vane hitting shelf

brman

Member
I am seeing witness marks on the shelf of my riser where a vane is hitting it - marks pretty much full length on the shelf. This appears to be pretty much every arrow and I am assuming it isn't just bad form (although I could be proved wrong!).
At the moment I am just getting used to the bow so not ready for proper tuning yet but it would be nice to understand the cause for when I get to that point.

So, what is likely to be causing it? From reading around I get the impression nock point too low or perhaps a low brace height? Is this right?

for info, the bow is basically untuned (just very basic setup at the shop), brace height is just over 22cm (70" bow, according to the manual that is at the bottom of the range) and nock point is about 3mm above horizontal). Rest is a hoyt superest, no pressure button yet.
 


Del the Cat

Active member
Raise your nocking point 4mm.
This allows the arrow to leave the bow fractionally nock high, to give clearance and avoid feathers sticking in your hand if you are a longbow archer.
Its flight will settle very quickly, if you see the arrow porpoising, then you've gone too high.
Del
 


brman

Member
Raise your nocking point 4mm.
This allows the arrow to leave the bow fractionally nock high, to give clearance and avoid feathers sticking in your hand if you are a longbow archer.
Its flight will settle very quickly, if you see the arrow porpoising, then you've gone too high.
Del
Thanks, I suspected that would be the answer. I have read that I should tune the brace height before the nocking point. Is that correct?
 


Del the Cat

Active member
Thanks, I suspected that would be the answer. I have read that I should tune the brace height before the nocking point. Is that correct?
The trick is to expect to do everything more than once...
I don't actually shoot modern type bows with rests. I make wooden bows, which often require some fiddling and fettling to match bow to arrow to archer.
The key to all this stuff is to understand why and how it all works. Even the humble wooden longbow is a lot more complicated than people imagine.
Experiment with small changes, become your own expert.
Del
 


Lammas

Member
... and I am assuming it isn't just bad form (although I could be proved wrong!).
...
Albeit form could play a role.
Inconsistent release (like index finger too early or too late) could cause similar problems.
I would do an initial bareshaft tuning to figure out the optimal nocking point position, and shoot a bareshaft now and then.
 


geoffretired

Supporter
Supporter
Tuning brace height first or nocking point first??
I would say nocking point first, for two reasons. 1) it is more than likely too low and needing to be adjusted. 2) when you get it right you will know, specially if you use a bareshaft to check.
If you tune brace height it is not always obvious when that is in the best position. Trying to find a best position when the arrow is rubbing the shelf won't help. The brace height may not need to change anyway.
 


KidCurry

Active member
If you have just had a basic setup at the shop you really need to do a full setup which you can follow with some basic tuning. Here is a good article from
Bow International that explains the process.

https://www.bow-international.com/features/technique/recurve-setup-and-tune/

You will notice the initial nock point is 1/4" above square, just over 6mm compared to your 3mm. This alone may get you clearance but it is worth going through the complete process as it will give you a good basic knowledge of your bow.
 


brman

Member
Thanks everyone. It has been a bit busy recently but I did get a chance to have a play with the nocking point. At around 5mm the marking on the shelf was almost (but not quite) gone so it definitely helps. I could try higher but I ran out of time.
I suspect I need to fit the adjustable rest and pressure button I now have and do some tuning as per that article.

EDIT: on the subject of form, I did get someone checking that (he even took a slow motion video of me) and he did not find anything obvious, other than you could see the arrow kicking down on release.
 


brman

Member
https://www.youtube.com/watch?v=qYTSgY9PDxI
I hope this works. I am not good with things like this.

Just checked. it does show what you want to see.
Thanks. Yes, I think I see what you mean there but it is more of a slight kick down on release but the arrow still flies pretty true (looking from the side)? Or have I missed something?
I think what we were seeing was a more pronounced "nose up" flight as the arrow left the bow. Difficult to say for certain though as a mobile phone is not great for this sort of slow motion stuff!
 


brman

Member
Nose up is equivalent to like tail down, so more lifting of the nocking point perhaps.
I think you are probably right. I have discovered that if I clamp my nocking points just right (they are brass) they do not move when shooting but can still be screwed up and down the string for adjustment. This will make things a lot quicker next time.
 


geoffretired

Supporter
Supporter
Good idea to be able to twist the nock sets up and down the string, for testing and adjusting purposes. I would make sure they are more securely fixed than that, once you have them where you want them.
 


jonUK76

Member
I think tiller can affect the arrow being pulled down/up on release issue. Tiller is the difference in brace height between upper and lower limbs. On a recurve bow it's usually measured by taking the distance from limb and the string where the riser and each limb meet (at the limb pockets). If they're both the same - that is neutral tiller. I think I normally end up with about 3-5mm positive tiller with how I set my own bows up, which means brace height 3-5mm higher on the upper limb compared to the lower limb.

From the sound of it, as it has a strong tendency to pull the arrow down on release, which indicates the lower limb is stronger than the upper limb, I think you might try either winding out the tiller bolt for the lower limb or winding in the bolt for the upper limb (both affect the tiller in the same way, but the latter will increase poundage slightly while the former will lower it slightly). Small movements count - try just a quarter turn at a time. Marking the limb bolts with a permanent marker will help keep track of any changes, and allow you to put it back to original settings if need be. Note, changing tiller can affect the nock point height.
 


Whitehart

Active member
could also be arrows too stiff or too weak. The rest has a basic flap of plastic as a button assume the rest fitted has the thick sticky pad, this still might not be centring the arrow correctly (far enough out).
 


brman

Member
This is my problem, lots of things that could be affecting it but I can't change all at once ;)

could also be arrows too stiff or too weak. The rest has a basic flap of plastic as a button assume the rest fitted has the thick sticky pad, this still might not be centring the arrow correctly (far enough out).
Yes, it currently has the thick pad - the arrow point is just outside the string line so I think it is roughly ok but my next step is to add a pressure button and adjustable rest so that should be checked properly then. I also suspect the arrows are a bit stiff but I did play with some weaker club arrows with no obvious improvement. Probably something to check again when tuning though.

I think tiller can affect the arrow being pulled down/up on release issue. Tiller is the difference in brace height between upper and lower limbs. On a recurve bow it's usually measured by taking the distance from limb and the string where the riser and each limb meet (at the limb pockets). If they're both the same - that is neutral tiller. I think I normally end up with about 3-5mm positive tiller with how I set my own bows up, which means brace height 3-5mm higher on the upper limb compared to the lower limb.

From the sound of it, as it has a strong tendency to pull the arrow down on release, which indicates the lower limb is stronger than the upper limb, I think you might try either winding out the tiller bolt for the lower limb or winding in the bolt for the upper limb (both affect the tiller in the same way, but the latter will increase poundage slightly while the former will lower it slightly). Small movements count - try just a quarter turn at a time. Marking the limb bolts with a permanent marker will help keep track of any changes, and allow you to put it back to original settings if need be. Note, changing tiller can affect the nock point height.
It currently has 3 to 4mm positive tiller (how it was set up out of the box) so I was planning on leaving that alone for the moment.

Good idea to be able to twist the nock sets up and down the string, for testing and adjusting purposes. I would make sure they are more securely fixed than that, once you have them where you want them.
Yes indeed. Once I have sorted it I plan on going to a tied nock as the brass ones are already making grooves in my finger tab.
 


brman

Member
A quick update - I fitted the new rest and pressure button tonight and got a guy down the club to help me tune them. Just basic stuff by watching the arrow flight, no bare shafts or anything fancy ;)
Looks like my arrows are a little stiff but with a soft button they fly much better and faster than before. In fact I had to raise my sight by 1.3cm at 40yds and the sight is much more centered than it was before. Also only very occasional hitting of the shelf which I am happy to put down to a dodgy release as it is no longer obviously tail down in flight.

For the moment I think that is more than good enough so will leave it alone and concentrate on my form ;)
 


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