Primitive Archer
Main Discussion Area => Bows => Topic started by: Red Dwarf on December 30, 2008, 08:02:54 pm
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I am trying my hand at a BBI longbow/flatbow. Specs. are 63 1/2" NTN, 1 3/16" at fades straight taper to 1/2" nocks. I am trying for 48# @ 28".
What do you think?
To me the bottom limb (on the left) looks stiff out of the dip area with a weak spot around mid limb.
I haven't pulled it past the 31# @ 15" from a 3" brace ht. yet.
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What is the shape unbraced? Looking at the last pic it looks good nothing major. A little scrapin in the fades and outer limbs. Should be a great bow
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I have to agree with Jesse. Keep doing what you are doing. But now go slow, it's "crunch" time. ;)
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Great question Jesse, sorry for not including the info on the 1st post!
It has 1" of Perry reflex when unbraced for awhile, 1/2" reflex straight after being drawn to 15"
Am I safe to pull further?
Red Dwarf
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Yep,agree with jesse,but gotta ask,are all the red patches covering up all the arrow holes?! ;D
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Auggie lol
The top patches are darts, the bracket for the board is on my tiller backboard but yes, I have to admit that some of the bottom ones have cost me an arrow or two, but a few are from pucks shot by my son that missed the net!
That is what a basement is for isn't it?
Should I also increase the brace height at this point?
RD
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I think your safe to increase the brace. If the same spots still need work then get them smoothed out and pull a little past the last spot you were at a bunch of times to see if it worked. I hear to not pull past your intended draw weight but I try to be extra safe and only pull the draw weight at full draw. Kinda sneak up on it as they say.
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Bow looks real good, and advice here is great. This is where I make sure the tool marks are sanded out since its just removing very fine belly wood shaving curls from now on.
Rich
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Thanks guys for the help so far. I tend to get a little nervous at this point as a few have gone bang at this stage in the past!
I have never worked with bamboo before; how do I prepare the back surface for finishing, and should I do that work as part of the tillering process?
Red Dwarf
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scrape off the waxy rine on the back of the boo,just dont go too deep youll dig into the power fibers.
under the waxy rine you will see a nice,almost butter like,yelow color of the boo.
stain doesnt work real well,but leather dye works dang good,just make sure its the dye thats alcohol based and not water based.
i have never used the boo as part of tillering,you are only taking off the rine of the boo and not actuall boo material so the affect on tilering is null.
good luck,like others have said looking good just go slow when ya think your going slow enough with it,slow it down some more. ipe can come in all of a sudden
on ya,if you aint going slow enough you will come in light,i know of what i speak took me three times to figure that one out.
ipe bows are awesomely fast shooting bows,light weight and just look cool as all get too.
tim
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what is the surface like now? rind still on? Some leave it like that but its hard to stain. I scrape the rind off and sand it really smooth like glass rounding the edges a bit. Careful not to go to deep.just remove the rind and thats it. its a bit of work around the nodes but get it ood so you dont lift a splinter later.I dont think you need to worry to much about it exploding on you if you glued it up well you will have a hard time breaking it without trying. If I recall Robustus on this site just leaves the rind on and he makes a killer bow.
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Sailor Dad beat me to it. What he said ;D
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Well, I did some more scraping and I thought things were looking good so I raised brace ht to 4 1/4" and slowly increased the drawlength, exercising about a dozen times at each inch increase in draw length until I reached my intended weight of 48#.
When I unbraced the bow I was disappointed to see that it has started to take set ot mid limb on each limb. Midlimb to midlimb shows about 1/4" of reflex and midlimb to tip shows about 1/4" deflex.
What did I do wrong and how should I proceed?
Here are pics at 4 1/4" brace and pulling 48# @ 23"
Red Dwarf
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Hi, Ive worked with bamboo for a few years and for what it's worth I don't generally remove the rind(dont know if you've done it yet). My reasoning is that we all take a lot of trouble to waterfproof and protect the backs of our bows, so why remove natures perfect protection? The only downside is (as already mentioned) it is difficult (but not impossible )to stain.Bamboo looks better with the rind off but lasts longer with it on.
As for your bow it doesnt look to me like you've done anything wrong , it's nearly unavoidable that boo backed bows will take some set, as long as it is not too much. looks like your doing ok, to me , go really , really slow from now on. Good luck.
didn't catch what the wood was???
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Dragonman
It is bamboo backed Ipe with the handle area built up with a piece of Elm I had laying around.
I like your reasoning on the rind being a natural sealer, somthing to ponder on.
RD
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Red Dwarf, the last bow I made was boo backed ipe 66" long, I glued on the boo with about 2 1/2" of reflex and the bow ended up with 1" of reflex, so it took 1 1/2", of set overall, I thought that was quite reasonable, if that is any help
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I guess what I am really unsure of is exactly how to proceed: do I just continue to lose weight from the entire limb or should I keep away from the areas that have taken the most set or should I try to reduce the amount of work being done by the belly by trapping the back a little in the mid-limb areas.........?
Red Dwarf
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James Parker, Robustus, makes some of the finest, fastest Bamboo backed bows, and his reasoning behind leaving the rind on is scraping and sanding can lead to lifting a splinter. BB bows sure look ugly wrapped with sinew. I quit doing it and have no trouble staining it. I just use a fine steel wool. James also has a lifetime warranty on all his bows, so it must work.
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definately keep away now from the areas that have taken the most set and by the looks of the tiller so far it will work out, I dont see how you can avoid working on the belly because I dont think you have surplus width, to tiller it width-ways.
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I have done a little more scraping trying to get things moving a little sooner out of the dips and have decided to put it in the drying box for a few days to make sure that MC isn't a problem.
Will report back for more advice when I get it back on the tillering tree.
Thanks for all of the help so far.
Red Dwarf
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I'll be interested to har what ( if any) difference the hot box made. It's my impression that really dense tropical woods like ipe take a long time to dry and I suspect that the change in MC you can make with a couple of days in a hot box is going to be pretty minor. Ron
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48#@23" I'd be giving it a good sanding, letting it sit strung for a few hours, and start shooting it. often its going to relax a bit while shooting it in. I'm usually checking the tiller while shooting it and seeing how it feels.
At this point very little needs to be removed and why sanding when you have a good tiller is less likely to change things much. Often when I'm shooting I'll be using a scraper lightly as the limbs work some. But what I'm removing can barely be seen, and is usually finer than using 600grit paper.
So be patient, take plenty of time. I'd make sure that hot box isn't too dry. Bamboo doesn't do so well when it gets too dry, and part of the reason I like to keep the rinds on. Bamboo being a grass can't recover from being a little too dry like most woods can.
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My drying box is currentyl at 35 deg C., not sure what that is in deg. F, and 23% RH.
This is my first time with a drying box as per Dean Torges. Is this too dry already?
Red Dwarf
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Red Dwarf, 50% relative humidity is about 8% mc and this is ideal. So your box is at about 4% and thats too dry for most finished bows as well. unless they are a little green/wet. I really don't think your bow is going to need drying any more than what the surrounding average is . I've shot these bows non stop in Missouri summers when its the most humid place in N. America and these bows hold up great. So a little more mc% is better than not enough by far.
BC shouldn't be too wet for your bows. often the house heaters keep the air where you live plenty dry.. ;)
Rich
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Rich
I have take the "bow to be?" out of the drying box and worked the dip areas a little more.
Here are a couple of pictures as things are now; pulling 45# @ 24" and just after removing the string.
I am reluctant to draw it any further without being certain of how to proceed. Maybe I should just sand it up as suggested and shoot a few arrows at 24" draw?
Red Dwarf
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Martyn,
The outer limbs are too straight, and the inner limbs about need to be bending more as well. Remember you have 63" bow with say an 8" non working handle section so the working limbs are really for a 58" bow. This makes them a little less tolerant to tillering mistakes especially on limbs that are already slender. These limbs need to start bending right out of the fades for a 28" draw and only the last few inches of the tips should be straight.
One trick I like to show new bowyers is, wearing safety glasses, look down the limb from the grip to the tip, with one hand on the grip and the other pushing out on the string where the arrow goes. This way you can really see whether the limb is bending in an arc or has flat spots, and you can flip the bow over and compare to the other limb. This perspective amplifies the flaws and makes them easier to determine where to remove wood next. You don't have to move the limbs much to see where the problems are so the load on the string isn't scary.
Everyone sees things a little differently and I try and show them as many angles of the limbs as possible to help them see what is going on.
After about 50 bows, any flaw in the tiller will stick out like a sore thumb...Yer doing just fine..
Rich
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Rich
I'll try working a little more on the dips & tips.
In your opinion is my target of 48# 28" still realistic?
Bearing this in mind, should the dips or tips get the most attention from here on in, or should I just go for good tiller and let the weight come in where it wants to?
Thanks
Red Dwarf
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One trick I like to show new bowyers is, wearing safety glasses, look down the limb from the grip to the tip, with one hand on the grip and the other pushing out on the string where the arrow goes. This way you can really see whether the limb is bending in an arc or has flat spots, and you can flip the bow over and compare to the other limb. This perspective amplifies the flaws and makes them easier to determine where to remove wood next. You don't have to move the limbs much to see where the problems are so the load on the string isn't scary.
Rich, I'm not quite getting what you're saying here. Your eye is right next to the grip looking towards the tip? One hand pushes out on the string? ???
Type slowly please, some of us are a little thick... ;)
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It's still realistic, but I'd focus on getting the bow to shoot as efficiently through getting the tiller right and this will get you what ever this bow is capable of at this point.
Both need attention. I think learning how these limbs need to move is part of the trick here.
This is why I mention this little trick, and yes you want the grip along side your head so when you push out with the string you see the limbs move from outside the grip to just inside the tips an a graceful arc, the tips are moving farther, but the inner limbs are moving at the same time. If the outer limbs and inner limbs are too stiff, it will look like the limbs are two straight parts bending in the middle because this angle amplifies this perspective and often makes it easier to see these flaws in the tiller.
If you have a bow with a good tiller, even if its a glass bow try this to get an idea..then look at it on them both on the tree..
When I'm floor tillering this is how I'll be sighting down the limbs since I believe getting it right from the start makes the rest of the process easy, and why I rarely use a tillering tree unless the bows are very long and heavy..
I've seen a few "skilled/famous bowyers do this same trick" I don't know if they ever wrote about it. I've shown this trick to many over the years and they still liike using it.
Rich