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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 12-06-2016, 09:42 AM   #76
gspearguns
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Re: Alemanni Demultiplied Rollerguns

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Originally Posted by Satdiver View Post
Hi Majd, I was able to find some XPS foam. I will do the test as you recommend. The lightest shaft I have for the test is 9.75mm x 170cm. Should be interesting to see the results.
And please include in that test your and Andres Gladiator.
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Old 12-06-2016, 10:23 AM   #77
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Re: Alemanni Demultiplied Rollerguns

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Hi Majd, I was able to find some XPS foam. I will do the test as you recommend. The lightest shaft I have for the test is 9.75mm x 170cm. Should be interesting to see the results.
That really would be fantastic! The XPS foam I use is Downing 35cfm ... it usually comes in 25cm but you can get 35cfm and even 40cfm or 45cfm (used in car parks). I have never been able to pass my Tuna Penetration test or 15cm of foam at 8 meters from tip of shaft to target with any gun I have tested so far. I do have an Abellan Albacore 130 (with 142cm stretch) that I think might be able to pass it at that distance ... but it has yet to touch water. Hopefully I will soon be able to put it through its paces. I have a 9mm shaft that I might throw at this if the 8.5mm shaft doesn't do it.

As for 10mm shafts ... I haven't shot one of those since the JBL days. If such a heavy shaft has good velocity, it can go through anything.
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Old 01-21-2017, 04:01 PM   #78
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Re: Alemanni Demultiplied Rollerguns

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The use of a "pulley" as a rear band anchor allows the band lengths to equalize on either side of the gun. Georges Beuchat had the patent on this pulley idea for a forward band anchor, but to my knowledge it was never used on a production speargun as a loop band works OK on a slotted end muzzle without resorting to a pulley.
Here is the Beuchat and Malaval 1946 French patent for a band anchor pulley which evens up the side to side band lengths.
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Old 06-09-2017, 12:27 AM   #79
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Re: Alemanni Demultiplied Rollerguns

Any updates on this?
Curious to see the comparison of the demultiplied gun design compared to classic guns as I haven't found any direct comparison online yet.
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Old 06-09-2017, 01:40 AM   #80
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Re: Alemanni Demultiplied Rollerguns

I came close to testing the Vela 135 in my pool, but unfortunately things did not pan out and the person who was supposed to bring it, brought in another Alemmani roller. At the moment, that is the only roller gun that I think can maybe compete with a powerful classic 3 banded gun.
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Old 06-10-2017, 03:20 PM   #81
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Re: Alemanni Demultiplied Rollerguns

Well,I think you still dont believe my effort to compare a perfectly set classic gun and my new polispats with absolutely same lenght and conditions.
It was a fair test and I had a good reason to be maximum objective, becouse both guns was mine.And trust me I would prefer hundred times to build classic guns,they are so much more easy.
My conclusion was that the roller shoots at 9 meters exacly the same way like the normal gun at 7 meters.Two meters advantage is verry serious on my opinion.
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Old 06-11-2017, 01:40 AM   #82
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Re: Alemanni Demultiplied Rollerguns

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Well,I think you still dont believe my effort to compare a perfectly set classic gun and my new polispats with absolutely same lenght and conditions.
It was a fair test and I had a good reason to be maximum objective, becouse both guns was mine.And trust me I would prefer hundred times to build classic guns,they are so much more easy.
My conclusion was that the roller shoots at 9 meters exacly the same way like the normal gun at 7 meters.Two meters advantage is verry serious on my opinion.
I have only one question that you still have not answered and that is why I am very skeptical of the results you posted. Where were you aiming when you were shooting at 6m, 7m and 8 meters? What was the shaft drop?

I have no doubt that you can power up a roller to extreme speeds, but with all the rollers I have tried ... the more you push the shaft velocity, the lower the gun shoots. If you have to aim way above the fish to be able to hit it and have to know how much above the fish to aim at different distance ... well ... it might be ok in the pool, but in the sea it is impossible to gauge distance in clear water ... that is why you need to keep the shaft flying as flat as possible.

I remember before buying and testing your 130 double roller inverted, you had videos shooting 9 meter targets as well, and that also looked very impressive. So if I am a little skeptical it probably is for that reason. I did test some other long rollers since then and to be honest, while they might compete with a 2 banded gun @ 130 ... they all get totally blown away when you go 3 bands and 8.5mm shaft on a well designed classic gun. It is not even close.
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Old 06-11-2017, 02:01 AM   #83
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Re: Alemanni Demultiplied Rollerguns

If there is significant shaft drop then that should mean the shaft has a low velocity and therefore has poor penetration or the flight path is not straight because there is some interaction with the gun and it should also have poor penetration at longer ranges due to poor hydrodynamics. I think to standarize these tests which has been popularized on this board by spearq8, we should use a side camera angle to observe the shaft flight path rather than asking the tester where he aimed.

Spearq8 could you name the rollers you've tested that had bad shaft drop? Im pretty sure it's because the wishbone ramp angle is too agressive and flips the shaft up just before exit. This can be easily fixed with tying two wishbones - one longer one for the sharkfin and one for the ramp.
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Old 06-11-2017, 05:09 AM   #84
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Re: Alemanni Demultiplied Rollerguns

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I have only one question that you still have not answered and that is why I am very skeptical of the results you posted. Where were you aiming when you were shooting at 6m, 7m and 8 meters? What was the shaft drop?

I have no doubt that you can power up a roller to extreme speeds, but with all the rollers I have tried ... the more you push the shaft velocity, the lower the gun shoots. If you have to aim way above the fish to be able to hit it and have to know how much above the fish to aim at different distance ... well ... it might be ok in the pool, but in the sea it is impossible to gauge distance in clear water ... that is why you need to keep the shaft flying as flat as possible.

I remember before buying and testing your 130 double roller inverted, you had videos shooting 9 meter targets as well, and that also looked very impressive. So if I am a little skeptical it probably is for that reason. I did test some other long rollers since then and to be honest, while they might compete with a 2 banded gun @ 130 ... they all get totally blown away when you go 3 bands and 8.5mm shaft on a well designed classic gun. It is not even close.
The 130 double roller that you had is NOT an inverted polispast,its a simple polispast.I accent on that becouse actually these are my namings that everybody use now.Before there was only "fusion",vella and names that doesnt give any idea about the system itself
The video that you are talking about is much older and made with the double full roller,wich is the first variation of the same body platform.The polispasts was not good developed then yet.
Full rollers can be verry good,if the muzzle stopper is designel well.This is their weak point.They tend to shoot a little low only if the stopper is too high.And most stoppers are high becouse people want to use big sharkfins.I found that better solution is lowest possible stopper with mini sharkfins.
What I notice is that most builders use the same "weak" stopper for polispasts,wich is wrong becose that system alows much simpler and effective stop systems,wich DO not lift the shaf tails and totaly eliminates the risk of tangles.
A major factor for roller performance are also the rolls.I see most builders are using "stainless" ball bearings from yahting parts.But if you notice most of them have stainless balls partly bearing on hard plastic shell,wich is ok for pulling boat ropes but bad under high pressure and high rounds per second.Other kind are inox ball bearings wich are too tide and not completely stainless.They fail quickly in salt water and must be replaced with better ceramic solution
The best material for speargun rolls bearing so far for me is the same they use for bearing boat transmitions and vals.It makes sence becouse its used in the same enviroment in similar conditions.I have never seen ball bearings,steel or ceramic for boat valls,at least here in my country.
So a good shooting rollergun is a combination of several factors that work good together.And it took me a lot of work to get to the right settings .Its not just like collecting a gun from different parts and say-this is a sniper...
My idea was to make rollerguns as simpler as possible and I noticed that in water enviroment simple things that consist of less parts are more effective.Simple muzzles,simple stoppers,simple line settings,bearings that consists of less parts,thats what I was working on last couple of years.
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Old 06-11-2017, 05:44 AM   #85
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Re: Alemanni Demultiplied Rollerguns

I think you underestimate how much research other roller builders have put in the last few years. There has been improvements in rollers and improvements in design. Alemmani is probably the most advanced roller speargun technically ... and the owner personally spends hours in the pool tuning every single gun he sells to make sure it shoots well. All the components he uses are absolutely the best you can find and if you just look at one of his guns, you can immediately sense that this gun is of a different class with regards to craftsmanship and materials used. From my testing, the Alemmani is the best shooting roller gun I have tried ... but it still in no way came close to the performance of my best classic 3 banded gun. It was competing with 2 banded guns ... but once you add that 3rd band it is lights out.

As for simplicity ... well roller guns are inherently complicated. Lot of parts and lot of lines ... this one a classic gun wins hands down. Classic guns are easier to load, faster to load and have less chance of a failure. But here we are not talking about simplicity ... I am willing to disregard the simplicity part ... what I want to see is a roller gun outperform a well configured classic gun in accuracy, penetration on target at distance and how flat the shaft trajectory profile is. While on paper a roller should easily outperform a classic 3 banded gun ... in real life I have yet to see this ... not even close.

With regards to you preferring to build classic guns rather than roller guns but choosing roller guns due to performance. Trust me ... if roller guns were performing better that would be the only spearguns I would be using and instead of all my videos showing how to improve a classic gun performance, they would be all about how to better tune your rollers. What is a show stopper for me is poor shaft trajectory of a roller ... which just makes accurate shooting impossible at distance in a hunting situation and which also tends to dissipate shaft velocity very quickly.
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Old 06-11-2017, 05:50 AM   #86
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Re: Alemanni Demultiplied Rollerguns

Quick question Seal - what bearings are you using? I don't get the "boat valls" thing, it might be lost in translation.
I do trust you that SS bearings wont be the best, but open ceramic ones should work well, no? I think some of the South African guys tested that and I think they are on Roisub's most expensive versions, too.

(As to who came up with what words the first, I don't care but, personally, I had to look up "polispast/polyspast" the first time I saw it on this board as it had no meaning to me, perhaps it does to an engineer? "Pulley", "compound" and "inverted", on the other hand, creates images in my head easier. But at the end of the day, doesn't matter at all, and I guess "polispast" sounds unique)

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Old 06-11-2017, 08:01 AM   #87
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Re: Alemanni Demultiplied Rollerguns

Majd, could I ask one question? What is the Weight of the 3 Band gun? what is the Weight of the Alemanni you tested? I know I know.. Weight is a wart on the ass of a well designed gun... but I've seen many well designed guns gain from simply having a weight fixed to them. But everyone wants to go sooooooo light with Rollers.
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Old 06-11-2017, 08:10 AM   #88
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Re: Alemanni Demultiplied Rollerguns

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Majd, could I ask one question? What is the Weight of the 3 Band gun? what is the Weight of the Alemanni you tested? I know I know.. Weight is a wart on the ass of a well designed gun... but I've seen many well designed guns gain from simply having a weight fixed to them. But everyone wants to go sooooooo light with Rollers.
For the 3-band gun, if it's the Albacore, then around the 4kg mark according to the manufacturer's website, maybe a bit more with Majd's CF wrap and handle mod. Alemmani doesn't have the mass of the guns published.
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Old 06-11-2017, 09:08 AM   #89
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Re: Alemanni Demultiplied Rollerguns

Majd,
Is there a video of the alemamni gun test? What was the rubber stretch on it? I remember popgunpete drew up an energy diagram of the Vela 135 according to the photo on their website and the bands were not close to 380%.
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Old 06-11-2017, 10:25 AM   #90
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Re: Alemanni Demultiplied Rollerguns

9lbs?? Man I didn't know that thing was such a beast? Majd how much does your CF wrap gun weigh in at?
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