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2015 LUNOCET PRO

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I agree that there should be no lateral movement.

The "stops" / range-of-motion limiters should never be reached. I don't know that it's even possible to reach them with a spring in place.
 

Thanks everyone sharing some tips. I checked all the bolts, and audible 'click' vanished. However, you can still see and feel the treshold followed by jerky movement when bending the spring. More testing required!

 
Is that a mechanical deadzone (correct word?) I'm seeing? A space where there is movement unopposed by the rubber spring in either direction?
 
Thanks for the video, finsailor. easy to see what you are talking about.

Given how sensitive these kinds of foil fins (Lunocet and Dol-fin) are to uneven kicks, the side to side movement is very likely to make the fin unstable under high levels of thrust, especially if it gets worse. Its going to want to tilt one way or the other in what will be hard to anticipate ways. From experience, if the fin tilts when it is stroked, it plays heck with power delivery.

Are you sure all the components in the pedunkle assembly are assembled correctly and tight?
 
There's should not be a "deadzone", as I've used mine longer than most out there and it's still real tight.
 
By examining my Luno, I can not find any components loose, @cdavis. Any suggestions what to look for?

After third workout (after that video), I can still feel "deadzone" while kicking. I think also that fin is quite sensitive to errors in technique . If I do not do kick perfectly, it feels off-balance, just as you guys speculated. After one not-so-perfect kick which feels off-balance, it take two to adjust course back to straight .

The positive side is that it's good for training ?

However, it bugs me to think that it is either faulty piece or general quality of these Lunos is not top-notch as marketed. Regardless of that, I'll keep training, there is so much to learn, even with this fin.
 
finSailor, I think in this case a dissection may be in order. I have found that my 15 Lunocet is quite maneuverable, yet never unstable or hard to steer-except for twice; once a shoe was coming loose, another time I forgot to tighten a fluke (as in, it was really loose). The result both times was poor stability. I am wondering if you have cracked a bushing inside and this is what is causing your issue. There is a two-part bushing around the pivot points, plus the bushings visible behind the c-clips. If any of these are cracked it could explain your issue, at least in theory. It isn't hard to take apart; I've taken mine apart a couple times already just to familiarize myself with the improvements made in this model.
 
Reactions: Chipswim
Hmmmmmm..... Two guys same set up? Three with AA I guess. One with issues, two without. Don't think FinSailor being new to the game is the issue..... Unless it's in little set up details the others routinely avoid.

Watching his close up videos repeatedly there is some unresisted movement in the center position that needs to go away.

A question for you FinSailor. If you deflect yours just slightly does it instantly return to center from either direction when released? That's a must! It occurs at the extremity of every stroke. Not returning automatically = wasted swimming motion and unresisted body movement. That in turn would lead to directional weirdness and suboptimal swimming experiences. It can't be real bad or you'd not be swimming as well as you've described.... It's a detail that's off a bit I think.

The video looks like there is a little slack in the dead center. That has to go away for you to truely experience you fin's capabilities.

The set up needs to be what I call "preloaded" so it's under a little resistance even at rest. That could be a small variation in assembly or parts. It is conceivable that adding another pin anywhere could do it. If not get creative. Don't let the spring be at rest even when centered!

I haven't experienced this new set up myself but think you shouldn't have too much trouble getting it right..... Which is tight! It doesn't have to be a lot of resistance in the center just enough to return on its own. The spring provides progressively greater resistance the more it is deflected which is ideal.
 
Good diagnosis Doc! Could be a bushing...

It could have been cracked when cut then failed under first use. I've never witnessed ANY wear in those nylon bushings after hundreds of hours of use / abuse.
 
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Dissect.

Re: instability, it isn't an issue with this model, so could be a bushing, or just a first-time-using-a-monofin type of thing.

Are you also able to post a video of your technique and the instability you mention?
 
I can't add any more at this point - would like to see the unit dissected as well as video of your technique if possible. Inspect the vertebrae pieces carefully for any cracks. This part is delrin and a crack may be hard to find. The vertebrae are the pieces which have both axles running through them.
 

Is it also worth, as part of the dissection, looking closely at the profile of the holes in the rubber spring:



to check for any signs of distortion. I seem to recall that this was a contributing factor to the dead-spot behaviour experienced with
the 2014 Pro?

Am I right in saying that the three on the left are for the stiffness pins and the other three are associated with the pivot points and should therefore be examined for distortion?


Regards

Philip
 
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Reactions: Chipswim
A small update. An autopsy has been performed and the patient is alive (re-assembled). If possible, symptoms got worse after this operation. I'll edit & upload videos later today. At least I found something..
 
It seems to point to either a manufacturing inconsistency or an assemblage problem, neurodoc from what I've gathered uses his almost all the time so any fundamental design flaw really should've shown up in his as well. I was thinking that being a bifinner with little to no experience at monofinning that perhaps your expectations with how you'd swim with it might be a little too high, but your last post makes me think there is a flaw with your particular fin.
 

Oh, guys. I'm first to admit I'm novice what comes to monofins. If you say the fin is working normally, I'd be very happy and go back to pool again...which I'll do anyway Do not get me wrong, I'm super happy to have my Luno. Try to take it from me, and I'll show you why Finns managed to prevent Russian invasion - twice - in WWII.

That's what I tried to say with my former post (Nirvana nevermind picture): look at the bigger picture, there is a dolphin! And I'm the baby in the middle

On the other hand, I'm some times quite a perfectionist, which is exactly why I like yo study any gear down to the details..
 
Reactions: neurodoc
Nice explanation, finSailor! Attention to detail is a good thing in this case. It's hard sometimes when there isn't anyone else locally to compare with-something I deal with everyday. The nearest other Lunocet to mine is probably Ted's shop in Georgia, a few hundred miles away. The slack that occurred in previous Lunocets was due to spring damage and oval/elongation of the pivot pin hole. This never resulted in clicking, however, just some deadzone in the middle. The '15 has those forces spread out over two pivots, effectively halving the forces on each hole so this is not likely for both reasons. Also, previous versions had the pivot run directly through the spring rubber; now there is a bushing there to prevent wear of the spring. A damaged bushing at a pivot, or the outer bushings for the peduncle pivot, is something that is always possible; now that you know how to dismantle the fin and reassemble it if the clicking gets worse take it apart again and study those bushings. As this is one of the few parts that Chipswim has not broken, it's unlikely to be a design flaw but could have been damaged some other way. He is our resident destructive tester and hacker. Think big, fast swimmer. If you're not sure what's wrong, and you're swimming in a pool, just keep using it and if something is wrong it will declare itself. Have fun, and post up some videos when you can. The group can offer a great deal of experience on swim technique.
 
Hmmmmmm..,.... If it got worse that could mean you had your hands on the variable effecting performance and just went the wrong way with it? Is it loose or looser in the center position? If so it HAS to be tight! NO side to side wobbling either!

You are correct in expecting your Luno to make you instantly studly in the water... Then even better with time. That is what it is made to do!

Perhaps you could leave it outside for a few months to freeze isolated with no supplies in your dark arctic sub zero winter forest..... Then drop it through thin ice of your lakes for swimming next spring when the Sun returns? Like you say that approach by the Finns even improved the behavior of the invading Russian armies in WWII.

Or.... If you are impatient like me come up with some way to eliminate the bad behavior over night! My home remedies are over documented in the 2014 thread.

Hope they aren't needed. They do work!

If you are suspicious that it's something in your technique these Lunos tend to be forgiving..... But as a test wear a full mask (not goggles) so you can swim distances inverted. I find myself to travel more peacefully, less aggressively maybe just naturally a bit smoother that way. Better or worse it will be different. Might be revealing. The view opens up beyond the pool tiles too!

Best to you FinSailor as you pioneer this new design. Many of us envy your experience and are counting on you to find the way!
 
About side-to-side movement.

If you haven't used a mono before, it could be more of a technique thing. At least when I tried a normal mono a few times after only using bifins previously, it was surprisingly difficult to go in a straight line initially because a mono can amplify any unevenness in your fin strokes and veer off to the side comparatively easily.

Ultimately the question is if your luno has more or less of a tendency to do that than a normal mono.. but that's going to be difficult to test unless you have one.

There definitely shouldn't be any mechanical 'play' though.
 
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