?
The thickness taper is the more important and I generally go for about 1.5-2 mm every 6" along the limb (excuse the mixed units!)
Del
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Give us some info.
What is the width taper on the limbs and what is the thickness taper?
The thickness taper is the more important and I generally go for about 1.5-2 mm every 6" along the limb (excuse the mixed units!)
Del
Happy to Del. The limbs taper from 1-1/4" to 5/8" at the tips. 1.25 to .625 if you prefer decimals. They stay 1.25" along the 3" riser bed, then taper inwards from there. They are 28.5" long. The aluminum bowstring nock you can see on either end gives me a nock to nock length of 70".
They are a uniform thickness of 1/2". Bubby and I talked about that a lot in this thread (http://www.primitivearcher.com/smf/index.php?topic=52135.msg706012#msg706012) and he convinced me to go with constant thickness, with some tillering required at the end.
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Ah! Right.
Constant thickness is fine if the width taper goes down to zero at the tip.
Now obviously this is impractical :laugh:... So what I'd suggest is you draw the taper on the limb going from full width (just out side of the riser) to zero at the tip. Then mark a pair of parallel lines from the tip, 1/2" maximum (as skinny as you dare maybe 5/16) running down the centre line of the limb until they meet the taper lines.
Blend these two sets of lines together and cut to that profile hopefully you get a better bend.
Other thing is to shorten your long string so that it only just goes on the bow, then once the tips are pulling back about 6" get it braced.
You may still need some tillering of the belly on the outer limbs, rounding the belly (taking off the corners) may be an easy way to do it.
Del
Those funny clamp things on the end of the limbs look like they are on back to front?
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Del - I'll round the corners. Do you think that the tillering on the belly that Bubby recommended would be enough to get me to a good pull? I'd rather not recut the profile of the limbs at this point.
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Yeah, sure it will. I just thought re-cutting the profile would be easier than rasping away at the ipe.
You probably have a fair thickness to take off if my guestimate of 1.5 mm every 6" is anything to go by!
Del
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Ok sounds good. Yea I'd rather rasp than recut at this point ;)
Planning on doing about ten-fifteen scraps on the outer portion of each limb to start, I'll try to take off a bit more at the ends to give it a bit of a taper. Do you have a good reference pic of what the bow should start to look like when I put it back on the tiller jig?
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Ok I spent some time with a card scraper this afternoon, tried to take a bit off the outer half of both limbs. Tried to be a bit more aggressive as I went along the length to get some taper. Probably took about 30 strokes on each limb. This part is hard, I feel like I don't have a great idea what I'm doing. Would really appreciate some input on how it's looking and how/where I should take off more material. Every time I pull it back I'm worried it's gonna break again but so far so good.
(http://i.imgur.com/yf2Ub5W.jpg)
(http://i.imgur.com/k3MHYSz.jpg)
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Del the whole constant taper / pointy tip thing i know, but with a straight taper and even taper works great, then you tiller and usually end up with a slight thickness taper but it gives a good launching point pre tiller
Will take a six inch straight edge and when you have it pulled like in the pics run it along the belly find the places with gaps and mark them then scrape the areas you did not mark
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Thanks Bubby that was a good idea. Wasn't surprised by what I found - the ends were still a little stiff. Scraped a good deal more on each end, doing my best to taper lightly by taking more off towards the tips. I think it's looking a lot more like a bow now.
(http://i.imgur.com/I0CXjKz.jpg)
(http://i.imgur.com/MqmXAtG.jpg) (http://imgur.com/MqmXAtG)
(http://i.imgur.com/MsGMSa1.jpg) (http://imgur.com/MsGMSa1)
Going to scrape a bit more off the end of that last picture, then try to brace it. Lightly. I'll go for the 6" brace height after I've worked the limbs a bit more.
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On Del's suggestion I tapered the limbs cause the curvature just wasn't right. I'm cautiously hopeful we're getting to something at least decent. Hope so, because tomorrow is the last day the woodshop is open for the year.
Not quite comfortable with full draw, might warm the limbs up and taper a bit more.
Suggestions appreciated.
really light brace.
(http://i.imgur.com/s7m2gd9.jpg)
cautious draw
(http://i.imgur.com/z64zTZW.jpg)
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Looking good in that last picture.
Tips on tillering - always work in the bow with 30 pulls when you have removed any wood. This allows the freshly exposed wood to 'settle' it. If you don't do this any areas where you remove wood will just look the same as they did before you removed anything, then all of a sudden you'll realise you've taken too much off!
Always pull to a specific weight ,decide on this now.
Never pull past a mistake.
Use a tillering gizmo constantly - you don't want an arc of a circle you are aiming for a mild elliptical tiller (bend).
Raise brace height very slowly - no big jumps to a higher brace height.
6 inch max brace height.
Take further pictures if you want help with the tiller :)
And most importantly GO SLOWLY now, you have very little wood to take off.
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That looks better take it up to 5-6" brace now and let it set for a bit then do as mike said
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Here's hoping you have an awesome 'last day in the shop'! You're very close now...
OneBow
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Enjoyable & learning read. Thanks to all. Looking foward to "final" pics!
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So I felt close until I got back to tillering this morning, and I'm a bit confused ???.
(http://i.imgur.com/qL7tMrv.jpg)
Here's the bow at 12" approximately - I'm still not sure where I should be measuring brace/draw height from. That's pretty tense and I get a little jittery pulling it beyond that. So I can't believe I'm supposed to be pulling it back 18 more inches, to my draw length of 30. What am I missing here?
Del also did a great job explaining tillering to me using a scale. I went out and got a luggage scale from the hardware store this morning. When I pull it back to this 12" nock I'm only at 15 or so pounds. I want to tiller it to 35-40, so do I just need to haul back on the string until the scale says 40, despite the fact the limbs feel like they're under a lot of strain already?
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Tiller is looking good just exercise it and slowly stretch it out till you get to 20" or so then i take mine and finish getting to draw by shooting the bow just short draw and slowly work my way to full draw
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Your also looking at about 69# at 30" draw, figure about 3# a inch of draw
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Your also looking at about 69# at 30" draw, figure about 3# a inch of draw
Well damn. Looks like it's time for me to get my card scraper out and get back to work. I'll post another pic in an hour. 11 hours till the shop closes.
Wait - question. If it's 3 lbs per inch of draw, does that mean I want it to be at 0 lbs until I'm at about 17 inches? And then for the last 13 inches it'll go from 0 to 40? That...doesn't seem right.
Sorry if I'm asking dumb questions this morning.
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Bows are mostly linear. If you measure the actual power stroke(from brace to full draw) and divide that into the draw weight that will give you lbs. per inch. In your case if you have a brace height of 6" and your draw length is 30"( I'm 6'1" and have a draw length of 27") you have a power stroke of 24". If you have a 48# bow you will have 2# per inch. So at one inch draw it will have 2#,2"-4# etc
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Take scrapes the length of the limb, do ten each limb and exercise the bow exercise it till u hit 40# then you will know how far you need to go to get the draw weight needed
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So Del told me to man up and pull it back and that's what I did. One of the scarier experiences of my life but we're still in the game so far. I got 35# when I pulled it back to approximately 24". I think I'll adjust my #40 to #35; I don't feel like stressing the limbs any more than that!
(http://i.imgur.com/j50S6zx.jpg)
~18 lbs
(http://i.imgur.com/fAXo1hA.jpg)
~22
I'm not sure what happens next. I'm getting #35 lbs at 24 inches. Maybe I should stop now? When I pull it back I can't get the string all the way to my face, but it's close and it feels...pretty good.
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The only thing keeping you from drawing any further is fear >:D
Don't worry that will pass
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I don't feel like stressing the limbs any more than that!
Your limbs or the bows ;D ;D
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I don't feel like stressing the limbs any more than that!
Your limbs or the bows ;D ;D
Yes.
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If the right limb is the top limb, then it's a tad stiff... if it's the lower limb it's pretty good.
Yeah, shoot an arrow quick before it explodes >:D
If it goes bang later, then at least it's had a shot!
Del
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If the right limb is the top limb, then it's a tad stiff... if it's the lower limb it's pretty good.
Yeah, shoot an arrow quick before it explodes >:D
If it goes bang later, then at least it's had a shot!
Del
easy to fix del, just switch limbs >:D
take a few scrapes on the right limb and you should be good
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If the right limb is the top limb, then it's a tad stiff... if it's the lower limb it's pretty good.
Yeah, shoot an arrow quick before it explodes >:D
If it goes bang later, then at least it's had a shot!
Del
easy to fix del, just switch limbs >:D
take a few scrapes on the right limb and you should be good
Switch limbs... D'oh
I knew that O:) ::)
Del
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Thanks everyone for your help. I took it to the range today, and believe it or not she held together! Shot a few dozen arrows. I'm still bracing it pretty low (getting plenty of wrist slap), but I'm not gonna push it till after the big presentation. Feeling pretty good and I owe it all to you guys. MVP award goes to Del for responding to a dozen PM's a day for several days.
I'll post a big breakdown with the whole process next week! Time to catch up on some much needed sleep.