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All About Guns What's your weapon of choice, and why? Discuss the beloved speargun here!

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Old 08-28-2017, 07:56 AM   #91
Behslayer
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Re: More about the inverted polispast rollers

Hi Nevin, thanks for the feedback. We had discussed Mid point connection shafts in another thread. I always though they were purpose designed for Rollerguns to help get the shooting line out through the bridge before the bands arrive.

Any video of your guns shooting?
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Old 08-28-2017, 03:06 PM   #92
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Re: More about the inverted polispast rollers

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Originally Posted by Behslayer View Post
Congratulations Seal on the WORLD RECORD taken with a SEAL 130 Inverted Poliplast Roller right out of the box.

Thanks Marc.
yes this catch is not a difficult fish to spear at all and does not reflect if the gun is good or not , it just reflect at least it is working even with unproper shaft and that nobody did spend any time to set it up in the pool for rubbers/line/handle/spanish mackerell or tuna foam targets in the pool to be shoted and killed shot from 5 or 6 meters away !

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Old 08-30-2017, 02:58 PM   #93
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Re: More about the inverted polispast rollers

Allow me a very very, basic and newbie observation - but a few weeks ago I was cutting some 14mm Small ID bands and playing with them, it dawned upon me how little they like being bent. Try it for yourself. Take a band and turn it 180 degrees around. It is quite substantial the amount of resistance the band is showing. Maybe normal ID bands are less opposed to the bending but I kept speculating that some of the energy loss could simply be to do with that. Especially on smaller rollers. I know this is as unscientific as it comes, but I was just surprised by it.
So, straight pulls by the bands in a inverted roller (dyneema has no issue going around a roller and pulleys) with the benefit of higher potential wishbone speed, possibly combined with a straight booster band does make a lot of sense to me after that simple observation.
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Old 08-30-2017, 03:50 PM   #94
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Re: More about the inverted polispast rollers

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Allow me a very very, basic and newbie observation - but a few weeks ago I was cutting some 14mm Small ID bands and playing with them, it dawned upon me how little they like being bent. Try it for yourself. Take a band and turn it 180 degrees around. It is quite substantial the amount of resistance the band is showing. Maybe normal ID bands are less opposed to the bending but I kept speculating that some of the energy loss could simply be to do with that. Especially on smaller rollers. I know this is as unscientific as it comes, but I was just surprised by it.
So, straight pulls by the bands in a inverted roller (dyneema has no issue going around a roller and pulleys) with the benefit of higher potential wishbone speed, possibly combined with a straight booster band does make a lot of sense to me after that simple observation.
That's why shape of pulleys channel is very important on classic rollerguns.
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Old 08-30-2017, 04:03 PM   #95
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Re: More about the inverted polispast rollers

Some of the companies do use these big continuous bands through rollerheads. It's interesting to watch Continuous Band Rollers from the Side view in Slow Motion to see what is happening. You do have more band stretch being utilized than a classic gun even if you only consider a Pretensioned Continuos band roller as only giving power during the Top phase and then bottom phase as only pulling the bands out of the way. If you look at an Alemanni, that band on top is quite thin and is also not Small ID. It has a piece of dyneema inside of it limiting the stretch and has thicker bands underneath providing the muscle. I had heard of guys trying Flat Bands as well. But sure it would make sense that bands pilling unimpeded in a stright line and ropes making a turn would be more efficient.
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Old 08-31-2017, 02:21 PM   #96
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Re: More about the inverted polispast rollers

I've found that the negative effects caused by a continuous band bending around a roller can be limited by a well designed muzzle riser and well designed sharkfin tabs on the spears. As long as the wishbones glide off the sharkfins at the muzzle and get caught on the sharkfin, jack up the back of the spear, and push the spear low this design can yield great accuracy.

While there is surely some lost energy involved in contracting around the pulley, I think this type of guns' simplicity and easy/quick loading offers an advantage over the inverted roller systems for some applications. I load my most recently built double roller exactly like any two-band traditional gun except I use a load-assist to get it started.

That being said, currently building an inverted roller and really curious to see how it turns out in comparison.
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Old 09-04-2017, 01:10 PM   #97
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Re: More about the inverted polispast rollers

Zero Friction system?
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Old 09-04-2017, 07:11 PM   #98
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Re: More about the inverted polispast rollers

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Zero Friction system?
funny strange guns ,




better to wait some might review what is not ok in those before to buy ha ha !
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Old 09-05-2017, 07:36 AM   #99
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Re: More about the inverted polispast rollers

Yes, but the concept is strong. Elimination of friction. I wonder if they could be further efficient using flat bands.
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Old 09-08-2017, 06:46 AM   #100
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Re: More about the inverted polispast rollers

Woodward, How did that Roisub go for you?
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Old 09-08-2017, 12:15 PM   #101
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Re: More about the inverted polispast rollers

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Woodward, How did that Roisub go for you?
i , yesterday , paid for the last ref: R0815 from Roisub , the 115 loaded with " big" 8,5 mm shaft .
should be in Polynesia in few days , then G will test it as he want it to replace his 115 Demo 3 he recently sold .

Roisub are precise guns , fast going shaft , no recoil , but are too complicated IM personnal O specially to be reload if you are in a " rush " and in a " dangerous area "
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Old 09-08-2017, 11:14 PM   #102
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Re: More about the inverted polispast rollers

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Woodward, How did that Roisub go for you?
Hi Jon,

I used it this past spring in Okinawa. A Demo 3 115 model.

I found it to be not as complicated as other inverted rollers....

Its loading system is different in the fact you don't load under the gun but on top, UNDER the shaft. The main shaft line of course is on tabs but band loading is under the shaft.

I found it easier to load than normal inverted rollers.

The shaft supplied sucks i.e. terrible tabs/welding and don't like the tip type.

Handle/mech is a pathos DII. When I used it in Oki, I used the stock mech and customized the handle to fit my hand. The mech is terrible. I ordered a replacement one but didn't have time to install, so used it stock. Ill get it swapped before next trip.

There is no noticeable recoil at all. It shoots smooth as any gun I have ever used.

Only took one practice shot in "the pool" (inside reef sand area) to get a feel of how it was going to shoot. Shot at a soda can at max range of double wrap and speared it center so was happy with stock accuracy and confident before using.

First fish shot was a 30kg GT. Shaft penetration/powe is so good the shaft went completely through its head. You know how hard those fish heads are.

Went on to use it as my primary reef gun for the trip. Shot usual reef fish and a couple small doggies <20k. Got spooled on a big doggie but, gun penetrated just fine.

Need to change shafts before next trip. Unless something changes, I am going to use it as my primary reef gun replacing my old trusty Aimrite 120.

Overall happy, small enough for reef use and powerful enough to use on large fish up to around 50kg or so. Accurate enough for the different Pacific snappers and other small reef fish. Not going to change anything in regards to bands and rigging.

Now if I could get this gun in a 120

https://www.alemanni-sub.com/en/prod...-105-cm-110-cm
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Old 09-10-2017, 12:00 PM   #103
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Re: More about the inverted polispast rollers

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@Jon ... little red around the collar ... I don't remember you putting up a fit when Seal (after about a year where he seemed reasonably happy with the test results) decided to call me a liar and that I had somehow faked his test results. Until then, I was happy to just let the thing go ... sure I was pretty pissed off with the way Seal dealt with things ... but I let it pass. Some customers get pissed and want to send the gun back if they get a new gun with a small scratch ... I tend to be more understanding, and I think I went out of my way to stay politically correct. But when someone starts calling you a liar, I really donít see any reason to keep quiet about stuff. I guess Jon you feel some guilt as you were also hyping the whole idea that the gun was shooting "chunks out of the pool wall" .... and ... "where is that tuna video?". All part of being a salesman I guess ... a little wink and pat on the back and all is good. Well I don't sell guns, I prefer to let the guns do the talking. Some people actually prefer it that way ... no smoke or mirrors ... just the real deal. Sometimes the truth disappoints, but the way to deal with it is digest the results, learn from them and improve ... not blame the messenger and bitch about the results. Why not ask Peter is Lame how the gun performed in his test since he also tests some of your guns?

By the way, I am sure Seal has learned from test results and has changed what doesn't work. A lot of progress has been made with rollers and they are improving daily ... and most likely there will be a breakthrough. Believe it or not, I am in touch with a lot of the guys pushing out the newest and latest ideas with rollers, and it is amazing and pretty exciting what ideas they come up with. The secret is keeping the shaft stable on exit ... pretty much like it is with a classic gun ... and from what I saw it does look there is big progress there ... I might test one of those creations soon. The Seal gun I tested did not perform well because that gun design did have some inherent design flaws that simply would not allow the gun to shoot well. It was not because I didnít know how to load the gun or didnít setup it up correctly. There is a long post on that test on this forum and you can read it here http://spearboard.com/showthread.php?t=187690. The gun in this test looks very different to the one I tested, but I certainly would not base my opinion based on the videos posted ... I seem to recall a similarly impressive video of a similar gun to the gun I tested shooting at 9m (actually the gun in the video is LESS powerful according to Seal).


http://www.youtube.com/watch?v=9LtktOdlMCY


Fool me once shame on you ; fool me twice ... etc ... I would also advise anyone who wants to buy that gun to ask for a trigger change ... unless his mother in law is a spearo that is. I donít know if he makes them himself or has someone do it for him, but Patek Phillipe ... well letís just not go there. Here are a couple of pictures of the trigger internals and the first picture showing track to trigger seating I had to deal with (try fixing that on a brand new pinned carbon gun!!!). If some picture looks skewed or some pins seem bent, be assured it is not an optical illusion. And the spring that seems to have been hacked from some wire ... that is the only thing pushing your trigger sear back and avoiding a misfire when you load (or a few seconds after you load). Not saying there is an absolutely 100% safe trigger, but this is just one area you just avoid cutting corners. Jon ... why not use some of those mechs on the 8 Ulusub guns you are building now ?!









I cannot see the pics
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Old 09-10-2017, 02:46 PM   #104
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Re: More about the inverted polispast rollers

Just few notes on a really emotive and dramatic tread!!! I begin with Roller Guns on 1999, then we made a group with Niko Brummer, John Warren, a gentleman from Australia and myself to study RG physics and design, on 2006 the group ended , but we all appropriate a knowledge about the topic, needless to say who was John Warren, nor Niko Brummer, great engineer and scientist, I don't count there , because I am a humble photographer doubled by a passionate gun builder since 1970, but here some points to take in count:
1ļ- Difference between a classic one band gun and a classic RG on the classic one band gun, we lose one third of barrel length, occupied by the length of rubbers in his unstretched state, and because the Hooke's law, they only pull the spear for the 20% at least of the barrel remnant length, on a RG WELL designed, the band stops at muzzle with at least 30% of stretch, and that way, a band speargun acts as a pneumatic one, pushing the spear all the way!!!!!, son a RG will be more efficient than a one band speargun with the same length barrel and spear
2ļ- the limit of the push of spear is the max contraction speed of the rubber itself, once you arrive to do the spear reach this speed, the amount of bands you add no make any sense!! that is why a 5/16" shaft ion a enclosed track with 8 5/8" bands no make any sense!!! because at 5 bands at 300% this shaft has the same speed that the max retraction speed of the rubber band material
3ļ- the poli past, there is the revolution, because the polipast with one fixed and one mobile pulleys DOUBLE the contraction speed of the rubber band, but lose the 50% of the force, so we need to put more rubber on it to compensate and attain a real advantage,. they are many designs on polipast RG's on the market, someone's work well, others not, but my grain of sable to the tread, sorry about my english
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Old 09-13-2017, 09:44 AM   #105
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Re: More about the inverted polispast rollers

I made recently a gun like Majd's "favourite".This is how the trigger looks like.This is the longest and normal working simple two part reverse trigger mech that somebody ever dared to mount on a speargun.You can't mount it on an wooden gun becouse the sear must fall deep into the handle to release the shaft.
Now I stick to a shorter new model trigger,wich is easyer to mount and allows a lower offset.All parts,triggers and pulleys are exellent quality and exellent finished.Here in Europe I had the chance to try most gun parts from the market and I still prefere to use mine,although its cheaper to buy from Italy or Greece.
By the way,that famous double roller we are talking about shoots exellent with one aditional booster band.This simple double polispast has similar power like the single inverted polispast in the same size.Here comes the explanation why I prefer inverted-becouse they shoot exellent with less bands and body volume.
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