can't seem to tune a center cut R &D LB, need help

[xtrema312]

I have this cut to center bow i am setting up and just can't get it right.  Stu's calculator says about  60#.  I typically find i do best about 10# less than it says on most bows.  I have tried to tune this bow for well over a week with carbons from 65# to 30# spine and only find one combo somewhere in the middle where the bare shaft flies like a bullet.  More or less spine and it shoots a bare shaft low and stiff.   The fletches arrows all shoot to the stiff side of where i look. I can' t get a weak shaft flight to save my life and i have the same issue with getting the bare shaft leveled out even shooting 3 under.  Finaly tonight after i lost light i tried to build out the side plate more just so i could make the bow need a weaker arrow so i could go stiffer yet to see what that would do.  I had found at least with a real stiff arrow it started to shoot on line of site and more level with the bare shaft but the bare shaft was shooting real stiff. The funny thing is that when i did some close range shooting in the barn tonight after adding more side plate thickness it looked like my middle of the road arrow was shooting a little weak.  I started shootimg paper and got it shootimg well even from out the door a food ways.  I have to wait until tomorrow to see what a bare shaft will do outside, but it looks like something changed.  I have tuned a lot of LB's and recurves the last few years and never seen this kind of thing, but they were LB's cut out a little from center or recurves cut past center.  Never one cut right at center.  I am not sure what to make of this.

[don s]

whats the bows poundage?, whats your draw? don

[Night Wing]

You might need to adjust your brace height. Both of my bows can shoot the same 421 grain 2212 aluminum arrow with a 75 grain point weight, but their brace heights are different.

My 42# bow has a brace height of 7 15/16" and my 37# bow has a 8 3/8" brace height. Many people don't adjust their brace height. A lot of them just add or subtract point weight and never change their brace height. That doesn't always work.

Furthermore, the recommended brace height for my 66" take down recurves is 7 3/4"-8". My 42# bow is in the recommended brace height range, but my 37# bow is 3/8" above the recommended brace height range. Food for thought.

[awbowman]

Good point Night Wing.  I recently placed a new string on my bow to stretch one as a spare on an upcoming trip.  I had pretty good arrow flight before, but a friend was always telling me to mess with the brace height.  Long story short I would never unstring my bow because I was "satisfied" with the flight.  While changing the string I changed the brace height, and man did it make the difference.  Now they are TRULY flying like darts and the bow is another 10% quieter.

[Night Wing]

I've been bowhunting since I was 14 years old and that was back in 1964. I've also been one to go against conventional wisdom when tuning arrows. I also shoot right handed recurves and my comments below are based on a right handed bow.

The conventional wisdom most people follow is to set their brace height, never change it and then start tuning an arrow by adding and subtracting point weight.

For discussion's sake, lets say you really like how an arrow flies with a 125 grain point weight out of your right handed bow. But, the arrow is hitting 9" to the left consistently on a target at 20 yards. The arrow is stiff. Conventional wisdom says to make the arrow weaker, you add point weight. So, you add point weight and the arrow is now inline where you're aiming at with a 175 grain point weight.  

Now comes the tricky part. You're not happy with the trajectory with the 175 grain point weight. It's inline, but much lower on the target at 20 yards so your mind has to get used to the heavier arrow to make the arrow hit where you're aiming at. But, you liked the trajectory you had with the 125 point weight, but it hits 9" to the left.

The solution. Raise the brace height by two full 360 degree twists and then go shoot the arrow with the 125 grain point weight about a dozen times.

What you'll find, the 125 grain point weight arrow will start to move to the right from where it was hitting on the target. If the arrow is still left of where you're aiming; but closer, say 2", raise the brace height again and this time, one full 360 degree twist.

Eventually, by raising the brace height, the 125 grain point weight arrow will keep moving to the right and be hitting where you're aiming at. You'll still have the arrow speed you like and no trajectory problem at 20 yards.

Let's say the 125 grain arrow is consistently hitting 1" to the left of where you're aiming at 20 yards. Fine tune it. This time, raise the brace height by 1/2 twist (180 degrees) on the bowstring.

And if you have to go beyond the recommended brace height the bowyer recommends, just do it. I did this with my 37# bow by 3/8", now 8 3/8", beyond his maximum recommended brace height of 8". The bow is whisper quiet with a pair of home made yarn wool puffs attached to the 12 strand 2 bundle Dyna97 bowstring.  

In closing, experiment. Don't always run with the pack (conventional wisdom) because there is more than one way to get from Point A to Point B.

[Jedimaster]

I'm gonna try your advice too Night Wing.  Thanks for taking the time to explain!

[xtrema312]

Thanks for the info.  I am guilty of not playing with my brace height as much as I should.   I tend to tune mostly with point and length.  Then note the height and just keep it there.  I should play more and will.

I think I got my problem about solved.  Now I just need to tweak the brace height.  I was shooting a 5575 and a CX150 and not getting it at all.  I thought I had it last night, and today it shot decent, but I started seeing traces of feather on the strike.  I knew then that it was false weak probably.  This was my first time shooting the CX150.  I picked up the one Beman 500 shaft I had laying around.  It was cut just a hair shorter than the 150.  I set it up with a point weight close to the CX150 and it shot nice.  I was able to move it all around with nock and point changes.  Very odd, but I was getting places now.  They are supposed to be real close on spine.  I raised the point weight more on the CX150 and started getting it.  More changes and I got it shooting fairly well.  The 150 shoots quite a bit stiffer than the 500.  I also found when I jumped up the next point weight from 145 to 175 added to A 100 gr. insert I got some odd stuff going.  Something to do with fast carbon reflex, extra arrow length, EFOC and cut to center bow I think. It was very hard to read and get consistent with this particular set-up.  I know I tried these point weights before, but something was just off when I did and I missed it. I also noticed the outside dia of the 150 is larger than the 500.  The 150 is about the same as a 5575 outside dia. and the inside is about the same.  Spine of the arrow aside, the outside dia appears to causes more issues than one would think.  It is odd that the weaker set-ups I tried using the 5575 shafts didn’t get close to right and shot way different with about the same dynamic spine.  

The more bows I play with the more I am finding the middle weight bows with carbons are best cut a ways out using lighter spine carbon or cut past using stiffer carbon.  Every time I get a bow cut about center at my draw length and weight I seem to struggle more trying to find the right balance between a longer stiff shaft with a pile of FOC and a lighter spine arrow with less FOC, but sometimes too light an arrow.  

These different shafts sure don’t calculate at all the same using Stu’s spine calculator.  There is no comparison with them all set up with the same dynamic spine number.  The 5575 shoots way to stiff.  The CX150 is stiffer then it should be, and the 500 is just about right, and that is using 20# under spine of what the calculator says to use.  Maybe it is just me, but I sure do find big differences.

[FrankM]

Originally posted by Jedimaster:
I'm gonna try your advice too Night Wing.  Thanks for taking the time to explain!

I'm also finding this quite interesting.

[amar911]

Sounds like a lot of good thinking and advise. One reason I mainly shoot AD arrows is the wide spine tolerance of those tapered shafts, but they probably do not fine tune as well as some of the straight shafts can.

Allan

[Night Wing]

I shoot aluminum arrows because aluminum is easier to tune in my opinion. Another reason is because I have a 30" draw length and I shoot 32" BOP (back of point) arrows. My 32" arrows are a constant. I don't go under 32" and I don't go over 32".

I can't shoot carbon arrows because the correct spined carbon shaft only comes in 30-31" full lengths. I can't make a 32" carbon arrow from a full length 30"-31" carbon shaft. I also don't shoot wood arrows because wood doesn't appeal to me in terms of straightness or in overall weight within a dozen wood arrows.

A different bowstring will also effect tuning. I just wore out the nylon serving on my 13 strand 2 bundle Dyna97 bowstring and this was the original factory bowstring that came with my 37# Blacktail recurve. I also thought the original bowstring was a 12 strand, but it wasn't as I counted the number of strands on the original bowstring. So, I ordered a new one from Champion Custom Bowstrings. Chad Weaver is the proprietor of CCB and he goes by the username of LBR here on TG.

I called Chad (LBR) and told him I wanted a flemish 2 bundle 12 strand (flemish loops padded to 18 strands) Dyna97 bowstring in red/black color. For the serving, since my aluminum arrows are installed with Easton Super Nocks, I chose 62XS in .025 size with the same red/black color.

I received the pre-stretched bowstring this past Saturday. Even though Chad pre-stretched the string, I knew it was still going to stretch a little more. At 4pm Saturday afternoon, I put the new bowstring on my my bow and set the brace height at 8 1/2". I checked it Sunday afternoon at 4pm. The brace height was down to 8 1/4". Since my old bowstring had a 8 3/8" brace height setting, I set the brace height a second time for the new bowstring at 8 7/16" expecting a little more stretch.

Come Monday afternoon at 4pm, the brace height was 8 5/16". I again reset the brace height for the third time, but this time to my old 13 strand bowstring setting of 8 3/8". Tuesday afternoon at 4pm, I checked the brace height and it was still at 8 3/8".

This Wednesday morning I put a single brass nock set on the bowstring and set it 5/8" high off the shelf which is my normal nock set height setting since I shoot 22/64" diameter aluminum arrows. I also shoot split finger; one over, two under.

With the brace height set at 8 3/8", I shot the bow for 40 minutes with my new bowstring. For the first 10 minutes, my 2212 arrows were hitting to the left about 1-2 inches at 20 yards. This was because as I was shooting the bow, the bowstring was slightly stretching. Then, for the next 30 minutes, all of my shots were hitting where I was looking. My 2212 test arrow was putting a serious hurt on a pine cone I was aiming at. I would barely miss it, skin it or hit it. I was shooting so good, I didn't want to quit. I checked the brace height and it was 8 5/16" and this is where I'm leaving it at. Then I decided to quit and that's hard to do when you're in.........The Zone.
 
So, by going from an 8 3/8" brace height setting with a 13 strand 2 bundle Dyna97 bowstring with nylon serving, this new bowstring requires an 8 5/16" brace height with a 12 strand 2 bundle Dyna97 bowstring (flemish loops padded to 18 strands) with a 62XS serving in .025 size. The difference from the old bowstring to the new bowstring is only 1/16" in brace height.

BTW, I installed a pair of home made yarn puffs on the bowstring before I put the new bowstring on my 37# bow.

[tecum-tha]

In my opinion, forget the fancy calculators and just get in the ballpark by converting to wood spine and using the appropriate corrections by rule of thumb. A 5575 is a .400 deflection and is statically equal to a (26/0.400)x1.21=79# and your CX 150 has 0.487 deflection and equals 65# Spine. Now Easton shaft convert pretty much 1:1, Goldtip about 5% stiffer and Carbon Express about 5# stiffer dynamically. Experience. And it makes sense, because different epoxies and wall thicknesses are used. The carbon fibers should be fairly equal, because there are not many fiber manufacturers. With those two shafts I don't see you shooting a 30# spine, unless you have a 350+ grain point weight...
Weight and length is "rough" tuning, brace height is fine tuning....

[Lost Creek Bows]

Check your arrow nock fit . A tight nock will cause bad arrow flight and tuning problems.

[xtrema312]

Nocks are losing.  I am still scratching my head on this tune.  I am shooting 29.5" draw with about 53# at that length.  My current best tune is a 30 1/2" CX150 with 100 brass and 125 point.  I went to paper and have a very good flying set-up at 5/16" nock height.  Shoots great all around from 15’ to 20 yd. with very nice and consistent holes.  Bare shaft flies straight low about 10" at 20 yd. compared to fletched shaft.  When I get the bare shaft flying better the fletched flies irregular.  Back to paper tuning to try and get it shooting split finger and my horizontal is fine, but I get vertical tears no matter where I set the nock height.  

I have tried the 5575 shaft at about 30 1/2" with up to 300 gr. on the front.  They fly stiff no matter what and paper shows the same thing.  My MOAB only pulls 2 more # on a scale, is cut out from center, and shoots the 5575 with 100 plus 175 points great and I can shoot tune it split or 3 under without a lot of problem.  I don't get why this new bow shoots the same arrow so stiff when there is so little difference in weight and it is cut to center.

[tecum-tha]

For me, that means your spine is now ok. Are the limbs timed correctly?

[T Folts]

Todd
I'll tell ya the goldtips tune alot easier than the CX shafts. I had a hard time with CX150"s changing point weight, length and not alot of response. Once I switched to GoldTips my tunning issues went away. I still used CX 150's for durability stuff but for target shooting and hunting I mostly shoot GT's.

[xtrema312]

Originally posted by tecum-tha:
For me, that means your spine is now ok. Are the limbs timed correctly?

How can I figure that out?

[xtrema312]

Originally posted by T Folts:
Todd
I'll tell ya the goldtips tune alot easier than the CX shafts. I had a hard time with CX150"s changing point weight, length and not alot of response. Once I switched to GoldTips my tunning issues went away. I still used CX 150's for durability stuff but for target shooting and hunting I mostly shoot GT's.

This is my first time with the CX150's.  I get some inconsistent bare shaft flight with them. I thought it was me and the new bow, but I played a little with them in another bow and had some similar experiences.  The Beman 500 bare shaft was more predictable, but they are not very durable at all.  400 are not too bad, but 500 bow up easy with a hit on something. Unfortunately the GT 5575 just looks to be way to stiff and I don't know why.  I have shot them in about every bow I have had 50-56#  @ 29 ½” and 1/8" out to 3/16" past center cut.  I can typically find a point and insert combo to get real decent tune. I think this new bow would like the GT 3555, but they only come 30” full length so not an option.

[xtrema312]

Well after several more days of thinning I had it about tuned only to fine it was false tune due to some bouncing of the arrow off the bow or something such thing, I never got a bare shaft to fly close to right consistent while getting the arrow to fly well also.  I finally think I got it figured out.  I ended up getting out a different bow and working on the CX150’s to see what was up with them. I ended up taking out all the front weight and going down to standard aluminum inserts and at the end, a 125 point.  This got me down to about 8 gpp.  This changed the erratic flight into just pain too weak. I went back to the problem bow and sure enough I was able to get them to shoot consistent and go from off and on too stiff and low flight to too weak.  Something about the bow design doesn’t allow me to level out the weak shaft on the new bow like I can on my other bow, but there is no doubt the CX150 is way too weak to shoot at my draw length and bow weights.

Next I went back to the 5575 GT with max weight on the front.  I just shot too stiff and dove too much.  All the info I have seen would say these two shafts should overlap a good amount with the big differences in point weight, but that didn’t seem to be correct at all.  I went to the max point weight I had and raised the brace height.  I started messing around with nock height and then shooting two finger split finger.  I got some improvements with a more consistency, closer to level flight and just a hair stiff of straight bare shaft flight.  Next I added a tip protector to the bottom limb and noticed my shaft leveled out even more.  More changes to split finger style, and gripping the bow resulted in better and better results, but still too stiff.  
I got rummaging through shafts and found a bare and one fletched 400 shaft ¼” longer than the 5575’s I was using.  I had an aluminum footing the same length as the insert on these, which adds maybe another 10 gr.  I put on my heavy points and 100 gr. brass inserts.  I shot the bare shaft and it flew almost straight and level.  The fletched shaft flew perfect.  I did this over and over again with consistency.  A little more adjustment and I got it to fly just a hair low and weak, but still stiffer than ideal.  Finally a bare shaft close to tuned and a clean flying arrow all at the same time.  Things may change today when I shot as it has about every day, but I never had this kind of results.  I went out and picked up two more of the same shafts full length and started full length with 100 gr. insert and 125 point.  That ended put almost right on for tune.

I then shimmed out to about 3/16” out from center and was able to finally shoot the 30 ½” CX150 with standard insert and 145 point.

At one point I started to suspect that there was something wrong with the spine of the 5575 or the CX150.  The 5575 are GT blems so maybe the spine was off.  However, the 400 shafts shot so close to spine given the difference in length and point that I have to believe the 5575 is very close to correct for spine. I don’t know if the CX150  is correct until I have a way of spine testing it, but it is without a doubt way too weak for me.  From everything I have read the CX shaft should be able to be made very stiff with light points, but I found no overlap in spine.  I was shooting arrows way to stiff or way to weak with no middle ground.  That was really making the process maddening.

Finally I shimmed out the bow to about 3/16” from center and got the CX150 to shoot with standard inserts and about a 145 point.

[Bow Bum]

This has been an interesting read. It sure makes carbon arrows seem real confusing with all the different numbers and spines from all the mfg's

That's why I like aluminum:

1.Pick an arrow, and point weight.
2. Cut the shaft shorter in small increments until bareshaft/fletched shaft tune is reached.
3. Fine tune by adjusting brace height.

I also like to add step 2a. I'll shoot with a heavier, and lighter point weight to confirm that I am at in the middle with my chosen point weight.

I'll also add that I owned a bow that did the same kind of things you describe. Me and it just did not get along well.

At least its frustrating in a fun way.

Regards,

Brian

[Lost Creek Bows]

I had tuning issue with CX 150's and 250' and, I went back to Gold Tips and they just work great for me.