# shaft selection software



## w8lon (Jun 2, 2012)

Yes, pm sent for Stu Millers latest DSC if you want to try a free one. Improved version was released last week.


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## fluke (Aug 12, 2012)

can you send me the link too?


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## leschrader (Jun 26, 2012)

Yes, please post a link for the new one....


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## w8lon (Jun 2, 2012)

With a few changes ie; using Hoyt Excel option spine will not show in green bar until plate thickness is input at actual riser to plunger number do to centershot, starts to show at .125. This in turn makes the spreadsheet more accurate as last version has .062 as plate thickness. Added arrows and spines as well as a personal form factor that adjusts to your form with +- 20 instead of previous +-15. A Mac version may be in the works as well. this version is for Windows Excel 2007 and later.
Have fun, I did as Stu added my favorite AMG GT20's didn't have a clue when I cut a little, shot a little, cut and shot to perfection, turns out the spreadsheet agrees.

https://www.dropbox.com/s/w2ux3sbseyj25zn/Dynamic%20Spine%20Calculator%20Rev%205-12%20%202007.xls


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## williamskg6 (Dec 21, 2008)

So, what do you recommend for a generic olympic recurve as a starting strike plate position? If I use 0, then my arrows fall within the correct dynamic spine range. If I use the default of 1/8" they're too stiff. Can the strike plate be considered the tip of the plunger to the centerline of the riser/limbs (which may be in empty space due to riser cut-out)? His graphics seem specific to traditional wood risers where you shoot off the shelf.

Also, when you enter your draw length, do you enter your AMO draw length or the "actual" draw length. For example, my AMO draw is 31.75" because my actual draw is 30.0 inches from string to pivot point.


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## LittleJP (Nov 4, 2012)

Can anyone post the link the newest revision? I only have the 2007 version.

Regarding plungers. When I emailed him directly, he said that strike plates are to be measured as normal, without accounting for the plunger, but you would add 10 - 15 # to the draw, depending on spring tension.


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## w8lon (Jun 2, 2012)

wiliamsk, use the Hoyt Excel option for bow, graphical display starts showing at .125 at least with the little fiddling that I have had a chance to do. If you know an arrow works for you adjust personal form factor, this is your combination that you know works. Choose another arrow combination with your personal form factor already adjusted, the new arrow should fall within your needed spine. As to AMO length I personally adjusted to a measured weight through the clicker on my draw board, this becomes my AMO and arrow length BOP. Quite intuitive once you become comfortable with the spreadsheet and can play with combinations to get an idea of a tune prior to the purchase of expensive arrows and components. Also measure the footing length of your point this has a dramatic effect on dynamic spine. I tend to also weigh my fletchings and use the option of other with actual weight of fletchings.

LittleJP the link above is the newest version released last Thursday, he kept the version as 2007 just to eliminate the need to create another dropbox account. See post #5 in this thread.


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## leschrader (Jun 26, 2012)

I've been using a version of this program for over a year with great success. For an olympic recurve, I use the "high performance recurve" and have used everything from carbon ones to aluminum 1816s with first time accuracy. They've bare shafted to at least "be tunable" to "dead on", depending on the arrow. I've not bought an arrow that was not tunable since I've started using this program. It has saved myself, and others I've built arrows for, hundreds of dollars and hours of frustration. It is also a great training tool for showing people the interaction of spine, tip weight, draw length, draw weight, strike plate(plunger) and nock weight on the dynamic behavior of an arrow. I've been using the strike plate setting the same as my plunger setting.....in the case for an olympic recurve, it would be a -1/16" to -1/8" depending on your arrow diameter and "center shot". As stated before, don't forget the foot weight.....anything over .9" (standard tip) is considered foot weight, so a nibb would have about 1" to 1.5" of foot weight. I have been using AMO draw length and it seems to work. The program seems to compensate for limb weight at 28" with longer draw lengths....you can play with the numbers and see the interaction. The arrow length is arrow only, nock valley to end of shaft....no tip. Be sure to weigh the fletching, nock and insert instead of using the generic weights on the drop down menu. Before I started using this program, I was waisting a lot of money and "believing" the easton charts. Now I can comfortably measure a person and their bow and get them a set of arrows that are usable and tunable the first time. The only improvement I would like to see on the program is the addition of the lighter spined arrows for the target crowd, or a "manual" spine value input like some of the other fields. I've been using the equivalent spine in an "aluminum arrow" as a substitute for some of the light spined carbon arrows that aren't listed and it seems to work OK. That's all I really use the Easton chart for anymore is to get the spine value of the different size aluminums to substitue in the program. Again, in my opinion, this is a great program and if Stu Miller is out there, contact me for a donation to the cause. Thanks for a great tool.

Schrader


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## w8lon (Jun 2, 2012)

Thank you Schrader for your nice writeup, Stu puts a lot of work into this with real world testing only to offer it free to the masses. I have shown the spreadsheet to a few college professors who teach Excel, their response is wow that would be a lot of work to create. 3Rivers Archery is the only online vendor that I am aware of that has an online version of Stu's calculator a try before you buy plan that works out for everyone:http://www.3riversarchery.com/spinecalculator.asp


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## leschrader (Jun 26, 2012)

An update......
Stu contacted me yesterday and the provisions for entering lighter spine target arrows is already incorporated in the program. In the "shaft manufacturer" field choose "other" and the AMO spine, GPI weight and diameter can be entered manually. The "measured" spine deflection to "AMO spine" conversion is located at the bottom of the program screen. This really completes the versatility of this program.

Schrader


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## Jim18655 (Sep 17, 2011)

It would be nice to see a version that will run on Open Office Calc. The formatting is off and some macros don't seem to work. I have Excel 2003 and it won't open properly.


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## Green Ring (Aug 13, 2012)

leschrader said:


> ...I've been using the strike plate setting the same as my plunger setting.....in the case for an olympic recurve, it would be a -1/16" to -1/8" depending on your arrow diameter and "center shot". As stated before, don't forget the foot weight.....anything over .9" (standard tip) is considered foot weight, so a nibb would have about 1" to 1.5" of foot weight.


Very helpful post!

I agree with your calculation/interpretation of centershot for an olympic recurve--I always use negative 0.5*shaft diameter, rounding down to the nearest 1/32". I've seen zero and positive values used by others who claim the software to be accurate--but this implies a button position pushing the arrow tip way outside of centershot, an unlikely configuration.

That said, the calculator has always recommended 1-2 sizes stiffer than what I have found to tune (like the Easton chart) unless I use some outrageous personal form factor like -12. I had attributed this to some calculation error for draws 31" and longer, but you have provided an alternate explanation--the need to include footing. Perhaps the full length target points I use greatly stiffen the generally weaker than recommended shafts. I always neglected the footing and tapered shaft boxes because I did not understand them and assumed they were unique to traditional archery. 

Next time I pull the points I will measure their actual length, but I'm sure they are >0.9".


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## leschrader (Jun 26, 2012)

Green Ring,
What size tips are you using. Post it up here and I'm sure somebody will have some they can measure for you. Play around with the program......change the footing and you'll see what I mean. Think about it....if you double wall 10% of the shaft with a tip footing (no flex), it would be almost like cutting off that much shaft length. That would raise the dynamic spine a substantial amount. Once you figure out the features of the program, it's an eye opener. Things start "clicking into place" regarding arrow component variables and arrow reaction in the arrow/bow assembly. This is a great tool and once people start learning the features and operation of the program, it should become the "standard" for arrow selection. I've run the numbers for dozens of combinations and it hasn't missed yet. But like any program, "garbage in, garbage out" as the saying goes......you have to give it complete and accurate information for it to work properly.

Schrader


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## Jim18655 (Sep 17, 2011)

Need a little help here. I've tried this in Excel 2003 and 2007 and keep getting an "Unreadable Content Error" in both versions. What am I missing? Enabled Macros in both versions.


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## arrowyn (Jul 4, 2013)

THey should just rewrite it in a java format so any PC type can run it . . .



Jim18655 said:


> Need a little help here. I've tried this in Excel 2003 and 2007 and keep getting an "Unreadable Content Error" in both versions. What am I missing? Enabled Macros in both versions.


try downloading the the 2007 / 2010 office compatibility pack (I think they are up to service pack 3 for it) and get the right one for your os (xp or win 7 and also 32 or 64 bit).

http://search.microsoft.com/en-us/D... for word, excel, and powerpoint file formats 

sometimes the OS will default to 2003 settings even though you may have office 2003 and 2007 or 2010, and get compatibility issues. Office was ment to be installed on one version at a time.


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## Jim18655 (Sep 17, 2011)

Both versions were on two different machines. I'll go through the updates and see if anything is missing. The old version, 12-25-10, ran.


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## Green Ring (Aug 13, 2012)

leschrader said:


> Green Ring,
> What size tips are you using. Post it up here and I'm sure somebody will have some they can measure for you. Play around with the program......change the footing and you'll see what I mean. Think about it....if you double wall 10% of the shaft with a tip footing (no flex), it would be almost like cutting off that much shaft length. That would raise the dynamic spine a substantial amount. Once you figure out the features of the program, it's an eye opener. Things start "clicking into place" regarding arrow component variables and arrow reaction in the arrow/bow assembly. This is a great tool and once people start learning the features and operation of the program, it should become the "standard" for arrow selection. I've run the numbers for dozens of combinations and it hasn't missed yet. But like any program, "garbage in, garbage out" as the saying goes......you have to give it complete and accurate information for it to work properly.
> 
> Schrader


120 grain ACG (not ACE-compatible)--if anyone knows the length inside the shaft

Almost wrote garbage in, garbage out myself!


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## w8lon (Jun 2, 2012)

Green Ring said:


> 120 grain ACG (not ACE-compatible)--if anyone knows the length inside the shaft
> 
> Almost wrote garbage in, garbage out myself!


Many of the Nibb points that I have actually measured are at 2.00 inches, try that then go .25,.5, either side of that length, it may not make that much difference.


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## Green Ring (Aug 13, 2012)

Green Ring said:


> 120 grain ACG (not ACE-compatible)--if anyone knows the length inside the shaft


I measured about 0.8 inch of point outside the arrow and estimate 1.6 inches of length is inside the shaft based found a pic found on Lancaster.

Assume the point mass is split evenly: 60 grains inside the arrow and 60 grains outside. So my interpretation is that I have a footing length of 1.6-0.9= 0.7 inches and weight of 0.7/1.6*60= 26 grains. The remainder of the weight (94 grains) is entered as point weight.

I also noticed I have been entering arrow length incorrectly (carbon to carbon) and changed this to nock groove to carbon.

After fixing both of these errors, there was virtually no change. I still need a personal form factor of -12 to get to the center of the tune range. If I set form factor to zero, I need 7# less draw weight or +3/32" change in strike plate position--fairly major errors.


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## w8lon (Jun 2, 2012)

Green Ring, footing length is length that is inserted in shaft or the 1.6" guesstimate that you made. What bow are you using with your selection as Performance Recurve is no where near what an ILF FITA bow is for shaft selection, use the Hoyt Excel option if that is what you are using. Better yet pm me your complete setup, actual OTF draw weight as pulled through clicker if using, strand count of string, dacron or FF, fletching type or weight as other, nock weight with pin or without, arrow length, type, spine, and length BOP to nock groove, and of course point weight. 

Recommendation can be made but the true test is bareshaft to fletch tuning, a tweak of the spring tension in plunger, centershot, and form is all up to the shooter. I had an archer next to me shoot his personal best with horrid arrow flight last Sunday as in arrows sideways to target as well as in target. Perhaps an added benefit with 1" tears in bull at twenty yard line with sideways flight.


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## Green Ring (Aug 13, 2012)

W8lon, very kind of you to offer--I will pm with details.

On your suggestion, I tried using Hoyt Excel instead of performance recurve. This cut the personal form factor required in half to -6. However, the strike plate distance is positive 0.063 (+1/16") by default. I interpret this as a button position extending way out past the centerline of the riser, which I have never seen recommended when setting up and tuning a bow. I assume for an olympic recurve it is the button, not riser cutout position that constitutes the strike plate position for the model. Am I missing something with how strike plate distance is defined?

Then I noticed I violated my own advice above when calculating strike plate distance; I needed to add 1/32". So now my personal form factor is down to -8 to -9 range. So clearly, proper strike plate position is critical.

Footing length in the program instructions is defined as only point length inside the shaft beyond 0.9". Very easy to make a mistakes!

I guess the main point here is it is unlikely for an inexperienced archer to actually enter all information correctly and completely and get a good shaft recommendation.


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## b0w_bender (Apr 30, 2006)

That's the first I've seen of Stu's excel sheet. 
That is a great tool to help folks understand how each component has the ability to affect how it will perform coming out of the bow. Really slick!


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## jafgx (Apr 25, 2019)

*Understand Footing & center Cut Strike Plate Position for Dynamic Spin Calculator*

Hi all;

After read a lot of posts to use Dynamic Spine Calculator i have trouble to fix two parameters, footing and Center Cut Strike plate Position.

To obtain Footing value for Easton CarbonOne 810 arrow with a 120 gr nibb 2,44094" long y show my brainstorm on next attach;







To traslate that information to DSC ¿what i need to put on Footing lenght & Weight yellowed on next attached image?






[/INDENT]

The next value to fill is Center Cut Strike plate Position parameter for a SF Superforged (Olimpic Bow ) with pressure button. This value must be 0?


Really what i need is know the philosophy for those values.


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## Viper1 (Aug 21, 2003)

j - 

It's all pretty much all BS. 
It's not rocket science, really.

The best thing to do is just work with someone at your range who knows what they are doing, or ask here

...and btw, you shouldn't be using a 120 head on an 810 C1, while it will fit, the head with stand proud of the shaft. 

Viper1 out.


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## f_thomas (Oct 12, 2006)

Viper1 
Thanks for being the voice of reason! Again!


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## Viper1 (Aug 21, 2003)

Fred - 

People just love making this way more complicated than it has to be. 
You're welcome, again .

Viper1 out.


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## jafgx (Apr 25, 2019)

Sorry, i have not explained myself correctly.

My question is what correct footing values (lenght & weight) must be filled in DSC if i use, as an example, a 120 gr nibb 2,44094" long, doesnt mater what shaft i use, i want to know the method.

Regards.


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## Skropi (Jan 1, 2019)

jafgx said:


> Sorry, i have not explained myself correctly.
> 
> My question is what correct footing values (lenght & weight) must be filled in DSC if i use, as an example, a 120 gr nibb 2,44094" long, doesnt mater what shaft i use, i want to know the method.
> 
> Regards.


And Viper1's answer was not to use the chart, but actually find someone knowledgeable to help first hand, or at worst, ask here. I blindly followed the advice offered here, from Viper1 and Limbwalker, and I got the right arrows. I could have gotten a tiny bit lighter spine, as I had to add about 1 pound of draw weight, but their advice was sound and I tuned the arrows almost perfectly. "Almost".....because I, myself am not perfect, so I cant tune as well as a better archer.


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## anmactire (Sep 4, 2012)

Dunno why we can't just help the guy understand the tool at the same time as giving practical advice...

The document from stu on how to use the calculator is here :
http://heilakka.com/stumiller/Dynamic Spine Calculator Instructions 7-18-10.pdf

Long story short, anything past 0.9 inches into the shaft would be considered as "footing".

Unfortunately you would need to know the weight per length of the point material to calculate that which is not a stat provided by the manufacturer of insert points.
If you happened to have a grain scale, a point you don't care about , and a hacksaw you could measure this directly however.
The calculator is a little more useful for hunting arrows due to the idea of insert style points.

The calculator is likely to get you in the ballpark of correct in my experience (mostly having already gotten arrows to work and checking does it agree after the fact) but you will need to measure and provide all the data correctly and understand that you will still likely need to buy a set of arrows and shoot them to see what happens.
If you have a few sets of known arrows that work with known set ups then you can sort of correlate this with the tool and make some future decisions using it but chances are by then you would know what you're doing and not need it!


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## jafgx (Apr 25, 2019)

Thanks for your invaluable help.

In next figure ( hand made) i want to traslate what i understand about Footing. Are correct the values traslated to DSC?


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## TER (Jul 5, 2003)

anmactire said:


> Dunno why we can't just help the guy understand the tool at the same time as giving practical advice...


Yes! Thank you for being the voice of reason. It's irritating when a valid question is met with answers for some other question about a different topic.


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## anmactire (Sep 4, 2012)

jafgx said:


> Thanks for your invaluable help.
> 
> In next figure ( hand made) i want to traslate what i understand about Footing. Are correct the values traslated to DSC?


Looks correct to me and I get good results using that method.


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## Bender (Dec 6, 2006)

One thing I will say is that no matter how detailed to the nth degree you get your input values for ANY calculator, no matter HOW sophisticated said calculator may be, don't just take the results and build the arrow to those results. 

No matter what, it is just a "simulator." It is just a guide to making initial shaft selection. If you want a GOOD arrow, actual real world tuning needs to still happen.


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## Nick728 (Oct 19, 2014)

With so many variables I've found it's wiser to look at spine charts, shaft selectors & calculators are starting point suggestions. Limb speed. string weight, brace height, cut arrow length, point weight, FOC, plunger pressure, nock fit, finger pressure, string material, release consistency & other variables, absolutely, makes tuning, fine tuning & testing essential. We can usually make a close suggestion work but a perfect fit requires more than those close suggestions offered making them a wild guess.
Many of the bow scales & chronographs I've seen or used are not 100% accurate. Without testing to prove the suggested shaft spine the choice, at best, becomes a close guess. With charts and selectors a fair & even bet is that if they err they err stiff for safety sake. Software used for compounds has a little more wiggle room. A drop away rest and a mechanical release from a D loop has far less variables. While just one of the recurves variable is limb speed a compounds main variable is speed followed by center shot. Truth be told with a compound the thing the matters the most is arrow weight. You can go up or down as long as the arrow weight is safe enough to not blow up your bow. Just my opinion of course. 
Nick


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## Captain Kirk (Sep 11, 2016)

Nick728 said:


> With so many variables I've found it's wiser to look at spine charts, shaft selectors & calculators are starting point suggestions. Limb speed. string weight, brace height, cut arrow length, point weight, FOC, plunger pressure, nock fit, finger pressure, string material, release consistency & other variables, absolutely, makes tuning, fine tuning & testing essential. We can usually make a close suggestion work but a perfect fit requires more than those close suggestions offered making them a wild guess.


The best summary you can write on this topic. :thumbs_up
For oly recurve with all the tuning possibilities including variable tiller bolts, spending money for theoretical shaft selection is simply useless.


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## Charles A Smith (Dec 9, 2014)

But arrows are expensive! I’ve struggled with choosing and then tuning. Still am. Any tool that helps is worth it in dollars and frustration.

And now I think I understand footing. I thought it was something to do with wooden arrows.

Now explain strike plate, for those of us that don’t have a strike plate. With the point of the arrow off the center line of the bow by half an arrow width then the plunger will be off centreline, to the right (negative?) by:

Arrow width/2 less Arrow width/2 x brace height/arrow length. About .12 less .04, so .08 of an inch. Negative or positive?


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## bvfd458 (Jun 16, 2017)

Interested too


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## jafgx (Apr 25, 2019)

In Quote #24 posted two doubts, first (Footing) remaked in Quote #31 and confirmed with Anmactire on Quote #33 (thanks Anmactire).
Second doubt dont answered yet (*Center Cut Strike plate Position *Parameter for a Olimpic Bow with pressure button) is posted once more by Charles A Smith on Quote #37.
Because one image is better tan 1000 words.....

















What value must we select in DSC?.
It´s a value thas has a big influence in Dynamic Spine, because that, we need to know it.


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## Captain Kirk (Sep 11, 2016)

Depending on your style of finger release spine can differ between 2 persons within 050-100 spine.

So the most reliable solution is finding the truth in bare shaft, walkback test and group tuning. (in this order)
Alone bare shaft testing on 20yds should be manageable for every slightly advanced archer. Including standard arrow offset and button pressure you should be capable shooting short to medium distances with no big issues. 
The lack of a consistent release will affect at this point much more than (slight) untuned arrow.


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## Charles A Smith (Dec 9, 2014)

“So the most reliable solution is finding the truth in bare shaft, walkback test and group tuning. (in this order)
Alone bare shaft testing on 20yds should be manageable for every slightly advanced archer. Including standard arrow offset and button pressure you should be capable shooting short to medium distances with no big issues. 
The lack of a consistent release will affect at this point much more than (slight) untuned arrow.”

All agreed. But, in my case I bought arrows, fletched them, trimmed them 1/2” at a time until they bare shaft into the group and am being told that they’re too stiff and are making contact with the plunger. So a program that helps me buy the right arrows before all that starts is very valuable. I’d like to own some (slight) untuned arrows. Emphasis on slight and not grossly.


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## Captain Kirk (Sep 11, 2016)

Did you set up center shot and plunger tension correct before bare shaft tuning? If so and the bare shaft grouped right, i think there is another problem than stiff arrows.


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## Nick728 (Oct 19, 2014)

You can make a stiffer spine work. Easton spine charts recommend on the stiff side. To get a perfect match you'll need a "good coach" & you'll have to do a lot of testing. I can tell you at 20 yards you can make anything work but the longer the distance the more important perfection in form an equipment becomes. For me, the Easton Chart is 1 to 2 spines stiff. The 3 Rivers calculator allows me to adjust & experiment. Software I"ve used for my compounds are useless for recurve. 
Viper wrote: "software is pretty muck BS"... I agree


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## ceratops (May 17, 2017)

Charles A Smith said:


> ...
> Now explain strike plate, for those of us that don’t have a strike plate. With the point of the arrow off the center line of the bow by half an arrow width then the plunger will be off centreline, to the right (negative?) by:
> 
> Arrow width/2 less Arrow width/2 x brace height/arrow length. About .12 less .04, so .08 of an inch. Negative or positive?


Yes, I'd like to know this also. I.e. how to enter plunger position into the centershot parameter. I've read all the guides/instructions for this software that I could find, and this point is not clearly addressed. Is it correct to simply treat the plunger tip position as equivalent to a strike plate position? Or not... since the plunger is not a rigid object as the arrow passes by? It's certainly possible that the calculation just isn't set up to deal with an elastic arrow positioning device!

That one parameter makes a huge difference in the dynamic spine values calculated by the software...


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## EvilGarfield (May 30, 2018)

Captain Kirk said:


> Did you set up center shot and plunger tension correct before bare shaft tuning? If so and the bare shaft grouped right, i think there is another problem than stiff arrows.


What is correct tension? Do you mean stiff plunger like it is in Tune for tens or correct tension determined by a walk back tune?


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## Captain Kirk (Sep 11, 2016)

Medium tension spring, offset for parallel shafts or tero to minimal offset with barelled. 
Like every other method describes ist - excluding tuning for 10s.

Start with bare shaft and proceed with walkback/french tuning if the archer is capable of shooting consistent up to 30-40m.


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