cutting to stiffen carbon shafts

[dick sable]

What is your best guess as to how much carbon shafts stiffen when shortened?  For example, a couple inches off a GT 35/55 to around 27", shooting out of a 56" recurve?  Any ideas? Thanks in advance.
Dick

[just_a_hunter]

What pound is your 56" recurve at your draw length?

Todd

[dick sable]

Sorry for the lack of info.  The bow is 56# @ 26".

[just_a_hunter]

That's a toughy...

I hate to give this advise in case the arrow breaks,.. but here goes...

I would first trim your arrows to the 27"... I'm willing to bet even with only 125 grains up front they are still going to be weak. At this point, if you feel comfortable that the arrows aren't going to end up as splinters in your bow hand, you could build up the side plate to overcome a weak spine.. Please use caution with this..

Or, you could P.M. me your address and I'll send you a used but good 55/75 with a couple weight adapters to try. I'll bet a 28" 55/75 with about 250 up front will be good medicine for that bow... You'll have to wait until I'm off of night shift though....

Good luck either way...

Todd

[Steve O]

Todd,

I think you mean a 27" 55/75 is going to be  STIFF  for a 56@26 bow.  Real stiff I think.

Dick, you are better off starting out long and keep cutting till you get good flight.  If you have to have a certain length, you are going to have to play with the weight to get good flight.

[Paul Mattson]

Cutting the shafts under 28" is going to stiffen them up.  A good starting point would be 271/2" see how it flys.  You can always cut more off if needed.

[xtrema312]

I would start to tune at 28", two inches longer than draw typically if I want a lighter point weight.  Cut from there.  Center cut of the bow is a big factor.  I would think at 28" with a standard insert and 125 head you would be in the ball park on spine.  Probably even too stiff.  If you are going to put more weight up front then I would agree that you can start out at 27 1/2".  However, watch the weight on that arrow before you go to far because a standard weight 500 spine shaft with standard insert and anything less than 200 up front could be under 8 gpp.  That 5575 shaft may not be a bad option.  It will give you more shaft weight and let you load up the front more to get your arrow weight up.

[JRY309]

Are you bareshafting them as you cut them to see how the fly? I find that carbons stiffen more rapidly as you get closer to your draw length,depending on how the riser is cut.For me I never just cut carbon arrows without shooting them as I cut them shorter.I pick a shaft with the point weight I'm looking for,and shoot and trim them until I get the proper dynamic spine I'm looking for.

[George D. Stout]

Them babies at 27" are going to be about 60#'ish spine, as I believe they are spined at 28" from the factory.  That would normally indicate a 55# @ 28" on the 35/55.  Carbon stiffens quickly when cut shorter as well so I would suspect they would be very stiff for your bow....unless it's cut past center.

You really need to take a shaft and experiment with the front weight you plan to use.  Don't guess; start at full length and work backwards, cutting only about 1/4 to 1/2 inch at at time.

[Buckeye Trad Hunter]

Originally posted by George D. Stout:
Them babies at 27" are going to be about 60#'ish spine, as I believe they are spined at 28" from the factory.  That would normally indicate a 55# @ 28" on the 35/55.  Carbon stiffens quickly when cut shorter as well so I would suspect they would be very stiff for your bow....unless it's cut past center.

You really need to take a shaft and experiment with the front weight you plan to use.  Don't guess; start at full length and work backwards, cutting only about 1/4 to 1/2 inch at at time.

X2    

[Bowmania]

Here's something from TradArchers' World in an article written by David Soza, "I also tested a number of other tuning factors.  Adding 100 grains of weight to the front of the .500 shafts made them hit six inches to the weak side.  That is the same effect as removing two inches of shaft length.  So, one can conclude that one inch of shaft lenght or 50 grains of point weight will move the bare shaft about three inches at 20 yards."

Very good article.  You guys should be subscribing.

Bowmania

[kat]

Do you have a way to cut carbon shafts?
Taking your time and cutting samll amounts will assure that you don't waste any shafts.

[SlowBowinMO]

Carbons get real stiff real fast, and can't be compared to any other arrow material in this regard.  As suggested above start long and cut slooooowly or you can easily end up with shafts that are hopelessly stiff.

[JC]

Originally posted by SlowBowinMO:
Carbons get real stiff real fast, and can't be compared to any other arrow material in this regard.  As suggested above start long and cut slooooowly or you can easily end up with shafts that are hopelessly stiff.

x10

I can see flight differences when cutting a carbon shaft 1/8". Imho, the only way to get perfect flight with a carbon shaft is the comparative bareshaft method popularized by OL Adcock, starting with a full length shaft and cutting down very, very slowly. If you follow the "rules" exactly as intended (feel free to ask if you don't understand bareshafting) and proceed with patience, you will be rewarded with arrow flight unlike any you've previously experienced. I've shot complete 3d sets with no fletching just to show folks what an arrow can do if it's tuned right.

There are just too many variables to tell exactly what carbon shaft length is needed out of a given bow/shooter combination without testing, again in my experience. Obviously point weight, draw length and bow poundage are the obvious factors but bow center shot, bow efficiency, string material, strike plate/shelf material, shooter's form, glove material etc. etc. are all variables that can effect spine choice.

[Traditional-Archer]

George is absolutely right.
I shoot almost the same set up. My Bow is 55/27 Schafer silvertip shooting off an elevated rest. The 35/55 shot just awesome at 28”. With my bow I could shoot them bare shafted out to 40 yards no problem, just perfect for my bow.
I then started messing around with EFOC and went to the 55/75 with a 100 g insert and a 250 g field tip. They flew awesome as well. I changed mainly because I wanted to gain some arrow weight. The 35/55 as a finished arrow only weighs in at 406 g that put me at a much lower GPI that I wanted. The 55/75 on the other hand was up there around 636. This is what I wanted at an EFOC at 33%.
If this is something you are looking for PM me I’ll give you my phone number we can talk about what I went through to get what I have and compare. I now shoot some of the best arrow in the market the Grizzlystik Alaskans my opinion, even though I like the arrows and they fly just perfect the FOC is a little light for me at 18%. Not bad but I think I would like to be at about 22/25%

Bruce  

[Lefty]

It has been my experience that 1 inch of carbon arrow equals about 5# of arrow spine.

[dick sable]

Bruce,
You are right, the GT 35/55 @ 27" are kinda light for GPI and overall weight.  I am using 100 gr. brass inserts and experimenting with 200 gr. points for the higher foc. Low weight - no good. Actually, that shaft setup is right around 550 gr. with the insert and head. If the higher foc doesn't work out, I wonder how weight tubes or Rob's method of internal footing would work to increase shaft weight?

[Bruce Martin]

If you are pulling 56 lb then you are right above the 10 gpp for good penetration. Should be a great hunting rig if its flying right. I'd suggest internal footing rather than weight tubes if you want increased weight AND EFOC. But at 550 gr I think you are good to go with the weight. Key now is to get them tuned.

[Steve O]

I messed with weight tubes ONCE.  I've solved some poor flight issues for others by having them take those worthless things out of their arrows...

[just_a_hunter]

Mr. Sable,

Sorry if I have somehow confused you.... No I did not mean to say a 55/75 will be stiff out of your bow.

Others have their experences and I have my experiences...

My advise was based off of my experiences.. I shoot a 55/75 out of a 52 @ 30" Zipper, the arrow being 31.5"... I have to wieght them up pretty heavy to get good flight...

My offer still stands, if you would like to try a 55/75 28" with about 250 gr. up front, free of charge to you or anybody else, you are certainly welcome to..

Sorry once again if I'm contributing to any confusion.

Good luck,

Todd