plunger springs

[DRT]

I have a Cartel Super Plunger and have to almost bottom out the spring adjuster to get bare shafts to group with fletched ones. My arrows were a bit on the week side so today I cut them down a little at a time until a bare shaft grouped well with the fletched shafts at 20 yards . I used a stiff plunger with the arrow set center shot. I then set the plunger to what I thought was medium ( @ 20 oz. ) and brought the arrow out so the inside of the shaft was in line with the string and center of the limbs. fletched arrows were now grouping 6" right of center. tightened the adjuster a couple turns to get the fletched arrows back to center. Tried a bare shaft and it flew way right to the edge of my target. Tried to move the plunger out some and it didn't really help. Plunger is now almost as tight as it will go and the bare shaft now groups with the fletched ones but not as well as before with the stiff plunger ?

does anybody know were I can get a stiffer spring for a cartel plunger ? The old Sauders ones I used years ago on my compound came with 3 different springs.

[rhust]

Worst case you could aways try putting a match stick inside the plunger, so that it has no play. I have used this before with good results.

[jhinaz]

Take your existing Cartel spring with you to the hardware store and get a heavier one that's real close to the same I.D. You may not be able to find one the exact length but if you find one that is twice as long you can cut it in half and you'll have a spare. (really, the cut-end won't negatively affect the way it performs). I think the light springs are around .018" thickness and the heavy springs are in the .028" - .030" range. - John

[DRT]

rhust instead taking the plunger apart and putting a matchstick inside I just screw one of those cheap Allen sharpshooter rest in backwards and use the end as a stiff plunger.

Thanks John I'll try that .

[van_fl]

First I am assuming that you are shooting right handed.

One must remember that the spring tension and plunger depth are interconnected when tuning. Or perhaps I should say that results can overlap.

A bow tuned with the shaft point set closer to center of the shaft will shoot a wider range of shaft spine. The better release one has the closer to center one can go. The closer to center one tunes the less forgiving the bow becomes. If set to close everything can go to hell in a hand basket real fast.

By changing the brace height one can move the center of rotation of the arrow, thusly moving the impact point right or left. Try lowering the brace height.

Also any interference of any kind, from flitching making contact to nock misalignment or to tight or loose will mask bare shaft results.


Ok, now how I start out tuning a new bow.

First I set the shaft center shot with the plunger spring turned in all the way in at the strongest spring tension. (I don’t use a match stick) I set the shaft/string alignment too slightly inside the shaft point, somewhere between the point and the right side of the shaft. That is, not on the out side the right edge of the shaft. (best guess)

Go to 10-15 yards from the target and let fly a bare shaft. If you are really off in spine retrieve the broken carbon shaft and replace it with a better guess depending which way it hit.

What I am looking for here is a impact just to the left (within one or two inches) of the aim point. With not a lot of soft or stiff shaft flight. Now the juggling act starts.

Adjust the shaft to string alignment with the plunger depth adjustment so as to bring the point of aim to the slightly to the left of center spot on the target. Then adjust the spring tension to bring the point of aim to the center.

Now the plunger tension, plunger depth, point weight, arrow length, and brace height juggling truly starts.
At this point if you think any thing went wrong with your shooting don’t count the results. Shoot a new bare shaft.

Adjust plunger spring tension for the best shaft flight. Readjust plunger depth to center of target if necessary. Now comes the feel part. You don’t want to adjust the plunger depth so as to be close to the center of the shaft. (What’s to close, is when the shaft goes wild).

At this point you should have an idea if you need to go stiffer or softer in spine. Or add/remove point weight.


Now adjust point weight You should be within one inch of paper tune rip. Re-adjust plunger spring tension to center of target if necessary.

We are at the point that the interaction of plunger spring tension and plunger depth becomes very apparent. And one may go back and forth with adjusting both before one achieves perfect shaft flight. Less then 1/8 turn of ether plunger depth or spring tension turn can cause a large shaft reaction. At any point here one may see the need to change point weight or shaft spine.

Now the fun part.

Go to 20 yards. – Resist the temptation to shoot a fletched shaft. It will just mess up your mind.

Reset plunger spring for best bare shaft flight. And aim point centering. Readjust plunger depth if necessary but be forewarned if you feel the depth setting ring move you most likely have changed it to much. Ha ha- Reset spring tension after.

By now you should have good shaft flight but you may not be at the exact aim point that you want, and you find that if you change plunger spring pressure to center the aim point that the shaft flight is slightly off. And you have readjusted from the beginning at least five times. Well all is not lost.

By adjust brace height and plunger tension you should find the correct point.

Go about it by only changing no more then two twists of the string at any time. And readjust plunger tension. And be advised by changing the string tension tighter the nock point will move toward the Stronger limb at full draw, and conversely when going to a lower brace height.

Now go to 30 and repeat the fun part.
You now may shoot a fletched shaft
Now go to 60 yards with bare shafts and flabbergast your shooting buddy’s

[DAS]

Not much to add except that the springs in the Cartels are pretty stout. I can't imagine needing a heavier one. The problem almost certainly lies elsewhere.

David

[DRT]

wow thanks Van lots of good info. I think the problem is with the shaft centering. I'll play with that.

David I think you are right.

[Windwalker]

It has been my experience that bare-shaft tuning/adjusting a “pressure button” can greatly produce misleading results if the person does not fully understand how to use and adjust a pressure button, and how to tune using a bare shaft and basically what a bare shaft is primarily supposed to indicate, i.e., correct nock height and proper arrow spine, all affected by form.

Fletch adds weight to the shaft, increases the dynamic affect of the shaft spine, and is a stabilizer for the natural paradoxes and oscillations that a shaft experiences when released. A bare shaft will have a (dynamic) lighter spine, is lighter in weight than a fletched shaft, and has no fletch to stabilize the shaft and control the paradoxes and oscillations that can now adversely affect the flight and flight-path of the arrow.

An adjustable “pressure button” is mainly used to adjust arrow-center and to decrease the inboard (horizontal) movement of the shaft, the degree of movement/flex governed by the tension of the button’s spring and the static length of the barrel of the button....depending on type of “pressure button” used. The cushioning of the button can tend to decrease the “dynamic” spine of the shaft, wood and aluminum. I do not use carbon shafts so I can only speculate, but I would believe that to the range of spine a carbon shaft provides, the same spine affect of the cushioning may not occur.

An important consequence to be aware of when you adjust the tension on the button, the arrow (static) center can be dynamically affected.

I have used pressure buttons for years, and thoroughly understand how to use the adjustments. However, I do as “Rhust” suggests. I lock the spring down (internal adjust) and primarily use the pressure button to adjust arrow center.

Although many shooters do successfully use the “bare-shaft” tuning method, Personally I have never been an advocate of bare-shaft tuning. I never liked having to interpret and tune the flight performance of shafts having different characteristics, to tune the shaft setup I intend to use.

Don't you often wish that everyone would be on the same page when giving advice?

****All my tuning is for the purpose of setting up hunting rigs.

[bcoulter]

Great info Van, I addred this thread to the index.

[DRT]

got it shooting alot better. Learned that you can have good arrow flight with a bare shaft and have it group to the right or left of the fletched shafts. You can also have crappy flying bare shafts grouping right in the center of your fletched shafts.