# Cam timing and synchronization



## lnz423

Hey everyone. I have a brand new Diamond Infinity Edge and the cam timing and synchronization seem to be off. I was doing some research and came across this thread http://www.archerytalk.com/vb/showthread.php?t=1646858&highlight=cam+timing so I understand the difference between the two.

In the manual, it shows that the cables should be between the two reference dots on the cams. Neither of them are between the two dots. They are both covering one of the dots, rather than centered between the two. I understand that I have to twist the cable to get it right, but I would like some clarification and a bit more info about doing so. I am most likely going to take it to an archery shop to have it done, but I took it to Bass Pro Shop's and the guy (archery specialist) said it was perfect, so I don't always trust other people. No one is going to treat my bow the way I will and no one will get it as perfect as I will.

Also, the synchronization is off. The stops don't hit the cable at the same time. What can I do to fix that? 

My last question is: Would shooting it like this hurt the bow? I haven't shot it for fear of damaging the bow.

Thanks everyone.


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## mdharcher

http://www.archerytalk.com/vb/showthread.php?t=1399457 Nut and Bolts tuning guide

This has everything in it you will need to know.

Shooting it like that will not hurt or damage your bow.


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## dwagoner

it wont damage bow, could make it louder and more hand shock and obvioulsy wont shoot as well as it will when tuned up. get it into spec soon, REMEMBER limb bolts maxed out when tuning. and glad to see you know the difference between timing and sync, should help you out getting it all right....


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## lnz423

mdharcher said:


> http://www.archerytalk.com/vb/showthread.php?t=1399457 Nut and Bolts tuning guide
> 
> This has everything in it you will need to know.
> 
> Shooting it like that will not hurt or damage your bow.


Awesome, thanks. I'm gonna have to give it a read. 



dwagoner said:


> it wont damage bow, could make it louder and more hand shock and obvioulsy wont shoot as well as it will when tuned up. get it into spec soon, REMEMBER limb bolts maxed out when tuning. and glad to see you know the difference between timing and sync, should help you out getting it all right....


I'm taking it in to Bass Pro today. We'll see if they can get it right. Thanks. 


I'll be reading the nuts and bolts guide, but what exactly needs to be changed to get the stops to hit simultaneously?


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## nuts&bolts

lnz423 said:


> Awesome, thanks. I'm gonna have to give it a read.
> 
> 
> 
> I'm taking it in to Bass Pro today. We'll see if they can get it right. Thanks.
> 
> 
> I'll be reading the nuts and bolts guide, but what exactly needs to be changed to get the stops to hit simultaneously?


One cable is longer than the other cable.

So,
you will need a portable bow press,
and you will need to squeeze the limb tips,
and then,
pick a cable
and then ADD or remove twists,
until you get the two draw stops to hit at the same moment.

Here is an EXCELLENT video about tuning a bow with a draw board,
to get the draw stops to hit at the same moment.

The bow is ON PURPOSE, set out of sync,
so you can see how to get the bow BACK into sync.

I would have you watch the entire video clip,
but,
if you want to fast forward to the 3 minute mark,
he talks about cam sync.


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## BTM

Inz423: You're to be congratulated for knowing that "timing" and "synchronization" are not synonymous. You're smarter than 90% of bow magazine writers out there!


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## ron w

BTM...well said!!

INZ423,
one point that I don't see much mention of, is to make sure your tiller is exactly even when checking timing. and I have learned that if tiller is perfect, the main element comes down to sync at full draw, make sure the stops hit at exactly the same time, if they do, timing will be automatically established , given tiller is right on. secondly, just exactly where the cams start from is not as important as where the end up at full draw. if there's any where to compromise, it would be in the position the cams are in, when they quit driving the arrow, or at brace, which is where you adjust timing., so, in order of importance,... tiller first, full draw synch second, and then timing at brace. the purpose of the string stop is to stop the string at exactly the same place every time, regardless of the attitude the string takes from cams being slightly out of time as they reach the point of loosing the arrow, or at brace.. 
obviously, the closer all of this is, the better the bow will perform, but the place to compromise is decided by the fact that the string stop is there to stop the string from driving the arrow at exactly the same spot every time, which is exactly the same function as the at brace timing.
basically, the stop puts a little forgiveness into limb deflection variations, and allows manufacturers a little more tolerance in the cost of limb production quality control. evidently, it's less expensive to put a stop on the bow than it is to control limb deflection variation to the degree that a stop isn't needed.


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## lnz423

Ok well after taking it to Bass Pro, the guy got it pretty close, but I can still tell it's a bit off. I'm almost done making my bow press and I'll be working on it from here on out. Since it's my bow, I'll spend all the time I need to get it just right. 

The guy at Bass Pro couldn't really figure it out so he undid all the twists in both cables completely and started from scratch. I didn't really like that very much and I asked him how many twists should it take and he said typically it's about 15 to 20 twists. 

What do you guys think? I know certain cables have specifications about how many twists per unit length they should have. How do I find out how many twists this bow should really have?


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## mdharcher

To measure a string/cable correctly, it needs to be measured at 100# of tension. Taking out the twist and then twisting it back up did absolutely nothing if he did not check the lengths.

The twist rate of a string/cable is part of the building process. some like more, some like less. The maximum twist rate is 1 twist per inch.

It scares me to think that people like the guy at bass pro shops are allowed to work on bows!


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## mdharcher

I should add that the lengths of the string and cables should be set to the manufacturers recommended lengths, then fine tuned form that point. They should be posted on your bottom limb, if not you will be able to find them on diamonds website.


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## nuts&bolts

lnz423 said:


> Ok well after taking it to Bass Pro, the guy got it pretty close, but I can still tell it's a bit off. I'm almost done making my bow press and I'll be working on it from here on out. Since it's my bow, I'll spend all the time I need to get it just right.
> 
> The guy at Bass Pro couldn't really figure it out so he undid all the twists in both cables completely and started from scratch. I didn't really like that very much and I asked him how many twists should it take and he said typically it's about 15 to 20 twists.
> 
> What do you guys think? I know certain cables have specifications about how many twists per unit length they should have. How do I find out how many twists this bow should really have?



Build a stretching device.

A fancy one will be a unistrut metal rail,
and two heavy duty angle iron brackets
and
threaded hooks.

Unistrut rail you can pick at any larger hardware store.
It comes in 10 foot lengths.

The brackets and threaded hooks are commercially available.











I put one end loop on the hook on the left.
Then,
I put the other end loop for the cable or the bowstring onto a hook for my dial spring scale.

Then, the top of the dial spring scale
goes onto the 2nd hook of the stretcher.

Crank the large knob
until the scale reads 100 lbs.

Measure from metal hook to metal hook for length.

*The guy at Bass Pro has NO CLUE.*

There are no "typical twists". You MUST measure at 100 lbs of tension.
*You MUST measure with a 1/4-inch diameter post (or hook) inside each end loop.*











So,
you have a twin cam bow.

You have two buss cables (cable with 3 end loops).

So,
take the two TOP end loops and put the two TOP end loops onto the hook on the LEFT side of your stretching device.

Put the single BOTTOM end loop onto the spring scale, if you have one.

Then, attach the other end of the spring scale to the 2nd hook of the stretching device.

Crank up the tension to 100 lbs.

When you have 100 lbs on your spring scale,
then,
measure from HOOK to HOOK.

If the measurement says your cable is TOO LONG,
then,
relax tension,
and then ADD TWISTS to the cable
and then,
stretch again up to 100 lbs
and measure again.

TOO LONG...add twists, then stretch to 100 lbs and measure from hook to hook, on your stretching device.

TOO SHORT..remove twists, then stretch to 100 lbs and measure from hook to hook, on your stretching device.

ONCE you have the FIRST cable PERFECT for length, measured at 100 lbs of tension (using your spring scale)....

then,
relax the stretching device,
and leave the FIRST CABLE on the stretcher and the dial spring scale.

Put the 2nd cable onto the stretching device.

So, the LEFT hook of your stretching device
will also get the TWO TOP end loops of the 2nd cable.

NOW, both cables are attached to the LEFT HOOK of your stretching device.

Now,
hook up the bottom end loop of the 2nd cable onto the hook for your spring scale.

Now,
the spring scale has the bottom end loops for BOTH CABLES attached.

STRETCH to 100 lbs of tension.

If the bottom cable (the FIRST CABLE) is TIGHT...but, the 2nd cable is LOOSE..

then, we know that the 2nd cable is TOO LONG.

Relax the stretcher,
and ADD twists to the 2nd cable.

REpeat this process until you have the FIRST and SECOND CABLES both TIGHT at 100 lbs of tension.

Now,
not done yet.

With both cables at 100 lbs of tension,
PINCH the bottom cable (FIRST CABLE) and then PLUCK it like a guitar string.

Now,
PINCH the top cable (SECOND CABLE) and then PLUCK it like a guitar string.

IF the SECOND CABLE makes a LOWER sounding tone/sound...
then, add a half twist, until the TONE of the SECOND CABLE matches the TONE of the FIRST CABLE.

When you PLUCK each cable
and you get the SAME SOUND...

then,
both cables are PERFECTLY matched for length and tension.


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## ron w

places like bass pro, gander, and cabella's are all about cost. the guy behind the counter is trying to make himself look cost efficient , in the eyes of management.....which is all they care about. for every dis-satisfied customer, there's 2 or 3 new ones to satisfy or sell something to, so don't waste unprofitable time on items that the profit has already been made on. some one came in with a problem, joe at the counter fixed it in a few minutes and the guy left happy.......joe gets to keep his job because he didn't give away allot of free, unprofitable time.....simple as that....it doesn't matter if the problem is actually fixed, they don't care.


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## lnz423

I completely agree with you Ron. I learned early on that I can't let anyone work on my Mustang. No one will care to do the job right. And nowadays with the internet, I can acquire more knowledge than any mechanic. The same goes for bows. Just by making this thread you guys have taught me more than the guys at Bass Pro know. 

Thanks for the awesome info Nuts&bolts,

I'm going to build the device to stretch the cables when I get the chance. I spoke to someone today that said if the axle to axle is right, then it should be ok. And my ATA is perfect in spec. So is he right?


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## Huston

Hello guys.
I'm new to the forum, just started out shooting compound. Been shooting traditional wood bows for some years. I got myself a Infinite Diamond Edge 2 months ago to try out compound archery (I dont have any archery club or LBS in the vicinity). I like it alot, the precision and consistency of a compound is awesome!  I recently noticed the cams were out of both timing and sync. I read this thread among others and watched several youtube videos. The tiller is good, the brace height is spot on 7", the cams are as good in time as they get (within the timing marks) but the synchronization is out (the draw stop hits the bottom cam first then it's about 3/8" left on the top). I tried to tune it so they hit the draw stop at the same time but then the cam timing is out. Does anyone have an idea about what's wrong? I live in southern Sweden and nearest bow shop is 125 miles away. I ordered the bow from USA so sending it back will be the last resort. I can upload pictures if it will help?

/Per


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## bugle_air

Pics will help. 3/8ths is a lot. Make sure both cam mods are on the same number, and if so, then the cables need to be tweaked to fix the sync. Either twists into one cable, twists out of one cable, or twists into one and out of the other. Post pics


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## bugle_air

Also, when checking those things, are your limb bolts bottomed out?


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## Huston

bugle_air said:


> Pics will help. 3/8ths is a lot. Make sure both cam mods are on the same number, and if so, then the cables need to be tweaked to fix the sync. Either twists into one cable, twists out of one cable, or twists into one and out of the other. Post pics


Both cam mods are on the same number. I did twist and untwist strings to make the cams time. But the same cables also affects the sync. Is there any way to only affect the sync without changing the timing? I will post some pics tomorrow. 

The limbs are not bottomed out (if you by that mean max power? sorry, english isn't my native language). They are set at ~55 lbs.

/Per


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## bugle_air

Turn each limb bolt in all the way to max poundage, counting exactly the amount of turns on each bolt. Then take pics of the mod-side of both cams would be good, and also pics from the back, to see if there's any cam lean too please


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## Huston

Okey, so here's the story. Yesterday when I checked the cam sync I drew the bow and my girlfriend looked at the cams. I also checked myself in the mirror. I tried to tweak best I could but wasn't satisfied and hung it on the wall until today. When taking pictures for you I wanted to get good ones so I went out to the garage and made a "rig" to hold the bow drawn. The result shown in the pics, its wasn't the same as yesterday (??). I can't explain why it was good today, maybe because the bow was fixed in the rig. Maybe something is wrong with my form, strange pressure on the grip so that it affects the cams? I did nothing since I think it's good enough. The cams are a bit out of time but ½ twist made it worse when I tried yesterday. 
I went out to try it and at ~15 yards I got these groups. To me, it's good. Only been shooting it for about 10 sessions so I'm still learning. Please tell me if you think I should try to fix the cam timing, I like fixing and tweaking my bows but for now I believe it's good enough for me 

Limb bolts equally set








Cam timing, left one is a bit out but still within the marks








Tiller is spot on








Bow + group


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## bugle_air

All that looks great. Good shooting as well. Doesnt look like anything needs to be adjusted further.


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## outdoorarchery

Hey guys I just bought my first bow yesterday, a diamond infinite edge pro, however I noticed my timing was off because my cables were on the reference marks for timing rather than being in between, I wanted to know if this was detrimental to the bow as the cabelas "prostaff" set up the bow and said it was good to go. Also my reference lines seem to be different from the above user who posted the pictures of his cables and timing. I only have one timing cable reference for the A setting, can anyone give me any advice as to what to do? Like i said the cable is resting on the reference dot rather than in between.


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## outdoorarchery

Sorry I forgot to upload the picture of my manual's timing marks, Ill be uploading a picture of my timing later today.


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## Huston

outdoorarchery said:


> Hey guys I just bought my first bow yesterday, a diamond infinite edge pro, however I noticed my timing was off because my cables were on the reference marks for timing rather than being in between, I wanted to know if this was detrimental to the bow as the cabelas "prostaff" set up the bow and said it was good to go. Also my reference lines seem to be different from the above user who posted the pictures of his cables and timing. I only have one timing cable reference for the A setting, can anyone give me any advice as to what to do? Like i said the cable is resting on the reference dot rather than in between.


One cable timing reference? Do you mean you only got 1 dot? Can you upload pictures of the bow like I did and maybe I can help you.


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## outdoorarchery

I will upload a picture later today, but what I mean is that there are two lines that represent the proper timing, the manual says that the cable should be between these two lines, however my cable is directly on one of these lines, therefore it's "on the edge before it goes out of the timing bounds", hopefully that makes sense, as I said I'll be uploading a photo later today.


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## Luke Cool

There are three parts to the cam’s power discharge cycle; the let-off valley, the power stroke, and the rest valley. The cams are basically tear drop shaped. The flat part of the cam near the end of the string is the let-off valley. The round part in the middle of the cam is the power stroke. And the flat part of the cam that is farthest from the end of the string is the let-off for the string arriving at rest. This last let-off will allow the string to arrive at the rest at a much lower power. With it, the power system will last a lot longer and the bow will shoot considerably quieter. 

The purpose of the timing marks is to provide a reference point so that you can synchronize the cams to hit each part of the power cycle at the same time. The marks do not have to be right under the cable, but they do need to be at the same reference point (the same distance and direction from the cable). This way you will get the maximum benefit from each section of the cam. If the timing marks are not synchronized; at full draw, imagine one cam against the back wall in the let-off valley, and the other cam only half way into the valley. The result would be a short valley with a weak back wall, and both cams would enter and leave the power stroke at different times. This will cause the string to move up and down during the discharge cycle.

The timing marks being synchronize, but not right under the cable, will only affect one thing. 
It will have a small affect on the draw length. Other than that, there are really no adverse affects.


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## Luke Cool

I just read "baldyhunter" rant mentioned in the first post. Its good read, thanks for the reference.
"The timing marks being synchronize, but not right under the cable" is the timing being off.
He said "you are also adjusting peak weight, draw length, duration or length of the plateau, lettoff, and how much energy a cam stores during the draw cycle".
He is correct, all of this things are tied to "draw length".
"Peak weight", and "how much energy a cam stores during the draw cycle" is a measure of the same thing.
In "duration or length of the plateau", he is referring to power stroke part of the power discharge cycle. 
If the draw length is longer, all parts of the cam's power discharge cycle are longer, including both "Let-offs".
Most RTH (ready to hunt) bows show up from the factory with the timing off a little. Nether the manufacturer nor I consider this to be a problem.
The timing does effect peak weight, draw length, duration of the power stroke, and both let-offs; but it being spot on will not necessarily put the bow to factory specs.
All bows, even of the same make and model, are a little different from each other. 
If you wanted more power, you could put a few more twist in the cables, but when you corrected the draw length, the extra power would go away.
The "draw length" and "timing" adjustments have the same effect. The timing can be used to fine tune the draw length.


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## Quiggly Quiggly

Ive been having the same problem with my Sons Diamond Prism. one cable is between the dots and the other cable is just outside the dots and not in between. the string stops were not touching at the same time either, I fixed the string stops so they are touching at the same time, well best I can do anyway the bottom touches a hair before the top. but the timing marks are still out when its at rest. not sure how to twist the cables to move the cams so the timing marks line up with the cables without messing up the draw stops again. any help would be very appreciated. been racking me brain. maybe I need to twist or untwist the string as well a couple turns?


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## nuts&bolts

Quiggly Quiggly said:


> Ive been having the same problem with my Sons Diamond Prism. one cable is between the dots and the other cable is just outside the dots and not in between. the string stops were not touching at the same time either, I fixed the string stops so they are touching at the same time, well best I can do anyway the bottom touches a hair before the top. but the timing marks are still out when its at rest. not sure how to twist the cables to move the cams so the timing marks line up with the cables without messing up the draw stops again. any help would be very appreciated. been racking me brain. maybe I need to twist or untwist the string as well a couple turns?


Step 1. Loosen the draw stops and have both stops NOT touching.
Step 2. Press the bow in a bow press (squeeze limb tips together with a portable press).
Step 3. You have two yoke cables (y shaped cables). So, pick ONE cable and only work that ONE cable. Leave other cable alone.
Step 4. You have two directions to go with that ONE cable. ADD more and more twists, or REMOVE more and more twists, until dots match.
Step 5. You pick adding twists to that ONE cable, and you take the bow out of the press. DARN...the dots are even MORE mis-matched.
Step 6. Back to the press and working that SAME cable, go the other direction and REMOVE more and more twists until dots match.
Step 7. With bow out of the press, confirm dots match. NOW...move the stops to touch the cable, when the bow is at full draw.

No, you do not need to twist or untwist the string. Untwisting the bowstring will lengthen draw length at tiny amount.
Twisting the bowstring, will shorten the draw length a tiny amount.
Work ONE cable (add or remove twists) to get dots matching.


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## Quiggly Quiggly

nuts&bolts said:


> Step 1. Loosen the draw stops and have both stops NOT touching.
> Step 2. Press the bow in a bow press (squeeze limb tips together with a portable press).
> Step 3. You have two yoke cables (y shaped cables). So, pick ONE cable and only work that ONE cable. Leave other cable alone.
> Step 4. You have two directions to go with that ONE cable. ADD more and more twists, or REMOVE more and more twists, until dots match.
> Step 5. You pick adding twists to that ONE cable, and you take the bow out of the press. DARN...the dots are even MORE mis-matched.
> Step 6. Back to the press and working that SAME cable, go the other direction and REMOVE more and more twists until dots match.
> Step 7. With bow out of the press, confirm dots match. NOW...move the stops to touch the cable, when the bow is at full draw.
> 
> No, you do not need to twist or untwist the string. Untwisting the bowstring will lengthen draw length at tiny amount.
> Twisting the bowstring, will shorten the draw length a tiny amount.
> Work ONE cable (add or remove twists) to get dots matching.


Thank you , I appreciate the help.


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