Primitive Archer
Main Discussion Area => Bows => Topic started by: Pat B on February 11, 2014, 02:06:17 pm
-
Since Guy suggested starting a separate thread for this subject I thought I's start one.
IMO you can add too much reflex to a stave. As a matter of fact I reduce the reflex if it is over 3" to 4" of natural reflex and generally won't add more reflex than 3" to 4" because I think by doing so you are over stressing the stave which can easily increase set.
For sinew backed bows I will add a little more tied up(strung backwards) reflex until the sinew cures but after my bows are shot in there really isn't that much reflex left.
-
HAHAHA you beat me to it Pat, i was even gonna name it that! I' gonna be watching this thread closely
-
I add 3-4" on every bow I build, almost. Ive learned to adjust that for different woods, different lengths and different styles. That could be a chapter in a book all by itself. I used to add excessive reflex, was told not to by the guys, and learned in my own time that it doesn't work without sinew or a glued hard backing. I would rather start with 3" of reflex and end up with 1.5" than to start with 8" and end up with 3". Taxed wood is taxed wood and held reflex alone doesn't mean much.
-
I made a form just like Gary Davis .. where reflex increases toward the tips.. It greatly reduced the amount of set i get, and like Pat said, if a stave has alot of natural reflex I take some out...least thats what works for me.... Brian
-
Been reading the various posts on this issue over the last few days. A good question Pat. I think I know the answer that I feel is right, but I have no hard evidence to back it up. Like PD above, 3-4 inches, settling at 1-2 inches depending on the length of the bow, and a few other variables. When I first began, I made a 58-59" Osage bow from a straight stave and I flipped the tips which gave it an inch or so of reflex. Liked it so much that I then added some set back in the handle, about an inch if I recall and that gave it 2+ inches of reflex. Liked it so much that I heated in another 2-3 inches along both limbs. A real beauty! 5 inches or better of reflex. It looked and felt amazing, like a high horned Brahma. It settled in at about 1/2 inch of string follow, most of that from mid limb out. Too much of a good thing. Better to have induced 2 inches and have it settle dead flat or better (I think), which is more of what I would do now. I'm interested to see what everyone else's take is.
-
Steve(Badger) has done a lot of testing on this subject. I believe he mentions anything over 2 inches being of greatly diminished benefit.
It has to do with how the wood is coping with the increased strain.
-
It seems bow length would play a part Patm. It does for me. I tend to add a bit more to longer bows that I know wont lose it so readily.
-
The more reflex, the wider the limbs have to be to stabilize the bow. This also means more mass that has to be accelerated.
I am struggeling on my own if to reflex a bow 2" and get zero stringfollow or adding 4" and get 2" reflex plus wider hand heavier limbs.
I would take 2" for a longbow and 4" for a flatbow with wide limbs.
Matthias
-
Wouldn't the issue here vary greatly depending on wood species for self bows and materials characteristics of belly and back pairs for backed bows?
For example, consider the difference between an Osage self bow, (which is very strong in both tension and compression and well ballanced between the two), and an ERC self bow, (which famously poor in tension, but pretty good in compression and poorly balanced between the two). The Osage self bow could almost certainly handle more reflex that the ERC.
Or for backed bow pairs, wouldn't a boo backed Ipe bellied bow be different than one with a Maple back and an ERC belly in the degree of reflex they can readily support?
OneBow
-
The amount of added reflex changes little Onebow. The difference in the woods would require more length or width to hold the same amount of reflex in the end.
-
With my black locust anything more than four inches on a 60-65" bow looks like trouble for the belly. After that I feel save adding one inch of reflex per five inches of bow length, but I'm sure that's playing safe.
-
so wait...there's such thing as too much? ;D >:D ;) 8)
lol
(http://i1251.photobucket.com/albums/hh544/bryceott/5f2d21ad-96bb-4927-a25e-433721740b91.jpg) (http://s1251.photobucket.com/user/bryceott/media/5f2d21ad-96bb-4927-a25e-433721740b91.jpg.html)
-
My take on it is that the more elastic a piece of wood is the more you can reflex it and get benefits, most woods are very similar in elasticity. I find with osage, yew, elm, for the style of bow I build which is a 66" long bow most of the time I like about 2" or 3" tops. Personnal shooting bows 1" is plenty. The bow I did so well at the flight shoots with this year had 3 1/2" but was a little bit of a freak because it never lost any durring the build. Yew and osage will sometimes surprise me with how much they will hold but I don't like to push it because if I am wrong I end up with a broken or at least broken down bow. I have also found that if I use too much reflex I need to make the bow too wide and thin which seems to cut back on the efficiency even though the force draw curve will be excellent.
-
The amount of added reflex changes little Onebow. The difference in the woods would require more length or width to hold the same amount of reflex in the end.
...which is to say that too much reflex for a given set of dimensions VARIES significantly by wood species in self bows and Belly to Backing pairs in backed bows. An Osage bow of X inches in length and Y inches in width can accomodate N inches of reflex before it is too much, whereas an ERC bow of the same dimensions can only accomodate N minus something inches of reflex before risking failure. Of corse it all changes if you add more material to share the work...
OneBow
-
I think PD's point is that adding more wood is a given for "weaker" woods.
-
I generally heat in about 4" of reflex when I start and end up with 1-2" when I'm done tillering. That seems to work pretty good for me.
-
That bow has help though Brycey! I think I can see some sinew maybe? That's when and how excessive reflex can start working for the better. You mighta' pushed the envelope on that piece! I still like where you added reflex, mostly mid limb out.
-
This bow is supposedly just wood and sinew.
http://anthromuseum.missouri.edu/grayson/koreanarchery/1998-0112-bow.shtml
-
Bryce brings up a good point...how do we explain the performance of a working recurve(its just excessive reflex isnt it?)..... 8)....here we go, lol... Brian
-
This bow is supposedly just wood and sinew.
http://anthromuseum.missouri.edu/grayson/koreanarchery/1998-0112-bow.shtml
PatM, I live just a few minutes from the Greyson collection and ive seen that bow and others like it in person...they are truly amazing and baffle my mind, lol.. Brian
-
Not trying to ruffle any feathers here, this topic is of high interest to me. Does anyone have any hard evidence or records of FPS readings of the higher taxed bows versus the bows that have been less strained? Or do you know of a place i can read about it? Also from what i'm gathering, a bow of higher reflex will work if backed with a material to shift the neutral plane higher giving the belly more wood to help resist compression, correct?
-
I mean if were talking just a few FPS difference in a bow thats been over strained versus one that has reflex but is well within the limits of strain for the particular species of wood. Then adding large amounts of reflex is just a waste of time. And i can start cranking out bows faster than with the long task of adding large amounts of reflex. Just need to focus on tillering without overstraining and bow design versus massive reflex.
-
Dang!
Another interesting Thread...
Watching This Un Too...
-gus
-
Ink, quite a bit of testing has been done, I have never tested one like the crab bow shown above but I have tested them with 12" of reflex. I don't see any evidence that past about 3" or 4" any speed is gained. If you put enough sinew on something to raise the weight enough there will be almost no limit to how much reflex you will gain, but you won't gain in performance, those types of bows have not shown well at flight competitions.
-
Thanks badger, that was kinda the jist i was getting from all the other posts as well. I guess nothing works better than grabbing rasp and doing tests myself :) In hind sight it looks like i got caught up in the typical more of a good thing is better mentality. Already have a 4" reflex stave off the caul and getting prepped for tillering. Going to sinew back the 10" reflex trade bow and show my results of the performance as the bows are completed. Great thread!
-
Doesn't explain the performance I was getting from the highly reflexed bows I was making 10 years ago while experimenting with heat-treating. Some of those bows had up to 6" of reflex after being tillered. Perhaps they would have performed just as well with only a couple inches of reflex but personally I doubt it. The performance increase may be minimal past 4" though and not worthwhile bothering with.
-
Mark, I thought about you when I answered. Your bows are a lot more consistently fast than mine, but I build enough to get my occassional screamer in that will pretty much match yours. In those cases I am usually at a hard 3" at least or slightly more. I will say that your bows are so idealized that you very well could get more benefits from reflex than most of us. A big problem with reflex is inadequate deflex and over stressing of the limbs. Your design does tend to minimise that.
-
Marc, do you have a link to a bow in the design that you guys are discussing?
-
Ink, you will see the design feature in nearly all of Marks bows. Kind of his trademark, he gets a nice smooth flowing deflex comming right out of the handle and then he gradually starts shifting it into reflex or recurves or both. It really givs a lot of protection to the belly wood in a stressed design, I feel a major part of our performance losses are due to overstessing belly woods.
-
ah okay badger, i see what your talking about in Marcs BBY recurve. I didn't realize that protecting the stress level in your compression wood was such a high priority. Learning all kinds of stuff today.....this site is awesome
-
Marc, Are you talking about your non-deflex bows in this case? I think we also have to differentiate between absolute max performance for a few shots versus longevity and high performance over an extended lifetime.
Did Kviljio ever get back to you about the performance of the flight bow you made him? I was curious if that design would outperform a non-deflex handle bow.
-
Just got in
thanks for firing this up Pat!
I see you did separate threads for how much and were at
they seem to me to go hand in hand
I did not remember much discussion on here latly and it looked like a good time to do it
I can't keep up with you folks , post come in faster than Ican read
I feel 3" of reflex is about all we need and agree that near the tips is best place for it
If we use Gary's formula or Papys flip the tips does not make a huge difference in the end! Y
There does seem to be some merit in what Pearly was saying about corresponding reflex with limb taper but either one of these methods gets you in the ballgame!
Good recurves get you close also but can be more work than the others ways.
Also think about Boardhawks recurved levers , I love them and hope to one day to do some myself!
with proper tillering methods we should not be loosing much reflex at all so no reason to put in more just to lose it
Have fun
Guy
-
Another very interesting topic I can't contribute much to. :laugh: ;D ...reading with interest. the little experience I have is that any reflex from 1-3" seems to make a noticeable difference. I have one that I put 6" of relfex into and it ended up with about 3" after tillering and shooting in. It performs very well. I will say that it does have a hickory backing. And I think I made some mistakes tillering. I think it took more set than it needed to. but I don't know. It shoots good so I'm happy with it.
-
For me,as Pearlie said learned a long time ago that adding 6 and winding up with 2 don't seem any better ,maybe worse than adding 3 and winding up with 1.And adding 3 or 4 instead of 6 is much easier to handle/tiller and hit weight. I am not really into speed but do want my bows smooth so adding 3 or 4 inches to start and flipping the last few inches seem to work best for me. :) I have seen a lot of different bows built and to be honest the recurves of the same weight and draw
aren't much faster than the straight limbed bows with a little reflex,I'm talking FPS,smoother,yes usually but faster not so much,at least for me not enough to make me want to go to all the trouble and risk to build many. :) Love reading all the different takes on it, interesting stuff. ;) :) I think most start out building a bow out of what ever they have to start,then move on to adding a little reflex,then a lot and then settle into what suits them the best and that is what this selfbow stuff is all about,what ever makes YOU happy, no real right or wrong, just different. ;) :) :) :)
Pappy
-
Looks like you guys got this one about whipped....most all the experienced guys concur as do I
-
Yep, Pat pretty much summed it up for me in his opening post. :) Josh
-
This was a good read. Learned a lot, and I think I may be inspired to try my hand a deflex/reflex design.
-
Marc, Are you talking about your non-deflex bows in this case? I think we also have to differentiate between absolute max performance for a few shots versus longevity and high performance over an extended lifetime.
Did Kviljio ever get back to you about the performance of the flight bow you made him? I was curious if that design would outperform a non-deflex handle bow.
Talking about both Pat.
I had forgotten about that bow I made Kviljio. I don't think he did get back to me about it.
-
This was a good read. Learned a lot, and I think I may be inspired to try my hand a deflex/reflex design.
Well put. +1
-
Marc, Are you talking about your non-deflex bows in this case? I think we also have to differentiate between absolute max performance for a few shots versus longevity and high performance over an extended lifetime.
Did Kviljio ever get back to you about the performance of the flight bow you made him? I was curious if that design would outperform a non-deflex handle bow.
Talking about both Pat.
I had forgotten about that bow I made Kviljio. I don't think he did get back to me about it.
Did you find that the reflexed bows had a slight edge over the deflexed handled type? Even if they dropped off a bit if overstrained.
-
If you're talking performance then no. I can't say I've ever made a deflex handle recurve selfbow to equal the performance I was getting with the straight handle bows I was making many years ago but then I didn't try very hard either.
-
I think the answer to this is:
- when it causes the back or belly to fail, whether prematurely, or later down the line,
- when it deters from the design, by causing stability problems like twist, or similar problems,
- or when it just goes against the bowyers personal preference.
-
Mark, I am surprised to hear that but happy to hear that as well. I always thought your deflexed handle bows were the fastest, I know they are fast.
My fastest design with either hickory or boo backed and even on self bows is the simple pull down the deflex to where mid limb is the same levels as the bottom of the handle then start reflexing out to about 4 1/2" If I can maintain over 3" I know I will have a fast bow. My chrono is not working right now but I have one I really want to test. A hickory backed cherry, I started with about 3 1/2" reflex and finished with 4 1/2". I was going for 50# but dropped it to 35# using the no set tiller method.
-
I guess it comes down to maximally straining the potential of your material. Personally I much prefer the straight handle with reflex over the deflex handle.
-
Here is something that has always puzzled me about reflex. Not sure if I can even explain it right. So if we have any engineers handy that can expalin it better please jump in and help.
The main reason I give a bow reflex is to have higher draw at brace height. The geometry on my bow determines how fast my bow will build pounds as I draw it. If I am getting 10# draw at say 9" (6"brace height) this means I have to gain a little over 2# per inch to come in at 50#. The style bow I builds faster than that so i have to lower the brace height tension until I can hit my 50#@28". The more radical designs with very low string angles and contact recurves can have a higher force draw curve and build weight slower so they can have higher brace height tension. Intuitively a lot of people think a bow gets harder as we draw it back because the wood is building up tension which isn't true, it gets harder because the angle we are pulling at changes as we draw it.
I think my point is that the amount of reflex we can benefit from has a lot to do with the style bow we are building.
-
Steve
I haven't built a lot of deflex handle selfbows and certainly not many as recurves. You need pretty good wood for that because all the reflex is heated in, the recurves more or less just get the tips back up to the handle. I like to start with at least 4 1/2" of reflex, better with 5 1/2", and if the wood is elastic enough I'll end up with 3"..
To be more precise it's actually partly true that a bow gets harder to draw because of wood tension.