Spine Calculator vs. the hard facts..

[BassBow]

Hello!

I recently bought some CE 250 @ 29.5" for my Dalaa Recurve. I have it dialed down to 47.5# @ 27.5. Enough of the technical specs...

I have been in the backyard tuning. I found my nock height but my spine has been showing weak with 175 grain tips. This is what the calculator told me to try. I went down to 145...125...100...bada bing, bada boom. Right down the middle.

Are there form issues that could cause this weak spine phenomenon?

It seems so far off from Stu's calculator(3 rivers version) I thought I'd throw it out there and see if anyone has any advice.

It was nice to see those things fly right down the middle....finally.

Thanks!

[JimB]

Well,if you keep lowering point weight and impact doesn't change,you might be going the wrong direction.It is possible to get a false weak indication when the arrow is actually stiff.I can't say if that's it but I would start going up in point weight and don't be afraid to go as far as you need to to see the change.

[Bjorn]

Are you bareshafting or shooting fletched shafts? Shooting style will have an effect on spine; but the biggest impact will be the riser cut and where you set that plunger if your bow has one.

[BassBow]

Sorry. I am bare shafting. I shoot a few bare shafts and a few fletched arrows. Thanks for the help...

I did shoot the 175gr and kept widening the the strike button on the dalaa, until it was as extended as I felt comfortable. That is a nice feature about the bow. It didn't do much to the tuning. Mind you this is at about 20 yards. The all seem fine at 10, but the inconsistencies become magnified at 20. The 175s bare shafts grouped about 6-10 inches right of the fletched.

[calgarychef]

You should be able to do all your tuning with the plunger.  If you can't it might suggest that your shooting isn't consistent.  The spine calculator has an input for centre cut, what number did you use for that and how did you determine it?

[threeunder]

Just thinking out loud, but CE 250's with 100 gr head sound very, very stiff even at center cut.  I agree, you may be getting a false weak.

I would think 175's would be getting close, but 225-250 would be better with your setup.

I shoot 250's out of my Kwyk Styk.  It is cut 3/16" past center.  52#@28", pulling 27".

They shoot perfect with 175-200 up front on a 30" arrow.

Set the plunger in tight and try some 250 gr points.

[BassBow]

Ha! Yes, I am sure there are inconsistencies in my shooting : ). I am shooting of the shelf, only using the strike button on the Dalaa for spine adjustment. It is set 1/8" past center. When I started seeing the weak spine, I slowly started letting it out to compensate. This is the method I have been using.

[Shawn Leonard]

Agree with the false readings. I am shooting two of the best performing bows out there right now, A caribow Tuktu EX and a Belcher riser with a set of Border Hex-5H's. I am shooting .487 and .500 spine off these bows, one cut to 29"s and one to 29.5"s. I draw 28"s with Tuktu and 28.5"s with Border one bow is 51#s at 28.5"s(border) and 54#s with Tuktu. I shoot 175-190 grain point weight on these two set-up.  Sorry but that shaft is too stiff for what you are shooting. If you are shooting with a plunger and such you can get most any arrow to tune, You could easily shoot a .500 spine cut to 29.5"s with at least 190 up front and I dare say more like 225 would be closer. Those 250s are close to .400 spine and when I shoot them pout of 51# bow at 29.5"s and 28.5" draw I need 275 up front to get perfect flight. Shawn

[BassBow]

Yes. I'll get me some heavier field points and go the other direction.

[Easykeeper]

I would pay attention to what the bare shafts are telling you.  I think the CE 250 is a .418 spine which doesn't sound out of line for a 47# bow.  A lot depends on the center shot of your bow, the point weight range you are willing to accept, and your own personal form.

What point weight you will need...let the bare shafts tell you.  As long as bare shafts group with fletched at 25 yards or so, that's all that matters to me.  I've found the calculators to be close, but if I went by exactly what they recommend I would not have a very well tuned bow.  The calculators are very sensitive to the values you input and even if you get everything right, they are still only a starting point.  A better starting point than a stab in the dark, but still only a starting point for your tuning...at least in my opinion.

[BowDiddle]

Originally posted by BassBow:
Are there form issues that could cause this weak spine phenomenon?

Yes.

The calculator can only calculate everything from center.

Many things in an archers form will deviate him from center. Grip being one of the primary ones that will effect spine.

That is where the "personal form factor" comes into play.

[flinthead]

Do not use spine calculator. I am sure there are many things wrong with my shooting form---but the 150's at 30 inch length are plenty stiff out of my 50# recurves[widow, robertson, dye bows] w/ 145 gr. point weight. Thanks, Roy

[Shawn Leonard]

.418 spine seems way oot of line for a 45# bow. Why do guys insist on thinking you can shoot arrows designed to be shot out of 60# compounds cut to 28"s with 100-125 grain points and than cut them to 29"s and shoot 125-150 grain point and think they will spine right for a 45# recurve, makes no sense at all. I believe a 600 spine is much more in line for 45# LB's and recurves when cut to 28-29"s and you can use 145-175 grain points on those .600 spine. Here is a classic ex. My Borders are 42#s(28.5" draw) when put on a 25" riser,with the plunger set so the bow is centershot and a moderate pressure I get absolute perfect tears in paper and perfect bareshaft tune with a .600 spine cut to 29"s and 175 grain point weight. Carbons recover very quicklt from paradox and most guys I see shooting them get them to fly ok fletched up but I say most guys should add 50-100 grains to the point weight on top of what they are already shooting and will get a lot better flight. BassBow try a .500 spine cut to 29"s with 225 ogf point weight, I bet you will like it. One last thing as too .418 spine being ok for a 47# bow, a few of the best shooters I know tune their 60-65# bows with .400 spine arrows they draw 28-29"s and shoot arrows from 29-30"s and all have at least 225 grains of point weight and up to 325 grains of point weight depending on the bow they are shooting. 400 spine out of a 47# bow, ya better leave it full length and even than shoot 325 grains of point weight at least. P.S. 99% of the calculators are garbage!! JMHO!! Shawn

[Bladepeek]

I have to agree with Shawn. My "high 40# - low 50#" bows shoot CE150s @ 30.5" nicely with 175 - 200 gr points. For the CE250s at that length, I have to up to at least 250gr or heavier. I can't imagine a 45# bow shooting weak with CE250s cut to 29.5"

[olddogrib]

I concur that that combo ought to be way stiff for your poundage. I like medium recurve grips with a good bit of "palm swell", but if I get the least bit sloppy with my hand placement I can make about any arrow act weak.  I think Moe recommends the meaty base of the thumb be pretty much directly in line with the centerline of the grip. I'm a rightie and for me this means consciously rotating the bow hand counterclockwise(as viewed from above) into the grip more than feels normal and keeping light pressure with fingertips on the face of the riser. When I get sloppy and my pressure point moves left of centerline I tend to rotate the grip clockwise(again as viewed from above) at release and that bare shaft will act like a nasty curveball thrown by a lefty breaking in on a RH batter.(as viewed from the mound)

[BassBow]

Thanks Shawn and Co.

I just had my new Toekle Whip out this morning...Shooting 48# @ 28". I am 27.5.

I shot Trad Only 500's 29.5 with 250 up front. Seemed to be getting good flight from them. Does this sound correct.

I am going to go back to the Recurve soon. With some heavy tips. 250's...I think I might try the same setup I used with the LB?

Thanks again for your expertise.

Mike

[xtrema312]

Sounds better.

I shoot CE 150's at just a little over 30" in my cut past center D/R LB's. I have 100 gr. inserts and shoot up to 175 points.  My bows are 50-55@29.

[Bowwild]

I've used different tuning methods for many years. I often used the charts to get a good idea where I should be.  I have never been as happy with any arrow selecting system as much as I am with Stu's Calculator!  

I don't even consider making a change these days without doing a little gaming with it first.  Then I proof the set-ups by paper tuning and then broadheads at distance. The calculator hasn't let me down since the day I discovered it here on Trad gang about 4 years ago.

[Mr. fingers]

I think the calculator is dead on . For me any way  it is in line with most of  the arrow charts you see that have recurve and long bow center cut and long bow cut before center. I don't understand how some people on here recommend such weak shafts. Paper tuning is crap for trad bows. Bottom line for me is if broad heads and field points group together your set . Bareshaft tuning is a good place to start but its not the end all.
JMHO.

[BassBow]

Thanks!