OFFSET LONGROD hrmmm

[jojo]

Heres an interesting question to the forum which has puzzled me for years.

When setting up a bow and your setting up your plunger (button) or your launcher (compound) common advice is that you put the arrow on the string then the plunger is screwed through enough to push the arrow off centre by a milimeter or thereabouts, now the centre of the bow is effectively the centre of the limb bolts top and bottom. Now here comes the crunch the advice Ive always been given is NEVER to align your arrow with the long rod and reason for that is that the longrod is never set up in true straightness out the front of the bow and is effectlely offset, this means that the bushing inside the bow is set off to one side, can anyone explain to me why the manufacturers do this and to what end.

[geoffretired]

I think that is a slight misinterpretation of the truth,scotstoxo. I think somewhere along the line, the Chinese whispers got in.
I believe the truth is that to drill and tap a hole in a bushing, to then fit the bushing into a riser and expect it all to line up on dead centre is almost impossible. Putting the long rod in, accentuates the amount of error in the work.Manufacturers don't deliberately get it off to one side, they just make a reasonably good attempt to be right and if not, they leave it. Sometimes the error is in the longrod so using it as a guide may not be the best way.
Setting centre shot by the long rod is not right or wrong it is a matter of where you start and what you consider to be true centre and dead ahead. Finding true centre or dead ahead is not as easy as it seems, if it was, there would not be so many different ideas about it. Some start by what looks right. Some start by measuring from specific places on the bow. Where you start is not too important in my opinion, so long as it is somewhere close. Where you finish is more important as that will be the set up you use for shooting. Some even say that the tuning does not need to be so close to perfect anyway.
I hope this makes sense and helps you with the puzzle.
All the best
Geoff

[jojo]

Geof your right in that its what the end result is and how you get there. However Im very sorry, but for example theres Hoyt reputed to have spent over ten million dollers in the past ten years into research and design and technology, and yet you say that no bow can be perfect and theres bound to be a flaw and if there is its gonna be there on the bushing, I thought CNC machined risers were cut out but robot and the holes too. No Im very sorry but Ive been shooting nine years and Ive never seen or heard of a bow which was perfectly drilled. So there must be a logical explanation for it.

[simon m]

Even if it was perfectely drilled (which a cnc machined riser should be,well i say perfect i mean so close you wouldn't notice)

Who can guarantee the longrod thread isn't slightely off?.

After all the longrod has an insert which has a thread on it....which could be off true....

[jojo]

your very right Simon but then most of the big manufactures of bow or longrods etc would have checked that surely, check out your own bow and see what you think. Ive had a number of different compound bows inthe past with many different longrods and all of them were offset.

[simon m]

I would guess they manufacture to "within tolerances" + or - half a degree or whatever...

My bet is they all have a special department who make the sponsorship kit for the top archers....to within tighter tolerances.

[joetapley]

Position of the long rod bushing is going to depend to some extent on riser design. With an expensive (good) riser and long rod you would expect the rod the be at least parallel to the bow plane and close to it. Perfection ... nobody can afford . Bear in mind that if the cog of the stabiliser system is not in the plane of the bow then torque will be generated by the bow recoil so if the rod is a long way out then some action will be required. (This happened to me once where the two threads of a V bar bolt were not square - a lot of head scratching went on until the penny dropped)

The alignment IMO anyway should be good enough to use the long rod for limb alignment and for checking any riser twist when drawing the bow (or checking bow hand position re riser twist, other side of the coin). As regards centre shot the arrow should be almost parallel to the riser (within its radius anyway with a typical rod diameter. "Almost" is however not a good gauge. Would use the string to set up centreshot (although you can use the rod as a guide to the alignment of the string).

[geoffretired]

I'm not too clear what you are saying here,scotstoxo.
Reading your last sentence first, it seems we agree that no bow has a perfectly fitting long rod. I think you are saying that this points to the makers doing it for a reason. I'm not sure that they would do that and never tell the archers what the reasons are.
I am not saying they do it wrong on purpose.
I am not saying they don't try to get it right.
Some will be pretty close to perfect, but not all.
I know that to get it dead right is not as easy as it sounds. Put any threaded rod into a tapped hole, and if the rod is long enough there will be an error show up.Threads do not fit that tightly together for a start. Put a log rod part way into the hole and it can shake about. When it is tightened down, the faces that meet, contribute to the error. If the faces are not square to the length of the rod or the hole,the rod gets pushed off centre.
I do not doubt the millions spent on research and development but I would expect a large proportion of that goes into designing new risers, new cams etc etc. Getting the long rod bushing perfectly in line, when they don't know whose long rod will be fitted into it, would seem wastful to me. Many bows are designed for the bowhunters not the target shooters. They use very short front rods which means the errors hardly show at all.
In a similar way, very few bows have limbs that are perfectly in line with the riser. This is not so obvious as the limb alignment is not so easy to check.
Interesting idea though.

[wingate_52]

Manufacturing tolerances being what they are. A few poorly made products will taint the reputation of a good manufacturer. They do seem keen to replace faulty products. Some manufacturers produce 2nd rate goods, poor threads, bad tolerance, look at some of the cheaper sights on the market, which shake themselves loose every end. Does the archery industry have better products than the motor or computer industries?

[TJ Mason]

A simple carbon long rod is good enough to align with, in my experience. There might be a theoretical reason for not aligning against the long rod, but in practice it's been as good as Beiter blocks on every recurve I've used.

Multi-rods such as the Beiter are not suitable for aligning against, since they allow some movement of the rods and can be pushed a fair distance out of line.