Accurate limb alignment (on plane)

[Shed tuner]

I'm a relative newbie - around 18 months. I can set the limbs alignment, hold the riser out, string passing through the right line of the riser and the bolt holes...

...but getting it exactly on plane (ie.. shifting the whole string/both limbs left/right) is giving me some challenges, largely due to the number of differnt approach, all of them a bit "iffy" IMHO

1) Long rod alignment - fine, but who's to say the rod is perfect, or the bushing ?
2) hold the bow out, look through it so you can just see barely the inside face of the "window" - OK, but not very measurable
3) lay an arrow along the inside of the window, and look down it's edge - better than the above. I quite like this actually, so long as riser machined true, but still not easily measurable
4) measure from the edges of the limb bolts to the string on each side (hard to be accurate due to the trigonometry, but at least it's measurable). Mine showed a 1mm error, which is consistent when you do the trig.
5) I made a string alignment measuring thingy - see pix below.


This bow I'm setting up, when using every single one of the above methods, points to the string being 2-3mm to the RHS, so I'm defo going to do the adjsutment.. but which is most reliable measurement method?

My bow alignment "thingy" is a vernier clamped to a set square. Make sure it's snugged up against the side of the limb, as well as the right angle section being snug down accross the face of the limb, adjust the verier till it just clears the string, spin the whole thing round and measure from the other side. Ideally it will also just clear. On this bow I have a 4mm variation (4mm off in second pic, just touching string in third), indicating 2mm off centre.

The good thing is the actual measurament doesn't matter, or even if the set square isn't exactly 90 degress - as you use the same set square at the same angle from both sides, so the difference the string is off by should be the same when you spin it around to the other side. If there is a difference, halve it, and you are that far off centre.

To me this is measurable, repeatable, and fairly accurate - but I'm a newbie so I'm probably wrong. Discuss

 

[dvd8n]

I never got on with the various limb alignment methods in the books either.

The only limb alignment method/tool that I found useful were 'tuning forks'.

They started out as a kickstarter but now you can just buy them: Recurve Tuning Forks™

There's a lot of flannel on the website but the truth is that they are kind of like Beiter alignment gauges but they are much taller, tall enough to introduce a bit of parallax into the alignment process that really helps you judge alignment.

 

[Timid Toad]

Tuning forks rely on the limbs/riser (depending on where you place them) not having any goopy varnish/paint on the edges etc.
Buzz Lightbeer did a very good set up guide on here some years ago.

 

[Timid Toad]

All you need to know about Recurve bow alignment !!! | Archery Interchange

 

[dvd8n]

Tuning forks rely on the limbs/riser (depending on where you place them) not having any goopy varnish/paint on the edges etc.

I'll admit that it could be a problem but it's not one that I've ever had on my high end or budget limbs. But maybe I've been lucky.

 

[wully]

All you need to know about Recurve bow alignment !!! | Archery Interchange

no photos showing for me- but it sounds good.

 

[Shed tuner]

no photos showing for me- but it sounds good.

post #14 quotes the original post, which has the photos.

The looking down the bowstring makes sense, but I'm still amazed no-one has come up with a better measurement tool

 

[Timid Toad]

I've pinged Dave about it - I'm guessing the pics haven't ported from the old site when the upgrade happened, sorry. I hope he can fix it. The photos do help it make a lot more sense!

 

[Stretch]

The truth of the matter is that until 1996 nobody worried about this at all. Sometimes you had a bow that needed a “different“ centre shot to shoot well.(and in some extreme cases interventions involving sandpaper and files). However, most bows shot fine. There were amateur archers throwing down 1350+ FITAs and the WR at 30m was a perfect 360.

If you enjoy the tinker that is great - your solution looks similar to something posted on ArcheryTalk a few months back… along with lots of other methods, some of which were bow dependent or required you to assume a surface that looked flat was flat. Your method looks sound but the depth of the limb butt providing your reference plane is subject to quite a bit of error (and some Nishizawa limbs were bevelled here and some Yamaha limbs were slightly rounded) So even with this level of complexity it is not a one size fits all solution.

If your bow sounds OK and shoots OK then leave it alone. Otherwise the steps provided by Buzz many years ago work. I’ve actually not had a riser that the longrod/Beiter clips method did not work on since 1991 (Economy Hoyt TD4+ with a squint LR bushing). Footnote: except risers with offset long rod bushings like some of the Gillo risers.

What I would say is that it is VERY annoying that manufacturers don’t give a reference point and measuring mechanism on each riser (or even something like the 24xx arrow trick on the old Hoyt Avalon). But then the consumer would see how well (or badly) the products are made - so they don’t.

No criticism intended. Just saying don’t get hung up on this kind of stuff unless you have a reason to think it is a problem (clearance, noise, vibration, poor grouping etc). I’ve seen many archers convinced that their bow alignment/tune is what is holding them back but I can count on one hand when it was actually true.

Stretch

 

[Timid Toad]

All very true...but...limb alignment features allowed manufacturers to make kit less accurately and cheaply and by'eck some do and even with expensive ones there's always a chance of a dud. Plus archery tends to draw the tinkerers and by the time you've got your arrows matched to within a couple of grains knowing how to check and maybe get the best out your hard earned kit is an interesting waste of a weekend or three.

 

[Shed tuner]

Thanks stretch.. yeah agreed.. even just by eye I knew it was out, but the post was more curiosity about a reliable, measurable approach being notably absent. But maybe it's simply not really needed to get the job done...

The bow wasn't shooting very well tbh, and bit noisy, and a bit slow for the poundage, so I figured i'd just go thru a basic tune (both the limbs and the riser are new to me), and fell at the first hurdle. I have another bow that shoots much better, so the difference was pretty obvious.

Now waiting for my shim washers to arrive as I now have 2 one one side (no spares), and nearly corrected it, but one more one will be near perfect and I can cary on with the tune...

 

[tabashir]

Can't remember where I saw the idea now, but when I last set mine, I taped a bit of thread running down the centre of the front, through the sight window, then another bit between the riser bolts at the back also through the sight window. This gave me 2 lines, so line both of them and the string and bingo.
Took all of a few mins to do and removes any of the question marks around bushing mountings and skewed long rods. For future ref, I then drew a sharpie line on the shelf between the lines so that I don't even have to mess with the theads in the future. I swap limbs a fair bit, particularly in Winter when shooting indoor and outdoor, so to be able to swap in a set of limbs and have a quick visual check that things look good makes things a little quicker.
I think I have some pics somewhere, I'll post them later and credit the original person if I can find.

 

[tabashir]

Not sure how to stop the image being rotated by the forum but hopefully it will give you an idea of how it works.

 

[Deleted member 7654]

The catch to this thread is the "(on plane)"...
What plane?
The plane defined by the string at full draw?
There is very little that sits on a common definable and measurable reference plane, and for every plane you care to define there are equally valid ones at some other state, e.g braced, unstrung or full draw.
Del

 

[Timid Toad]

And with a longbow...well waste of time, yes.

Unstrung: no that's daft.
Full draw: maybe
Braced: better
Point arrow leaves string: better.

Throwing spurious questions out there again, Del?

 

[Deleted member 7654]

And with a longbow...well waste of time, yes.

Unstrung: no that's daft.
Full draw: maybe
Braced: better
Point arrow leaves string: better.

Throwing spurious questions out there again, Del?

???
I fail to see how it is spurious, perhaps you could just answer the question?
If the plane (formed by the string) at full draw isn't co-planar with that at your "point arrow leaves string", then during loose the arrow will acquire momentum that isn't on co-planar and thus the alignment won't be correct.
Del

 

[Shed tuner]

Tabashir, I do like that. removes the paralax error problem you get otherwise - thanks...

teal and toad.. yeah.. the midpoint between full draw and braced would probably be perfect, but tricky to measure.. as we all know it's about imparting linear forces to the arrow through it's centre, to reduce any unhelpful velocity components laterally.

 

[Timid Toad]

Tabashir, I do like that. removes the paralax error problem you get otherwise - thanks...

Or you can tape a small mirror ( I have a polished 2" square of stainless steel ) against the top limb immediately above the riser. That way you see two images of your string and gives a much greater impression of distance - which magnifies errors - and is great with low brace height bows.

 

[Shed tuner]

Or you can tape a small mirror ( I have a polished 2" square of stainless steel ) against the top limb immediately above the riser. That way you see two images of your string and gives a much greater impression of distance - which magnifies errors - and is great with low brace height bows.

another good idea... I figure if you line the actual string up with the image of the string, provided the mirror is tru to the limb, that will be a very accurate method. Thanks, I do like this forum

 

[ThomVis]

The catch to this thread is the "(on plane)"...
What plane?
The plane defined by the string at full draw?
There is very little that sits on a common definable and measurable reference plane, and for every plane you care to define there are equally valid ones at some other state, e.g braced, unstrung or full draw.

The recurve riser has a plane defined by the grips pressure point and two limb bolts. You can align the limbs straight from each other (at brace) but have the grip's pressure point a smudge to the left of right.
When you start drawing the risers will straiten out, twisting the limbs slightly. Everything (grip pp, limb bolts, limb tips, string) is on or close to be on plane at full draw.
Imagine the rotational forces at work when you release from the untwisting limbs and the impact on string/nock.

There is a whole discussion going on about this on Archery Talk which also contains this video:

I like the method used by tabashir in post #13 here better than the "measuring off the riser" part in the video.