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How to Improve Your Arrow Spine Testing

12K views 32 replies 10 participants last post by  Boomstick300 
#1 ·
Going back a few years ago I first brought the topic of "Spine Testing" along with "Weight Balancing" and "F.O.C." to these forums. Since that time a great number of articles and discussion has followed and as it applies to crossbows specifically, much has been tested and learned about how to dramatically improve the performance and accuracy of your crossbow by matching and tuning your arrows.

I've been thinking that it's now time to publish some new information that should help many of you who do your own arrow building. This article is focused on the best way to improve the ease and performance of your static spine testers. This article will reference the RAM QC Spine Tester, but the same methodology can be applied to any spine tester that uses a hanging weight in order to produce shaft deflection readings to measuring spine stiffness.

The key to improving the performance of the RAM QC Tester is a rather simple modification outlined below.

The RAM QC Spine Tester utilizes a pair of synthetic hooked arms in order to hang on an arrow shaft for arrow spine testing. These same arms are made of a plastic material that constantly grabs the carbon fibers of your arrow shaft as one attempts to rotate the shaft under the unit’s needle bearing to obtain readings from the meters dial.

Even slight movements of rotation back and forth of the shaft will cause the arms to grab and the shafts material and in turn the meters dial to jump and bounce instead of providing smooth, accurate, precise readings from each spot around the shaft. This causes constant deviations of the pointer arm on the meter and a sizable amount of effort and time to re-check ones readings.

Once we rectify this problem and create a silk smooth rotational capability by eliminating the arms of the 1.94 lb. weight from sticking to the arrow shaft, we end up with a measuring tool that is not only far more accurate and precise, but it’s also much faster and a pleasure to use.

So how do we accomplish this without breaking the bank or making major modifications to the overall spine tester???

Well, like all things I’m sure there are numerous ways of going about this, but I’m only going to outline one of the more simple ways it can be done for a very reasonable price. Hopefully, this will fire-up the thought process across our membership and possibly generate some additional ideas for your consideration.

These are the modifications I used on my own equipment a few years ago and I’m very pleased with the results and performance attained. I could never go back to testing shafts the old way, prior to these modifications. I’m sure after you see and experience the difference this makes in the functionality and performance of your equipment you’ll understand and agree with my perspective.

The key piece of equipment I used in the modification process is a simple tool made by Firenock for their Aerojig Fletching Vice. It’s called their Water Leveling Tool and was designed to hang on an arrow shaft prior to fletching to ensure the shaft is perfectly level. This is to eliminate glue run-off. The water level sells for $24.95 and is made with two sets of high quality Roller Bearings that are arranged to sit on top of an arrow shaft. If you go to Firenock's Website (Firenock.com) you can view the Water Level under the Aerojig Accessories page.

There’s an O-ring type washer on the end of the brass Thumb Screw that secures the Water Level to it's shaft Once removed the Thumb Screw can be unscrewed and removed This Thumb Screw is an un-needed part for the conversion.

The Thumb Screw is a ¼” x 20 thread, which means the hole that it came out of is also this size.

Step 1 Remove the synthetic arms from your 1.94 lb. brass weight to your RAM QC Spine Tester, since they will also no longer be needed.

Step 2 Drill a hole through the brass weight from the top down in the exact center of the weight. This hole should be just under a 1/4" in diameter, so it can be threaded with a 1/4" by 20 Tap for threading. For those who don't possess the tools any machine shop will do this for about $20.00.

Step 3 Using a Tap and Die set, now thread the hole you just drilled using a ¼” number 20 Tap.

Step 4 Countersink the bottom side of the weight around the hole you just drilled. This will be to ensure no part of the bolt you’re going to place in this hole sticks out. You want a smooth level weight base with the head of the bolt to sit up inside the countersink area of the hole.

Step 5 Obtain and screw in a ¼ x 20 x 3” bolt from the bottom up, so only the bolt threads are exposed about ½” out of the top of your weight.

Step 6 Screw on the Water Level until snug and position it as desired.

Step 7 In order to achieve the 1.94 lb. weight, you can drill additional holes on the underside of your weight, if desired. Each hole continues to remove material from the brass so you must use a gram scale to determine when you reach the desired weight.

Understand that the 1.94 lbs. has no bearing on anything. It was originally developed as an AMO measurement standard in conventional archery for the purposes of comparing different spine readings across different manufactures products. It goes hand in hand with an arrow length of 28”. Unless we are conforming to the 28” length standard, the 1.94 lbs. has no relevance of any type.

You now have a weight that easily hangs on your arrow shafts and rolls as smooth as silk regardless of which direction you’re rotating each shaft.

Step 8 Since the length of your weight is now slightly longer than it originally was, you’ll need to us a 1” or 2” spacer under each leg bracket of your spine tester to raise it enough for the weight to hang free from each arrow shaft without touching the surface below it. I use a pair of 4" long pieces of 2" x 4".

Here’s two pictures of the finished product so you’ll understand how easy this is and what you’re seeking to achieve. Picture 1 shows the roller bearings and water level threaded onto the weight. The 2nd picture shows the countersunk bolt threaded thru the weight to attach the water level.

Light Light fixture Lighting Sconce Brass
Brass Metal Copper


When completed, you've turned your spine tester into a high quality instrument that can easily identify the exact "Stiff Side" marking position with much less effort, time and much more accuracy than any standard tester.

Hope this helps improve your tuning efforts.

Xbow755
 
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#2 ·
I actually used your method for a few years until a member of another forum built a couple of sets of the hooks with bearings. A few years back I modified the custom tester RAM built me to be able to have a quick to change the on center distance. I am currently waiting on RAM to build a tester with theses attributes. I will try to remember to get a picture of the weight and hooks today

 
#3 ·
The key here is the fluid motion that is added to the tester. Arrows tested in this manner calm down much quicker and IMO the readings are far more accurate. Adding the bearings has reduced our testing time for a dozen shafts, I would say it cut it in half.
 
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#4 ·
Hi Jerry,
As always, thanks for sharing the additional information and picture with our readers. The statement related to IMO is far more than just your opinion. As an experienced user of this modified equipment we both know that what you're pointing out is absolute fact. We have the testing results to fully support these statements.

When testing the many different sizes of arrow shafts that you work on daily, having the ability to adjust your on-center distance easily and quickly makes perfect sense.

These modifications we've recommended put your test equipment into a class that doesn't exist in the retail world. It's custom or it doesn't exist. Manufacturers are not willing to produce a product of superior quality because it decreases their profit margins and they feel there isn't enough call for it to warrant the cost factors.

The truth of the matter is that the basic RAM, like most spine testers due a very rudimentary job of meeting their purpose. We've simply identified short-comings in the product and built a version that's now fit for purpose.

My old saying still applies "Good Enough" is the arch enemy of "Better and Best". If you're a "Good Enough" type of person, then this modification probably isn't for you. If your looking for a big step up in the ease and performance of your equipment or a way to build more precise arrows, then we're providing a pathway to do so.

Xbow755
 
#5 ·
I have built about 50 set of those for many customer and myself before I finally decided to do the next step and come up with a PAPS. The down side of this is that you are stilling dealing with a bearing that is flat on the edge. Another reason is cost, As I only use APEC 7 being and the cost that 8 bearings from reliable source like BOCA bearing in florida is over $150.00, add the water level, and a Ram, I am at over $400.00. Which is why I price my PAPS at $375.00. The down or up pressure applies on the bearings will always be at an angle which forces the ball and rail of the bearing to be not smooth enough, If you use bigger bearing, that can solve some of the possible issues, but you will also introduce others like the width of the bearing which increase the distance from the center of the bearing to where you actually want to measure. Last there will always be 8 point of contact on this system I used to use. Ideally it would be 3, but with a round shaft, I need 6. The true center base on simple physics can only be accomplish by using a round to a round, thus the invention and a custom built of a crown bearing with a shoulder screw as center. They are currently use on a APS and PAPS!


 
#7 ·
That depend on what you get. The price is on Boca bearings, you sure can check. chrome steel ABEC#7 is cheap but when you get SIC stainless... that is where I started. Full ceramic ABEC#7 start at $130.00 each on the smaller ones!!!
 
#9 ·
Just for clarification purposes, my opening thread was mostly focused on those people who already have invested the money in some type of a basic "Static Spine Tester". It was intended to help them turn their basic tester into a high end, silk smooth tester for the very small additional price of adding the water level to achieve the roller bearing functionality to their units.

I'm not opposed to people purchasing either spin testers or PAPS testers if they're in the market for completely new spine testing equipment.

Doing a new thread comparing all the different types of Spine Testers in the market and the Pro's and Con's of each would be a highly interesting topic that many members would be interested in. This one was just a simple modification article.

Xbow755
 
#10 ·
With all due respect to you and Dorge.I have built my own spine tester.It cost me less than $25 for the dial and bearings! It works smoothly.When I test arrows purchased from Jerry at SSAS it References the same marks he has left on the shafts. I'm sure it doesn't have all of the features etc of the Paps and Ram testers.But it does accurately tell me where the spine is on my shafts and the deflection differences between any given shafts.I'm in know way comparing mine to anybody else tester or system.Its rude and crude but it works great for my needs.I have since bought new bearings for it off ebay since I took these pics.Abec 11 bearings for less than $15 for 8
Sewing machine Toolroom Machine Machine tool Antique
Auto part Rim Bicycle part Wheel Metal
 
#11 ·
When considering testing we should understand how arrows fly (dynamic spine). Once we understand this we can evaluate the types of testing processes available to find the most viable.

When arrows are launched from a bow they will all react the exact same way in that the stiff static spot or point is actually a stiff plane 180 degrees through the shaft.

Now just for simplification of understanding the stiff plane reacts like a positively charged north and south pole. Now lets assume the energy that is applied by the bow to the shaft is positively charged and as it is applied to the arrow the north and south poles of the stiff plane force or repel that energy down toward the center of the shaft and then out 90 degrees from the stiff plane, this area is called the neutral plane. This process forces the shaft to begin to flex to dissipate energy.

Now with this in mind we need to understand it is absolutely crucial to identify the true stiff plane of each shaft for the best possible consistency.

IMO there are only two ways to guarantee you achieve this level of consistency:

A RAM type tester that has a built in dial gauge that will show the static deflection so you can identify the peak of stiffest point.

The second is a frequency analyzer that imitates (somewhat) the way dynamic spine reacts during flight.

Any other process will produce good results but if the process/equipment does not have a dial gauge you cant be guaranteed you are seeing or finding the static stiff side.

Here is why:

A characteristic of any shafts even shafts that seem perfect is they will have a stiff plane or natural bend and there will be a weak point somewhere on that tube. If you compress that tube there is a possibility for the tube to give and bend at the weak point rather then the natural bend or stiff plane which has zero to do with the dynamics of dynamic arrow flight. We must not confuse the attributes of a statically tested shaft with the attributes of the arrows dynamic spine.

Compressing type testing processes will work but not at the level of consistency of a tester that has a dial gauge.

Earlier I referred to the stiff plane as the same point of the natural bend of the shaft. When any tube is made it is impossible to keep the wall thickness 100% uniform. Because of this as carbon shaft resins harden they do so more slowly along this thicker area of the shaft, this causes the shaft to warp or bend slightly.

When looking at the value of this level of testing, aligning the planes of an arrow in the form of indexing we need to understand out to 40 or 50 yards indexed arrow will perform very well, but 100 yard accuracy is a whole different animal.

Today @ 100 yards 1 1/2 in groupings cane be a reality if arrows are indexed, weight and spine matched but I cant help but wonder how arrows will respond and what level of testing will be required shooting 100+ yards at 500 FPS.

We currently build arrows that are straighter than .001, have tight spine deflections variances of +/- .0025 and weight variances of less than 3 tenths of a grain to achieve the 1 1/2 groups.

We can stiffen the shafts very easily and it is likely the present testing processes will still provide a level of accuracy needed to handle these higher speeds to maintain 1 1/2 in groups at longer distances, maybe even 200 or 300 yards only time will tell.
 
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#14 ·
Sam, the issue with that is 99.99% of todays archery shop knows nothing about indexing, testing and matching arrows. Most buy factory fletched arrows. I had a guy come into my shop the other day who was in florida on vacation, he was a part owner in a shop, they dont own any fletching jigs.
 
#15 · (Edited)
First up, let me thank Jerry for so accurately articulating the differences between Static and Dynamic Spine Testing and explaining 500% accurately the way in which the Stiff Side and Neutral Plains work from a physics point of view.

Next, to Stalkers point, home made spine testers will work and are a good thing as long as the person doing the build has enough knowledge to do it correctly. That said, one of the biggest differences in top grade static spine testers is the quality of the needle bearings and other tiny components located inside the bezel unit. These components are what allows the pointer arm to accurately register the slightest amount of shaft deflection during rotational testing.

While cheap helps us out in the pocketbook it can cause a certain amount of deviation or inaccuracy on the arrow shaft.

I think a great article might even be based on how to build a very inexpensive spine tester for under a $100.00 bucks. Many people who are budget constrained and want to get into building there own arrows might be interested in these step-by-steps.

My intention was to take a good industry tool such as the RAM QC Static Spine Tester and turn it into a Super Quality Static Spine Tester. Another words, take what is good and significantly improve on it.

As Jerry so accurately explained, in order to improve your accuracy and achieve maximum repeatability at medium to longer distances you'll require arrows that are very well matched in multiple ways. Spine is the first and most important element that needs to be perfectly matched. Then Nock Orientation, Vane Placement and Arrow Weight.

This is all part of the arrow building process and like Jerry has stated and I've been writing about for years and years now, there are only a very, very small number of Pro Shops that possess the knowledge or have the equipment necessary to do this type of work. Once you receive a set of arrows from any source, what makes you think even for a second that the maker has taken the time to do all this and still be able to sell you the arrows for a reasonable price?

I've been doing this for over 40 years consistently and know of only 3 operating shops that are capable, but only 2 that will offer it to there customers and both are represented on this forum.

To say that shooting correctly matched arrows is important would be a complete and total understatement of ones understanding. If you wouldn't go out hunting or target shooting with a pocket of mixed ammo from different manufacturers and randomly grab bullets of different weights and grains, then why would you do it with your crossbow?
Non matched arrows are the same equivalent as the bullets outlined above and the resulting performance is equally similar. You might get a couple to hit close together, but for the most part it's a crap shoot.

Xbow755
 
#18 ·
Dare I say -
While the info laid out here looks interesting for the most part, it also sounds a "lot" like "pixel peeping" when working with digital cameras..!

I'd bet you'd (most all of us) become more adept at hitting your target with more actual practice at the trigger than trying to make the arrows, that are already "ok" to being 5% or "maybe" 10% better.

Mike
 
#21 ·
Dare I say -
While the info laid out here looks interesting for the most part, it also sounds a "lot" like "pixel peeping" when working with digital cameras..!

I'd bet you'd (most all of us) become more adept at hitting your target with more actual practice at the trigger than trying to make the arrows, that are already "ok" to being 5% or "maybe" 10% better.

Mike
Fact is you would become a better shot with more practice. but lets look at those who are at the top of their game. @ 100 yards with around that arent setup correctly you would be lucky to see a consistent dinner plate size group. Im referring to factory made arrows, it would not surprise me that some of the
Jerry
On your Ram tester you have 3 dial gauges on it . one in the middle and one @ each end.
What are you using the ones on the ends for ?
When I use 3 dial gauges at the same time I can see if the arrow is straight on each end and middle at the same time.
 
#19 ·
Hi Mike,
For the record, so that everybody understands just how big a difference we're talking about in reference to factory made arrows versus spine matched, nock indexed and weight balanced arrows let me explain it for you. On a standard factory produced set of arrows, you might be able to take four arrows at random and possibly keep them inside a 10 - 12" paper plate at 50 yards. At 80 yards you'd be fortunate if you could keep them within 18" and at 100 yards, it's doubtful if you could keep all 4 on the same 30" target.

When your arrows are built as specified above, many of us are able to consistently stay within 2" of the center of each target we're shooting. We don't ever shoot more than one arrow at each target, due to the fact we destroy to many arrows if shooting groups.

At distances up to 60 yards I only shoot at a group of (8) 1.5" fluorescent orange adhesive dots with 3/4" fluorescent green center dots. Staying within the 1.5" dots is easy. Staying on the green dots is the challenge. This can't be done by anybody unless using spine matched, nock indexed and weight matched arrows.

I shoot consistently at least 8 - 9 months a year and numerous times each week, so while agree that time on the trigger amounts to experience and certainly should improve most people's consistency, all the practice in the world won't help you achieve the type of results that have outlined above.

I can watch video's of people who claim to perform 100 yard shots of sub 3" groups and have for several years. In each case it's relatively easy to determine if they faked the shouts by shortening the distance considerably and placing the camera in a position to make it appear real, versus those who can actually perform the shots. The custom building of the arrow set accounts for the results in every case.

The difference is not a 5% or even a 10% difference. It can easily be a difference of 30% - 40%.

To outline just how big a difference it is, don't take my word for it. Let all our members who've gone to Jerry at South Shore Archery and him make them up a set of matched arrows tell you how much of a difference in accuracy they obtained compared to what they used to shoot? Keep in mind the work they're having done in most cases is only a spine matched, nock oriented set, but doesn't include the weight balancing.

Xbow755
 
#24 ·
For the record, so that everybody understands just how big a difference we're talking about in reference to factory made arrows versus spine matched, nock indexed and weight balanced arrows let me explain it for you. On a standard factory produced set of arrows, you might be able to take four arrows at random and possibly keep them inside a 10 - 12" paper plate at 50 yards. At 80 yards you'd be fortunate if you could keep them within 18" and at 100 yards, it's doubtful if you could keep all 4 on the same 30" target.
With all due respect Jon this is a over statement IMO.Maybe you haven't shot any factory built arrows in a long time.

In no way am I comparing Jerry's,or any custom spine indexed/matched,weight matched arrows to factory built arrows.However I have tried many that will achieve a 4-5" group at 50 yards.Even with broad heads. There are some terrible factory built arrows out there. But if you cant get better than a 10"-12" group at 50 yards then you need to practice and or switch arrow brands or bows.No offense just saying.

With that said I do recommend Jerry's or other custom spine indexed/matched,weight matched arrows.It does make a big difference.
 
#22 ·
Hi Jerry,
So is it fair to say that you are measuring factors well beyond spine deflection, which would utilize only the center gauge?

Measuring the straightness factors of the shafts ends should be irrelevant to the spine deflection factors, but when using the RAM QC for other measurements such as end to end straightness they would be make the tool much more versatile.

Xbow755
 
#25 ·
Hi Stalker,
With all due respect, I'll agree with your correct and retract that portion of my last statement, since I'm sure many of you do know more about that aspect of what's now being produced than I do. I probably haven't bought or attempted to shoot anything factory made in several years so I'm nowhere near current on factory produced arrows.

The last factory made arrows I attempted to even shoot were the PSE TAC15 Crossbow Arrows and they turned out to be an all out disaster on all fronts.

One thing that's also worth noting is the fact that when using a crossbow any deviations in arrow perfection are much more noticeable than when shooting a vertical bow. This is because it's far easier to bench rest a crossbow in order to attain a much steadier shot. Between steadier shots and higher velocities for less droppage or arching of the arrow we are now able to notice many more imperfections that were previously blamed on shooters error or other things.

It also means that we are equally able to reap the benefits of straighter, more well matched and balanced arrows. Consistent tight shooting is what it's all about and well matched arrows are the most important aspect of achieving this result. As mentioned by others, time on the trigger, practicing is the big factor.

Xbow755
 
#26 ·
Hi Stalker,
With all due respect, I'll agree with your correct and retract that portion of my last statement, since I'm sure many of you do know more about that aspect of what's now being produced than I do. I probably haven't bought or attempted to shoot anything factory made in several years so I'm nowhere near current on factory produced arrows.

The last factory made arrows I attempted to even shoot were the PSE TAC15 Crossbow Arrows and they turned out to be an all out disaster on all fronts.

One thing that's also worth noting is the fact that when using a crossbow any deviations in arrow perfection are much more noticeable than when shooting a vertical bow. This is because it's far easier to bench rest a crossbow in order to attain a much steadier shot. Between steadier shots and higher velocities for less droppage or arching of the arrow we are now able to notice many more imperfections that were previously blamed on shooters error or other things.

It also means that we are equally able to reap the benefits of straighter, more well matched and balanced arrows. Consistent tight shooting is what it's all about and well matched arrows are the most important aspect of achieving this result. As mentioned by others, time on the trigger, practicing is the big factor.

Xbow755
I couldn't agree more.

You cant put $2 crap line on a $500 fishing rod and reel and expect it to perform as it should.

How many beginners start out with bad arrows and wonder what there doing wrong?Is it the scope?is it the crossbow.Is it me?Or adjust their scope back and forth. Shooting several different arrows (same make and brand point etc) believing they all will all have the same poi?They all look the same. A lot of head scratching and frustration can be avoided by using quality arrows.And or at least numbering your arrows and keeping track of their poi in relation to each other.Price doesn't always indicate quality either.They all claim to be great on the boxes they come in from the factory.

I haven't tried all that many.But these are the best factory arrows I have found and about the cheapest.$30 for 6 Easton 2219 xx75 aluminum Magnums.They shoot good out of my Horton crossbows.Ranging from 260-310fps.Here's a group I shot at 1/2 dots at only 30 yards but they are accurate after rotating a few of the moon nocks 180 degrees. Because Easton cant make a concentric nock for them apparently.
Tree
 
#27 ·
Hi Stalker,
First up, very nice shooting.

Next, for those less experienced shooter they might find it interesting to understand the differences between aluminum and carbon?

For those who don't know carbon arrows are roughly only about 15 years old and the early versions left an awful lot to be desired in straightness, lack of consistency in shaft wall thickness and weakness in shaft fibers. That said, they possessed a number of other good factors that made continued development a worthwhiled endeavor.

Aluminum shafts had been around for over 50 years, so the process and production of aluminum shafts had reached a level of perfection and consistency many years ago. There are also at least 5 different grades of aluminum used in the arrow making business. Names such as "Game Getter", 24SRT, "XX75", XX78, X-7 to name a few.

As the quality of the aluminum increases, so does the straightness, strength, quality and price tag. Even the highest quality aluminum shafts are less expensive than average, medium quality carbon shafts.

Most people want to shoot carbon, but understand little about why. The fact today is mostly because everybody else does and that's what their archery shop is recommending.

In order for me to shoot carbon arrows, I had to wait until the development of carbon exceeded the quality of the better quality aluminum arrows. This only happens at the top end of the carbon shaft manufacturing process, so there's a definite price difference.

One of the few big pluses with carbon shafts is the fact their strength does not diminish at all based upon shooting impacts. Aluminum over enough shots will begin to fatigue and weaken the shafts strength. That might take 1,000 shots or more, but it will break down over time. Aluminum, other than X-7, can also be bent based upon certain type of impacts can be bent.

Carbon can't be bent! It will either survive an impact and return to its original straightness or it breaks. Breakage is a far better thing than trying to shoot a bent arrow.

This takes us back to Stalkers original points about arrow quality. If top quality carbon shafts are an impact on your budget, consider trying a top quality aluminum shaft, since they will cost you half or less of what good carbon shafts will cost.

Last, most aluminum shafts do not require a spine tester in order to locate the Stiff Side of the spine. This is due to the fact that under good lighting one can see the line along the shaft where the aluminum was seamed. In all cases this is the Stiff Side of the shaft and should be used to orient your nocks.

Xbow755
 
#28 ·
As a comment to post 19.

Again, people were hitting their targets long before "spine" checking became all the rage..!
While I understand that carbon fiber has a little more criticality in its build than aluminum, the old wood "bolts" were even more critical than C.F. as far as stiffness, and bending off the centerline.
And again...animals were still being eaten for dinner..!

Mike
 
#29 ·
Yup, they were, but we're not talking about where somebody puts one shot at 20 or 30 yards on a deer and contacts a vital organ within a 6" area.

Until the last 3 or 4 years the effective range of most crossbows was under 40 yards. This was largely due to the fact they were not reaching speeds exceeding 300 fps. The crossbow was absolutely no better than a conventional bow until they began reaching speeds of 350 fps. and up.

The higher velocity coupled with much better quality arrows was finally allowing some shooters to achieve consistent shot after shot repetitive capabilities within a very small grouping at all distances up to 100 yards. Faster crossbows now also made it possible to produce enough K.E. or Momentum to effectively hunt very large game successfully and keep ones shot within an inch or less, due to the accuracy and penetration attainable with these weapons.

There's much more to be said for aluminum that most people realize. The process for producing aluminum was perfected almost 50 years ago and it was produced in at least 5 different grades of quality. Carbon fiber has only caught up and surpassed aluminum in the last 2 or 3 years, yet everybody's been buying carbon shafts for the past 10+ years.

The two principle pitfalls of aluminum that carbon doesn't have is that aluminum can be bent due to impacts and aluminum wall structure becomes fragile based upon fatigue after enough shots have been put on it. This might take over 1,000 shots, but never the less it breaks down over time. Carbon does not retain bends or weaken due to stress fatigue. These are two of the main reasons the development of carbon shafts continued and eventually replaced aluminum.

We could launch a spear from a crossbow or a long bow, but that doesn't make it effective, consistent or accurate.

I have a famous saying that I used countless times when writing threads or articles on the topics of archery or crossbows. "Good Enough" is the arch enemy of "Better and Best"! This means if you're the type of person who is satisfied with Good Enough, then much of what we write in these articles is not meant for you, since it will always be deemed as overkill. If you're like some of us who are always looking to improve or increase our capabilities, then you'll find extra value in the information.

Neither is wrong, it boils down to your individual point of view.

Xbow755
 
#31 ·
Going back a few years ago I first brought the topic of "Spine Testing" along with "Weight Balancing" and "F.O.C." to these forums. Since that time a great number of articles and discussion has followed and as it applies to crossbows specifically, much has been tested and learned about how to dramatically improve the performance and accuracy of your crossbow by matching and tuning your arrows.

I've been thinking that it's now time to publish some new information that should help many of you who do your own arrow building. This article is focused on the best way to improve the ease and performance of your static spine testers. This article will reference the RAM QC Spine Tester, but the same methodology can be applied to any spine tester that uses a hanging weight in order to produce shaft deflection readings to measuring spine stiffness.

The key to improving the performance of the RAM QC Tester is a rather simple modification outlined below.

The RAM QC Spine Tester utilizes a pair of synthetic hooked arms in order to hang on an arrow shaft for arrow spine testing. These same arms are made of a plastic material that constantly grabs the carbon fibers of your arrow shaft as one attempts to rotate the shaft under the unit’s needle bearing to obtain readings from the meters dial.

Even slight movements of rotation back and forth of the shaft will cause the arms to grab and the shafts material and in turn the meters dial to jump and bounce instead of providing smooth, accurate, precise readings from each spot around the shaft. This causes constant deviations of the pointer arm on the meter and a sizable amount of effort and time to re-check ones readings.

Once we rectify this problem and create a silk smooth rotational capability by eliminating the arms of the 1.94 lb. weight from sticking to the arrow shaft, we end up with a measuring tool that is not only far more accurate and precise, but it’s also much faster and a pleasure to use.

So how do we accomplish this without breaking the bank or making major modifications to the overall spine tester???

Well, like all things I’m sure there are numerous ways of going about this, but I’m only going to outline one of the more simple ways it can be done for a very reasonable price. Hopefully, this will fire-up the thought process across our membership and possibly generate some additional ideas for your consideration.

These are the modifications I used on my own equipment a few years ago and I’m very pleased with the results and performance attained. I could never go back to testing shafts the old way, prior to these modifications. I’m sure after you see and experience the difference this makes in the functionality and performance of your equipment you’ll understand and agree with my perspective.

The key piece of equipment I used in the modification process is a simple tool made by Firenock for their Aerojig Fletching Vice. It’s called their Water Leveling Tool and was designed to hang on an arrow shaft prior to fletching to ensure the shaft is perfectly level. This is to eliminate glue run-off. The water level sells for $24.95 and is made with two sets of high quality Roller Bearings that are arranged to sit on top of an arrow shaft. If you go to Firenock's Website (Firenock.com) you can view the Water Level under the Aerojig Accessories page.

There’s an O-ring type washer on the end of the brass Thumb Screw that secures the Water Level to it's shaft Once removed the Thumb Screw can be unscrewed and removed This Thumb Screw is an un-needed part for the conversion.

The Thumb Screw is a ¼” x 20 thread, which means the hole that it came out of is also this size.

Step 1 Remove the synthetic arms from your 1.94 lb. brass weight to your RAM QC Spine Tester, since they will also no longer be needed.

Step 2 Drill a hole through the brass weight from the top down in the exact center of the weight. This hole should be just under a 1/4" in diameter, so it can be threaded with a 1/4" by 20 Tap for threading. For those who don't possess the tools any machine shop will do this for about $20.00.

Step 3 Using a Tap and Die set, now thread the hole you just drilled using a ¼” number 20 Tap.

Step 4 Countersink the bottom side of the weight around the hole you just drilled. This will be to ensure no part of the bolt you’re going to place in this hole sticks out. You want a smooth level weight base with the head of the bolt to sit up inside the countersink area of the hole.

Step 5 Obtain and screw in a ¼ x 20 x 3” bolt from the bottom up, so only the bolt threads are exposed about ½” out of the top of your weight.

Step 6 Screw on the Water Level until snug and position it as desired.

Step 7 In order to achieve the 1.94 lb. weight, you can drill additional holes on the underside of your weight, if desired. Each hole continues to remove material from the brass so you must use a gram scale to determine when you reach the desired weight.

Understand that the 1.94 lbs. has no bearing on anything. It was originally developed as an AMO measurement standard in conventional archery for the purposes of comparing different spine readings across different manufactures products. It goes hand in hand with an arrow length of 28”. Unless we are conforming to the 28” length standard, the 1.94 lbs. has no relevance of any type.

You now have a weight that easily hangs on your arrow shafts and rolls as smooth as silk regardless of which direction you’re rotating each shaft.

Step 8 Since the length of your weight is now slightly longer than it originally was, you’ll need to us a 1” or 2” spacer under each leg bracket of your spine tester to raise it enough for the weight to hang free from each arrow shaft without touching the surface below it. I use a pair of 4" long pieces of 2" x 4".

Here’s two pictures of the finished product so you’ll understand how easy this is and what you’re seeking to achieve. Picture 1 shows the roller bearings and water level threaded onto the weight. The 2nd picture shows the countersunk bolt threaded thru the weight to attach the water level.

View attachment 31829 View attachment 31830

When completed, you've turned your spine tester into a high quality instrument that can easily identify the exact "Stiff Side" marking position with much less effort, time and much more accuracy than any standard tester.

Hope this helps improve your tuning efforts.

Xbow755
Hi Jon!

I’m about to have this completed to my weight that came with the RAM. My buddy currently has the weight and will be drilling and tapping the weight and then mating the Firenock jig to it. My question to you is where did you place the indicator gauge in relation to where the weight sits? In other words the indicator gauge would read the arrow when placed in between the two plastic arms of the original brass weight configuration. Do you place it on either side of the Firenock jig? Thanks for your help!


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#32 ·
The simple answer is yes, but remember since the water lever mounted on the top of the unit is not needed you can also have a hole made in the top that would allow the needle plunger from the RAM's bezel to have the room to drop right thru the opening so you can center the weight below the plunger for readings. Either to the side or thru the center will work. Just make sure if you put a hole in the center of the water level make it over sized for ease of allowing the plunger plenty of room to drop thru.

Jon
 
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