Handshock

[Rich Saffold]

I think most bows with hand shock is because they aren't as finely tuned as they need to be and much of this comes from experience and sometimes a bit of hands-on  coaching.

I can relate Steve, and sometimes it's why I'm checking out what the guys are making to help them reach the next level as opposed to working on bows. I do that enough at home..

If this stuff was easy, it would be boring

Rich

[Marc St Louis]

I don't believe timing has anything to do with handshock. How the bow is tillered makes a big difference. Light tips will make some difference. Handshock happens when the string slams home and the residual energy has no place to go but to travel down the limbs and into the handle, this is especially so in bows that bend mostly in the inner limbs. If a stiff handled bow is tillered to work more of the limbs and just leave the tips stiff then when the string slams home much of that residual energy will go into the limbs by flexing them rather than traveling down the limbs into to the handle. Also the additional mass in the outer limbs don't help either

[brian melton]

      Marc described my exact feelings. Arrow weight can have a effect (like Marc said) by NOT obsorbing residual energy from the limbs....but there are limits when it comes to arrow weight. Great description Marc...

Brian

[George Tsoukalas]

Timing is crucial. I used to think that bows that bend in the handle result in more hand shock. Brad Smith called me on that and he was correct. Bend in the handle bows are not automatically shock filled. Marc, I agree that tiller and timing are related but a character bow that appears out of tiller is not necessarily so because the limbs flex and return in unison. But I already sad that in a previous post. Here's the link for anyone who is interested. Jawge
http://mysite.verizon.net/georgeandjoni/seneca.html

[Justin Snyder]

Steve, I suspect that timing and mass have a lot to do with it.  

Kviljo's theory would have to do with timing and mass.  I think that if a bow has the mass near the handle return to rest sooner the whip tillered ends would act as shock absorbers because they bend easily.  If the the tips return faster then the handle area and your arm are the shock absorbers.  In these bows with both limbs hitting brace height at the same time then you would receive from to back vibration.

Some bows could have one limb reach brace height before the other then pass it before the string slams tight. The limbs would have to vibrate back and forth to reach equilibrium at brace height. This would give you hand shock where the top moves forward and back while the bottom is doing the opposite. This is exactly why I have always been scared to make a spliced bow with top and bottom limbs of different wood.  
 
I have some ideas I think I will try today to test these ideas.  Justin

[Badger]

Some interesting replies. When I refer to limb timing I don't actually mean they are not returning to brace at the same time because I believe they have to as they are attached by the same string. I have seen smooth bendy handle bows and shocky ones as jawge pointed out, I have also seen whippy ended bows that have shock. Too much mass in the last several inches I agree is a common culprit. I am leaning toward a primary cause being tiller shape not agreeing with the front view shape of the bows, for instance a pyramid bow will have approx equal thickness and a circular bend, they almost never have bad handshock, recurvesm and dr bow will usually have paralell limbs with stiff outer limbs, they very seldom have any real handshock, well made elb style bows with even tapers both in width and depth will seldon have handshock to speak of. Bows that have long paralell limbs but still remain relatively stiff in the outer limbs or even circular circular in tiller will often be the worst offenders. I think if a limb is paralell it should progressively bend more into the paralell until the limb starts to taper and at that point start to stiffen up a bit. (elyptical). I think if there is anything on the bow that doesn't seem to make sense or logic it will cause shock to one degree or another. Steve

[George Tsoukalas]

For grins and giggles put a bow that has excessive hand shock on a tiller tree, preferably a bow that seemingly has no obvious reason for same, pull it to full draw, let it down and see if the bow rocks in the cradle which would be indicative of poor timing.  Gotta go. Jawge

[Badger]

Thats a good point jawge, could maybe move the nock position around a bit also as Art suggested and see what happens.  Steve

[adb]

I agree with George. Bendy handle bows are not necessarily shocky. I have a beautiful Bickerstaffe longbow, bendy handle, full compass tiller, 74" NTN, with horn nocks. It's absolutely expertly tillered, and it's the most quiet and smooth bow I've ever shot... NO hand shock. I use fairly heavy wood arrows. In speaking with Pip this past summer, he mentioned the importance of proper timing in the limbs, keeping the tips as light as possible, and the value in using non-stretch string material like FF, which he supplies on all his bows.

[George Tsoukalas]

I've thought about the physics involved. I hate doing this even though I love science. I spent my adult life teaching youngsters about science and trying to transmit my love for it to their lives. I mean I was out in 15 degree F temps watching the last lunar eclipse. For some reason I've chosen to limit my involvement in the science of archery. But here goes, I had some help with this but I forget who it was on here, I do believe that in properly timed bows the force vectors result in a forward movement propelling the arrow forward allowing for the most efficient energy transfer. Imagine 2 billiard balls going at the same speed each say at a 45 degree angle to each other and impacting another billiard ball. If everything is timed properly that billiard ball will go forward. Imagine those first 2 balls to be  the bow's limbs. If they are synced all is well. If they are not one will hit before the other and cause erratic motion in the third ball. Same with an untimed bow. The energy is transferred to the arrow but perhaps at different times. The shock is felt by the archer. That's  it. I hope I wasn't too unclear. The concept of vectors is tough to get across. As an aside the best and brightest 2nd year chem students had difficulty thinking of vectors in regard to molecular shape. Ok that's enough science. I'm retired. Jawge

[George Tsoukalas]

As Art mentioned varying where the arrow is shot even by small degrees may mitigate handshock. The archer will also have to change the nock point. My last hickory bow was pretty shocky when I first shot it. All is well now. I flipped the bow around and shot it the other way. The limbs must have been untimed in the first instance. Flipping it around timed them nicely. Go figure. Sometimes it's hard to see limb timing on the tiller tree. Ok. I'm done. Jawge

[Justin Snyder]

Great analogy George. 
Steve, you are right in that the string will become tight on both limbs at the same time.  However one may have reached brace height faster than the other and gone beyond. The string would get tight before the second reached brace height.  Both limbs will eventually settle at brace height, but they will oscillate to get there.  Think of an overbuilt 60# limb on top and a super efficient limb on the bottom. The speeds will vary for these two limbs much like it would for two different bows. Like George said though, this could be corrected by raising or lowering the nocking point. I guess it will be easy to test this theory, take a sweet shooting bow and shoot it with the arrow 1/2" lower then 1/2" higher and see if it has different hand shock from what it did originally.   Justin

[George Tsoukalas]

Thanks, Justin. Good idea about varying the nock point. Jawge

[Marc St Louis]

For grins and giggles put a bow that has excessive hand shock on a tiller tree, preferably a bow that seemingly has no obvious reason for same, pull it to full draw, let it down and see if the bow rocks in the cradle which would be indicative of poor timing.  Gotta go. Jawge

George
That's not poor timing. That's just a bow that has one limb too strong for the other(out of tiller). I have said this before and Steve said it above. A bows limbs have to return in unison because they are pulled back that way.

If one limb is much stronger than the other then I would have to agree that it could deliver more handshock but not necessarily so. If the stronger limb is tillered to be stiffer in the outer limb then that would increase handshock.

[Marc St Louis]

I have built a lot of very efficient bows and when shooting those bow have varied the nocking point. If the bow is tillered right then moving the nocking point up or down does not increase handshock.

Now adb3112 mentions above a longbow he has that does not have any handshock. He also says he shoots heavy wood arrows from that bow and most everyone knows that heavy arrows is one way to tame handshock. I've never met a longbow that didn't have handshock, unless shot with heavy arrows.

A good way to tell if your bow has handshock and this is a full proof method is to test that bow with an arrow of 6 or 7 GPP, even better if you use an arrow of less than 6 GPP. I have shot some of my bows with arrows of 5GPP and handshock is negligible with a well tillered and efficient bow