High nock height resolution

[BenBow]

I posted this on the Bowyers Bench but since there have been several people who have had trouble with having to use a high nocking point I thought I'd post it here too.

For years I have had to use at least 3/4" or more to get level arrow flight. I shoot 2 fingers split corner of the mouth anchor. I've tried from 1/2" positive tiller to 1/8" negative and the negative tiller helped slightly. My bows have always had a medium high grip. I did a slow motion video of a bow I finished and was amazed at what I saw. The nocking point was at 3/4" and you can see the nock end of the arrow drop on release then bounce off the shelf. I used to shoot target compound bows and the grip on those bows was low and I was taught to put the grip pressure an inch low on my thumb pad to keep the pressure in a straight line to the shoulder. This worked great with the compound so I've never changed besides it is easier to hold that way when fatigued.
Here's the slowmo video. You may have to run it through a several times to see how it caused the arrow to porpoise.
   
My sander is still in the shop so I took a trashed riser and mounted a trashed set of limbs so I'd have something to shoot besides the zombie bow I built. The riser was made with actionwood and it started splitting apart in a couple of places so I didn't feel bad taking a rasp to it. I cut the grip down a ways and kept shooting and taking more wood off until it started shooting well.
Here's what it finally looks like.
I've taken about 1/2" off the lower portion of the grip and cut away some more below that where the lower part of my hand rested on before.
     
Here's the belly side of the grip showing a small flat spot just below the low point of the grip. You can see the splits in the wood so I hope my sander gets back soon so I can get a new bow made up. But at least now I have a pattern that works.
   
I went out this morning and did a bare shaft test at 30 yards. I'm shooting 28.5" Beaman ICS speeds with 150 grain brass inserts, 250 grain points, 4 3.5" turkey feathers and a 4" aluminum outsert. Total weight is 685 grains and 31% foc. The bow is 44# at 28" and I draw about 28.5". I have the nocking point at 3/8", brace height is 7 1/8", tiller is dead even and the limbs are equal length from center.
Here's my 30 yard group the bare shaft is 3" left of the group which shows slightly weak for my left handed shooting but I'd rather slightly weak than too stiff. I think I've got the nock high issue solved
     
Here's the bow on the tiller tree. Draws nice and straight.
   

[twitchstick]

Very interesting! Thanks for sharing.

[Doc Nock]

You tried some Super Glue down in those cracks and clamp it to see if it helps?

You're always into some interesting project, Galen...

Where'd you get a slow mo camera that good?  That's pretty slick!

[BenBow]

Dave I used my Panasonic Lumix and then slowed it down some more on youtube.

[dirtguy]

Nice slo mo and great point.
Sometimes we forget how a small smount of grip pressure can have a big affect on how the arrow flies.

[Orion]

Glad taking down the grip worked for you.  Basically what you found is you shoot a low wrist grip better than a high wrist grip. Or, looking at it another way, lowering the grip had the dynamic effect of changing the tiller of the bow/timing of the limbs. It may or may not work for others depending on how they grip the bow, where they put the most pressure on the riser.  

Another factor that interacts with the outcome of different pressure points on the riser (and ultimately the tiller or timing of the limbs) is the distance above center that the arrow shelf is cut.  Most bowyers cut the shelf about 1 1/4 to 1 3/8 above the center of the bow, but some bowyers place it as much as 2 inches above the center of the bow.  Even, applying identical pressure on identical parts of the grip will cause the limbs to flex differently/unevenly for arrow rests that are different distances above the center of the bow.

[BenBow]

I agree, dirtguy & Orion

[BenBow]

Mike got me wondering about the spine so I turned the plunger in somewhere between 1/8 and 1/4 of a turn and here's the 4 arrow group. I'm happy with it. Now if I can just replicate this with the new bows I've got started.
   

[Doc Nock]

Dude...

That's some sweet shooting...especially for a LEFTIE!    :rolleyes:    

[LongbowArchitect]

Geez BenBow- I wish I could shoot that well.

[BenBow]

Some days I'm luckier than others lol

[Doc Nock]

...and always sooo modest, Galen!      

[Sockrsblur]

Great thread Ben, thanks for taking the time to post and share it... So turning the plunger in towards the riser weakens the shaft spine, right?

Awesome tuning!

If you don't mind, why the shoot the bare shaft? What does that tell you compared to the fletched shafts.

[BenBow]

James fletching can mask tuning issues so if your bare shaft arrow hits with your fletched shafts they're coming out of the bow the same. I'm left handed so a weak bare shaft would hit left of the fletched group and the opposite if they were too stiff. Since the bare shaft was left in the first group I screwed the plunger in which moved the shaft away from the window of the bow which caused the arrows to act stiffer. If you have to make large adjustments the spine on your arrows is too far off.
Doc says I'm modest but the fact is some days I am luckier than others. I've had several surgeries that have weakened me. I kept trying to shoot but the weakness caused me to pick up some bad form that I'm trying to get corrected. This bow even though it is built with trash parts is shooting better than any bow I've had. I am so thankful to people who have shared their knowledge which has allowed me to make the bow fit me instead of me trying to fit the bow.

[Doc Nock]

Good explanation, Galen. Simple and clear and to the point.

You ARE modest.  You might be lucky, sure, but we sometimes create our own luck with a humble heart and that, Sir, have you!!!

Has nothing to do with humility itself, it has to do with your allegiance to a higher power and simple trust in all things.  

Your friendship has taught me much about my own "walk" and where I need make serious corrections.

I'm glad you're strength is such you can still shoot and I hope you get your sander back to build a bunch more bows and risers!

Peace, my brother!  Thanks for your friendship!

[Sockrsblur]

Galen thanks for the further explanation, and good for you working your way back from adversity.