Primitive Archer
Main Discussion Area => Bows => Topic started by: simk on November 13, 2018, 03:16:29 am
-
Hi Folks
There was a little yew stave waiting to become a bow. It was short and narrow...not too many options with that one - either a childs bow or some kind of experiment...
Tapers from 1" at the handle to 8/10" at the tips.
Tried to do a pentagon cross section first time which i found quite difficult to work to an even thickness taper. How do you generally judge a pentagon cross section? Does it make sense? Advantages/disadvantages?
Takes a bit of set that dissapears again over night. Shoots quick and dirty. Don't dare to pull it past a 26" draw (Probably not taking full advantage of that tip solution).
The fd-pic might cheats due to handle/hook-position. Will take a real fd pic in hands when my wife is available - hope i will not have to retiller. Until to thiis pic the bow was balanced in my eyes, also the arrows lifted well from my hand.
Cheers
-
more
-
more
-
more
-
Neat bow. Those tips! What are they made of? How did you attach them? I love the experimentation, but I've got to think those add a lot of weight. What's your thought process behind them?
-
Halfbow took the words right off my keypad. It's a beautiful bow. Bend looks fantastic. Tips are certainly out of the box. Beautiful but seems a bit heavy out there. Very nice workmanship.
Bjrogg
-
Tiller looks good! I think the sharp belly ridge possibly adds to the set. The nock system is quite clever and makes use of maximum length of the bow but it will probably slow the arrow speed down and add some hand shock because of the mass. I think if you reduce it by 70% it wil actually work great!
-
Agreed. Beautiful bow and interesting experiment. I was thinking the set is coming from the high crowned belly too. The tips although very well done look as if they may add too much weight out there. Very well done though I must say.
-
Hi Folks
Thanx for your comments! Still curious about further opinions about the pentagon cross section which I occasionally have seen on bows in the www
I thought you might be curious about those tips 8)
As the stave was very short I had concerns about stacking and string angle. I was thinking about mounting some kind of shiyas but was afraid of getting a well fitted splice. So this design avoids stacking I think and surplus provides 2" of reflex.
It's made of epoxy, enriched with a bit of charcoal. I don't think it's really havier than stiff wooden shiyas....?
I'm not really a expierenced shooter but didn't notice hand-shock (i was afraid of). Sure it would have been possible to reduce them further, but not 70%. Prefferred to stay on the safe side. Will try it again, probably less extreme.
This epoxy method provides uncountable easy tip solutions in any colour you like and always perfect glue lines ::) If it wasn't epoxy I like it a lot.
Cheers
-
Cool experiment. I really thought it was horn of some type.
I'll wait to see the bow in hand before I comment on balance. Like you said, I'm not sure about your cradle and pull hook positions. Making the bow perfectly balanced could help some with the hand shock. The rest will be in reducing tip weight. It doesn't look like your handle area is bending too much, but I'm just a beginner on these bendy handle bows.
-
Outlandish looking or just different type tips on your bow.Congratulations!!!Very nice work.As short as it is hand shock should'nt be a problem.I could hang that bow from a twig in a stand anywhere I pleased.
-
Interesting... funky, weird. Looks like you need to pull just a tad more to get lift off as the string unwinds off the cams.
Looks like the Yew would take some more bend... specially if it's not me that's pulling it* ::) ;D
Great for teasing compound shooters.
Del
BTW.
The other day I mended a Yew ELB for a guy. he'd somehow sheared the tip off, it needed a little re-tillering too (he'd made it on a course and it had a weak area and a couple of thick spots that needed blended in).
I made sure he pulled the rope when it was on the tiller >:D.
-
Outlandish looking or just different type tips on your bow.Congratulations!!!Very nice work.As short as it is hand shock should'nt be a problem.I could hang that bow from a twig in a stand anywhere I pleased.
Didn't think of this! You could hang this bow anywhere. That's a great feature!
-
The tips take some getting used to but i like experiments and trying different stuff.
-
Yeah del, the string doesn't lift of with my tiny 26" draw - so the next one maybe will be shorter 8)
in the meantime my little son helped me out with the fd pic...its not perfect but combined with the above pic you could get an idea of the tiller.
Cheers
-
Very novel idea and well executed. It must be a bear to brace. Nice bend. For future reference "V" joints on the tips are very easy to do. The wood is thin enough to flex a bit so a good glue line just happens :)
-
Really nice work, but if you have no string lift off, that epoxi thing only adds mass and makes your bow slow.
I admire the idea and like experimenting also.
-
Simson, thanx for making that clear - i'm not completly through with bow mechanics so it was try and error.
so this epoxy thing has zero effect on stacking as long as the string doesent lift???
ok. what if i tune it a liitle bit and bevel and round more from the bottom? ther's still room for doing that i think.
while building i often thought about the relation between the exact shape of this epoxi thing and draw curve. i was even close to ask here at pa...should have done that.
cheers
-
Simson, thanx for making that clear - i'm not completly through with bow mechanics so it was try and error.
so this epoxy thing has zero effect on stacking as long as the string doesent lift???
.......
Yes no effect, you can see the string is just at the end of the yew limb. As said that epoxi is just additional mass at the most critical point - at the end of the limb= end of the lever.
You should think over the mechanics of a recurve bow. There are a lot of parameters that influences the efficiency.
Here is a very good article: https://www.bio.vu.nl/thb/users/kooi/thesis.pdf
If you don't believe me:
Measure the speed now and compare with cut of epoxi. I'm absolute sure you will see a great influence of the lighter lever (= limb).
-
Nice experiment! Looks like the stick they use in China for transporting two buckets of water!
PS: yes im in! Going to write you a pm!
-
Thanx +1 Simson - the bow is now temporary stored in the hall of shame 8) maybe I will do as you suggested...cut it off and measure speed before and after.
Thanx + 2 Simson for the link - very very scientific, almost rocket scienece from my point of view - maybe something for the upcoming long and dark winter evenings.
Allow me one more question: With the shown draw of 26" the string angle is almost 90 dergee. Would there be a positive effect of this epoxy thing if drawn further??? Del?
bttw: Maybe I could sell it in china for good money? Looking forward to hear from you.
Cheers
-
If drawn another say 3" the string would lift off and effectively lengthen, lowering the draw weight like the "let off" on a compound.
Imagine you bound the string so that it couldn't lift, if you draw another 3" the tips would pull back say another 1". If the string is allowed to unwind off the epoxy that will let the string come back further... so for your 3" of extra draw the tips would only be coming back maybe 0.75" .
So what does that mean?
At 3" extra draw, as the sting unwinds the pounds per inch of draw weigh is less (let off) and there is less strain on the bow that there would have been without the epoxy cams.
Another way to look at it.... you are suddenly putting an extra few inches of slack into the string, so it draws further.
In terms of performance, this will give a slightly more gentle acceleration over the first few inches of the loose, which should give less arrow flex and less wasted energy.
All the above is just my understanding of it, I'm happy to be shown to be wrong... terms and conditions apply etc etc ;)
Del
-
Sound's interesting del :D Maybe I'll mount my fullface helmet and draw it to 29" (and take a lot of set... :()
I was also thinking about changing tiller and let it bend more on the outers so that the "let off" effect will begin on earlier draw - but this will probably cost me draw weight.
Cheers
-
Smik I wouldn't change your tiller. It looks great. Just the shape of your tips. They need a bit more radius or less angle to let the string come off before full draw. I personally like a fairly gentle curve that increases the amount of string that is let off as the last few inches of draw are drawn. I wouldn't put that bow in the hall of shame. It's a interesting idea. Just might have to tweak it a little. Hope to see it again.
Bjrogg
-
Hello bj
This option I was also evaluating when falling asleep yesterday (-; The problem is, that the tips are fairly reduced with the hole so that I'm getting into statical problems with further reducing to a bigger curve. So I thought to just deepen the middle groove for the string what will virtually shorten the bow and get that better radius so that the string lfts off earlier - as you suggested!
That might be the plan now. My update will follow.
Thanx 2 all. You are so helpful!!!!!!
Cheers
-
Smik, just throwing this out there. Could you add more epoxy mix to change angle of tips. Maybe cut some off and add some on. Not sure just a thought.
Bjrogg
-
It appears that you cast the epoxy as a block right onto the tip and then shaped it by hand, from a pattern, maybe? Very unique idea! Nothing wrong with a short(er) 26" draw length, either! Nice bow!
Hawkdancer
-
Just had another look at your construction.
If you like to do another experiment, think of this:
What about glueing on that epoxi thing on the belly (not on the back ), making just a Quarter of a circle. Limbs more or less straight at brace. When drawing the bow the string unrolls from the cams. Just an idea ...
-
another good idea bj. I'll give her some time now to decide on how to become a working bow. She'll be back 8)
Hawk: Just place the stick in a cup/form filled with epoxy, place the stick in it and let it react. Where you don't want the epoxy to stick put some wax or grease first. If you plan simple nocks wax the tip and the sand it down then. The epoxy will only stick where you want it. For UV-protection you should lack the epoxy (pic).
Simson: That sounds interesting. Still hard to imagine...my inner eye somhow doesent work with your description. If you do you suggest some kind of deflex-construction @ the fades wouldn't this lead to a very low initial draw weight? Of course it's to consider also that it's tillerd out with 2" of reflex. I'm still lookin' for the best solution and I'm open for experimental ideas. Maybe you could try to explain again or draw on your weiss-beermat for me ;D
Any design-suggestions welcome for those epoxy things!!!!!
Cheers
-
This is a great looking bow and cool ideas with the tips. Reading everyone's responses has been educational as well. Thanks for posting this simk! :)
-
what I meant:
Unbraced: continous reflexed limbs
Braced: a straight bow (tip to tip) when braced, braceheight comes from the mounted epoxi - thing (= mounted on the belly at the tips, a quarter Draw: of a circle, radius looking outwards)
the string will lift of continously when the bow gets drawn, and is full lifted off at full draw.
Btw. , a string angle > 90° makes no sense in my opinion.
-
This popped into my brain. Heavy pull until string lifts off rings and then it lightens up. Primitive let off. ;D Adjustable by the size of the rings and length of the levers. Am I missing something obvious. Maybe a little wobbly?
-
Ok fellows, here's fancy yew 1.1.
Did the most simple correction - we have a virtually shorter bow now and the string lifts off over an even round...should work better now.
Still open for new designs as adding epoxy and changing would still be possible. tomorrow I'll first shoot her in the new setup.
Cheers
-
DC & Simson
It took me some time to think about your suggestions: You both suggested some kind of artificial deflex constructions. What's the intention? Less stress on brace? Longer draw length for a short bow? Geometrical correction of version 1.0? Did you mean something like this Simson?
Very Interesting - thanx
Edit: DC, studied it again - weird idea...what would be the draw curve? Would it store more energy? After the string lifts off the rings it would be the same bow as before/without...
Edit2: Simson: Some Guy in the german forum did experiments with so called zero brace height bows with "decurves"...maybe you have a similar idea...I stole a pic... it's about brace height and efficency
https://www.fletchers-corner.net/phpbb/viewtopic.php?f=15&t=30676 (https://www.fletchers-corner.net/phpbb/viewtopic.php?f=15&t=30676)
-
I've thought about this off and on and I think if you squint and hold your mouth right you can see that my drawing is really just an R/D. The string changes direction instead of the bow but I think that the FDC would look much the same.
-
Wow! Amazing, beautiful work
-
No bow with that fine a tiller should be in a "Hall of Shame". Nicely done.
I think the tips are unique and give you good 1-1.5 extra inches of draw.
Jawge
-
That is the weirdest bow I have seen in a long time. Weird in the best possible way though. I love what you have done, very clever.
-
Very cool love the tips
-
The bow in bend is great, but those tips are just added weight.
-
Craftsmanship WOW. That a strange beauty. I find no advantage to it as far as performance. Now if that cam worked like a compound. That would be a different story. It just an opinion. Again craftsmanship wow. Arvin
-
That is really novel and you deserve huge applause for trying something new. It isn't all that often that I see something totally new in a 10,000+ year old technology. Really interesting and I suspect you have opened a door that a lot of others will now walk through to a bunch of new ways to affix a string and alter the F/D curve of a bow.
Well done!
Matt
-
Missed this the first time around. Very creative idea. 55” is plenty of length for a bend through the handle bow with 25” draw length. 2x draw is the limit for a bendy handle bow on average unless the design is made to handle more or less. I would guess that this is about as much or more work than reflexing the tips but looks very unique and interesting!
-
Neat!
-
Yessir! That’s a helluva way to add recurves for low string angle and increased preload, and it looks like it could be lighter than if you had 3 more inches of wood on each tip. It just looks like you need to do the same thing but shape them more elliptical and tear dropped off the end of/around the tip toward belly so that the string will lift away somewhere around 23-24” of DL...which would drop you into a sweet, non stacking...almost a let-off as you come to anchor. Man, you are on to something right there. Work of art and a promising bit of engineering smarts to-boot.
-
As for set...considering the size limitations you are facing and not having a clue about that cross section...I’d sinew the snot out of that thing and waterproof with some sturgeon. Purdy no matter what.
-
thanx guys - it was a real fun build. what motivates me in bowbuilding is to do something new to me with every bow. it seems that I'll have to repeat that one tough, with better design. (-S
-
Thanks for taking the risk and thinking out of the box Simk. Sure this design has issues, but it illustrates some cool points too. Beautiful bow and excellent craftsmanship. Very interesting stuff, as always