Striking shelf

[briandean]

Perhaps someone can help me here, please. I'll give a bit of history to help.  I started shooting about 2 years ago - borrowed, then bought a Martin longbow (45 @ 28).
 
The previous owner bought it off a catalogue (we're in South Africa) and when it landed here, found he couldn't shoot with it - just couldn't hit anything.  It worked for me, but I have ALWAYS had the problem of the arrows hitting the shelf.
 
 
 
 
I have adjusted the nocking point endlessly, replaced the shelf material and so on and so on.  The long & the short of it is this: I can hit a 9 inch plate quite consistantly at about 25-30 yards.  I have hunted many pigeons (and others - but pigeons are small) and recently won a trad 3D competition after working my way up through the ranks over 2 years.  The point is that I shoot accurately despite the shelf strikes.
In fact, the shelf wood is now wearing away and all my arrows have marks on them.
 
Is this normal? Should I be worried? Is there a solution or should I just carry on?  My arrows last - with a stripe.  The fletches aren't coming off and my hand is not being hit.
Thanks.

[Cable Guy]

Wow.
1st thing I think of is stiffness....but thats not the issue with a 3555.
Lets ask this...
Whats the recommended brace height for that bow?
I would raise the brace height within the recs,
and also observe my release......paradox.

[Cable Guy]

......almost forgot to ask about your arrow weight as well.

looks like the riser is scooped out rather than being flat, to alow arrow to bend away from flat of window, maybe biuldup shelf a bit 1/4 inch or so,

[briandean]

Thanks for the replies.
The recommended brace height is 7.25 to 7.75-set at 7.5 at present.
The arrows vary - I shoot 30 inch Gold tip 3555 or Easton 500's @ around 405gn for competitions and 29 inch Easton aluminium 2018's 590gn for hunting.
If the riser is scooped out, shouldn't the arrow be hitting the riser and not the shelf?
I think I'll put a match under the skin on the riser to lift it a bit - could do it.
The brace height thing makes sense - to release the arrow earlier so it can 'paradox' round the riser.  Maybe increase it to max 7.75. Make sense?

[xtrema312]

 Bouncing arrows of the shelf until you wear off the wood is not the most accurate way to shoot, but I did well that way this summer after some changes in form started this for me.

You could be very stiff.  What is your draw lenght and point weight? At 405 gr. I don't think it is much.  
 
If all else fails try this link and see if you are possibly having this.  If so let me know if you have any questions.  I have it fixed for the most part.


  http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=6;t=005013

[Cable Guy]

Yeah, this compression will weaken your spine early enough to curve around the bow.
7.75.....or until the arrow flies better.

Let me know how it turns out.

Chip.

[xtrema312]

Raising the brace raises the draw weight and that makes the arrow flex more.  1/4" is not going to get you much if your arrow is about 10# too stiff.  Gt3555 30” with standard insert and 125 point is about 420 gr.  If your bow is say 1/8” cut out from center and you draw 28” with some silencers on the bow you could easily be 10# too stiff on the arrow.  You need to determine if you have the right arrow spine for starters.

I don’t get the dished shelf.  I have seen that, but not on many bows.  I would think some amount nock height would allow it to work by flexing the arrow out and up more on the back, but it has not for you.  I would put a strip of leather or something down in the dish to level it out to see if it helps, but check that spine.  

If you arrow shoots straight now bouncing off the shelf, I can almost guarantee you it is too stiff.  It has to be to bounce off the shelf and fly straight.  If it was spined right and hit the shelf it will fly way weak.

[xtrema312]

The more I look at your pic's the less I think it has a dished out shelf.  It looks more like the shelf and riser have high points to minimize the arrow to surface contact.  It looks like the shelf curves down from the high point, and the angle of the pic's make it look a little dished.  In the last pic of the riser it looks like the bottom of the arrow is well above the edge of the shelf.

      http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=6;t=005013

[Quinn]

I had a similar issue. It seemed like the arrows were bouncing off the shelf. I did the same as you, all over the place with the knock height and no relief. Finally figured out it was two things. My release was putting too much spin on the string because of nock pinch the arrows were too weak a spine and they were hitting the outside of the shelf as the came around the bow. I adjusted my fingers on the string to ease off on the pinch and I raised the brace height on my bow. Raising the brace height does raise the draw weight, as extrema said, but it stiffens the spine because of less "drive time" on the arrow.

[Cable Guy]

I thought raising BH actually weakens the spine because of its more explosive start.
Guess I had it the other way around.....ooops

[xtrema312]

Originally posted by Cable Guy:
I thought raising BH actually weakens the spine because of its more explosive start.
Guess I had it the other way around.....ooops

I am with you.  More # of bow is more bend in arrow on release.  Max # is max # regardless of travel distance.  The #’s decrees as the arrow moves forward so I don't see how it would have more bend in the arrow due to stroke length.  A longer stroke length will make for more speed.  I have cut to center bows and tune for the best brace for the bow.  It is a lot harder for me to tell small changes to brace and arrow dynamic spine so I can’t tell really with my bows.  However, I take the above from those that do know.  I have also heard it both ways, but this is most logical for me.  One problem is the old too stiff arrow issue.  If you are there and you drop your brace height and stiffen your arrow it will look to be getting weaker because it will kick off the riser or shelf even more.

[briandean]

OK. I raised the shelf with a match under the shelf cover - increased the brace height by a quarter inch - set the nocking point at 5/16.
Then the arrow really started hitting the shelf!!
So, I played with the nocking point and eventually, at 1/2, the arrow was leaving the bow in almost a straight line.  Before that, the back of the arrow was jumping up & left after hitting the shelf.  So now the arrow actually points slightly down from level with the nocking point 5/8 above centre!!  Now the arrows are flying dead straight and I've been putting 3 in a diameter of about 4 inches at about 27 yards.  Thanks for all the advice.
I'll post some pics of the setup as soon as possible.

[BlueBarred]

Having your nock 5/8 above center seems pretty average for many shooters I know. I think that your arrows are too stiff for a 45# bow. 30",405 grain 35/55's seem pretty stiff to me. I would shoot some identical bare shafts with your fletched arrows and see how they group. Also, depending upon your release, your arrow nock could be slipping down the string slightly before it leaves the string. I recently tried tying on a second string nock, under my arrow nock, which removes any chance of slippage and I'm pretty happy with what it did to my groups, you may want to give that a try. But for sure, bare shaft tune your arrows, even if your arrows are currently flying dead straight as you see them. Good shooting.
Dave

[briandean]

Here are some pics of the alterations
 
 
Thanks BlueBarred - didn't know it was normal for some people.  Most advice start with 1/2 or 3/8 as a point to start & then smaller.  I have bare shaft tuned - they seem ok.  I'll give it a try with one of my son's - he uses Easton 600's.
Thanks again for all the advice

[xtrema312]

What is your point weight?  That would help us get an idea of shaft dynamic spine.  You could be shooting your arrow off the riser because it is so stiff.  You can do that if you are real consistent and get the spine just right so it works, but it is not what you want.

Also I would put a piece of white electrical tape, or masking tape on that shelf edge just to make sure you are not rubbing it.  You will know in short order if you are still hitting it that way.  Turn that Beman around to get fresh paint and you will know the first time it hits if it does.  Trust me on that one.

[Cable Guy]

You are welcome.

[BlueBarred]

Briandean, each bow/shooter is different, there are so many things that can influence the shot and that is why I think bareshafting is so valuable. That said, I think 780's or even 900's would be worth exploring. Carbons seem to behave more stiffly than the numbers would make one think. Also, someone here may know better, but I think the optimal place to locate the highest spot on the shelf is directly over the throat of the grip. Yours appears a bit too far forward. Of course, if your arrows are flying well, then forget everything I said!
Dave

[kill shot]

try a lower spined arrow.check out the black widow video.

[turkeyslayer]

I was gonna chime in earlier,but didnt,JMO,i think you might want to try a weaker spined arrow (what kill shot said).