Primitive Archer
Main Discussion Area => Bows => Topic started by: DC on December 29, 2018, 12:02:21 pm
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I'm just finishing up a Yew ELB and now I know what hand shock is :o I want to decrease it(obviously) without affecting the draw weight too much. I think reducing tip weight is the first step. If I confine my weight reducing to the tip 8-10" will that minimise the draw weight reduction?
What else might it be? The bow looks the same as any other ELB I've made and this is the first one I've had with hand shock. Lucky I guess. The tiller looks as even as I can see. As a matter of fact I was rather pleased with this one.
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I might have a different opinion on this than most but my experience has been that tiller shape is the primary cause of handshock assuming you don't have big bulky outer limbs. I started using a gizmo a few years back and the first thing I noticed was all of a sudden my bows started getting handshock because the tiller was too even and the limb tend to come back all at once. A circular tiller is the worst offender. Using a slight increasing bend as it goes away from the handle means the near handle wood comes back first and the last thing to come back is the tips. It lays the limb out more like a fly line and doesn't produce any shock. I still use the gizmo out to about 23" draw and then I start increasing my tapers in the outer and mid limbs.
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So I should make it a little more elliptical?
If I try a heavier arrow and it helps does that tell us anything about the root cause? Like if a heavy arrow helps, does that mean the design/tiller is OK but the tips should be lighter?
I tried lighter arrows and it helps. The shocky ones are around 350 ish grains and the heavy ones are 550 ish.
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It looks like you already have an elliptical tiller, how is the shock with the heavier arrows? B-50 or FF?
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FF and there is less shock with the heavier arrows. I reduced the tips and took a few scrapes off the outer half of both limbs. It feels better but I might just be getting used to it. I'll shoot another bow for a while and then come back to it.
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Yes I agree with Steve. Tiller shape does play an important role in hand-shock. Keeping the center section relatively stiff especially in a low weight ELB will reduce hand-shock
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I’m wondering if the tips are bending too much for this bow. I normally like my tips to break away from the ellipse sooner than that, around 6” or so from the end.
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Something I did notice building this one is that it's not physically balanced. One limb is heavier than the other. It's odd because it's made from sister billets. One limb was much stiffer than the other so to get it to bend I had to reduce it more than the other. I checked the thickness and width every 6" and made them the same. The stiff limb is around 1/32" thinner most of the length.
While I was measuring the thickness I noticed that one limb, the heavy weak one, is deflexed a bit. I'm going to try to heat treat and pull it straight. That should make it stiffer and allow me to reduce the physical weight. maybe make it balance.
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DC, you mentioned that one limb was "deflexed a bit". That limb is not doing its share of the work which means it needs to bend more than the other.
The picture perfect, eye candy tiller is not always the best for the bow.
I'm not in the tiller shape affects hand shock camp.
Jawge
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You're right George and I knew that. Just somewhere in there I lost track of what I was doing. I'm not sure now if the deflex was there earlier on in the tillering. It may be set. I did a little heat treating earlier on and maybe I did one limb more than the other. Whatever, I screwed up and now I get to see if I can fix it. It's all fun and learning ;)
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You could also turn it around and see if it is less shocky. Jawge
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I think hand shock is one of those grey areas, what one perceives as hand shock, another may think is fine.
I suspect that one cause is simply poor grip comfort.
ELBs (especially laminates) of tend have rather flat backs with a noticeable corner where sides meet the back, that can really bang into the knuckles.
Similarly if the belly is too flat and the grip poorly shaped it can bruise the lower thumb joint.
I've noticed this on some fairly wide warbows and a bit of fiddling and fettling round the grip sorts it. I have an 80# hickory backed Yew and I added a leather pad on the back, blended in to give a rounder grip which made a huge difference. (It looks odd without a leather grip covering the whole grip area... but I can't be bothered! ::) as I rarely shoot it... it's my only 32" draw bow, so it's just for demo' )
Personally I don't believe arc of a circle tiller is to blame as such, maybe it's more like excessive bend in the centre.
Some longbow "designs" are roughed out even thickness and with over the centre section (maybe 20"), which to me is wrong. My thickness taper starts pretty much from the centre (or a couple of inches either side), and I do fade up a whisker to the grip, so you automatically get a slight thicker grip.
I think there are other contributory factors like brace height too low (or too high? :o ::) ) Arrow not well matched to the bow etc.
Maybe it's a lot of little details like much of bow making. Once a bow is shootable there is still plenty of tuning to be done.
Maybe just lightening the tips won't help, but if a few other things are done as well, hopefully the problem will get resolved.
Del
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You have been in full RD mode for a while. they are the smoothest by far. The two designs are on opposite ends of the spectrum.
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That's a very good point to remember there Chris.
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You have been in full RD mode for a while. they are the smoothest by far. The two designs are on opposite ends of the spectrum.
It's probably mostly this.
Put a nice Gilman Keasey style cork handle on it and use the arrows that soak up most of the energy and call it good.
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It's a nice day(but cold) today so I'm going to try a few bows and see if there is a big dif between my RD's and ELB's. I heat treated the weak limb yesterday so I'll let it sit outside today to re-hydrate. I would like to blame my arthritis but it was a different hurt/thump. It definitely irritated the arthritis though and I wouldn't be able to shoot it much.
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PD was right :D.I shot a couple of ELB's and then shot an RD. Night and day difference. Hardly even felt the arrow leave the RD. The ELB's didn't seem to kick as bad as the one in question but I'm probably getting used to it now. Good one PD, I'll definitely remember this, thanks
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DC,, I have thought alot about this,, and I am guessing that if you weighed the long bow and the RD,,, there would be a difference in relation of mass weight to the draw wieght,, i am guessing that the long bow,, has more mass weight relative to the draw,,,
its easy to do that,, cause making them longer is traditional,, but adding unneeded mass,,,,, will increase handshock,,
an extreme example would be making one 72 inches ,, 40@ 28,,,
now cut it off to 60 inches,, and re tiller to 40#,,, its gonna be smooth as butter ,, it might take a bit of set,, but it will have less handshock than the too long,, too much mass bow,,,
yes I feel there is a difference in hand shock with different designs as well,,for example ,, a short sinew backed bow that is light in mass,,, is gonna shoot like a feather,,, (SH) a self bow that is too wide too long and overbuit,, is gonn have a nice side profile and not take set,,, but its gonna kick,, and not be pleasant to shoot,, even though it would have the appearance of being right on,, its mass to draw weight is out of balance,, :)
even if I am wrong about the relative mass weight between the two bows,, reducing the mass of the long bow and re tillering,, could have a positive effect on reducing the shock,, if you are not happy with shooting it,, you have nothing to loose,, and might get it to shoot a bit sweeter,,,,, and yes I have cut the horn nocks off one to do just that,,,, it was awful thinking about it,, but when the bow shot better I was ok,, :BB
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Good thought so I went and weighed and measured them. Amazingly they weigh the same, 476 grams. They are the same length, 68" but the RD has recurves. And they are both right around 40#. The ELB ain't so L ;D. You can tell that the weight distribution is totally different though. The ELB has a skinny handle so more of that weight must be out in the limbs. The RD is quite strongly reflexed and recurved so the limbs are lighter for the same draw weight. They are completely different animals. The RD has most of the weight in the handle and the ELB has it in the limbs. Sounds like a recipe for more thump in the hand(I changed that from handshock) to me. Oh, I never did get past the temp nocks on the ELB.
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well tht makes since bout the distrubtion,,
I think u are right about the rd having lighter limbs,,
so tiller the long bow to have lighter limbs, ,and that should help,, make the center a bit stiffer etc,,,
good point,, I still think the long bow could go a bit shorter reducing mass a bit,,,but I am just guessing and spit balling,, (W