Bow cant and tuning

[khardrunner]

I've read both ways... so which is true?

1) The cant of your bow does not effect what you see when tuning (bareshaft or paper). That means horizontal tears truly are spine effected and vertical are nocking point.

2) The cant of your bow DOES effect tuning results. You have to factor in the degree of cant to what you are seeing on paper.

Any ides which is really the truth?

[Bjorn]

The cant of your bow will definitely affect an unfletched shaft. I always make sure my bow is dead vertical for the bareshafts. IMO anyway.

[ChrisM]

Physics says #2

[Prairie Drifter]

Originally posted by Bjorn:
The cant of your bow will definitely affect an unfletched shaft. I always make sure my bow is dead vertical for the bareshafts. IMO anyway.

That's been my findings too.

[khardrunner]

I love the mention of physics... I teach physics and certainly lean toward #2. Most of the writing I have read though does not mention that.

[ChrisM]

Originally posted by khardrunner:
I love the mention of physics... I teach physics and certainly lean toward #2. Most of the writing I have read though does not mention that.

College or high.  
I teach algebra and geomerty in high school,  and I want to get physics certified.

[khardrunner]

High School. I recently got certified. I already had Gen Science and Chem. I teach mostly chem but still really enjoy physics.

As a math guy you will probably like it. Physics is really applied math.

I'm really thinking through the physics of this. For the most part we are assuming the arrow going around a surface on a single plane. Depending on nocking point and the portion of paradox that may not be necessarily true. That can lead us more to a #1 answer rather than a #2.

[BowDiddle]

#2

Physics aside, all you have to do to see the effect is to shoot your bow from different degrees of cant, and you will clearly see the result.

Not long ago, a friend of mine taught me the following, and after applying it to my bare shaft tuning I have always been able to achieve the best result:

Regardless of cant, or lack there of -

1 - Always consider the spine attitude of your arrow at a 90 degree angle to the strike plate.

2 - Always consider the nock set attitude of the arrow at a 90 degree angle to the shelf.

Before learning this I had a heck of a time bare shaft tuning. Now it's a snap.

[ChrisM]

Or in math nerd terms the deflection of the shaft is the X axis and the nock is the Y axis and attitude of the bow rotates it around the center which is the shelf.  

[khardrunner]

nice chris!

[Thumper Dunker]

My head hurts.

[wtpops]

My little logical brain says #2.

The the forces that act on an arrow to show a week arrow,Tail left, Right handed shooter on a vertical bow. Now cant the bow at a 45, those same forces are still there. Now as the arrow leaves the bow it will show tail high and left instead of just tail left. Now cant the bow at a 90 and you have tail high. OUCH my head hurts now.

[wtpops]

Originally posted by ChrisM:
Or in math nerd terms the deflection of the shaft is the X axis and the nock is the Y axis and attitude of the bow rotates it around the center which is the shelf.      

OK now my eyes hurt to..

[khardrunner]

I wish I could draw a pic to show you what I'm thinking here, but I would expect all of this to depend on three things, not just the single plane concept we have been looking at.

1) shelf/side plate shape
2) where in paradox the arrow contacts the shelf/side plate if at all
3) where on the shelf/side plate the arrow contacts

It's not a simple side plate perpendicular to the arrow travel (think arrow Z axis side plate y axis). The shelf also acts as an x axis and since this is all connected by a curve at the rear of the shelf (depending if that is where your arrow is contacting) then the simple plane method is useless.

Also consider many of the slow-mo videos showing very little if any contact once the string is released. No contact=no force. That would leave the string and string angle as the only force inducers. Perhaps this is dependent on a proper brace height as well.

Right now I get a tear high and slightly left. I am left handed, so this would show weak. The thing is, it does NOT change much at all with a vertical bow. It tears higher and more directly straight. I have thought nocking point height would explain this. However, i cannot get that to change. I have tried nocking above and below and at just about every height from 1/8 up to 5/8. I get almost exactly same tear every time no matter what I change. I also changed point weight at one point to stiffen it up a bit. No difference.

[30coupe]

You guys are making this way too hard. If the bare shafts and the fletched shafts hit in the same place and the place they hit is where you were aiming, you are done. If they don't, change something until they do.

No math, no physics. Shoot, observe, adjust, shoot, observe, adjust, until you see the result you want.

Simple. No wheels, no sights, no lasers...s.i.m.p.l.e!

[toddster]

To stir the pot, it depends on what bow and how it is made!  If you shoot a longbow off the hand then it doesn't matter because the arrow is in the same position as the bow "rolls" around it.  Deeper cuts means it will move more as the cant changes and hand position changes.  One of the big reason's for traditional gear I gave up paper tuning, and matched arrows to bow with perfomance and sound.

[FarmerMarley]

No lasers?!

I would agree that depending on the bow there will be at least some difference if the bow is canted. I always try to bareshaft with the bow vertical. Canted bows will show a different result due to the change in the axis/-paradox.

[khardrunner]

30coupe... physics IS simple! It's also interesting and fun to try to figure out. Newton was doing this hundreds of years ago.

Anyway, the issue I have with tuning straight up in the first place is that I don't ever shoot that way. Why tune an arrow to fly out of a bow that is vertical when I will never shoot that way. Draw length, timing, hand position on string and bow, and several other things are subject to change when I shoot vertically that can all change how an arrow is tuned.

[ChrisM]

The side plate should not touch the arrow once paradox is started with the properly spined arrow.  What the side plate position does is it dictateds how much or how little bend is needed to get around the riser and off cleanly.  Basically you want the tip of the arrow to end up on the z axis traveling to the target exactly as the string is with the x and y values being zero. For a lefty a weak shaft will bend too much and the tip will go too far into the x negativemand make a left hit, viasa versa for a stiff shaft.  The nock point can be influence by alot but it needs to be high for the bottom hen feather clearance if the shelf is wide.
I think.

[Jeff Strubberg]

I'm gonna go against the grain here.

#1, if you've done it correctly.

The arrow paradoxes around the bow riser regardless of what degree or horizontal or vertical that riser is being held at.  Remember, the string hand is also rotating as the bow rotates.  All should be in the same plane if you aren't commiting some kind of form error.

If the bow is upright, the shaft is flexing (mainly) east and west.  If you lay the bow over 90 degrees, the shaft will now flex north and south.  The same flex and recovery will be required in both positions to get good arrow flight.

The flex of the shaft has nothing at all to do with up, down or sideways.  The direction of the initial flex is away from your fingers, regardless of whether that means horizontal or vertical.