bare shaft tuning query

[Michael Burrows]

Hi using a new Mybo Revolution with drop away rest set at 49lbs with an arrow speed of 245fps (using chronograph) using Skylon Precium 450 spine arrows 29" long with 125 gr break-off points. My issue is that it paper tunes a perfect bullet hole both fletched and bareshaft. I then French tuned and walk back tuned. Made small adjustments left and right (nock was height correct). Checked paper tuning again - perfect bullet hole. BUT when I bareshaft tune at 30m the bareshafts fly poorly and end up quite a lot right of the fletched shafts and were nock left - a sign of weak spine. I've made sure that is no face contact. I then took one fletched and one bareshaft and changed the points to 80 break off grain but if anything the bareshaft is worse and the fletched shaft not much different. The skylon spine chart says I have the right spine for the arrow length and speed although in my experience with arrows for my barebow they do tend to suggest weak. Before I cut them down I was wondering if anyone had any ideas.

 

[jerryRTD]

If you are getting bullet holes then the arrow is coming off the bow clean and straight . Why are you worried how the bare shaft flies?

 

[RatherBinTheWoods]

Agree, if it’s working for you perfectly using your usual shooting setup in my book that’s tuned :0)

 

[Geophys2]

Absolutely, bullet holes, French Tuned, walk back tuned, good to go.

 

[Michael Burrows]

Well I guess I'm looking for perfection! It's just that I can get my barebow to bareshaft tune so why not my compound? Also what I really don't get is that with a compound the arrow flexes vertically on release so why do they land right (or left is too stiff). I get it with a recurve because of the horizontal flexing - perplexed !!

 

[jonUK76]

It might not be indicating what you think it is. I.e. I suspect the usual diagnosis of bare shaft left = stiff arrow, bare shaft right = weak arrow (or the opposite when shooting left handed) may not be valid here because the set up is completely different to a recurve where you have a pressure button pushing the side of the arrow influencing things and a finger release introducing horizontal movement. You have a drop away rest designed to minimize arrow contact, and a mechanical release which should be introducing minimal horizontal movement, providing the forces applied at the time of release are in a straight line and not off to one side.

For what it's worth I'd agree with the others and say if it's shooting perfectly with fletched arrows then just leave it at that. If it's still an itch you have to scratch then perhaps adjusting the bow weight is a less permanent change you could make rather than cutting arrows.

 

[jerryRTD]

Well I guess I'm looking for perfection! It's just that I can get my barebow to bareshaft tune so why not my compound? Also what I really don't get is that with a compound the arrow flexes vertically on release so why do they land right (or left is too stiff). I get it with a recurve because of the horizontal flexing - perplexed !!

If you are chasing after prefection you are wasting your time Perfection will always be that tiny bit out of reach. If you are shooting barebow you won't get perfection you will need a sight for that.
I do not get a change the point of impact left/right. when I change from 380 Protours to 400 cheap carbons I think you may be gripping the bow which is causing errors.

 

[Shirt]

Well I guess I'm looking for perfection! It's just that I can get my barebow to bareshaft tune so why not my compound? Also what I really don't get is that with a compound the arrow flexes vertically on release so why do they land right (or left is too stiff). I get it with a recurve because of the horizontal flexing - perplexed !!

You're thinking about it as though it's a perfect system which is essentially a rifle.
Stop that now.
How much torque do you have in the system at full draw?
- is your hand position good
- how close to the arrow do your cables run
- what cable slider are you running - PSE wheelie thing, AAE slide, Hoyt... How far from the bar are the cables
- what is the cam lean at static and full draw
- what letoff setting have you set the cams to, and is that complementary to how you shoot
Once you've thought through all the impact that can have on your bareshaft, what are your stabilisers doing at full draw?
- are they set to resist any errors from you (heavy angle to side rod) or to be balanced and support aiming (more neutral, weight under elbow)
- how much weight do you have on them, because 2oz on a front rod is going to do sod-all
- what happens to the bareshaft if you take weight off the side rod or move it further out

Bareshaft is "quite a lot right". What's your definition of "quite a lot"? 4 inches at 30m, 12 inches, barely hit the face, only just stayed out the grass...?
Also, what happens when you do the bareshaft test at 18m?
What do you intend to use these arrows for - 30m is a decent test for field, but no use for target because it tells you nothing about your 50m group. Equally they're too skinny for indoors. Are you testing at the relevant distance if you really want to get the bareshaft right?

Finally, why do you care about the bareshaft? Do you ever plan on shooting it in a scoring round?

 

[Michael Burrows]

You're thinking about it as though it's a perfect system which is essentially a rifle.
Stop that now.
How much torque do you have in the system at full draw?
- is your hand position good
- how close to the arrow do your cables run
- what cable slider are you running - PSE wheelie thing, AAE slide, Hoyt... How far from the bar are the cables
- what is the cam lean at static and full draw
- what letoff setting have you set the cams to, and is that complementary to how you shoot
Once you've thought through all the impact that can have on your bareshaft, what are your stabilisers doing at full draw?
- are they set to resist any errors from you (heavy angle to side rod) or to be balanced and support aiming (more neutral, weight under elbow)
- how much weight do you have on them, because 2oz on a front rod is going to do sod-all
- what happens to the bareshaft if you take weight off the side rod or move it further out

Bareshaft is "quite a lot right". What's your definition of "quite a lot"? 4 inches at 30m, 12 inches, barely hit the face, only just stayed out the grass...?
Also, what happens when you do the bareshaft test at 18m?
What do you intend to use these arrows for - 30m is a decent test for field, but no use for target because it tells you nothing about your 50m group. Equally they're too skinny for indoors. Are you testing at the relevant distance if you really want to get the bareshaft right?

Finally, why do you care about the bareshaft? Do you ever plan on shooting it in a scoring round?

Hi using a new Mybo Revolution with drop away rest set at 49lbs with an arrow speed of 245fps (using chronograph) using Skylon Precium 450 spine arrows 29" long with 125 gr break-off points. My issue is that it paper tunes a perfect bullet hole both fletched and bareshaft. I then French tuned and walk back tuned. Made small adjustments left and right (nock was height correct). Checked paper tuning again - perfect bullet hole. BUT when I bareshaft tune at 30m the bareshafts fly poorly and end up quite a lot right of the fletched shafts and were nock left - a sign of weak spine. I've made sure that is no face contact. I then took one fletched and one bareshaft and changed the points to 80 break off grain but if anything the bareshaft is worse and the fletched shaft not much different. The skylon spine chart says I have the right spine for the arrow length and speed although in my experience with arrows for my barebow they do tend to suggest weak. Before I cut them down I was wondering if anyone had any ideas.

Well in my pursuit for better arrow flight I thought I would try a method I came across on an American forum, what was there to lose. Firstly I did a bareshaft through paper at a meter and got a perfect bullet hole. Then I advanced to about 5 meters and got a massive high and right tear. I was really surprised at the difference. Why would it be good at a meter and not good at 5. Anyway corrected that and moved to longer distances making adjustments until I had a bareshaft perfect bullet hole at 18m. Then tried bareshaft and fletched and guess what they all landed perfectly together. So (my) problem solved and an interesting exercise in tuning.