Predator & carbon bare shafting

[xtrema312]

I have been bare shafting my 60” 46# @28” predator with Beman ICS bow hunter .500 shafts.  I draw right about 28”.  I am shooting very good groups at 25 yd with just a little week on the bare shafts.  I think I am tuned.  I am shooting the shafts at 31.5” with 100 gr. Inserts and 100 gr. Points.  I have just switched to my 60” 50 lb. limbs.  That arrow shoots about 8” week at 20 yd.  I would like to be shooing 125 gr. Points.  I am wondering if I cut ½” off the shaft for the next round of testing if that is too much.  The 31.5” was my first cut so I don’t have much to go from, and this is the first time I have bare shaft tuned carbons.

[Bob Morrison]

Cut only 1/4" at a time. Keep it a little weak, 1-2" from fletched shaft.

[R H Clark]

Before you cut try to make the shaft even weaker with more point weight.If you have even lighter tips also try to make it stiffer.Always try to confirm your reading with heavier and lighter tips before you cut.That way you will know for sure that you aren't getting a false reading from riser contact before you cut your shafts.

I also agree that 1/4" at a time is best.Even then only cut a couple and shoot them a bunch just to make sure.

[xtrema312]

I have confirmed the tune with the arrows and the 46# limbs with point weight changes.  I have 75 gr. to 225 gr. field points.  Now I am up to 50# limbs and want to put even more weight up front.  I am reasonable sure I am week.  

I am shooting two bare and two fletched.  I have been shooting a lot of arrows before making point changes and then shooting a lot more to make sure I am getting a consistent read on it.

I don't have anything to square cut the carbon shafts so I have to pay to have them cut.  I just don't want to cut a 1/4" four times or more if I am a ways off.  It is a fairly dramatic weakening of the spin with the extra 4# draw weight, so I can see where a little change does have a fair amount of affect.  I guess the first ¼ cut will give me some feedback on future cuts.

If I scribe a line on the shafts with very light pressure from a tube cutter and then cut and grind with a dremel tool can I get close enough for testing with field points?  Will a slight out of square damage the shafts or throw off field points?  I am using 100 gr. Brass inserts hot glued in and shooting a fairly beat up block.

[Tajue17]

I shoot a pred also,,, so this is my opinion only,, try twisting your string 2 turns tighter at a time and see what that does, it will raise the brace and soften the force on the arrow???  

also what I have noticed in my bareshaft testing which is the only way I set up my bows is if its showing a tiny bit weak or a tiny bit stiff the broadheads still fly perfect!  also in the winter when you have some extra clothes on you may short draw that bow juat a tiny bit anyway which will then make up for that weak spine and cause it to even out and shoot perfect.

finally 31.5 is long for a 28" shooter unless your gap shooting its useless to even be there, I'd cut that down to 29" so its an only an inch longer for broadheads and its not in the way of your sight picture--> some people feel if they have been shooting hundreds and hundreds of fieldpoints and blunts then all of a sudden in september they then see a big broadhead when they draw back on a critter it messes them up in the head because that now reminds them that "this shot is for real"  and they then lose focus,, alot prefer not to see any broadheads so they can concentrate (unless gapping) on picking the spot
 
@ 29" the spine may be dead on or a touch stiff which will be fine with broadheads.

my opinion but hope it works out.

[xtrema312]

Thanks for the input.  

It is still cold here so I am shooting in a heavy jacket and not too far off my fall dress arm cover.  To go heavier I tend to use vests and thinner layers to keep the arm bulk down.  

I was measured once at about 28", but I have been working with my anchor, and by the looks of it I could be drawings more than that.  I have to have the wife mark an arrow for me now that I am settled better on my anchor.  

I have been playing with brace from about 7.5" to 7 5/8" for sound.  I did notice a little change when doing this.  Right now with the extra draw weight of the heavier limbs, and if I put more point weight on, I don't think brace will be a big factor, but I will remember to try that to tine tune when it looks like I am in the ballpark.

I would think 1 1/2" cut down would be way stiff.  I don't know.  I want to stay with 125 points, just because they are very easy for me to get local.  I would rather have that than a shorter arrow.

[R H Clark]

Raising your brace will actually allow you to shoot a slightly stiffer arrow.You will be shortening your power stroke but the effect of a different paradox point will alow you to shoot a stiffer shaft.

When I want to be very precise I wrap electrical tape around the fletch area to match feather and glue weight and then I don't have to guess how weak to leave my shafts.

Another point on brace height is that you may shoot tighter groups with a higher brace.I shoot DAS bows and in the past have braced about 7.5 inches.I didn't think too much about it because I couldn't tell much difference in noise and vibration and liked the extra speed.An IBO shooter convinced me to try 8.5 and with my long limbs on my 21" riser it made a world of difference in accuracy.I've been shooting the tighest groups of my life with that combo.

You can try having the shop cut one shaft 1/4" one 1/2" and one 3/4". You can also add a fletch wrap to stiffen them a little if needed.