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Spring Vs Magnetic Plunger

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Desert Island Trading Co.
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i cant really see from that angle the arrow reaction on the plunger tip.

But if your alignment is correct and arrow tuned, i have no idea why you get a groove on the arrow.


Chris
 

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i cant really see from that angle the arrow reaction on the plunger tip.

But if your alignment is correct and arrow tuned, i have no idea why you get a groove on the arrow.


Chris
I will upload a rear view slo mo of NPX arrow launch and also one of the new X10 soon
 

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I am beyond ocd with my gear and set up :).

Bow is in alignment using multiple beiter blocks, also by using arrow shafts on flat sides of riser and measuring string to arrow shaft. Limbs are Uukha SX100 and are not twisted.

Regarding my form, I know that my elbow is out away from my body more than it should be but due to pre archery injuries, I cant get ideal alignment so it is what it is So who knows if that is contributing to the extra time of arrow contacting plunger

Slo mo of NPX launch. Absolutely no contact with bow other than plunger on release and the clicker is NOT bouncing back and scraping the shaft as it passes.

Sorry to hijack your thread OP.

Same here. No matter where the tune is I get the wear with either shaft with the beiter. When I mentioned it to Jake he was surprised I had not heard of the issue and said it was common. I typically shoot a tune that is a bit stiff in spine which I think might make it worse but I have tried moving to a weaker tune with a new set of shafts and go the same wear. I have a newer set of shafts one shot with the AAE tip and no wearing of the shaft. It is. It much but is definitely there. The shaft only touches the plunger tip for a few cm so I don’t know if it makes much difference over time but I prefer not to wear expensive shafts..,


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I will upload a rear view slo mo of NPX arrow launch and also one of the new X10 soon
The darker footage is the new X10 600’s with Easton pin and nocks that I started tuning last week. Arrow is 28” from nock to end of shaft and has 120gr SS points 28” draw and 36.5lb and beiter button is now 4.0 with sight unchanged from the NPX setting

Bare shafts and fletched are within a couple of inches at approx 23 metres which is good for my level of shooting. Centreshot on X10 is just under 1 arrow width left of string for straightest arrow flight of bare and fletched

The closer image is the NPX700 with Beiter out nock and plunger on 6.0

 

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Same questions for those without a groove -
Which colour tip is on the button, and what arrow rest(s) was it used with? Do you find the tip of your button tends to accumulate a layer of crud that leaves a dark streak if you wipe it off? Does the surface of the button stay shiny when used? What target material do you use most with those shafts and does it leave a residue on the shaft?

Another possibly important factor that could determine why some people have a visible groove after a few shots while others have nothing after decades - if you have a worn in tab and measure the width of the region from where the string sits at full draw to where it last loses contact with the string, how far across is it? Mine has a clear line where the lines from the center serving stop and the leather that never touches the string and is covered in suncream residue begins, and it's about 14mm at the widest point.

For those who have been using them since the 90's, if you've also bought shafts in the last decade does there seem to be any difference in how quickly they wear down from the target and how long the decals last?
Answers to questions in order:
  1. Black mainly but over 20+ years I have also used blue, light grey and light green (different barrel lengths and collar on plunger) and ranged from 47# to 38# across two spine sizes giving everything from overly stiff to a tiny bit weak (tiny bit weak is my preference). 32”+ 410 and 450 most often with 100gr points - both the orginal 90-110 gr SS and more recently tungsten.
  2. Cavalier FreeFlyte Elite; cheap Ukranian Yamaha copy; ARE; W&W; Shibuya
  3. Not so much - generally they look scuffed (like you used a med grain sandpaper). In the best tuned setups there was little or no marking. Tended to get some accumulation with straw bosses
  4. Only when very clean tuned - so not always. Definite signs of accumulation when I had a clearance issue - second contact with the back of the arrow at the leading edge of the vane (alignment issue)
  5. Everything from Stramit, Egerton, Danage, layered foam and ProBoss. Straw targets leave gunk. Foam not so much - a little as the foam gets to end of life
  6. I can only tell you what the current line is which is around 16mm (very deep hook past the joint on top two fingers). But I can also tell you my release sucks right now - still adjusting to a 3# drop in weight.
  7. Logos on early shafts wore quicker but then I shot more and better so that could be a factor. Most recent set of 450s still look OK after about 2 years with no significant visible degradation.
At the moment the 20+ year old shafts are used for blank boss only. They were 410s and they are shorter than my 450s that tune pretty close but a touch stiff. So shooting maybe 1.5 spines too stiff and no flatspots.

Limbs in use have been a fairly broad range of “normal shape” recurves. Recently picked up a set of Border semi-Super Recurve (if that is a thing) and they tune a stiffer arrow but even shooting weaker arrows etc I have not seen any flatting. A 410 is about the same amount stiff as a 450 on Velos limbs at pretty much the same draw weight - Borders maybe 0.5# heavier.

My bows are always tuned just a touch outside center - so put the shaft in line with the string and then turn it out a quarter turn. At the most the tip of the arrow on the left edge of the string.

Only thing I can add is none of these setups were particularly fast. Even at 47# it was only just over 200fps. I briefly shot a setup that was about 210fps (Hoyt FX limbs) but we did not get on.

Only other ponderance is whether the long SS 120 is creating an overly stiff front section which is riding the button too hard. X10 600 also seems very stiff at 28” (including or excluding point?) and 36.5#. My 450 is stiff at 31 7/8” shaft length off 41#. So that is 5 boxes on the Easton chart but only 3 spines different. Bareshaft says otherwise … but…

Stretch
 

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Answers to questions in order

Only other ponderance is whether the long SS 120 is creating an overly stiff front section which is riding the button too hard. X10 600 also seems very stiff at 28” (including or excluding point?) and 36.5#. My 450 is stiff at 31 7/8” shaft length off 41#. So that is 5 boxes on the Easton chart but only 3 spines different. Bareshaft says otherwise … but…

Stretch
28” is to end of shaft, so point not included. With the 120gr point unbroken, the line starting to form on the new X10 shaft is about 1-2cm behind where the shank of the 120gr point would end inside the shaft.

Given that this same thing happened with ACE 670 with 100gr point which has much shorter point shank, I dont think that shank is causing this

Another thing to note is that my new 28” long X10 600’s with 120gr are coming out at 187fps @ 36.5lb and 28” DL so maybe the speed of limbs are contributing as all the grooves that have formed on the 3 shafts have been with Uukha limbs.

Does anything look unusual in the slow motion arrow launch videos?
 

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There is an easy solution. Just use the shaft with the aluminum tip from an AAR plunger. I’ll post pictures and make some measurements of the flat spots on my x10s when I get some good lighting so it can be seen clearly but it is similar to what has been described.
Could you measure the length and width of the line please, or just give a rough description of it? It would be interesting to see how similar it is to vscarf10's. Do you have any way of measuring its depth?
When you were using the Beiter button, did you get built up crud on the tip after a while? What about residue on the shaft? Do you get any built up material on the other tips?
Looking at your finger tab, how wide does the worn region look? Could you measure that width (like in the tab picture a few posts back)? Or if there's no tab wear yet, maybe a bit of powder or something else that's easily removed to see how far the string slides against it before it's no longer pressing against the material?

Does anything look unusual in the slow motion arrow launch videos?
It's really hard to tell with the shutter speed giving it that much motion blur, but in the lighter video (can't see in the darker one) it looks like the arrow is exerting enough force on your button to press it inwards for about 4 frames (guessing 4ms?), which is a lot longer than I've seen both in high speed videos from top archers (Natalia Valeeva 1-2ms error due to frame rate, Park Sung Hyun and her magic release 1ms ). That would give it significantly more contact length while the friction force on the arrow from the button is reasonably high - given the result you're seeing on the shaft, probably high enough to get abrasive wear either from the button surface directly, or any crud (or bits of the previous shaft) being pressed between the button and shaft giving three body abrasion instead.
From my own experiments with button contact time (shamelessly here), I get the same duration (2ms) whether I'm using a tuned arrow or one that's a bit or very weak or stiff, and it doesn't matter whether the button is at the right pressure or if it's too weak or stiff - so it doesn't seem to be something that can be changed by doing anything to the arrow or button. My expectation, though I don't yet have data to prove it, is that the button contact time is determined by some "human" variable that is consistent within one person (so group size is unaffected) but variable betwen people (why most people don't have the issue), like the shape of your hand as you release, hence asking about finger tab wear.

There's also possibly more sideways string movement than I'm used to seeing (based on my bow and on those of other in competitions using 1000 fps and a 1/12800" shutter) but that could easily be caused by the camera only. Unfortunately getting rid of the motion blur and increasing depth of focus means needing either outdoor lighting or an uncomfortably bright incandescent bulb, which isn't always achievable.
What does the width of the wear on your tab look like?
 

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I also have been having this problem and decided to take some data to try to mitigate it a while ago.

As can be seen in my other thread, my X10s are acting weird, hitting the plunger a second time just behind the logo.
I shot 25,000 arrows with my 380s in one orientation with the black beiter tip, which caused them to develop a 0.23mm flat where the plunger is hitting the second time. It is a little hard to see the flat in a picture, so I modeled it to scale in Fusion 360 and rendered a slice of the arrow at the worst point to visually show the problem easier. Having the aluminum core gives perspective on just how much carbon is being worn away.

After I had measured this, I machined a brass insert to glue into the white beiter tip, making it the same length as the black one. Once I made this, I rotated my arrows 120 degrees counterclockwise and shot another 15,000 arrows until I got new 325 spine X10s. While there is a light mark where the plunger hits, there is no longer a flat spot like I had been shooting with sandpaper on my plunger.

Since there has already been some high speed video in this thread, I thought I would post mine as well for some comparison.

20210722_092600.jpg 20210722_092826.jpg 20210722_092852.jpg EastonX10_Flat_Visual.PNG 20210722_093043.jpg 20210722_092644.jpg

 

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I also have been having this problem and decided to take some data to try to mitigate it a while ago.

As can be seen in my other thread, my X10s are acting weird, hitting the plunger a second time just behind the logo.
I shot 25,000 arrows with my 380s in one orientation with the black beiter tip, which caused them to develop a 0.23mm flat where the plunger is hitting the second time. It is a little hard to see the flat in a picture, so I modeled it to scale in Fusion 360 and rendered a slice of the arrow at the worst point to visually show the problem easier. Having the aluminum core gives perspective on just how much carbon is being worn away.

After I had measured this, I machined a brass insert to glue into the white beiter tip, making it the same length as the black one. Once I made this, I rotated my arrows 120 degrees counterclockwise and shot another 15,000 arrows until I got new 325 spine X10s. While there is a light mark where the plunger hits, there is no longer a flat spot like I had been shooting with sandpaper on my plunger.

Since there has already been some high speed video in this thread, I thought I would post mine as well for some comparison.

View attachment 7436521 View attachment 7436523 View attachment 7436524 View attachment 7436525 View attachment 7436527 View attachment 7436526

Nice clear video, though I think could hear my arrows whimper in sympathy in the next room at that second hit. Did you figure out the cause of the contact? I found I could make contact happen in some extreme cases, like a very stiff shaft with no point hitting a few inches from the nock, and a very weak shaft with a very soft button hitting both the clicker and button near the middle of the shaft.

Do/did you get any grooving or other wear from the first contact between the button and shaft?

About that 200 microns - I once sanded down a 470 ACE on opposite sides of the barelled part to see how an "elliptically spined" arrow would fly. It took 150 microns on each side on roughly the middle 15cm to turn it into a 570. As the thick and thin side of the shaft resonate at audibly different frequencies when pinged, I get a "wub-wub" beat for a spine difference of 0.050" between the sides, and something closer to this for the 0.100" spine difference. Your flat spot is not as long of course, but I would be interested to know if it was audible. Not that it means anything concrete in terms of grouping of course, it's just an interesting musical side effect.
 
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