Setting height of spring blade rest on compound

KidCurry

Active member
.... A firm grip on the hinge release improved things and ... 
Be careful here. You need to pull strongly into the stops. This will give you a good repeatably, solid, release. But do not grip the hell out of the release. Pulling hard into the stops will also steady the aim.
 


chuffalump

Member
Thanks for that. Less a death grip and more three fingers properly and firmly hooked. (EDIT - two fingers plus thumb, third finger only curls round to release) Not sure how I'm doing it but I still manage to draw the hinge safely. Not looking at it too hard in case I lose the knack. 😅

I've set the draw stops to the slightly softer setting available. Means that there is less of a jolt, I found I was anticipating the let off and pausing during the draw to avoid knocking the arrow off the rest.
 


chuffalump

Member
X7s arrived. 2214s instead of the old 2016 XX75s because that's what the spine chart said would suit.

Reset my rest to centre and supporting the arrow level with button hole with minimal weight. Reset nocking points to put arrow dead level with button holes. Fitted the stiffer blade.

Hope to get time with the paper box in the garage tomorrow.
 


chuffalump

Member
Well there's one measure of consistency.

Paper tuned the X7s and had to move the rest slightly further right than where it was with the XX75s. Didn't have to lift it as much this time.

Looks like the side oscillation of the string is fairly consistent in terms of amplitude and direction at point of nock separation. I was very careful to minimise face contact with the string too and used the thumb trigger release.
 


chuffalump

Member
Hmmmf. Shot my first session yesterday with the X7s. They flew very nicely and straight down the centre at 40 yards/20 yards. I should be happy. But....

I don't understand at all how the vanes can't be catching the riser. Gonna take the lipstick today and check but resting the tail end of the arrow on the blade means the vane is slightly curled by touching the metal.

Either something very weird with the bow or I have extremely consistent torque on the grip....

Or the bubble on my sight isn't level and I have a permanent cant? Ordered a pocket level this morning at 4.30am.
 


geoffretired

Supporter
Supporter
I used to find little scuff marks on my inside fletch near the foot. I guess that gave the back end of the arrow a little nudge, causing that fletch to rotate or move aside. perhaps enough to clear a riser.
I also noticed one prong of the blade always wore more than the other. That takes a while to show up.
 


chuffalump

Member
Well the lipstick was rubbish but I piled a load into the vane closest to the riser and shot away. No sign of any smearing on the riser so no contact I guess. No idea how. Wonder if I can get myself filmed. Don't think I'm torquing the bow either. I've tried multiple changes in hand position and none of them indicated that I could start moving the rest back out to the left.

However, a really turned in hand seemed to give a much steadier aim and undisturbed release so that's a plus.

One of those little mysteries. I don't fancy shelling out for a full set up session but maybe I'll ask the Merlin crowd next time I'm up there. See what they think. They made the bow after all.
 


geoffretired

Supporter
Supporter
I've tried multiple changes in hand position and none of them indicated that I could start moving the rest back out to the left.
Does torquing the bow move the rest? I thought it moved the sight, in relation to the rest.
 


chuffalump

Member
As far as I'm aware, torquing the bow can throw the arrows right of left depending on which side the pressure is. So my paper tuning could be thrown off by compensating for bow torque. I should retune with different grips.....

I'm mixing it up with paper tuning and walk back tuning but if torque can effect the way arrows leave the bow then paper tuning will be influenced too....

The compound is still more logical to me than the recurve.
 


chuffalump

Member
After watching the excellent slo-mo video posted earlier in the thread I saw that, despite a mechanical release, there was still sideways oscillation in the string. Sideways oscillation presumably throws the nock left and right whilst the rest contact stays constant(ish). It seemed therefore that the purpose of paper tuning is to align the rest, string and target in a straight line at point of nock separation. Thus producing bullet holes.

Torque in the grip would most likely cause or exacerbate this sideways oscillation. Therefore consistent torque in the grip could cause reliable, repeatable oscillation. Meaning it would be possible to paper tune to compensate for torque. Not that you'd ideally want to but it's a compromise between the ideal robot precise grip and a squishy human.

In walk back tuning you move the sight at close range and the rest at long range. So if the arrows started landing right at long range with a better grip. I could move the rest left, away from the riser. I have doubts that this part of my logic chain is true though. As you say, torque also moves the sight, causing aiming problems. I suspect that after a grip change you should paper tune again.

EDIT - the whole theory is complete rubbish. My brain must be thinking these things over while I'm asleep. Anyway, I realised that running my theory backwards I should be able to look at rest vs string position and determine what the original paper tear was. My rest is a long way to the right. If string oscillation is the cause then the string must be to the right as well. Meaning that, if my rest was central, I should have had a tail RIGHT tear instead of tail left.
 


geoffretired

Supporter
Supporter
As you draw the bow, and the limbs bend ,they are drawn slightly off line by tension in the cables as they pass over the cable guard. Or you can look at that and describe it as the riser torques as the cable guard is put under side pressure from the cables. At full draw and pulling against the stops, the cams are drawn into line with the pressure point at the bow grip. The riser is torqued and the sight moves accordingly. On the power stroke things eventually return to " normal".
I think the bow does its own thing in the power stroke. From seeing the results through paper, it is possible to decide on a hand position that gives bullet holes. It is also possible to adjust the rest centre shot and then find another hand position to give bullet holes again.
I don't think it is the hand gripping and twisting the grip; rather that a relaxed hand puts pressure into the grip to one side or the other of the grip's centre line.
 


chuffalump

Member
Well now. I've just moved the cable guard slightly as I thought the vanes might be a bit close to the cables with these bigger arrows. I've seen descriptions and videos of people taking about tuning with the cable guard and moving the cam spacers. Bit more than I'd want to try, although I did notice that the bottom cam isn't as central as the top one. Maybe one mm out.

So I can see the limb twist due to cable guard causing unavoidable side oscillation and I can see that hand pressure on the grip could make this worse, or alternatively, counter-act it. I would guess that a right handed bow would throw the string left on release as the cams straighten up. Annoyingly, I don't have yokes so can't tweak the lean that way. I think the next step is to paper tune with a different grip and to move the cable guard as close as possible without catching the vanes.

Unfortunately the garage is filling up with the gear of a relative who's moving house soon. 😀
 


geoffretired

Supporter
Supporter
I did notice that the bottom cam isn't as central as the top one. Maybe one mm out.
That could be deliberate; my Hoyt is.
I made my own cable guard some time ago. Instead of the rod being parallel to the bow plane, I angled it across towards the string at the loose end. So, at full draw the cables were less displaced to the side. As the fletchings moved towards the cables on the power stroke, the cables were further away to give normal clearance. Seemed a good idea at the time; until I shot with it.
 


chuffalump

Member
Hmm. It does seem like a good idea. Theoretically you should be able to keep the cam lean at zero throughout the entire stroke. Possibly what you want is a split cable guard so the arrow goes through the centre. 😂
 


geoffretired

Supporter
Supporter
One manufacturer used a spring type cable guard. As forces increase it bends towards the string.
I made a lot of split cables in the past. It made a cable guard redundant; and reduced cam lean. With cables having more tension than the bow string, I think the cams did still lean slightly.
 


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