Thread: Cam Timing

I have been assuming my Cam timing was 'about right' from the factory.

I came to understand that if I adjusted the weight the bow pulled (poundage, lbs), that the bow should really be tuned again, or at least checked in every aspect.

So as I'd adjusted it down from 62 lbs (max) to about 45 lbs and then yesterday to 50 lbs. I embarked on the tuning process again.

1/. arrow at 90° to string
2/. centre shot checked

3/. Cam timing, this is interesting.

I'd made a draw board, 2x2, pulleys, rope etc. and this made the repeated drawing of the bow, easy.

What I found was that the top cam was hitting the string stop, in advance of the bottom cam. Watching all the youTubery, this meant that I should put turns onto the cable end on the top cam (tighten). Using a portable bow press from eBay.

Then I was getting a large click from both cams when the bow was drawn back by human (me). On examination this was because the cams were at a 3 or 4 degree angle from the cables. I had to then, go and adjust the yoke ends of the cables, to swing the cams back, to line them up with the cables.

Then I thought of something that made a lot of sense to me and is not really portrayed on the youTubery.

If I am measuring the cam timing, when the bow is being held at the pivot point of the hand grip (i.e. where the hand grip, rolls on the thumb/palm intersection) and the string is pulled at the nock point, the string is not being pulled off both cams identically, it is pulling more off the bottom. So the cams are being synced with slightly different amounts of string when the nock point is released. See 1st image.





Then I figured that the bow should be held at the berger hole, when the cams are being synced, so I put a small rope through the berger hole and synced the cams from that stand point, where the string is being pulled off the cams in equal amounts.

When the arrow is released, the fact that my hand is on the hand grip is of no importance once the arrow starts moving, the bow should be figuratively 'sitting still in space' for that briefest of moments, whilst the arrow leaves. Then it is in the interests of accuracy, that the arrow is centred and at right angles is the the string and the bow should pull the same amounts of string from top and bottom to do this.

See 2nd image.






again this stuff is new knowledge to me, I post what I've learned, out of interest.

Maybe it's helpful, to another newbie like me

I can't seem to edit this post, the images are transposed, the green line one should be at the bottom and the red lined one should be 1st

Very interesting. I’m too chicken to play with anything on my bow without help from the bow shop. Seems like you’ve got it worked out tho

I hope I've got some of it worked out ! Jeez there's so much to consider, I guess that's where experience comes into it.

Whilst I have learnt a lot from the uTubery, I really have to watch 10 or more videos on the same point, to get an idea of who knows what they're talking about, and who is, "I just bought a bow, look at this..."

The biggest take home idea, I got from this above is that the bow, once the arrow is released, should be set up to be symmetrical in every way possible. And that nothing should apply pressure to the bow's axes (axis plural).

That is why the grip, really, is not a strong firm grip at all, the bow should, roll slightly on the thumb/palm intersection as the arrow is released with the fingers being relaxed and not exerting any force on the handle which is what the uTubers call "torque" . Or as I understand it, "twisting". 'mericans have a different view of English.

And this is also where the stabilisers come into play, the bow should be "balanced", i.e. not top heavy, or side to side leaning, from the balance point, as discussed above, when the arrow is released, the symmetry should reference, not the handle, but the berger hole.

And why is it called the "Berger" hole? from Archerytalk.com talking about recurve bows -

"Berger was a brand name for a cushion plunger and that hole is actually called the cushion plunger hole but it seems that most everyone calls it the Berger button hole. It's sort of like calling an adjustable wrench a Cresent wrench though Cresent was the brand name, not the type of wrench."

and the "Cushion Plunger" was at the centre of the bow and the arrow... or shoulda been.

Hi there MarkN,

Good to see a thread like this, but a word of advice, get some help before messing with cams too much. A good draw board is your most powerful tuning tool so good that you already have one.

My experience comes from target shooting, not hunting, but the same principles apply.

NZ has/had a couple of really good compound archers (Shaun Teasdale, Steve Clifton, Linda Lainchbury etc.) so you should have a couple of clubs that have knowledgeable people, worth joining.

Important to know what type of cam system you have, Single cam (old Matthews) Cam+ 1/2 (older Hoyt), Hybrid (older PSE) or Binary (most modern hunting bows).

Judging by the pictures it looks like a Binary cam bow, where both cams are slaved together and draw length is adjusted by moving the modules/stops on the cam.

Unlike the older cam types which offered great adjustable feel through timing but ultimately slower speeds, the binary cams are most efficient when timed according to manufacturer's recommendations.

Check online for a user manual and look up cam timing and tune charts. These are crucial as they have the bow specs as they left the factory (or should have). Taking the bow far out of spec usually ruins performance.

Be very careful with adjusting cam lean. Some systems are 'adjustable' but this also means you can inadvertently take them past the limit. Look up 'compound bow derail' if you have not already.

Nock travel is an often debated subject which is worth discussing but not worth trying to adjust, at least not now.

I would not worry too much about the equipment for now. Get it 'shootable' then work on your technique. As that improves then you can adjust the equipment to suit.

Archery is about consistency, and keeping your form/technique and equipment consistent with each other is part of the puzzle.

Best of luck.

Originally Posted by caberslash

Hi there MarkN,

Good to see a thread like this, but a word of advice, get some help before messing with cams too much. A good draw board is your most powerful tuning tool so good that you already have one.

My experience comes from target shooting, not hunting, but the same principles apply.

NZ has/had a couple of really good compound archers (Shaun Teasdale, Steve Clifton, Linda Lainchbury etc.) so you should have a couple of clubs that have knowledgeable people, worth joining.

Important to know what type of cam system you have, Single cam (old Matthews) Cam+ 1/2 (older Hoyt), Hybrid (older PSE) or Binary (most modern hunting bows).

Judging by the pictures it looks like a Binary cam bow, where both cams are slaved together and draw length is adjusted by moving the modules/stops on the cam.

Thanks for your comments, invaluable to a newbie like me.

The photos in this thread are not my bow, but sourced from the web for illustration. But my bow does have the 'both cams are slaved together and draw length is adjusted by moving the modules/stops on the cam'

Unlike the older cam types which offered great adjustable feel through timing but ultimately slower speeds, the binary cams are most efficient when timed according to manufacturer's recommendations.

And this is my (sad) problem, the bow I ordered and the bow I got, are slightly different and the only specs I could find, are on the listing on eBay from the Chinese Seller. So I don't know what the manufacturer's specs are supposed to be.

I am happy to progress with this bow, I am embarking down the path of understanding every little thing, about this bow to get it tuned to it's best configuration, and that will only accomplished by hours of time and trial.

Well I wanted another hobby

Check online for a user manual and look up cam timing and tune charts. These are crucial as they have the bow specs as they left the factory (or should have). Taking the bow far out of spec usually ruins performance.

Be very careful with adjusting cam lean. Some systems are 'adjustable' but this also means you can inadvertently take them past the limit. Look up 'compound bow derail' if you have not already.

As I noted, no manual to be found, but no worries, I've worked out how to do the measurements and I can see when the control cables are lined up or not lined up so I can avoid derail.

Nock travel is an often debated subject which is worth discussing but not worth trying to adjust, at least not now.

I would not worry too much about the equipment for now. Get it 'shootable' then work on your technique. As that improves then you can adjust the equipment to suit.

Archery is about consistency, and keeping your form/technique and equipment consistent with each other is part of the puzzle.

Best of luck.

Thanks again for your comments, I'm nearly at a stage where I can work on sighting in properly.

Only a basic sighting in of the top pin done at the moment, I want to get the cams timed as well as I'm able to, before I move on, once the cams are timed to my liking, the sighting and grouping are next.

Cheers

My Bow

note: despite the angle of the photo, the top and bottom cams and modules are identical in size and design

Originally Posted by caberslash

Hi there MarkN,

I would not worry too much about the equipment for now. Get it 'shootable' then work on your technique. As that improves then you can adjust the equipment to suit.

Archery is about consistency, and keeping your form/technique and equipment consistent with each other is part of the puzzle.

Best of luck.

I personally think that those couple of paragraphs are the most important and critical aspects of this thread.
As long as your Bow / Arrow combination is within cooee of a tune, you the shooter are the biggest handicap.
After a few months and many arrows you will know if you have reached the accuracy limit of your current setup .
I don’t believe I’ve maxed out my Bows capabilities yet and it’s not perfectly tuned .
That being said I think Cam timing is an important aspect of getting within the “cooee “ of a tune .
I’m interested to see what you come up with .

Yep and I just spent another happy couple of hours, playing with the cams and I'm happy that she's as symmetrical as she's going to get, arrow at right angles to string centre shot OK and cams hitting the cables almost perfectly, no lean.

Now I have to wait for lvl 2 to go down to my little range and paper tune and sight in.

So the bow is at 50lbs now and I'll leave it there until I'm proficient. Or until I want to do this all again