True Centre of the Bow

AndrewK

New member
Just wondering what peoples thoughts were on this.

One of the surprises which I got this Christmas was Simon Needham?s book and DVD. Seen as I was about to rebuild a load of new indoor arrows I thought I would go about making sure the bow was set up correctly so I could do a bit of tuning at the club this week.

Going through Simon?s 12 point process of setting up the bow, he talks about finding the true centre of the riser, using the long rod as a guide. Doing this I have noticed that my long rod is off to the left of true centre to the riser, and there for I have set everything up to that setting. Therefore if you look down the true centre of the bow now, it is all lined up slightly to the right of the end of long rod.

I was just wondering how many people set their bow up this way or do people just take the long rod position to be true centre of the bow, and if anyone has set up their bow this way, did they notice any improvements in their groups.
 

geoffretired

Supporter
Supporter
Buzz wrote an excellent piece about getting your bow limbs etc aligned. I would use that to get the limbs set up first. Then I would put tape across the limbs near the riser ,so I can mark the centre of each limb;on the tape, not the actual limb surface.Then mark about 2mm either side of that centre line to give marks 4mm apart. Stand behind the bow and position yourself so the string appears between the two lines on both limbs.There will then be some feature of the riser that you will notice is aligned with the string line, so, on centre.It might require another piece of tape with two lines drawn on.The tape can be moved across the riser( and re positioned) till the marks are each side of the string line, when the limb markers also straddle that string line.
I feel that the real issue is where the arrow is positioned after the tuning/setting up is finished and they are flying true. Once found, the simplest way to note it, in case you need to re-set after some changes, is by measuring how far out the button tip is from the sight window of the bow. I used a depth gauge made from a thin bolt with two nuts that could be locked in place, one against the other. Adjust till the end of the bolt is on the sight window of the riser, while the tip of the button just contacts the under side of the lower nut.
 
Hi Andrew
The hole for the long rod may well be on the centreline of the riser, but who is to say that the axis of the hole is not at a slight angle to the plane of the riser? If it is at an angle but you presume that it is an accurate datum, then you will set the bow up inaccurately. I would suggest that the most accurate datum face would be that on to which the sight is screwed. Project that face and check if the axis of the longrod is parallel to it. If it is, then carry on and use the long rod as the datum; if not use the sight mounting face on some sort of surface plate or straight edge. This is not as easy but it is worth doing this check before you do lots of changes to the bow.
Regards,
Dave
 

Whitehart

Well-known member
Hi Andrew
The hole for the long rod may well be on the centreline of the riser, but who is to say that the axis of the hole is not at a slight angle to the plane of the riser? If it is at an angle but you presume that it is an accurate datum, then you will set the bow up inaccurately. I would suggest that the most accurate datum face would be that on to which the sight is screwed. Project that face and check if the axis of the longrod is parallel to it. If it is, then carry on and use the long rod as the datum; if not use the sight mounting face on some sort of surface plate or straight edge. This is not as easy but it is worth doing this check before you do lots of changes to the bow.

Dave
Not all sight block fixings are straight either there are very few if any points on a riser that you can reliably use.

Stick to what Buzz says and it will save you a lot of time otherwise you would end up with a straight bow with the limb tips out of line.
Regards,
 

Desbob

New member
Dont trust the long rod. if the bushing that the long rod sits in is fitted so that the rod is in the true plane of the bow and not off to either side then you are fortunate.

The method that I use to get the limbs centered as well as lined up with each other is as follows;

With limbs marked or limb gauges fitted it is possible to get the string 'lined up' by adjusting the limbs left and right but this does not ensure they are centered, they may be both off to the left or right by the same amount

So first get the string central as follows;

Identify a part of the riser that has parallel flat sides somewhere just under the handle maybe, hold two parallel arrows (not ace's or x10's) onto the flat sides of the riser extending back past the string and see if the string is the same distance from each arrow. If it is nearer one arrow then the limbs need to be adjusted towards the other arrow to take the string into the centre.

then line the limbs up;

Look at the bow from the front (the target side), take a line between the two limb bolts (you can do this 'by eye' or tape string to the riser between the centers) and adjust the windage on the sight so that this line, the sight pin and the bowstring are all in line with each other.

Now go back to the rear (the archer side) and line the string up with the pin then see where the string is positioned in relation to the limb gauges, you will be able to see which limb needs to be moved which way to get them lined up straight.

Do another check to make sure string is in middle of arrows

Now the limbs are lined up and the string is in the center of the bow as it should be, remember to put your windage back where it's meant to be.
 

Darryl

New member
Buzz wrote an excellent piece about getting your bow limbs etc aligned. I would use that to get the limbs set up first. Then I would put tape across the limbs near the riser ,so I can mark the centre of each limb;on the tape, not the actual limb surface.Then mark about 2mm either side of that centre line to give marks 4mm apart. Stand behind the bow and position yourself so the string appears between the two lines on both limbs.There will then be some feature of the riser that you will notice is aligned with the string line, so, on centre.It might require another piece of tape with two lines drawn on.The tape can be moved across the riser( and re positioned) till the marks are each side of the string line, when the limb markers also straddle that string line.
I feel that the real issue is where the arrow is positioned after the tuning/setting up is finished and they are flying true. Once found, the simplest way to note it, in case you need to re-set after some changes, is by measuring how far out the button tip is from the sight window of the bow. I used a depth gauge made from a thin bolt with two nuts that could be locked in place, one against the other. Adjust till the end of the bolt is on the sight window of the riser, while the tip of the button just contacts the under side of the lower nut.
Just a tip, don't use tape on the limbs, or if you decide to make sure it has low adhesion such as insulation tape. Tapes such as masking tape can remove lacquer as I had some ZR330s that had some lacquer that came off. It wasn't until after I had them replaced under warranty that I recalled that I had put some masking tape on them with a center line.
 

geoffretired

Supporter
Supporter
That is interesting. Masking tape would have been my first choice, as I've used it several times with no probs. I guess it depends on the lacquer, but not worth taking risks.
 

AndrewK

New member
The method that I use to get the limbs centered as well as lined up with each other is as follows;

With limbs marked or limb gauges fitted it is possible to get the string 'lined up' by adjusting the limbs left and right but this does not ensure they are centered, they may be both off to the left or right by the same amount

So first get the string central as follows;

Identify a part of the riser that has parallel flat sides somewhere just under the handle maybe, hold two parallel arrows (not ace's or x10's) onto the flat sides of the riser extending back past the string and see if the string is the same distance from each arrow. If it is nearer one arrow then the limbs need to be adjusted towards the other arrow to take the string into the centre.

then line the limbs up;

Look at the bow from the front (the target side), take a line between the two limb bolts (you can do this 'by eye' or tape string to the riser between the centers) and adjust the windage on the sight so that this line, the sight pin and the bowstring are all in line with each other.

Now go back to the rear (the archer side) and line the string up with the pin then see where the string is positioned in relation to the limb gauges, you will be able to see which limb needs to be moved which way to get them lined up straight.

Do another check to make sure string is in middle of arrows

Now the limbs are lined up and the string is in the center of the bow as it should be, remember to put your windage back where it's meant to be.
Desbob, this is very similar to the way Simon Needham does it, however he used the arrow shafts the other way to see where the long rod sits, if the long rod looks like it sits in the middle of the two arrow shafts he uses the centre of the long rod as centre and if it sits to the left, or right, he uses that point as centre, and that is the way I have set the bow up.
 

Cruise

New member
Desbob, this is very similar to the way Simon Needham does it, however he used the arrow shafts the other way to see where the long rod sits, if the long rod looks like it sits in the middle of the two arrow shafts he uses the centre of the long rod as centre and if it sits to the left, or right, he uses that point as centre, and that is the way I have set the bow up.
Same here.
I followed Simon's tips and use both an arrow on the flat face of the sight window as well as a long rod.

First time I did it, I was surprised to find the long rod 2-3 inches off to the left. That's when I realised that you can set up using the Beiter limb guides and still be way off the true centre of the bow. Till then I had been fine tuning the limb and string alignment using Beiter limb guides after having watched my local archery shop do a tune up for me.


I can now use the long rod as a rough guide when raising the bow to start drawing.
There are also little things like, more arrow clearance, easier to line up string next to sight pin and bow falling away more smoothly after release.
String tends to touch my arm guard less after the release too.

Yes, the long rod hole could be out of alignment but it's only one of the reference point Simon uses. I now always use a long rod as a guide AS WELL AS the Beiter limb guides when helping beginners check their bow set-up. :)
 

Desbob

New member
Desbob, this is very similar to the way Simon Needham does it, however he used the arrow shafts the other way to see where the long rod sits, if the long rod looks like it sits in the middle of the two arrow shafts he uses the centre of the long rod as centre and if it sits to the left, or right, he uses that point as centre, and that is the way I have set the bow up.
Aye, makes perfect sense. thanks for that
 
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