Primitive Archer
Main Discussion Area => Bows => Topic started by: thomas74p on August 27, 2015, 10:23:55 am
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I'm working on another bow. longest one I ever made. think it's about 65''. has nice big recurves starting at 5'' from the tip end. recurve up almost 45 degrees. it's thin maybe less than 1/2'' wide and nearly as thick. when I went to brace it for the first time I quickly noticed that both tips curved or twisted to the left making the string run a good 2-3 inches out to the side of the handle. looks super bad. looks like it's gonna snap one off if I draw it like that. I have no idea what to do. My first thought is that I made it too thin and my only option is to cut the recurves off. but thought I would ask first before doing anything drastic. let me know what other info is needed to diagnose this situation. and thanks in advance for any hints or help.
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Is your bow only 1/2" wide? Pics will help us help you with the problem. Uneven thickness and lateral instability come to mind. being that narrow with recurves added is most likely the problem.
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Too late now :-[, but always leave bows wider than necessary at the ends until it's drawing about 20" or so.
It's a common problem with English Longbows and even more so if you have reflex...
Del
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If you read recurve builds by the masters you'll see that even the most experienced guys will leave the tips wide until they're sure the tiller is correct. That way you can prevent twisting by slightly shifting the tips to one side or the other. 1/2" is pretty narrow for a recurved tip, even if the limb is a normal width like 1.25-1.5".
When I have misalignment of tips on a recurve I typicslly first check that the limbs are properly bending (one side isn't thicker than the other) if it looks good then I know it's misalignment of the tips. I will then use some mild heat bending to try to align the tips properly. This is best done slowly, a little bit at a time. A little goes a long way on recurve alignment. Heat bend a bit to the side you need, then let the bow cool fully, maybe an hour, check alignment, repeat until string is tracking properly. DO NOT TILLER FURTHER AT THIS POINT. The tips may be too dry. Just brace the bow to check alignment. Once yur alignment is on, let the bow rehyrrate for a few days to a week ... The is no such thing as waiting too long, but starting back on tillering too soon is a real concern.
If alignment becomes too difficult to achieve or if you don't have enough stability due to the recurves, you can shorten them an inch at a time until you have enough stability to continue. Go back to heating the tips for alignment as I discussed above after each time shortening.
Moral of the story, go slow at first, never narrow the tips until you absolutely have to (I.e. The bow is nearing completed tiller). A little bit of going slow in the early stages will save a lot of going slow at the end.
I'm sure others with more experience will chime in with their approaches as well.
Again please clarify the limb width so that others can direct their advice most accurately.
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thanks guys. never thought to leave it wide till after it is being drawn. I've been trying the heat corrections all week. a spot here a spot there only one correction a day and checking the progress each day before trying more. nothing seems to be helping. I feel its just to thin and weak. the limb taper down to 1/2 inch and are only about 1.25 at the fades to begin with. so it's thin all around. but down at the tips its damn near a square profile. I don't want to tiller any more off as it's spot on now and pulling the weight I was shooting for. I think I'll try cutting an inch off the recurves. 1 inch at a time till it's right. I'll post some pics when I'm done. you guys will either love the color or hate me for messing up such a beautiful piece of wood. it's the darkest most reddish orange osage I have ever held. I'm in the process of rubbing in a 50/50 mix of bees wax and lard into the wood. good lord its amazing looking. I think I like sealing it with this better than the helmsman stuff. probly just gonna use it for now on.
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Welcome to the wonderful world of making recurves...sometimes they can be cantankerous lining up...but once ya got em licked its worth it imho.
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I usually always correct my recurves, even if they're off just a little.
Strap your bow down side ways so when you put a weight off the end of the hook
It'll bend the way you want. I always try to get the twist out right before the recurve.
I use a heat gun. I usually set up a ruler, or some blocks so I don't over bend.
I hope that makes sense, I know pics would've better.
Tip allignment on recurves is actually pretty easy, but my tips are around 3/4-1" wide at this point
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wizard. thats close to what I've been doing. I've noticed with all other heat corrections over the years that they do tend go back a alittle the direction they came once the tention is released. shall I "over correct" just a tad? thats about the only thing I haven't tied yet. I will give it another week of trying before I go for the saw!
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Will you post pics?
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Welcome to the wonderful world of making recurves...sometimes they can be cantankerous lining up...but once ya got em licked its worth it imho.
Yep...... 10-4 on that one Chirs
I'm working on a "sort of molly" static recurve with real thin tips, not Blackhawk thin, but thin, and had to add some horn string bridges to keep string from coming off. Its shooting pretty well at the moment. Twist can be a problem with long thin tips...
DBar
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Just finished re~recurving it as I had lost some while trying to get the twist out. Don't really want to brace it yet again till I'm sure its had time to settle in place. Not sure if makes a difference, just don't want to make it any worse. But here's a look at what I'm doing so far and its gorgeous color
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One more of the mid limb where it has some nice snakey. Not much but enough to give it a nice shape at least.
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I, too like to leave them wider until after recurving, but often the twist is actually lower down the limbs, too, where there is uneven thickness side to side, or wibbles and waves.
I almost ALWAYS end up doing some heat and crank work on selfbow recurves.
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Here's a link to the photbucket. Its the original photos so it shows em better. Still look blurry to me. I can't ever seem to get a clear picture. http://s104.photobucket.com/user/THOMAS74P/library/Mobile%20Uploads?sort=3&page=1
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think I may have the twists fixed. and have got it out and shot it on 3 occasions. seems to be a good bow but feels too tall for my personal taste. can't get over the color though so it will probably be one of my main shooters. oh yeah, it turned out 46lbs @ 26'' draw. and shot 500 grain arrows pretty consistantly around 160-165 FPS http://s104.photobucket.com/user/THOMAS74P/library/bows?sort=3&page=1 (ftp://s104.photobucket.com/user/THOMAS74P/library/bows?sort=3&page=1)
heres some pics on photobucket and of course the FD
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I thought you said big recurves.?That thing just has a little curve to it. ;)
Many people really work on the recurved portion to try to remove twist but often the twist can be a slight degree of twist in the limb. Make sure you try to locate where your twist actually is.
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yes sir. thats big recurve for me. the twists were in different places mostly in the limbs around the knots. hopefully after a few months of shooting I'll have a better idea of how good it is.
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Hey, that actually turned out pretty well!
So, looking at the pics closer, just some thoughts for next time. One of the disadvantages of recurves is that they often have massive outer limbs in order to ensure stability. Since the tip is not more or less aligned with everything else, it provides leverage for TINY misalignments of stresses and forces to torque the limbs sideways and create vibration, etc..
In this bow, starting only 1-1/2" wide was probably fine, but on a recurve or severely reflexed tip, if you taper the WIDTH of the limb down too early, as you noted, the limb BELOW the recurve is the problem. If it is 1/2" by 1/2" at the BASE of the recurve, there is no reason for the limb to bend the way you want it, back toward the string, because it can bend sideways as easily as it can bend backwards. The recurve provides the off-center leverage, and BTW it is amplified by the reflex, or setback handle, too.
So, keep a recurve limb WIDER further out the limb. If I make a bow 64"x 2" wide, say, with 5 or 6" recurves, I might taper the limbs only the last 10". You can always smooth a little away later. So the base of the recurves is almost an inch wide x the 1/2" thickness.
But, we don't like heavy tips, right? Well, tough, you need the stability. However, you CAN bnlend a little away, improve the tiller, mess with the trapping, or the cross section, reinforce the curve with cables, backings or overlays, etc, and most IMPORTANTLY shorten the limb. Shorter limb means less weight at the tips, cuz it's GONE! The recurve takes care of the energy storage, smooth draw, etc...
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Pat M is right.The recurves I've made with propeller in the limb can be tedious and it's best to take the propeller out of the limb while holding your tip straight in line and in place.To make more aggressive recurves a straight piece is best,less trouble and your limb width would need to be wider too to handle the near handle bending,but now the base of your recurve can be 9/16"wide 4" from your tip yet and be stable if you have things in line.I'm not an expert but it has worked for me on half a dozen bows.They can be suckers.Looks like you got this one though.Nice job.
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Looks like you got it all worked out, turned out nice, way to stay with it , that's part of the game just keep at it until you either screw it up so bad it can't be fixed or fix it. ;) :)
Pappy