# DIY Spine indexer



## landongold (Dec 29, 2017)

Here is an overhead view of the arrangement of hardware connecting the bearings to the brace, and brace to the angle iron.

I chose to build the bearings first and then mount the brace to the angle iron but doing it again I would mount the brace first. It needs to be squared with the top of the iron.










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## landongold (Dec 29, 2017)

Make sure to space the bearings exactly 26 inches apart. This will give you enough distance to allow the arrow to flex under the weight of the weight but not so far apart that your arrow won't fit.









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## landongold (Dec 29, 2017)

Before assembling the bearings to the brace I used a dremel to cut out a notch so the brace would not contact the arrow.









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## landongold (Dec 29, 2017)

Finally you need to take a fifth bearing and tie a piece of paracord to it. I took about 9 inches and pulled out the internal strands to I was left with just the shell of the cord. I then flattened it around the exterior of the bearing and melted the tag end to itself creating a loop. 

To tighten the loop around the bearing I tied a series of double overhand knots reversing which side the knot layd each time. The knot is the exact one John Dudley uses to to tie in his knock sets. I just kept trying until the cord was very tight around the bearing. Finished with a dab of super glue.

With the other end of the cord I tied on a 2 lb diving weight.









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## landongold (Dec 29, 2017)

Now, I clamp the contraption to the edge of a table with some clamps. I take a bare shaft and slide is through single skate bearing attached to the 2 lb weight. I put the shaft on the brace bearings and let the weight hang dead center at 13" between both braces.









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## landongold (Dec 29, 2017)

With the weight hanging dead I'm able to rotate a bearing on the brace to rotate the shaft. I can feel the heavy side of the arrow jump and visually see it as I rotate the arrow. The arrow will naturally want the stuff side bending down towards the weight which means the weak side will be facing straight up towards you. I mark the weak side cause it's easier then take the shaft out and Mark the opposite stiff side with a sharpie. I can now infect all my arrows and orient the stiff side to be the same for each arrow. 

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## landongold (Dec 29, 2017)

The results of this were amazing. My group size shrunk dramatically especially at longer distances. 

I think this step is essential for anyone wanting to maximise the tuning process. I work on all my own bows and build all my arrows so this is now just another step in my arrow building process. I know there are some shops and arrow builders that will index a customer's arrows eliminating the need for this but if you want to take control of the process and your set up I would highly recommend adding this to your arsenal.

In all it cost me around $55 to make. I live in Hawaii where alot of the materials were more expensive than what they would be on the mainland so I imagine most of you guys could build this for cheaper. 

I hope you enjoyed this. Sorry for any mistakes or errors. This was a long post. If you have any questions just ask. And critiques are welcomed too. 

Mahalo

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## landongold (Dec 29, 2017)

Last pic









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## labyrinth888 (Jan 11, 2019)

Wahhhhh that is something !!

great job !
really inspiring !

thanks for sharing it !!!


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## labyrinth888 (Jan 11, 2019)

does the stiff spot was always in the side according to the stikers on the arrow ?
i guess No 
they must be printed randomly i guess at the factory....


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## Stepping wolf (May 5, 2019)

Not to deride from your device but to conform to the industry standard, the span should be 28" not 26" but in this case it really won't matter because of the second correction. What you are finding is the natural bending plane not the spine. When looking for the spine, you are looking for the plane that wants to bend the least amount. In your case, the weight pulls vertically and the easiest place for it to bend,is were it naturally want's to bend. Hense, the natural bending plane.
The spine will be at 90 degrees to the natural bending plane,(give or take a few degrees). The shaft bent easiest, vertically, so the plane it didn't bend in, was horizontal. 
In your case, the estimated spine is at 90 degrees to the horizontal plane your weight is finding.


Stepping wolf


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## landongold (Dec 29, 2017)

Stepping wolf said:


> Not to deride from your device but to conform to the industry standard, the span should be 28" not 26" but in this case it really won't matter because of the second correction. What you are finding is the natural bending plane not the spine. When looking for the spine, you are looking for the plane that wants to bend the least amount. In your case, the weight pulls vertically and the easiest place for it to bend,is were it naturally want's to bend. Hense, the natural bending plane.
> The spine will be at 90 degrees to the natural bending plane,(give or take a few degrees). The shaft bent easiest, vertically, so the plane it didn't bend in, was horizontal.
> In your case, the estimated spine is at 90 degrees to the horizontal plane your weight is finding.
> 
> ...


I opted for 26 because my arrows are cut to 27 already, but that's good to know 28 is standard. 

As for your other correction, are you saying that the spine is perpendicular to the vertical bend I'm putting in the shaft using the weight? 

With what your saying is spine also the stiff side of the arrow? I'm not following very well

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## Stepping wolf (May 5, 2019)

There is a difference between simple indexing, which is what you are doing and "spine indexing"
Simple indexing can be most easily understood by taking a flat ruler, if you bend it along the flat side, it will bend back and fourth easily. This is the natural bend, it is also the neutral bend. It will bend back and forth equally, making the bend neutral.
The edge side, which is at 90 degrees to the flat side, would be the spine. Trying to bend it along this plane, will most likely break it.
Spine indexing is very different because it deals with the deflection of the shaft when it is suspended between two point 28" inches apart and a 2 lb. weight is applied.
The following video explains this very nicely.

https://www.youtube.com/watch?v=J00I4yi0rYU

Stepping wolf


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## RusteeGold (Jan 5, 2015)

Nice build. Very inspiring

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## RusteeGold (Jan 5, 2015)

Stepping wolf said:


> There is a difference between simple indexing, which is what you are doing and "spine indexing"
> Simple indexing can be most easily understood by taking a flat ruler, if you bend it along the flat side, it will bend back and fourth easily. This is the natural bend, it is also the neutral bend. It will bend back and forth equally, making the bend neutral.
> The edge side, which is at 90 degrees to the flat side, would be the spine. Trying to bend it along this plane, will most likely break it.
> Spine indexing is very different because it deals with the deflection of the shaft when it is suspended between two point 28" inches apart and a 2 lb. weight is applied.
> ...


Hi Wolf,
I read your comments and watched the video and I think I learned quite a bit. However it seems to me that "simple indexing" and "spine indexing" are the same thing. Both are really just finding the stiff plane and marking it. Also you don't have to have exactly 28 inches to do indexing. Indexing just means you are finding the stiff side or plane and marking it. The video confirmms that because he was using 20 inch shafts (for a cross bow i guess). The video also showed index matching which appears to be ranking the relative weakness of all the shafts and throwing out the extremes. But to be honest, I'm not sure why the guy disregarded the one he measured at 91 because all the shafts were within 10 thousands of each other. They all seemed good to me.

The guy who built this indexer here on this forum is finding the stiff spine plane every bit as accurately as the guy in the video. He is just using a 2 dollar skateboard bearing instead of 150 dollar dial indicator.

Genius!



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## Stepping wolf (May 5, 2019)

RusteeGold said:


> Hi Wolf,
> I read your comments and watched the video and I think I learned quite a bit. However it seems to me that "simple indexing" and "spine indexing" are the same thing. Both are really just finding the stiff plane and marking it. Also you don't have to have exactly 28 inches to do indexing. Indexing just means you are finding the stiff side or plane and marking it. The video confirmms that because he was using 20 inch shafts (for a cross bow i guess). The video also showed index matching which appears to be ranking the relative weakness of all the shafts and throwing out the extremes. But to be honest, I'm not sure why the guy disregarded the one he measured at 91 because all the shafts were within 10 thousands of each other. They all seemed good to me.
> 
> The guy who built this indexer here on this forum is finding the stiff spine plane every bit as accurately as the guy in the video. He is just using a 2 dollar skateboard bearing instead of 150 dollar dial indicator.
> ...


LOL!!!
This falls into one of those yes and no quandaries. The OP is actually finding the natural bending plane. That being said, by finding the NB plane, the spine will always be at 90 degrees to the neutral plane and the "natural" bending plane, is usually on or around the "neutral" bending plane. other than that you are mostly correct.
To actual match "spines" is a little misleading also. The process to match the spines, involves first finding the stiff plane and then rotating the shaft 90 degrees to the "neutral" plane. This is the deflection value that needs to be matched.
If you think about it, matching the actual spine deflection numbers does very little for consistency. All of the oscillation that occurs in the shaft, will be done anywhere except at the stiff plane. That is why it is called the spine, it is the stiffest location on the shaft. All of the action will be directed to expelling all of the instilled energy in the easiest possible manor, through oscillation at the neutral plane.

Stepping wolf


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## landongold (Dec 29, 2017)

Stepping wolf said:


> LOL!!!
> This falls into one of those yes and no quandaries. The OP is actually finding the natural bending plane. That being said, by finding the NB plane, the spine will always be at 90 degrees to the neutral plane and the "natural" bending plane, is usually on or around the "neutral" bending plane. other than that you are mostly correct.
> To actual match "spines" is a little misleading also. The process to match the spines, involves first finding the stiff plane and then rotating the shaft 90 degrees to the "neutral" plane. This is the deflection value that needs to be matched.
> If you think about it, matching the actual spine deflection numbers does very little for consistency. All of the oscillation that occurs in the shaft, will be done anywhere except at the stiff plane. That is why it is called the spine, it is the stiffest location on the shaft. All of the action will be directed to expelling all of the instilled energy in the easiest possible manor, through oscillation at the neutral plane.
> ...


Ok so if I understand what you are saying, if I mark the bending plane and nock my arrow I should get a somewhat equal reaction shooting the arrow whether I shoot it with my mark up or down? 

What I found when indexing my arrows was there was consistently a spot on every arrow where the arrow would rest under weight in the same orientation. It was so noticable that when rotating the arrow slightly in either direction there was resistance to turn and the arrow would rest in the desired orientation. If I rotated it 180 degrees the arrow would not rest like it did on the opposite side. Can there be a weak side and a stronger side to the bending plane?



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## Stepping wolf (May 5, 2019)

"Ok so if I understand what you are saying, if I mark the bending plane and nock my arrow I should get a somewhat equal reaction shooting the arrow whether I shoot it with my mark up or down? "

The short answer is yes and what you are doing is perfectly fine as far as it goes. For instance, if you take a skinny arrow and a fat arrow. Then use your device to find the natural bend of each shaft. The shafts will have similar reactions but different impact points because they are different shafts. Simply aligning the natural bending plane, within a group of the same shaft will get you 80-90% of the way there, some nock will most likely still be needed.

"If I rotated it 180 degrees the arrow would not rest like it did on the opposite side. Can there be a weak side and a stronger side to the bending plane?"

No









The fact that the reaction is not the same at 180 degrees simply confirms that you are on the natural bending plane and not the neutral bending plane. This is why most seek the stiff plane and then rotate to the neutral plane but what you are doing is fine for simple indexing. As long as you realize that there are several levels above what you are doing.
Play with what you have created and when you are ready foe the next step then advance.

Stepping wolf

An example of finding the "neutral" plane.

https://www.youtube.com/watch?v=oncXSFLR5RE


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## hgian808 (Jul 22, 2014)

I just watched that video with the golf club shafts.. pretty interesting..looking at your diamgram.. so when you say find the stiff side then rotate to neutral, which way is neutral compared to the stiff side?


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## gfwireman (Jan 14, 2006)

Now I have another project, nice build.


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## Stepping wolf (May 5, 2019)

hgian808 said:


> I just watched that video with the golf club shafts.. pretty interesting..looking at your diamgram.. so when you say find the stiff side then rotate to neutral, which way is neutral compared to the stiff side?


The neutral plane runs through the entire shaft, this is why the shaft will oscillate in a straight line.


Stepping wolf


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## 264co (Sep 8, 2014)

Very cool thanks


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## tka4217 (Feb 1, 2009)

nice work


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## Mustanglego (Sep 29, 2014)

I like it!!! Great job.


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## landongold (Dec 29, 2017)

Thanks for all the input and feedback BTW

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## 264co (Sep 8, 2014)

Where do you want the nocking orientation in relationship to the stiff side of the arrow?


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## landongold (Dec 29, 2017)

264co said:


> Where do you want the nocking orientation in relationship to the stiff side of the arrow?


So what I did which works for me is when I have the weight on the arrow and I find the bending plane I mark the top of the arrow. After I take it off the contraption I mark 180 degrees opposite to the mark I originally made. I then nock that mark straight up when I nock all my arrows.

My thought and observation is that when I find the natural resting place of the bending plane that is where the arrow naturally wants to bend. When I shoot the arrow it should deflect in the same direction, so I want that deflection to go up in relation to my rest so the deflection isn't pushing off the rest causing erratic arrow flight

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## 264co (Sep 8, 2014)

Thanks


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## Yellowhorse6 (Jun 27, 2019)

Nice build and good info about natural bending plane versus neutral plane


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## rlawless (Feb 15, 2015)

Great idea and a very useful tool. I have not tried this yet, but a competition shooter told me he fills his tub with soapy (bubble bath type) water and lays his arrow shafts (carbon) in the water and the shafts will float which shows you the same thing. He marks the top side and goes 90* from the top mark. Great thread though.


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## rodco03 (Feb 5, 2019)

Great work! Very well thought out.


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## Simon223 (Dec 26, 2019)

divers weight ... good idea HAHAHA


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## mr mossyhead (Feb 9, 2014)

Great job man!


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## yakchin (May 29, 2016)

Now I'm kicking myself for cutting up and recycling the old metal bed frame. Seems it would have worked for a spine tester.


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## upchurch_k (Jan 13, 2020)

Looks like quality work.


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## Goldensombrero (Jan 13, 2020)

Well explained easy DYI. I like it


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## DaveMFLock (Aug 1, 2016)

It looks like a whole lot of science went into this post!


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## ARCHERY4LYFE (Dec 8, 2018)

Well done man! I cant believe I never thought of this. Thanks for sharing. Looks like I'm off to home depot.


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## landongold (Dec 29, 2017)

ARCHERY4LYFE said:


> Well done man! I cant believe I never thought of this. Thanks for sharing. Looks like I'm off to home depot.


Thanks man! Best of luck on the build

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## Dalyjl3 (Aug 11, 2019)

Thats awesome nice job!


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## NJnewbow (Feb 10, 2020)

very cool


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## rjoe (Jun 6, 2009)

tagged


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## 5ks (Feb 20, 2020)

Nice work


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## Kimel (Feb 5, 2020)

Definitely learned a few things with this post. Thanks!


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## IdahoHunter208 (Feb 24, 2020)

Great post! I might have to build myself one of these


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## Jcsrookie (Feb 11, 2020)

Sweet. 
Thanks for sharing the idea


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## adamsarchers (Jan 31, 2016)

Great idea - lots of good information, too. Thanks.


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## Stickbowfan 112 (Mar 6, 2017)

Cool build I do the same thing when I build fishing rods I put the stiff side up so the weak side naturally flex


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## washingtonchan (Feb 27, 2020)

Cool!


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## washingtonchan (Feb 27, 2020)

very cool! awesome!


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## jorman17 (Sep 18, 2018)

thats a great design. Think i will try it. Thank you.


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## 22donk (Feb 20, 2014)

What the heck, am I the only one who’s still lost. Maybe I should have rode the short bus to reading comprehension class possibly.


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## landongold (Dec 29, 2017)

22donk said:


> What the heck, am I the only one who’s still lost. Maybe I should have rode the short bus to reading comprehension class possibly.


Haha I probably could have explained it better. Where are you lost?

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## 22donk (Feb 20, 2014)

landongold said:


> Haha I probably could have explained it better. Where are you lost?
> 
> Sent from my SM-N960U1 using Tapatalk


Lost on where the spine actually is located in this design of indexing machine, Forget neutral or natural bending plane...
Is it literally 90* from the bend of the arrow, in other words, after hanging the weight, the spine will be facing you, outwards from the device?


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## Stepping wolf (May 5, 2019)

22donk said:


> Lost on where the spine actually is located in this design of indexing machine, Forget neutral or natural bending plane...
> Is it literally 90* from the bend of the arrow, in other words, after hanging the weight, the spine will be facing you, outwards from the device?


Yes and no. 
The Ram style of spine finders is not designed to index from the natural bend but yes the physical spine or stiff plane is "approximately" 90 degrees from the natural bending plane. It is exactly 90 degrees from the "neutral" bending plane.
The Ram is designed to find deflection, which is then mislabeled as a spine value. To use the Ram style spine finder correctly, you first find the stiffest point on the shaft or the point of least deflection. Mark this point and then rotate the shaft 90 degrees in either direction to the "neutral" bending plane, measure and match the deflection value at this point. It could be located on or near the natural bend but it most likely will be 10-20 degrees different


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## 22donk (Feb 20, 2014)

Stepping wolf said:


> Yes and no.
> The Ram style of spine finders is not designed to index from the natural bend but yes the physical spine or stiff plane is "approximately" 90 degrees from the natural bending plane. It is exactly 90 degrees from the "neutral" bending plane.
> The Ram is designed to find deflection, which is then mislabeled as a spine value. To use the Ram style spine finder correctly, you first find the stiffest point on the shaft or the point of least deflection. Mark this point and then rotate the shaft 90 degrees in either direction to the "neutral" bending plane, measure and match the deflection value at this point. It could be located on or near the natural bend but it most likely will be 10-20 degrees different


So the OP’s device finds the natural bending plane, not the neutral bending plane. So if the side of the arrow facing you would be close to the spine but maybe not exact. The exact spine would be 180* from that point?


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## Stepping wolf (May 5, 2019)

"So the OP’s device finds the natural bending plane" correct but it is designed to find the stiff plane or physical spine, not the natural bending plane.

"So if the side of the arrow facing you would be close to the spine but maybe not exact' correct but only because the physical spine is at 90 degrees to the natural bending plane. This is why it is designed to find the deflection and not spine directly but you have to use it to find the stiff plane in order to be able to rotate the shaft 90 degrees to find the projected "neutral" plane. this is the actually deflection value that is closest to the neutral plane. To actually find the exact neutral plane you would need to use Flat line oscillation but the Ram style spine finders get you c;ose enough that F.L.O. is not really warranted for most people. 

"The exact spine would be 180* from that point?" No, The spine and or the neutral bending plane runs through the entire shaft. Just as in the description of the flat ruler, somewhere above. A ruler will bend naturally back and forth along the flat edge, the spine of the ruler would be at 90 degrees to the flat edge and runs entirely through the ruler.


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## arrows slinger (Mar 16, 2013)

Nice


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## Baileylab (Mar 14, 2020)

Can’t you float a bare shaft in water and the spine turns down?


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## Stepping wolf (May 5, 2019)

Baileylab said:


> Can’t you float a bare shaft in water and the spine turns down?


Some try but it is not very accurate or consistent. If weight was the only contributor maybe but weight isn't even in the top 5 determining factors for spine


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## Mike2712 (Sep 28, 2019)

Thanks for bringing this thread back to the top.
It's an excellent build, an excellent idea to check the index of your spines, and definitely something that I will do soon.
Thanks, 

Mike


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## fmfdoc1987 (Mar 19, 2020)

I was just watching youtube videos on this..thx


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## cristigeo (Jun 6, 2019)

great idea with the bearings !


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## sbing (Jun 21, 2020)

Thank you for sharing, it give me good idea


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## JSTTH5US (Dec 12, 2012)

Just saw this and thought it might help some of you out with aligning vanes consistently. 

https://youtu.be/lH3CdQtiCv0


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