Primitive Archer
Main Discussion Area => Bows => Topic started by: DC on June 13, 2017, 09:34:19 pm
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I'm about to take the next step in bowyery.(sp--word?) I want to get something straight. I make the bow and tiller it out to about 20". Then I reflex it and apply the sinew. Then I put it back on the tree and finish tiller as usual? I guess what I'm unsure of is if there is any difference in tillering a sinewed bow and a self bow?
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The tillering is the same. It is possible that the tiller will not change if the sinew is applied evenly on each limb and both limbs but the weight will increase. Realistically expect to have to at least freshen up the tiller.
When I build a sinew backed bow I tiller it out partually, estimate my ultimate draw weight at my draw length then add the sinew. This way you have a limited amount of weight you have to reduce and you should be able to get the tiller right while reducing the weight. Be sure the tiller is right before you add the sinew.
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i have found that the sinew bow responds a bit different to wood removal,, so going slowly is advisable,, (-S
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i have found that the sinew bow responds a bit different to wood removal,, so going slowly is advisable,, (-S
Yep happened on my last one
DBar
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I would suggest getting the bow heat shaped and lined right up, then tillered out to 18-20" max, then apply sinew with a slight reverse brace. Brad and Bill are right on. Exercise the bow more than usual between scrapings.
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You only get those 'problems' IF the sinew isn't totally dry. 1mm sinew = 2 weeks, 2mm - 4weeks, 3mm - 9weeks, 4mm - 16weeks.
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You only get those 'problems' IF the sinew isn't totally dry. 1mm sinew = 2 weeks, 2mm - 4weeks, 3mm - 9weeks, 4mm - 16weeks.
At what RH?
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Good advice above!
Be sure to get the sinew on in an homogen thick layer. If not, one way is to fill up with new sinew (+ waiting and reverse brace), or tiller also on the back (before you touch the belly)
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With reflexed sinew bows it's easy to miss your target weight you really need to get the sinew working to show it's true colors I try to bring the bow to brace about 20 lb. above my target weight the last one I was working on had about 7 in. of reflex it took 100 lb of weight to get the limbs neutral and after sweating for 2 hrs at neutral it only took 70 lb to neutral I think it depends on the amount of sinew you use also. After trying different cure times from 1 month to 10 weeks I agree with Mikes method of cure as much as I hate to weight for cure !
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The bow is a static recurve. How far into the non bending part should I take the sinew? I had to kerf the recurve and I like the look of the dark insert. Does the sinew have to wrap over the side much? I'd rather not cover the insert unless it's needed.
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Just feather the sinew into the center of the curved portion. The sinew does not need to wrap around the sides nor should it need circular wrapping at the extremities.
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Thanks Pat. The bow has a high crown, are you of the school of thought that says concentrate the sinew on the top of the crown and just barely bring it out to the edge?
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Yes but I still like complete coverage even if thin at the edges.
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If in doubt as to whether your sinew is cured, wait.
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i have done some pretty fast cures,, cause I have a problem with patience sometime,, the bows did gain weight, but performed well,,,, that being said, there is no doubt waiting longer could be better most the time,, (AT)
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I'll let it cure a long time with our RH. Normal is 70%.
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I'm thinkin' I'll take a shot at this tomorrow. Last question ,I hope, is there any rush once I start? Do I have to get all the sinew on before--- something happens. If the house catches fire can I stop sinewing to put it out or do I keep going and let the insurance company worry about the house ;D ;D
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On the last few sinewed bows I built I waited a month between courses, 2 weeks after the snake skin was added and let it rest a month, during the winter to cure. It might have been over done but I was comfortable with it.
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DC....The first couple of days after sinewing it should be in a rather cooler place like below 65 degrees to let it gell and bond good and proper.I think it helps to avoid lengthwise cracks from drying too fast in the beginning.Then taken to a dryer less humid drying area,even with a slight air flow going by it.
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It's done. Turned out OK I guess. I think my glue was a little thick. Does anyone have a mix ratio for dry glue/water. I know everything says the thickness of thin syrup but that's kind of regional I think. I used the ratio that guitar makers use. 2:1 water to glue. It gelled quickly but I could keep up. Where I think I noticed was when I was wrapping and heating to get the excess glue out. Two wraps and that was it, no more glue came out and it doesn't feel jelly like any more. I measured the thickness of the bow before and after and I got about .100-.150" after it's compressed but not dried. I think that means I need another course. It better shoot good, this is a lot of messing around. Not sure if I want to do it again.
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Take a pic.
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Yes we wanna see it!
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It's Ocean Spray and was 60" before I bent the tips.
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Looks good. You can lightly cloth wrap it if it looks like it's drying too fast. You do have to watch for mildew forming at this time of year though.
Also increase your reflex a bit. Tie a double string across and use a stick to twist it a bit tighter every few days.
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When it turns from milky white to clear is it getting close to it's final dimensions or does it still shrink a lot. Where it's clear it's about 1/16" thick. One limb is almost all clear, the other about half way. That seems like it's drying a bit faster than I expected but what do I know. I realise I've got a month to go but I wasn't expecting it to "look" dry so fast.
PS I just measured the clear part and it's still shrinking.
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Looks real good Don....
+1 to what has been suggested about putting some reflex in the limbs while the sinew is wet.
DBar
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looks great, good job, dont be shocked,, the bow gods have blessed you,, (-P
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OK I put 2 1/2" making it 8" total.
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When it turns from milky white to clear is it getting close to it's final dimensions or does it still shrink a lot. Where it's clear it's about 1/16" thick. One limb is almost all clear, the other about half way. That seems like it's drying a bit faster than I expected but what do I know. I realise I've got a month to go but I wasn't expecting it to "look" dry so fast.
PS I just measured the clear part and it's still shrinking.
Manage your drying rate then. Double up the cloth on the clear parts and single wrap the milky part.
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Somewhere in my last few days of surfing I saw a little chart that showed how much various thicknesses of sinew changed the weight of a bow. Now I can't find it. Has anyone else seen it and maybe have a link?
Thanks
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It's leveled off at a little better than 1/16" thick. Is that going to be enough or should I put another layer on.
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keeping a record of how much sinew you applied, the weight,, will help you make adjustments on like design bows in the future,,
if you tell me how much you applied ,, grains ,,, I can give you an idea how its gonna respond,,
I would go with what you have on this one, ,and make adjustments as needed on the next bow,,
(-P
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keeping a record of how much sinew you applied, the weight,, will help you make adjustments on like design bows in the future,,
if you tell me how much you applied ,, grains ,,, I can give you an idea how its gonna respond,,
I would go with what you have on this one, ,and make adjustments as needed on the next bow,,
(-P
Thanks Brad that gives me a direction. I don't know how much sinew I put on. Next time, if there is a next time.
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No man has ever done a successful sinew job and said that's it. ;)
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It's been a long time since I did a sinewed bow but I always reverse braced adding nearly all the reflex I wanted before applying the sinew. The reason being is that I believe that the reflex you get from the sinew drying mostly pulls out during tillering and then the sinew actually starts to work.
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No man has ever done a successful sinew job and said that's it. ;)
We'll see :D. I started this because when I started making bows I collected all the stuff I might need. So for two years this sinew has been sitting on a shelf. Also I was getting way to many bows and thought that if it took longer to make each bow I could keep busy and not run out of wall space. That said, pounding and stripping sinew is not my favourite thing to do. Arthritis doesn't help. Someone said they strip it out while watching TV. That may help. Anyway, my quest is speed and if this bow doesn't get into the 170 range I may just trade off my glue and sinew.
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keeping a record of how much sinew you applied, the weight,, will help you make adjustments on like design bows in the future,,
if you tell me how much you applied ,, grains ,,, I can give you an idea how its gonna respond,,
I would go with what you have on this one, ,and make adjustments as needed on the next bow,,
(-P
When you say keep track of how much I applied I'm assuming you mean just sinew, not glue and sinew. Do you just weigh your stash of sinew before and after? I tried doing that but the bag of sinew was so big I couldn't see the scale underneath and I didn't know how much the bag weighed so I gave it up as a lost cause. I'll have to put more thought into it.
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I noticed when I was pre soaking the sinew that the bundles straightened out nicely and stayed that way when they started to dry. It occurred to me that might be a good way to store them. Nice even straight pieces that you could stack like kindling. Easier to weigh. Soak them overnight before use. Is there a downside here?
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I prefer to hydrate sinew before applying it. I think it helps the glue saturate the sinew. I'll lift a bundle from the warm water, squeegee off the excess water, dip in the glue and squeegee off the excess glue and lay it down. I start soaking it in the warm water while I'm getting everything together.
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Well..............I have a little different opinion. Not to be causing trouble just different thoughts...
I like soaking my sinew in warm glue. then squezzing out the excess glue before laying it down. I think it dilutes the glue if you use water to soften the sinew.
DBar
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Well..............I have a little different opinion. Not to be causing trouble just different thoughts...
I like soaking my sinew in warm glue. then squezzing out the excess glue before laying it down. I think it dilutes the glue if you use water to soften the sinew.
DBar
I thought about this and I wonder if the glue(from your warm glue) actually goes into the sinew. It occurred to me that the sinew might actually filter out the glue so that only the water gets into the sinew. Kind of an osmosis thing. Soaking it in glue seems like it would be better but it may be such a small amount as to make it unnecessary.
PS And once the sinew has cured and all the water is gone, if any glue did soak in would it do anything. After all apparently sinew and glue are molecularly identical. Actually I'm not sure they are :D
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I've always done the same as Pat B but can see DBars' point.I think the main point here is that the sinew is'nt hard and not able to soak up glue or moisture.If you've ever done that applying hard sinew just dipped into hide glue the results are'nt good.
I presoak my sinew in warm water.I even went so far as using distilled water.Does'nt seem to make a difference.The only way to tell the difference of proof is to put the sinew on an extremely stressful profile.
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Your glue is constantly evaporating so DAMP sinew isn't going to dilute your glue to any significant degree. Remember you are usually double dipping and stripping out excess glue so it's definitely going to be saturated with glue rather than just water.
Glue and sinew are the same thing but not structurally the same thing. Otherwise we would just paint multiple coats of hide glue on.
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I think if you take that into consideration on the thickness of the glue,, soaking in water will work, I do see your point,, I dry my sinew on paper towel before dipping in glue as well,, most the time it stays on,, :NN )P(
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I also take the sinew out of the water and lay it on paper towels so it is not sopping wet but rather about like you would want rawhide before gluing it on.
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OK the month is up(well two days short) so I braced it and started pulling a bit but now the string alignment is out. It was good to 20" before I sinewed, now the string comes off at 18" and the bow hops all over the shop. I'm guessing heat is out so how can I get it back into alignment?
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could we see a picture (-P
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Here's a few. Any more? Of what part of the bow? From what angle?
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Manually torque it into line. You need to train it into line as you work the draw back. Install some deeply grooved bridges to hold the string centred while you do this.
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Once i get it in line will regular use of the bow keep it that way. It seems to me that the pulling would tend to line everything up.I have a habit of bring wrong though. ;D
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It should. I have a few bows that have sat for a couple of years and they needed re-training since they drifted back a bit. Regular use promotes straightness.
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I'm getting it closer I think but every once in a while the string comes off. When you torque it do you twist it hard over and leave it for an hour or so or is it a little more subtle than that. I'm out to about 22" now. I've put bridges on but I wasn't sure where they should be so they are a little inboard of where the string leaves the bow at brace height.
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thats looking great
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Thanks, but it's going to be unusable if the string won't stay on :D
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You have to be pretty bold and it's best to try to twist through the whole length of the bow rather than trying to just tweak it in one spot. I usually grip one recurve between my feet and torque the other end while(carefully) sighting down the length of the bow.
Make sure the string isn't slipping and keep your head clear though.
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You might be surprised how little heat it takes to correct that and how well the sinew/glue will handle it. You have nothing to lose if the string wont stay on.
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put your fears aside and proceed with courage,, (W
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Best of 170 fps@10gpp. My fastest ever and I still have some weight to take off the recurves. It did register one of 312 fps but I think that was an error ;D ;D ;D
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No man has ever done a successful sinew job and said that's it. ;)
175 ;D ;D ;D ;D ;D
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I did about twenty or so shots when I was chronying it and it worked great. Then it threw the string >:( >:(. I pulled it to 27"(about) and the string barely lifts off. If I pike it a bit making the recurves shorter do you think that will reduce the tendency to twist and throw the string or should I just keep looking for that sweet spot.
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I'd work on it a bit before resorting to shortening the curves. Are you using a timber hitch by any chance?
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No I made a double loop string.
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yes I think you almost got it,, just fine tune the curves,,
leave it strung quite a bit, if will help hold it straight,, it wont hurt it to leave braced for hours at a time,,
great performance,, congrats on a great bow,, (-S
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How deep are your string grooves? I'm sure you've considered this, but I've had trouble with the string slipping and once or twice simply deepening the grooves did the trick.
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How deep are your string grooves? I'm sure you've considered this, but I've had trouble with the string slipping and once or twice simply deepening the grooves did the trick.
Actually I had just redone the string nocks just before it came off this last time. I just redid them for pretty a few minutes ago and the were kind of slipshod. They're better now. I am finding that I can heat the limbs enough to get them to stay in the new spot. Just enough heat to move it and then aim a fan at it. Now I get to shoot it for a while.
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:OK