Tuning forks?

albatross

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My tuning forks arrived this morning. Along with a demand for <> £14.00 payment from the PO before I can have them. £5.87 VAT + £8.00 PO handling charge. I only hope they work!
 


LionOfNarnia

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I'm sure you'll let us all know if it was worth it.

The extra charges for anything from 'murica are a total pain, for sure - I got mugged by them for an engine blueprint, just a poster really, a few months ago. The charges were more than the value of the item, which just seems WRONG to me.
 


albatross

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I am pretty sure my school history book stated that Dick Turpin was dead. Obviously a misprint. Looks like he is still alive and kicking and working for the postal service!

As it happens they were. They showed that I had to put a small shim under one side of the limb pockets. It was a bit of a pain trying to work out what was wrong until I did away with them. I aligned the string through the tiller bolt holes on the rear of the riser. Put the tuning forks on - straight away could see that the string was passing through the tiller bolt holes, but was off to one side on both forks. It had to be that one side of the limb pocket was lower causing the limbs to 'tilt' one sided (or it could be that one side of each limb was slightly thicker - doubtful). It is a carbon Fiberbow riser which are moulded rather than machined.

I will try the same procedure with my Hoyt GMX and see if a machined riser reacts any differently!
 


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albatross

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This morning I carried out the same procedure on my GMX riser. I aligned the string with the tiller bolt holes. I fitted the 'Tuning Forks' and immediately I could see the the string was perfectly aligned with all the riser holes and the tuning forks. So that indicates to me that the Fiberbow riser is not perfectly square in the limb pockets. In fact I inserted a shim of 0.8mm in both pockets to get the correct alignment.

I think the big advantage that 'Tuning Forks' have over Beiter Gauges (which I also have) is the fact that the string alignment is done away from the limb surface and nearer the string itself. This, as in my case, showed-up the riser pocket problem which the Beiter surface mounted gauges cannot.

I suspect that is as good as I could expect for a 'moulded' carbon fibre riser as opposed to an accurately machined metal one. But I still love shooting it!
 


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JohnK

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My personal experience with the tuning forks is that they are extremely useful, but they can be thrown off my minor blemishes on the limb surface itself.

If they seem to show the bow isn't aligned, I run through all the other checks (limb tip alignment, swapping the limbs around, etc.) to determine whether there is actually a twist somewhere. In other words, they can show a false positive result for bad alignment, which is what happened the last time I used them to check my bow.

As for the Fibrebow, I'm afraid I've heard many stories of their limb pockets being poorly aligned. Sorry you've run into the same problem.
 


albatross

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@JohnK.
I found it very difficult to use them straight away (but now I know why). I think the best way to use them is as I did. Align the string with the riser limb bolts and then use the Tuning Forks as a second check. I am a bit surprised at the limb pocket fault especially as my riser is the is the TeXtreme model! Some quality control is lacking somewhere.
 


JohnK

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Not all limb bolts are in the true centre of the riser, or so I hear, but I believe it's a good idea to line up by eye first and then check.

It is a shame to hear that Fibrebow still has this problem. I remember hearing about a number of Fibrebow users who had to have their riser pockets shimmed several years ago. You'd think they'd have it sorted out by now.
 


albatross

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"It is a shame to hear that Fibrebow still has this problem. I remember hearing about a number of Fibrebow users who had to have their riser pockets shimmed several years ago. You'd think they'd have it sorted out by now."

Shame that designer appears not to care about 'bad press' or it cannot be cured! How did other archers find out there was this problem? I will be shooting mine tomorrow, so I will soon see if there is any improvement.
 


JohnK

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I believe Border Archery helped out a few Fibrebow owners who had trouble aligning their Border limbs by doing some work on the pockets. As I recall, they had to stop offering it as a service because it was actually pretty time consuming, and got in the way of actually making bows.

Good luck!
 


Cereleste

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This morning I carried out the same procedure on my GMX riser. I aligned the string with the tiller bolt holes. I fitted the 'Tuning Forks' and immediately I could see the the string was perfectly aligned with all the riser holes and the tuning forks. So that indicates to me that the Fiberbow riser is not perfectly square in the limb pockets. In fact I inserted a shim of 0.8mm in both pockets to get the correct alignment.

I think the big advantage that 'Tuning Forks' have over Beiter Gauges (which I also have) is the fact that the string alignment is done away from the limb surface and nearer the string itself. This, as in my case, showed-up the riser pocket problem which the Beiter surface mounted gauges cannot.

I suspect that is as good as I could expect for a 'moulded' carbon fibre riser as opposed to an accurately machined metal one. But I still love shooting it!
How does the result with the tuning forks compare to what you'd get from balancing arrows at the base of the limbs (the sticky limb alignment post)? I'm curious as my fiberbow 6.3 (bought 2012) shows up straight using that method but always "feels" like the riser is pointing a different direction to the limbs.
Though I suppose the real question would be: now that it's aligned "properly", other than a small horizontal sight adjustment, is there any difference to the sound/tune/consistency of the bow?
 


Timid Toad

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That's an interesting point, as I believe one person's fiberbow has a grip that off from the limb's alignment. As an aside, my fiberbow S4 has the most amazing eccentric wobble. No tuning forks needed to identify it. It's quite fascinating to watch.
 


albatross

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Hello Cereleste. I shot the bow today and it seems different! I only adjusted the limbs on Friday and indoors so I only had the riser with a short extension to mount it with during my 'fiddling'. Today at the range I got a not so nice surprise. The thing is. If the limbs are now correct, then the longrod (Fiberbow S3) is way off centre (pointing <> 10 deg to the left of the arrow tip) when viewing from the rear and aligning the string down the centre of the riser! I will have to so some checking with an engineers square to see if any of the stabs fittings are out of square. I have never used the 'arrows on the limbs method' as I thought it would only show limb twist. I would have to find a method of mounting one vertically on the riser, possibly against the flat inner face above the arrow rest and see if there was an angle of 90 deg with an arrow mounted on each limb. Up to Friday I never thought there could be anything amiss. If I cannot find a problem with any of the mounting faces then it might indicate that the longrod mounting thread in the riser is at fault. If that is what I find I will be sending a comment to the manufacturer in Italy!

Due to the limb alignment my centreshot and sight had to be adjusted today, but I guessed that would be the case. One surprising thing is my sight mark has definitely changed. Shooting 70M my previous mark was just about 80 on the scale. Using it today I put the first 6 arrows over the boss and in the grass. I had to reset it to 70 to bring the arrows down to the gold height (not that I managed to hit very often)! So perhaps the re-alignment has improved performance!

I wonder why I prefer shooting my longbow at times!
 


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albatross

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Well today I spent a fruitful morning checking out this riser and bits. It is NOT the riser - neither is it the limbs! It is not the 'Tuning Forks' either. The problem lies in viewing the string and the tuning fork alignment marks. If you use the method of viewing described in the instructions it is very easy to get the sting to show misaligned. To use the manufacturers method have have to be EXACTLY OVER the string and I mean EXACTLY. Try doing that and rotating your head whilst standing - unless your head is pressing against a solid surface. Failure to do this will give a false image of the string location, as I found.

To start this morning I set the bow up mounted so the riser was horizontal using a short extension in a 'workmate'. Without disturbing anything I placed two plain shafts (no flights or points) on the limbs at the exit of the pockets. Immediately I could see the excessive tilt away from horizontal caused by the shims I put in the pockets. I removed the shims and the arrows aligned in the horizontal plane. But the tuning forks showed the string was not aligned with the centre of the riser! So what is going-on?

When I realised what the problem was, I had to find an alternative viewing method. I found that standing at one end of the bow and viewing along the string I could see the string location in the 'upper' part of the nearest tuning fork and by adjusting my viewpoint using only my eyes I was able to see the lower alignment mark and any string misalignment (NO Head movement required) on the other tuning fork. I did the same with the opposite limb. I checked the results with my Beiter gauges - all good.

So. They are a good idea, but you have to be VERY careful about viewing them. Will they end up in my archery bits cupboard gathering dust? Hopefully not. I will use them to help other club members all of whom are pleasure archers like me.
 


Rik

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I started using my phone camera for checking alignment, when I became aware that I had variation issues due to head movement while switching my viewpoint from one reference to another. Significant? Probably not. But it plays hell with your confidence in assessing it.
 


Timid Toad

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I have a small mirror with a line down the centre, that I tape flat to the limb hard up against the riser. It makes it easier to eyeball.
 


Cereleste

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Hello Albatross,
It's good the riser didn't turn out to be misaligned - though now there's the mystery of about a centimeter of difference to the 70m mark. If nothing else could have changed between your previous mark and when you added the shims, then I'm puzzled as to how "twisting" the riser by adding the shims would increase the efficiency, especially by that much. Looking at my old sight marks, I got about a 1cm increase at 70m from adding about 5lbs draw weight with my setup. I suppose the torsional resistance of the limbs means that even if you keep the draw length constant and somehow prevented the riser from twisting in your hand, pulling the string in a direction out of the plane of the limbs would require considerable extra force which should in turn give a faster arrow. Though I'd also expect the string to move back into the plane of the limbs early on in its path, which would impart more sideways motion to the nock end of the arrow.
 


albatross

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I have no idea. I thought that the 'limb twist' may have made them a bit stiffer. I checked my tiller - it had increased from 6mm to 8mm (no tiller bolt adjustments made)! However. I sent a copy of my testing to the developer. He sent me a very nice email reply and I believe he is going to 'edit' his manual. He is also sending me another pair of tuning forks in appreciation. I wonder if this has been a bit of a problem all along?

OOPs: I just double checked my settings it should have bee 75 > 70 (not 80 as I mistakenly wrote).

EDIT: I just received this reply.

"Thanks, much appreciated.

Just to touch on some of the points from the email and the thread:

Your case is the first time difficulty has been brought up, and it's very much appreciated. My goal is to make Tuning Forks as user-friendly as possible (alignment/tuning is hard enough), but the process is dependent on the user. Abilities differ. Some eye-ball it, some use a camera.

Often when I'm using them, holding the bow by the riser at arm's length down by my waist is usually good enough (bow is steady, easy enough to shift eye gaze). If I've had too many coffees, I might rest the riser on a table. :)

I've seen people forget to keep one eye closed, which can cause issues. It's a simple problem, but an easy fix.

I'll be evaluating your method to see if there's a simplification that I could incorporate into the directions to make it easier for users. I always intended this to be an evolving process, which is why I put a version number and a change list in the manual.

At the very least, you can always do a quick sanity-check to see how your alignment is doing by looking at only one Tuning Fork at a time (move head/eye position so that the string covers the bottom indicator, it should be in line with the top indicator, if it's not there's an issue somewhere). The two Forks are needed for cross-alignment/twist check (adjusting alignment to only one Tuning Fork at a time can cause a circular adjustment loop or each could be in alignment individually but not together).

As for the sight mark/tiller change: there could be a number of factors at play here. The twist of the limbs changes the geometry of the limb/energy stored (tips further out, more potential energy needed to bend and twist limb), the bottom limb could be arriving at brace earlier than the top (nock arrive lower requiring tiller/nock change)... if you shim there could be a slight tiller change from the original setting (though not by much). I think you'd have to chrono the arrows pre and post to see if it's due to increased energy or a change in bow tune. I suspect it wouldn't be due to a faster arrow but I'd be curious at the results.

Again, thanks for your feedback and your help with the account setup.

(Feel free to post the above in the forum if you'd like)

Keith"
 


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albatross

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Dick Turpin is alive and well!

I just got an email from UPS stating my tuning forks will be delivered in the next couple of days. Great I thought. Then a warning notice came up 'Import Duties are payable in this item'!

I went to the relevant page. They want £23.00 import duties! This is for an item that has been identified of FREE of charge!

This is more than I paid when I purchased the first pair. I tried to contact UPS and query the payment - impossible to get to anyone except their 'on line' Q&A computer thingy, which does not include my problem.

I decided I would not pay this ransom and wanted to cancel the delivery - no chance - it can only be done by the sender.

So I have messaged the sender and told them about this fiasco, I have requested them to cancel the delivery.

If it turns up I will refuse to accept it. Someone is taking the proverbial p***.
 


dvd8n

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Yes, I've been through this as well, although usually with the Post Office.

The really annoying thing is that there doesn't seem to be any appeals process; its basically 'pay what we demand or you don't get your stuff'.

One particularly annoying case was when the sender put the insurance value ($1000 IIRC) on the customs form instead of the true value ($10, I think). There was nothing that I could do so I told them to keep it and ordered another one, telling the vendor to be more careful filling out the forms.
 


albatross

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Some companies are great to deal with. I emailed Early Human and got an immediate reply.

He was amazed I was being charged. He sent me the payment amount electronically straight away.

How's That for customer care!
 


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