Arrow Jumps during cocking

[WildWillie]

All -

I've been heavily practicing with my Tac-15i the last few weeks getting ready for Archery season and have a really annoying problem.

I connect the traveler to the string and knock an arrow. When I start cranking it back about 1/2 to 2/3's of the way I hear a loud click and the arrow usually jumps off the string and I have to re-knock it. It is still hanging in the whisker-biscuit!

It seems to happen at the same spot everytime cranking it back.

Does this happen to anyone else ? Could it be something withing the cams/bow limbs ?

Once it's cocked and fired it seems to be shooting OK. Though I'm still not getting that great of groups at 60yards (about 9").

I got the xbow for Christmas the end of last year.

Also do most of you paper tune the Tac-15i before shooting ?

WildWillie

Tac-15i
HHA Optimizer
Stock Tac-15 arrows
G5-Montac Broadheads

 

[Len Backus]

Paper tune first.

Read the thread on scope parallax.

Email my son about string jump.

[email protected]

 

[jon.henry755]

Hi WildWillie,
I might be able to identify and solve your problem, if it's what I think it might be.

You need to pay very close attention and carefully watch your arrow as it comes back during the cranking operation. I've had and seen this problem numerous times before. The only difference from the way you're describing it, is that it almost always takes place when you are within about 1 1/2 to 2 inches of being seated in the "full cock" position. What was taking place is that as your arrows nock reaches the front edge of your Weaver Rail, the under side of the rail is beveled or angled so that when the nocks touch the rail, they are forced underneath it until they drop into the seated position. As your nocks spread open more from shooting them, the top edge of the nock catches the underside of your rail and is forced forward off your crossbows string as you are cranking the cable back. This obviously dislodges the arrow from its cable position and forces you to let down the cable and attempt another load.

The solution, if this is the problem that is happening on your crossbow is two steps. I would suggest taking a grinding wheel on a dremmel tool and turn your TAC15 upside down on its back. Then grind the edge off the under side of the Weaver rail to remove any edge and possibly create more of an angle to allow a smoother transition.

Secondly, replace the PSE nocks with "Firenock D's, since they are a much stiffer synthetic material and don't have a tendency to spread as easily as the PSE nocks. They are also cheaper by the dozen than the PSE nocks.

Last note, If you have reviewed my article on getting rid of your Whisker Biscuit, you'd know that more and more TAC15 owners have been replacing their Whisker Biscuits with a QAD Drop Away Arrow rest and also cutting 2.75" off their Weaver Rail. This totally eliminates your nocks or vanes from ever having any interference with your scopes rail or anything else on your crossbow.

One of our other very highly respected field testers is in the process of having a brand new QAD Drop Away Bracket machined to his high level specifications and is also having his machinist make the modification to his Weaver rail, so the angle is perfect and he will maintain a perfect finish to his powder coating.

Either way, he now understands the performance advantages derived from performing these modifications. If you are interested, he may be producing several of these arrow rests and might offer them for sale. One of the big benefits is that a shooter is no longer locked into using four fletch arrows, so you can not only use standard three vane arrows, but you can also maintenance your arrows with any standard fletching jig.

Hope this helps,

Jon

 

[WildWillie]

Secondly, replace the PSE nocks with "Firenock D's, since they are a much stiffer synthetic material and don't have a tendency to spread as easily as the PSE nocks. They are also cheaper by the dozen than the PSE nocks.

Jon -

I already use the Firenock "D"'s, and it happens with them as well the stock nocks.

Also it is happening before the carrier assembly with arrow gets to the scope rail. It happens at the same point each time which is about 2" forward of the scope rail. (As the carrier passes over the back end of the long hand groove under the rail)

When I am cranking it back there is a noticable "Click" coming from the front end of the bow. Sometimes if a am cranking very slowly it does not occur, but 90% of the time it does.

It seems as if something is binding in the limbs or cams and when it gets to a certain point it free's itself causing a snap in the string.


Willie

 

[Thegunt]

I hope someone has the answer to this as mine started to make this same sound. I have only fired my bow about 50 times.
I get that loud snapping sound from the front right side of my bow. It occurs no matter how slow I crank it back. The only difference is my arrow will stay on my string.
I am afraid that something is about to fail in a big way.

Also I noticed that the string stops are spit 1/2" deep from the string impacting them. I guess a call is in order to PSE today.

 

[infantrysold]

Lmao!!!!!!! Do not and i repeat do not grind anything on your xbow. It is a easy fix i had the same problem it is when you pull your string out past your d loop. It is like a fishing reel it all winds up then slides off the spool and thats where you get your jump pull the string all the way out and reel back in and make your string go to one side or the other and it will fix your problem i hade a heack of a time with it untill i talked to the pse engineer thanks trav

 

[WildWillie]

I do not plan on grinding anything on my xbow.

After removing the upper and inspecting everything, I tried cranking the string with some tension on it. As infantrysold mentioned, the problem is when the string starts spooling it piles up on itself. At some point the string finally slips to the side and that is where you get your "jump" from. If you've ever fished offshore with some of the big reels you have to help guide the string as it is being wound on or else it piles up on one part of the reel. Same thing with the xbow. The string is piling up, but under the tension at some point it slips off the pile and that is where it jumps.

After putting everything back together I was able to test by guiding the string as I cocked the xbow and the problem went away. If I do not guide it the problem returns.

After shooting at paper, I noticed I was getting a tear to the bottom. Adjusted the rest and have taken most of the tear out.

WildWillie

 

[jon.henry755]

Hi WildWillie,
The information that i supplied was wrong for your particular problem, but it was correct for the problem that I described.

Your cause was coming from a different source, but myself and others have encountered the problem of the arrow nocks clipping the edge of the Weaver Rail as the cable sled reaches almost the full draw position. This does not ever occur on the TAC15's, but it does take place on the TAC15i's.

Glad somebody else on the forum had experience with this problem.

Jon

 

[Andy Backus]

On the last page of PSE's Tac 15 instruction manual is a section called "Trouble Shooting". The second item there might be what you need.

Here's what it says:

Issue:

When cranking, a clunk is heard and the arrow may pop off the string.

Solution:

The draw cord is not spooling up properly. The draw cord is initiating its spooling in the wrong direction. Looking at it from the back it should spool to the left first. Remove the lower and unspool the release all the way. Start cranking it back and use your finger to start the spooling in the proper direction. NOTE: When pulling the release forward, only pull it far enough forward to attach it to the loop. This will prevent the first wrap around the spool from winding in the wrong direction.

 

[jon.henry755]

Hi All,
To add to the instructions that Andy has provided also do the following:

If you do pull excess cord out to attach your D-Loop to the winding sled release or forget about the sled long enough to use your right hand to apply tension and guide the excess winding cord back onto your cranking spool while you begin cranking with your opposite hand. Always start the spooling from the left side of your spool and guide it toward the right as instructed by PSE.

Whoever it was that stated their Cable Bumpers are split 1/2" deep, they need to replace these immediately to avoid problems. There are at least two different bumpers sold by PSE. One is the original bumper that is used in the manufacturing process and there is also another that looks almost identical to that one, but it's sold as a Vibration Dampener for their compound bows, by PSE and can be found on their website under the vibration dampening accessories.

Both will fit your crossbow the same way, but the second one I mentioned is a softer rubber than the first. It does a better job with the vibration dampening, but I have no statistics on how long it will hold up yet because I only have about 100 shots on one. The price for the the non factory cable stop is very inexpensive. I have no idea what PSE charges for the original factory dampeners.

Super 91 also has purchased and used some after market cable dampeners that are supposed to be very god, but I don't have any details on the ones that he's now using. Possible he can fill in the details when he see's this thread.

Jon

 

[WildWillie]

Just wanted to give another update on the "string jump". The string jump is 99% of the time caused by the string not spooling up evenly on the spool. After about 100 shots with perfect cocking, mine started "jumping" again. This is twice it has happened since I received a new upper about 2 months ago. Both times I found that the pin that secures the gear on the winding shaft has shifted so it is sticking out on one side or the other. There is a set screw that holds that pin in place and the set screw was loose. Once I slid the pin back so it is centered and tightened the set screw the "jumping" goes away. It seems that the pin sticking out was catching the string and at some point the string would finally slip past causing the string to jump. Next time I'm using a little loc-tite on the set screw.

WildWillie

 

[jon.henry755]

Hi WildWillie,
For the record there's two types of Loctite available. One is "Loctite Blue" which makes it difficult to back out a screw after it's been applied, but with some force you can still remove it without too much trouble.

The second type, which is "Loctite Red", secures a screw and makes it impossible to ever get the screw out unless you heat the threads with a torch before trying to turn it.

I think you are probably referring to Loctite Blue for this application.

BTW - Great find. This should help a lot of people since we've been hearing about this problem for quite a while now.

Regards,

Jon

 

[Super 91]

Just wanted to give another update on the "string jump". The string jump is 99% of the time caused by the string not spooling up evenly on the spool. After about 100 shots with perfect cocking, mine started "jumping" again. This is twice it has happened since I received a new upper about 2 months ago. Both times I found that the pin that secures the gear on the winding shaft has shifted so it is sticking out on one side or the other. There is a set screw that holds that pin in place and the set screw was loose. Once I slid the pin back so it is centered and tightened the set screw the "jumping" goes away. It seems that the pin sticking out was catching the string and at some point the string would finally slip past causing the string to jump. Next time I'm using a little loc-tite on the set screw.

WildWillie

Any chance you could take a picture of the pin and so forth?