# Micro tuning draw length



## Danport

I read that small adjustments in draw length can make a significant difference in holding steady.
I have a Hoyt Vantage Elite Plus with GTX cams.
Can anyone advise me on the best way to adjust draw length in small (1/8 to 1/4 inch) increments?
Do I twist the string or cable and how much?
Is it pretty much trial and error?
Advice much appreciated.


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## WVaBuckHunter

It depends on whether you want to lengthen or shorten your dl. If your cams are in sync, I would make adjustments with the string (as long as it is micro adjustments). If you want to slightly shorten your dl, then add a couple of twists at a time, until you get it where you want it. If you want to lengthen the dl, take a couple of twists out of the string. Just keep track of how many twists, you added or subtracted so that you can get back where you started.


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## FS560

Unless the string has almost no twist or is twisted up like a pretzel, three full twists either way should keep the peep with the same alignment.


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## SonnyThomas

Yes, it is a trial and error situation. 1/8 to 1/4" may take some twisting of both bow string and cables. First, record ata. Maintain ata and draw weight is not effected.
Two methods are used. One is a 3 to 1 ratio and the other is a 4 to 1 ratio. One twist of each cable equals 3 (or the 4) twists of the bow string. Example; One full untwist of each cable and 3 (or the 4) twists of the bow string will shorten the draw. This advances the cams and as such, the draw stop. To lengthen, one full twist of each cable and 3 (or the 4) untwists of the bow string will lengthen the draw. This ******s the cams and as such, the draw stop.
See nuts&bolts tuning manual - Sticky at top of General Archery Discussion.


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## nuts&bolts

Danport said:


> I read that small adjustments in draw length can make a significant difference in holding steady.
> I have a Hoyt Vantage Elite Plus with GTX cams.
> Can anyone advise me on the best way to adjust draw length in small (1/8 to 1/4 inch) increments?
> Do I twist the string or cable and how much?
> Is it pretty much trial and error?
> Advice much appreciated.


I am working on a Contender Elite, to do EXACTLY this.
Spiral X 4.5 cams.
XT2000 limbs.

I am trying to drop the draw length 1/4-inch.

1/4-inch REDUCTION in draw length for a fixed draw length cam (Spiral X) is actually a HUGE adjustment.
This is the MAXIMUM adjustment, cuz fixed draw length cams are only available in half inch sizes.


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## nuts&bolts

Sooo,
since you have the GTX,
which has the adjustable draw length module...

the draw lenght module is ALSO only adjustable
by half inch adjustments.

So,
a 1/4-inch adjustment is the MAX adjustment.

Yes,
micro-adjusting the draw length will have a HUGE change in how steady you hold.

When I work with advanced level shooters,
sometimes a half twist or a full twist adjustment makes the difference in improving the x-count...LARGE difference in FEEL.


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## nuts&bolts

Sooo,
here are the basics.

The buss cable (cable with 3 end loops) controls the ATA.
When you SHRINK the ATA, the bow DL increases...slightly.....let's call this a medium size adjustment.
Excellent for fine tuning the DL.
So, the buss cable IN-DIRECTLY affects draw length.


The bowstring, controls the draw length setting DIRECTLY.
So, you make LARGER adjustments when you twist or untwist the bowstring.

*NOTE: the bowstring ALSO controls the timing position of the cams.*
This is VERY important.


When you TWIST the string, you obviously SHORTEN the bowstring...
but,
the side effect is that the cam starting rotation position moves CLOSER to the riser,
and this results in a *smaller valley* 
and a slightly HIGHER holding weight, 
and a tiny, itsy bitsy bit LESS draw weight.

On the Hoyt Spiral Cam,
this effect is VERY VERY noticeable,
especially at the higher poundages.

So, this effect is TRUE for all cam designs,
but HOW much of this effect you FEEL,
depends on the draw weight, and how aggressive the cam design is.


Soooo,
when you UNTWIST a bowstring,
you obviously....increase the length of the string,
you increase the DL setting.

This ALSO moves the cam starting rotation position AWAY from the riser,
and this also results in a CHANGE in feel,
where the valley is a tiny bit larger.


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## nuts&bolts

Soooo,
tweak the bowstring to get the draw length where you want it.

ADD twists to the bowstring to shorten the DL setting.
REMOVE twists to the bowstring to lengthen the DL setting.

MAX adjustment is 1/4-inch,
but I would go a step at a time,
and just try 2 complete twists or say
3 complete twists,
and shoot 100 arrows,
and see how you like the CHANGE in FEEL.

Let's discuss the SHORTEN draw length direction.

So,
you ADDED say 3 twists to the bowstring to SHORTEN the draw length.

Sight pin float is a bit tighter...x-count is a tiny bit better (use a shooting log book).

So,
now, you go up to a total of 6 extra twists in the bowstring.

WOW!
Definite improvement is sight pin steadiness,
and you can FEEL yourself engaging your back muscles,
and your hinge release is now firing MUCH crisper, with less effort.

BUT,
every so often,
you get a WILD flier arrow. Sight pin float is really tight, but also really fast,
the pin dances in a small pattern, but kinda darty. VALLEY is much smaller than before.
(shortening the bowstring has rotated the cams TOWARDS the riser).

So,
we need to build the VALLEY back up a skosh.

ADD a HALF TWIST to the buss cable,
to shrink the ATA
to INCREASE the DL a TINY amount (buss cable half twists make a smaller adjustment than...a half twist to the bowstring).

Small adjustments go a LONG WAYS here.

Shoot another 100 arrows,
with this EXTRA half twist to the buss cable,
to bring back the valley a SMALL amount.


Ok.

Sight pin float is still a tiny, small pattern,
and the x-count is slowly CLIMBING...scores are getting better.

BUT,
the arrow groups are skinny (LEFT to RIGHT direction)...

but,
you NOW are getting the occasional flier at 12-o'clock HIGH
and sometimes...
getting the occasional flier at 6-o'clock LOW.

Telephone pole shaped groups.


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## nuts&bolts

If you are getting telephone pole shaped groups...

occasionally...

then,
you need to CREEP TUNE your hybrid cam bow system.


This just means to FIND the sweet spot
for HALF TWIST adjustments to the control cable (cable with only 2 end loops).


The control cable is just like a bicycle chain,
and it connects the top cam to the bottom cam.

The control cable acts like an anchor on the bottom cam,
due to the tight wrap around the cable track on the bottom cam.

So,
when you LENGTHEN the control cable by just a HALF TWIST ADJUSTMENT,
you are changing the TOP CAM starting rotation position.

So,
when you SHORTEN the control cable by just a HALF TWIST ADJUSTMENT,
you are changing the TOP CAM starting rotation position.


So,
if you are getting telephone pole shaped groups (high low misses)...

then,
your draw length setting has been micro-adjusted VERY WELL (horizontal misses are at a minimum)
and
now,
we need to find the SWEET SPOT for the control cable length...a HALF TWIST adjustment at a time.


When you are adjusting the control cable it the CORRECT DIRECTION (either lengthen or shorten)...

the TALLNESS of your telephone pole groups will SHRINK....vertically.


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## nuts&bolts

Sooo,
like SonnyThomas says...

go in back and forth steps.

SHORTEN the DL with extra twists in the bowstring....several twists at a time.
SEE improvement in your scores, in the FEEL, due to the shorten DL setting.

Restore the VALLEY by ADDING a half twist to the buss cable
and CONFIRM that the scores are still going in the correct direction.

SHORTEN the DL some more, with several EXTRA twists in the bowstring.
SEE improvement in the SCORES, in the FEEL of the draw cycle
see improvement in the sight picture.

Restore the VALLEY by ADDING a half twist to the buss cable
and CONFIRM that the scores are still going in the correct direction.


So,
back and forth.

Keep going until your scores are at MAXIMUM...
and any ADDITIONAL changes (another round of EXTRA twists)
causes the scores to creep back down.

Go too far on the adjustments,
and then go back the other direction,
and undo the last round of adjustments.

This way,
you KNOW you have hit the sweet spot for micro-tuning your DL setting.


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## little buddy

Wow good stuff here. Thanks for all of the above. It's going in my favorites.


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## claymx

been doing just that for the last cpl weeks with a buddy that knows how to do this. Takes a bit to get it dialed in but well worth the pain. Might want to take your bow to a string guy and have them custom build a set for you after. My string and cables were so twisted up.....it works tho.
Great thread and info on here.


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## srb99

Great stuff here....


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## Trykon Mike

Subscribed


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## Tallybowman

great read!


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## CDURFEY

yep...very good stuff


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## padeadeye

Hey N&B, how does this work with binary cams? I shortened my draw length by twisting the strings but now my cam orientation is off a little and ata is 1/16" short.


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## devin1

Subscibed, good stuff


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## carlosii

i'm lost on most of this, but i have been using the draw stop on my Shadowcat to make minor changes in dl...is this kosher?


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## Scott.Barrett

Thank you N&B!!!! Great description you've provided here!!! A true asset to the AT community!


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## nuts&bolts

padeadeye said:


> Hey N&B, how does this work with binary cams? I shortened my draw length by twisting the strings but now my cam orientation is off a little and ata is 1/16" short.


Hello padeadeye:

With a binary cam system,
you have two control cables...

and

you have the bowstring.

So,
ATA only controls the max draw weight.

To adjust draw length say a TINY BIT, say 1/8th inch short, say 3/16ths inch shorter....

(changing the modules would be too much of a change in DL...this is where you want to make a smaller change in DL)..

then,
you really have only one option:

a) bowstring twists (extra twists on the top and bottom), but as you noticed...this changes the CAM starting rotation position.

I do not recommend tweaking BOTH cables, cuz the binary cam system is sooooo sensitive to cable pressure/tension.
Keep the holding weight at 20% of the draw weight, by tweaking twists in the cables.


One more thing you could do,
is to use some grip tape around the bow grip,
to build up the thickness.

This THICKER grip,
will do the same thing,
as trying to shorten the bow DL setting.


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## Scott.Barrett

So I have to ask the opposite....how about a single cam like on a PSE Supra One cam?


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## ru4auto

Great thread


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## Reverend

Subscribed.


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## nuts&bolts

carlosii said:


> i'm lost on most of this, but i have been using the draw stop on my Shadowcat to make minor changes in dl...is this kosher?


Sure.

The draw stop system, especially if you have a slot for the draw stop,
makes your DL infinitely adjustable.

When you use a draw stop system, to tweak DL,
you also are changing the holding weight.

Move the Draw Stop in the shorter direction,
you also increase holding weight.

Move the draw stop in the longer direction,
you also decrease holding weight.


I had a Martin FireCat, with a DL module and draw stop system.

One trick,
was to decide what DL you want, say for example 29-inches.

Then,
I would adjust the DL module to the 29.5-inch position,
and
move the draw stop to the 29-inch position,
stopping cam rotation EARLY on purpose.

This would give me the 29-inches of Draw Length,
AND
it would increase the holding weight (better for at target shooter with a hinge release).


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## nuts&bolts

Scott.Barrett said:


> So I have to ask the opposite....how about a single cam like on a PSE Supra One cam?



Hello Scott:

I have not worked with a PSE Supra One cam system,
sooooo...

I can only discuss what I have to do with my Mathews Apex 7 Single cam.

You can draw conclusions and general ideas about FIXED draw length single cams.


So,
as you know,
with a single cam system,
you only have two pieces to the rigging system:

a) super long bowstring

b) standard buss cable.

With the FIXED DRAW LENGTH single cam system,
you do not have many options.


1) YOU CAN twist or untwist the bowstring.

2) YOU CAN twist or untwist the buss cable.

That's it.

So,
since the Mathews APEX 7 has timing holes/reference dots...
there is ONE cam starting rotation position that the factory recommends.

After much testing, I have to agree.

The nock travel is HORRIBLE, when the cam starting rotation position is NOT CORRECT, on the Mathews Apex 7 cam.
Gotta get the timing holes/reference dots to form a line that is DEAD parallel to the bowstring, when the bow is at rest.


So,
pick a buss cable length...add or remove twists,
and
then you have ONLY ONE bowstring length that will work,
cuz the bowstring length controls the cam starting rotation position.

Sooo,
tweak the bowstring length with extra or less twists...

then,
there is ONLY ONE buss cable length that will work, to get the cam starting rotation position correct.


TWEAK the bowstring length correct, to get the DL correct,
and then,
the cam starting rotation position is OFF.

So,
tweak the buss cable to get the cam rotation position correct,
and now DL is off.


You see,
at least with the Mathews Apex 7 FIXED DRAW LENGTH Cam....design,
the buss cable affect ATA,
which ALSO AFFECTS DRAW LENGTH,
and to a smaller degree,
cam starting rotation position.

Well,
the bowstring length also controls, primarily, draw length,
but,
the bowstring length also controls CAM STARTING ROTATION position.


So,
to folks who say a single cam is the EASIEST to TUNE,
....ummmm,
....welll,
like a challenge,
if they want DEAD LEVEL nock travel.

It is possible,
but not easy to do.


So,
MY Mathews Apex 7, with factory brand new bowstring and cable,
came with a 29-inch FIXED DRAW LENGTH Apex 7 cam....

but,
the measured on a draw board AMO DL = 29.25-inches.

So,
if you want to keep the factory reference dots in position, on the Apex 7 cam,
there is ONLY ONE OPTION...

to get down to 29-inches of AMO draw length.

NEW buss cable, at a different than factory length and
NEW bowstring, at a different than factory length.

If you ask custom bowstring builders,
it is common knowledge that the factory specs, 
may or may not deliver AMO DL, for the FIXED DL cams.

Sooo,
at least for a target shooter,
a FIXED DL cam that delivers 1/4-inch too long on the DL,
will just not work.

I like a challenge,
and found the NEW buss cable length and the NEW bowstring length,
that WILL deliver 29.0-inches of AMO draw length,
AND
have the factory recommended starting cam rotation position.

ONLY way to reduce the draw length 1/4-inch on the FIXED DRAW LENGTH single cam system,
is to reduce the brace height 1/4-inch,
cuz the power stroke is the same (same 29-inch APEX 7 cam)...

so,
we have the same amount of cam rotation,
paying out the SAME amount of bowstring,
when the the draw stop hits the buss cable.

So,
with a LONGER string
and a LONGER buss cable,
the ATA increases,
and the brace height decreases.

The trick is to find the amount of increased buss cable length,
to get the 1/4-inch BH reduction,
and
then,
to find the correct amount of increased bowstring length,
to get the correct cam starting rotation position,
for the APEX 7 cam,
with the new buss cable length.


I guess this makes a single cam EASY to tune, right?


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## nuts&bolts

PS:

Since folks were asking in another thread,
which cam system is EASIER to tune....

I up and went
and installed a set of Hoyt Spiral X cams in size 4.5
onto my Mathews Apex 7.

My first.....Spirapex 7 frankenbow.

Had to take some Diet Coke aluminum can shims,
and hammer some custom thickness shims
(helps to have a digital caliper that reads down to 1/10,000ths).

The Spiral X cams actually fit quite nicely inside the Mathews Apex 7 limbs.
Top shim required thickness and
bottom shim required thickness are different,
but it works GREAT.

Adjustable letoff percentage.

THREE piece rigging system (buss and control and string).

Hard draw stop with adjustable position = adjustable letoff.

EASY CREEP TUNING with the "separate control cable"...instead of the super long bowstring.


Seems to me,
that an Apex 7 with SPIRAL X cams,
is soooooo much easier to tune,
the the solo cam system.

AT least, for me.


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## Scott.Barrett

Luckily, the PSE Cam has adjustments and modules for the draw lengths...

I am guessing that adjusting in between lengths is going to cause the cam to change starting point. So if I adjust it back using the buss cable, I will either lose or gain brace height depending on the direction...

SB


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## nuts&bolts

Scott.Barrett said:


> Luckily, the PSE Cam has adjustments and modules for the draw lengths...
> 
> I am guessing that adjusting in between lengths is going to cause the cam to change starting point. So if I adjust it back using the buss cable, I will either lose or gain brace height depending on the direction...
> 
> SB


Hello Scott:

Yup,
you can do a combo when adjusting in-between DL module sizes.

Assuming that the PSE DL modules are 1/2-inch apart...

and you want to tweak draw length say 1/8th inch or 1/4-inch...


you can do one of two things,
or a combo...

a) just twist the bowstring to adjust the DL a small amount in the shorter direction

b) just untwist the buss cable, to increase ATA, to decrease BH, so you get a small decrease in the DL

or

c) a combo of both.

You can split the difference.

Say you want a 1/4-inch DL adjustment.
You would boost the ATA longer (untwist the buss cable), to decrease the DL say 1/8th inch.

Then,
you could also ADD twists to the bowstring, to decrease the DL say another 1/8th inch,
to get a TOTAL 1/4-inch DL reduction,
and
you get a boost in the holding weight, this way.

Whichever method you choose,
depends on how you want the back end of your draw cycle to FEEL.


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## grantmac

Any hints for pre-04 Hoyt Accu-wheels?

Thanks,
Grant


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## turtle_man515

So if i untiwist my string one complete twist on both ends that will keep my cam in time but will it move my d loop up or down? and how much will that gain me in length?.... thanks in addvance!!


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## jhumble123

save for later


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## ArcherXXX300

Tagged. Good question for Nuts&Bolts. I've got an Alpha Elite and a Conquest 4...now on the Conquest 4, I had it restrung and have been tuning for days. I wanted the DL shorter than the 28" that it is set at and 27.5" the sight picture is too fast and I feel cramped. So I put it on the 28" post (mini max cam) and I took twists OUT of the string and OUT of the cable and measured it to be 26.0" from throat of grip to string at full draw which equates to a 27.75"DL. I'm wondering why it is that UNTWISTING the bowstring and cable shortened the DL? Is it just that by untwisting both I increased the ATA? I first twisted the string only 12 twists in (6 top and 6 bottom) and ended up going from 26.25 to 26 3/8". Cam timing in spec per pics from Mathews. So I untwisted the string and cable to get the DL I wanted, and timed the cam with the cable...is this correct or not?


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## 5965derek

Marked for reference. Thanks


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## nvcnvc

I' am tagging this for reference too. Great stuff!


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## Hittingguru

tag


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## blueidexx

tag


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## BHWoodyard10

Saved good stuff


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## SportsmansRanch

Subscribed


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## ctownshooter

ttt


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## Tallybowman

subscibe


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## johnny liggett

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## steve101610

Good info


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## 419donny

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## prozko

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## jamesbusbin

I just procured an Elite Plus, so this is very useful. Now just to find the time to get this all done!


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## Mainefella

tagged


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## multi-target

Subscribed


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## northshoremb

Wish there was a way to just save individual responses so you can build a library. That way you don't need to go through all the other posts to find your answer. If the answer say was on page 23 of 43 pages of responses then it would take forever to find. I sometimes take screenshots but then that even takes a bunch of times to get it all. Thanks though Nuts&bolts

Sent from my SM-G900W8 using Tapatalk


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## multi-target

Good to know.


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## hlee61

nuts&bolts said:


> Hello padeadeye:
> 
> With a binary cam system,
> you have two control cables...
> 
> and
> 
> you have the bowstring.
> 
> So,
> ATA only controls the max draw weight.
> 
> To adjust draw length say a TINY BIT, say 1/8th inch short, say 3/16ths inch shorter....
> 
> (changing the modules would be too much of a change in DL...this is where you want to make a smaller change in DL)..
> 
> then,
> you really have only one option:
> 
> a) bowstring twists (extra twists on the top and bottom), but as you noticed...this changes the CAM starting rotation position.
> 
> I do not recommend tweaking BOTH cables, cuz the binary cam system is sooooo sensitive to cable pressure/tension.
> Keep the holding weight at 20% of the draw weight, by tweaking twists in the cables.
> 
> 
> One more thing you could do,
> is to use some grip tape around the bow grip,
> to build up the thickness.
> 
> This THICKER grip,
> will do the same thing,
> as trying to shorten the bow DL setting.


Hello nuts&bolts,

How would this work on a twin cam bow? For example, if I wanted to see if increasing or decreasing the draw length would tighten my groups?

Best,
Hansol Lee


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## jmeyer

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