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.
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
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.
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