Primitive Archer
Main Discussion Area => Bows => Topic started by: lauderw55 on February 16, 2016, 09:18:01 pm
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Hello I am fairly new to the forum. I make a lot of board bows and was wanting to try and make one with reflexes tips or recurved. I was wondering if anyone had some good successful techniques of doing this? Like maybe thin the tips down and boil them and bend them around a form and add reinforcement wood to the belly to prevent it from bending? Also have had heard some things about cutting kerfs in to the end to recurve it that way. Any help would be greatly appreciated, thanks for your time !
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Steam/boil get them down to about 1/2" thick and go about 45-60 mins in the steam, I put the tip in the water while it steams. I also soak the tip in water for a couple hrs first, they don't need any wood added unless it's to thin
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I've done it with dry heat, steam, boiling, and kerfing. Which method I choose depends on the piece, it's moisture content, construction methods, materials and adhesives used up to that point, if any, and more. The kerfing method is pretty slick, doesn't add any moisture to the wood, or dry it out, plus it really holds the shape. It can be used on selfbows, backed bows, trilams, etc.
The short lam inserted into the kerf can either be ground parallel and tillered to work, or ground to any of various tapers to work less, and even act static.
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Ok thanks. So dances with squirrels if you would could you explain the process of how you uses erf to recurve the tips on your bows.
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I'm in the process of finishing a bow that I used kerf bending recurves for. It's a black locust stave, and the recurves held nicely with the kerf bending. I put in a contrasting, dark, wood veneer to fill the kerf.
(http://i66.tinypic.com/2ushe7t.jpg)
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That looks really good. I just a little confused on how actually to do the kerf. Do you just cut the tip in half and clamp it in the form with no heat or steam prior to that. And do you have to have the lamination
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Cut the tip in half, clean the cut with sandpaper, put glue in there (a lamination is optional) and clamp in a form.
No heat needed, which makes it suitable for laminated bows, or (sinew/rawhide) backed bows.
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That is neat. How severe of a bend can you get with that method and can tite bond 3 be used for that. And also do you think a copen saw would be able to make that cut because dont currently have a band saw?
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hey Lauderw, what happened to the boo bow??
dont use a coping saw, use a hand saw like a tenon or panel saw...you dont need a band saw.!!! its pretty easy and works well , they dont pull out like steam
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Ok bad is this sounds I not sure what those saws are so I will have Look further into those. And I am getting the materials together for the boo bow Thanks with the help with that btw!
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Lauderw55, yes, you need the lam to fill the void. I have always used Smooth On epoxy for this job... never tried Titebond. I'm not saying it wouldn't work, just that I've never done it. I have a lot more trust in Smooth On for stuff like this.
No heating and bending needed prior to glue up, so long as the pieces are thin enough and able to bend.
I have always used a bandsaw, but I suppose careful use of a good handsaw would work as well.
Regardless of what saw you use, you will need to find the lam thickness that suits the kerf left by the saw. Here's an easy way to do that...
Make or buy a pair of tapered lams that taper down to almost nothing. I usually kerf in about 10-12", so I make those taper lams about 18-24" long, depending on degree of taper. I'll tell you why....
After the kerf is completed in the bow/blank, insert the tapered lam into the kerf sideways, perpendicular to the limb, at the bottom(where the cut ended), and slide it in just until it gets snug. That is the exact size of your kerf, but you need room for glue, so back the tapered lam out just a little bit, until it loosens up just a weeeeee bit, and mark it. Cut it off at that mark. During glue-up, it will be inserted into the kerf until that end, the end you cut, bottoms out in the end/bottom of the kerf. No gaps. No voids. Perfect glue lines.
Start clamping there, at the bottom of the kerf. It will help hold the pieces in place as you work your way toward the tip with succeeding clamps.
This picture is of such a kerfin', but I doubt you'll be able to see it in the picture. I could take a close up of the kerf if you like.
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Yea that looks really nice I can't even tell you used a kerf to make that a recurve. How would you go about making a lamination and I currently just have just hand tools besides a jigsaw? What could happen if you didn't use a lam and try to just fill the gap with glue or perhaps sawdust even? But thanks for the help that was good informative post
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The making of a lam and cutting a straight slot of appropriate length may be beyond you with your skill level and available tools.
A spliced in tip is easier to form and obtain the required degree of tip set-back.
V splice it in, underlay the splice and overlay the top with a strip of linen and wrap the whole joint tightly with thin cord set in epoxy.
(http://i399.photobucket.com/albums/pp78/pat_05/IMG_0704_zpsukytm8uf.jpg)
(http://i399.photobucket.com/albums/pp78/pat_05/IMG_0708_zpsvlgbfojq.jpg)
(http://i399.photobucket.com/albums/pp78/pat_05/IMG_0706_zpsborvd8be.jpg)
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That looks good and I have been toying with that idea as well. I seen something similar in TBB2 I believe where one the authors glued recurved end on the board bow. Have you had any trouble with it coming loose and could I use titebond 3 for such a job
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You could use TB if your v splice is very precise. Epoxy is much more forgiving.
I've never had one budge. It's a very strong joint.
The TBB one didn't show any action shots. Looked more like a theory. ;)
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So what kind of epoxy u suggesting and is it waterproof
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Good epoxy. Meaning slow setting 24 hour at least. Epoxy is waterproof.
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Would it be possible to give me a particular brand or product name
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Where are you located?
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Southern ohio
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You can likely just order some Smooth On or get some System Three, WEST etc.
Check for boatbuilding or woodworking shops in your area.
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Do u kno if smooth on needs heat to cure because currently don't have a heat box
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It doesn't. A higher cure temperature makes it more resistant to future high temperatures and for most epoxies it also increases their ultimate strength.
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What a neat concept! I thought the whole kerf bend thing was more of a theoretical possibility but it's cool to see it in use. Reading your accounts makes it seem pretty straight forward and I love the look with the contrasting wood. Thanks for sharing! Nate
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With smooth on if you mix 2 parts a to 1 b it increased the heat resistance without a hot box
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I did some initial searching but have yet to find a straight forward Build-Along type example of this method for re-curving tips. Is there one that anybody here would recommend?
OneBow
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See page one. If that doesn't make it clear then no book on the subject will either.
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See page one. If that doesn't make it clear then no book on the subject will either.
You might have just said "Nope, I don't know of any such Build Along"... ::)
Obviously, I read the first page of the thread sir. I did not feel like it was the exhaustive last word on how to do the job so I asked if anyone had a Build Along they would recommend. Some of the items I'd like to know that were not addressed in the first page of the thread were as follows:
1] Are there particular wood species this method is best suited for?
2] What approximate range of dimensions will it work for?
3] Are there any particular suggested precautions when doing this method? (i.e. - ...things that might have gone wrong before for someone that has used the method that they might be able to advise another on as a forewarning.)
4] At what point in the build process should this method be implemented? (i.e. - ...at floor tiller? ...completed tiller? ...untillered blank stave or board perhaps?)
5] Can this method be utilized to recover some of the effect of set that has occurred in an older bow?
6] A bandsaw was mentioned as the preferred tool for the work. What TPI blade is suggested for this work? Will a Japanese pull saw work as an effective substitute?
7] What-ever-else tips might be locked away in the mind of someone that has actually used this technique a few times previously that they might be able to share.
I've never used it, but would like to try it this weekend. If you've done it and can answer such questions, PLEASE respond.
OneBow
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A build along is unlikely to address many of those questions. There seems to be a real resistance to learning by doing these days.
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I've never used this technique but now I can't wait to try! Love the look of it!
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One bow, it will work on any wood but is especially effective on woods the don't like to bend with heat, epe and other tropicals, I don't do recurves till I get the bow to about 18" of bend so whatever you have dimension wise at that stage. A pullsaw will work but whatever you use be precise in your cuts. I don't think adding a recurve to offset set helps because it actually adds more stress, and if the wood will manipulate with steam or dry heat i would just use that and not add all that extra work, hope that helps ya, Bub
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Thanx Bubby. I appreciate the input. I'll keep researching and see what I can find.
A build along is unlikely to address many of those questions. There seems to be a real resistance to learning by doing these days.
What is crawled up inside you Pat? I told you I plan to use this method this weekend. I'm not resistant to anything. I am trying to read and research some before I try so as not repeat the errors of others needlessly.
A build along may not have the answers to some of those questions, ...but then again it may. It is infinitely more likely to have some of those answers than the first page of the thread, which is all that you suggested. Have you EVER DONE THIS? I'm guessing not. If so, and IF you have any input you'd like to share to help, please feel free to speak up. If you are just as ignorant as I am, please feel free to not comment.
OneBow
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Sure I've done it. I prefer other methods. I guess posts asking for every single detail in a short period of time rather than hitting all the stepping stones along the way have worn out my patience.
We see more and more of that on here now.
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Onebow can I suggest that you take an 18"-20 pc of wood and make some practice cuts and even do a glue up to see how everything goes and what you need to do
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Onebow can I suggest that you take an 18"-20 pc of wood and make some practice cuts and even do a glue up to see how everything goes and what you need to do
Very good idea! I'll give that a try. I actually have a couple old bow limbs from bows that exploded that I might use for that testing. Beats throwing them into the burn pile... :-\ :)
OneBow
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after you put the recurve in the exploded limbs, then splice them together and continue shooting them :)
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Onebowwonder, I'll try to answer some of your questions. I don't know of any such build-along, but I don't think it's necessary.
1] Are there particular wood species this method is best suited for?
Not really. I've used it on various bow woods and in various designs and construction methods... d/r, hybrids, recurves, in selfbows, bamboo backed bows and trilams.
2] What approximate range of dimensions will it work for?
I'm not sure I understand this question. What dimensions? Do you mean thickness of limb prior to kerfing? If so, the best suited thickness depends on how drastic of a curve you intend to inflict on it upon glue up. If you're going full recurve, it should be nearly working limb thickness prior to kerfing. And of course it could be a wee bit thicker if you were simply inducing some reflex. It will behoove you to do this with outer limbs that have neither much ring or grain runout. If they do have runout, I would opt for reflex rather than more radical recurve shapes.
3] Are there any particular suggested precautions when doing this method? (i.e. - ...things that might have gone wrong before for someone that has used the method that they might be able to advise another on as a forewarning.)
See above ;^)
Also, use a method similar to what I mentioned in an earlier post about finding the proper thickness lam dimensions, because if you you force the lam down into the kerf, it can easily cause a split starting at the bottom of the kerf and running into the limb.
4] At what point in the build process should this method be implemented? (i.e. - ...at floor tiller? ...completed tiller? ...untillered blank stave or board perhaps?)
I've done it in all of those instances... as long as when kerfed, each individual piece is able to make the bend you intend.
5] Can this method be utilized to recover some of the effect of set that has occurred in an older bow?
Sure. Though, depending on other factors, it may cause it to take more set elsewhere.
6] A bandsaw was mentioned as the preferred tool for the work. What TPI blade is suggested for this work?
This isn't a critical factor. I've used blades as course as 3/4" with 3 teeth per inch. Cutting accuracy and tool familiarity is more important.
Will a Japanese pull saw work as an effective substitute?
Perhaps. I've never tried.
7] What-ever-else tips might be locked away in the mind of someone that has actually used this technique a few times previously that they might be able to share.
When everything is ready, glue is applied, lam slid into place, and you're ready to pull the pieces down into the jig to effect the bend..... The FIRST clamp should go right where the kerf ended BEFORE any bending is done. I had one crack there one time when I pulled it down into a recurve jig and I'm convinced that wouldn't have happened if I had placed a clamp there first.
Any other questions or concerns.... fire away.
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Whoa there fellas,
This link is to a two page posting on paleoplanet; quite nice pics and a drawing.
http://paleoplanet69529.yuku.com/topic/14941
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Thanx for all the input guys. I'll post my results if they are worth seeing after this weekend...
OneBow
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Ok bad is this sounds I not sure what those saws are so I will have Look further into those.
Doesn't sound bad. That's exactly what google is for....
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My input is this..... TB III is strong enough to do a kerf-and-splice recurve, but I have had a lot of failures anyway, because the hardest part is getting the cut even, smooth, and consistent size. My best luck has been with a pull saw. MAKE PENCIL MARKS! It helps.
You CAN simply thin that limb down and recurve it, then add a belly splice overlay, too. Not hard, looks good, and the thinner the wood, the more you can recurve it.
Pat's method is awesome, too. I was afraid of it, but learned that if you make careful marks and cuts it works super. when I did this, I layed up multiple lams over a tight curve, cut it in half and used them for the siyahs. Get the alignment level on the back of the bow so you don't have to sand into the back to make it nice, then work the belly to fit and add another la, or wrap it with cord at the joint. The glue will take it, though.
The best thing about adding recurves is that you CAN make the limbs pretty thin, so they will bend for you, because the recurves raise draw weight dramatically.
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I will post pictures when I get back to my PC. However; we tried this yesterday and had a very bad time of it… :( :( >:(
OneBow
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Well - Here is the pictorial of the doomed effort Patrick and I made at doing a kerf style recurve.
First mistake was that we talked ourselves into trying this out on a bow blank that was still promising to become a bow instead of one of my old blown-up bow limbs. ::)
Patrick laid out the lines to cut the kerfs. Then he cut them while I took pictures. Up to this point, we were still pretty hopeful...
OneBow
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Next we tapered the inserts out of some walnut I had on hand.
...Then we used the heat gun to 'pre-bend' the hooks into the tips prior to glue-up. Also, Patrick sanded the back side of each hook to accommodate the brush nocks he had planned for this bow. (...did not get a picture of this step.)
OneBow
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...and then fainally, the fail, which came during the glue-up and insertion into the caul step. The hooks shattered badly and and were not at all readily bent.
OneBow
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I don't understand. It looked like you were there. Did you try to bend it more after the glue up?
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Lessons Learned:
1] We should NEVER have done this first effort on a stave that had promise still. (duh!)
2] We attempted a curve that was probably too aggressive for this method.
3] Sanding off the belly side split AFTER we had cut the kerf left one side considerably less thickness than the other. The kerf should be in the center of the limb so that the two sides of the kerf are pretty much equal in strength before bending them.
4] The insert lam was made of some very dry (read as - STIFF and brittle Walnut). They should probably have been more flexible.
5] Especially tight radius kerf bends should probably be made WITHOUT an insert lam altogether.
There may have been more lessons to learn from this experience, but these were the ones we were pretty clear on.
We are not done with experimenting however. The next day, we boiled a wide piece of Sweet Gum and bent it over another caul. Next stop, ...Siyah town!
OneBow
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I don't understand. It looked like you were there. Did you try to bend it more after the glue up?
No, we used the heat gun to 'pre-bend' the osage dry before the glue up. But when we tried to go for the full bend at glue-up, it all burst. Pre-bending may have been an error as well, since the heat might have hardened (aka 'heat-treated') the surface of the Osage. Live and learn...
OneBow
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I'm with DC, I thought you had it. Honestly, the tip of the bow was still pretty thick, but your swa work looked stellar. AND, I don't understand how it broke after you had such pretty pre-bending done
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I'm wondering if the walnut had gone right to the end if it would have survived? I don't know how you had it in the caul but the end of the walnut would be a big stress point if you were bending it there.
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I'm wondering if the walnut had gone right to the end if it would have survived? I don't know how you had it in the caul but the end of the walnut would be a big stress point if you were bending it there.
Yeah, the pictures don't show it very well, but during the glue-up stage the walnut taper did go all the way from the tip of the kerf line to the end of the limb. They busted up pretty badly as we bent them into the caul during glue-up attempt.
OneBow
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Maybe that, like it over hung too far? I have had a couple failures when the kerf was all uneven itself. Like where, by the time I got the saw marks sanded out inside the kerf there were places it gapped 1/8" and places it gapped 3/16". Also, a couple where I tried to jam a just barely too fat shim in, and it cracked open in the bottom of the kerf.
Neither of those should have happened here.
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Maybe steam and also bend the insert? I was thinking this would be the answer for major hooks. And if you bent the halves one at a time it would give you better access to sand the inside of the kerf.
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they look to thick to me,, osage is osage,,its the thickness of two bows or more
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3Here's a little tip, on short thin wood wrap it in a soaking wet towel and nuke it in the microwave for 3-4 mins bends like butter
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Zooming in a little, pre glue-up, I'm thinking this was the start:
(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/Pre-bent1.jpg)
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If you would have posted pics prior to glue up, I would have predicted that failure. You pushed it too far on too many levels. Oh well that's how ya learn, and hindsight is 20/20. The kerf wasn't accurately cut, and there was a serious shuck and jive in it where it broke. The pieces were too thick, except where Patrick ground it down for brush nocks... that was way too thin and violated the grain/rings on the belly side. The bend radius was to small. You didn't leave it much choice. It HAD to break :^) He should have waited until afterwards to do that grinding.
Compare yours to mine on page 1. Since that bow, I have reduced the size of the bend radius some, but not to the degree you attempted.
Any time you kerf, you should fill the void with an appropriately sized piece... do not eliminate the lam because of radius.
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I hate to 'beat ya up' any more, but I felt the need to mention... while it may not have directly contributed to the failure, your walnut lam insert was sub par. I wouldn't put something like that in a limb for that purpose. I use only straight grained, clear, sound, same species, same or better quality wood for such inserts. May not mean do or die, but I do it anyway
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I hate to 'beat ya up' any more, but I felt the need to mention...<snip>
Thanx for your input Mr. DWS. I don't feel the least bit beat up. - OneBow
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<snip>...and violated the grain/rings on the belly side.
Are you suggesting that we needed to chase a ring on the belly side of the kerf? That's not one I would have even thought of doing. Hmmm... I guess I see how it might help though.
The bend radius was to small. You didn't leave it much choice. It HAD to break :^) <Snip>
Yeah, that's kinda what we came to on that one too. Oh Well...
<snip>Any time you kerf, you should fill the void with an appropriately sized piece... do not eliminate the lam because of radius.<snip>
Yeah, that idea came from someone else that's done a few of these. He apparently makes fairly sharp hooks with the Kerfing method and leaves out the insert for those tighter bends. I thought it might help some, ...but what do I know???... :( :( :(
OneBow
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No, not chase a ring on the belly side necessary... you just don't want to be quite so agressive. He violated it too much prior to making the bend. Should have finessed it more than forced it. Wooden bows are like women.
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Well we learned a few things, and it is definitely something I would try again. I know that part of the fail was from me grinding down the belly side after cutting the kerf. But it could have partially been the process of clamping. Reading some of these post I think I had the wrong caul set up. I had it more like a steam bending caul, where you hook one end and roll it over the caul then clamp it. I'm going to get back on the horse and try it again.
Thank you guy's for all the input!
Patrick
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Yeap, I see it now. Having to crank that gap down during glue up, esp if it was already partly fractured, probably did it.