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popgun pete 11-26-2016 02:45 PM

Alemanni Demultiplied Rollerguns
 
2 Attachment(s)
I was asked to take a look at these "Alemanni Demultiplied Rollers", so I have selected these two guns. Very clean looking construction that seems to have squeezed a lot of rubber and pulleys into the "eurogun" format. "Demultiplication" is what trigger mechanisms do, hence interesting to see that aspect declared up front. Any "hoist" or "block and tackle" system drops the tension going to the wishbone drive, hence one demultiplication step halves it and two demultiplication steps drops it to one third. In order to restore the "missing" tension the "band battery" has to be either fattened up with thicker diameter bands, or more rubber band strands added, such as Siamese pairs, or even Triplets!!

Once you realize this fact the operation of any rollergun can be analysed at a glance, provided you can see all the cable and band run without them being obscured by shields, housings or covers on the gun body.

popgun pete 11-26-2016 04:24 PM

Re: Alemanni Demultiplied Rollerguns
 
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Finding space on the gun to mount the slack band length and yet still have the required wishbone travel to propel the shaft the full length of the gun's shaft guide track is often a problem. Here is a "wiggler system" cable gun that did the same thing as wrapping bands from the top to the bottom deck using large pulleys, however the "wiggler band battery" preserved the wishbone travel stroke without any "hoist" or "block and tackle" mobile sub-pulleys. The prospect of the "wiggler band battery" rollers gobbling up more energy than it was intended to add ensured that the gun was never built!

For those with long memories the "wiggler" was part of a SDI high energy beam, anti-ICBM weapon, but there any similarity ends.

popgun pete 11-26-2016 09:28 PM

Re: Alemanni Demultiplied Rollerguns
 
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Sorting out what is what on this Vela 135 Special took some doing. Any more cables and rubber bands on it and you could probably play a tune on it! An amazing number of bands have been fitted onto this gun and they act in uneven pairs (or triples) if you look at what actual bands the moving shackle sub-rollers connect to.

Tim.G 11-26-2016 10:14 PM

Re: Alemanni Demultiplied Rollerguns
 
This is great Pete, I've been trying to understand these guns and how they shoot.

Would I be right in saying that they create their power with shaft speed and not necessarily kg's of force driving the spear? Being a 2:1 ratio the cable wish bone has to move 2 time the speed of the bottom rubbers to make it to the muzzle bridge, am I right?

phil herranen 11-26-2016 10:19 PM

Re: Alemanni Demultiplied Rollerguns
 
Quote:

Originally Posted by Tim.G (Post 2124989)
This is great Pete, I've been trying to understand these guns and how they shoot.

Would I be right in saying that they create their power with shaft speed and not necessarily kg's of force driving the spear? Being a 2:1 ratio the cable wish bone has to move 2 time the speed of the bottom rubbers to make it to the muzzle bridge, am I right?

Yes but only if they have enuff band power ti get the shaft moving up to the retraction speed by the time it reaches the muzzle .

popgun pete 11-26-2016 10:41 PM

Re: Alemanni Demultiplied Rollerguns
 
The split pulley drive is not a speed multiplier as Phil pointed out, it will only drive at the velocity that the bands are capable of moving the spear. Interesting to see wishbone 2 on band group 5, my guess is that loads first to steady the shaft on the sear tooth. That way when you are hauling the main act back with all four band groups opposing you the shaft tab will not rock or move around as you try to hook the wishbone on the tab. There are only two moving sub-pulleys, but they are shared by the band groups, that is why I show four on the diagram to indicate their half main wishbone travel power stroke.

Wonderful workmanship in producing such clean and symmetrical surfaces, this gun is a work of art almost too good to take diving.

Tim.G 11-26-2016 11:26 PM

Re: Alemanni Demultiplied Rollerguns
 
Ok, do I understand this correctly.

If the below bands have enough force to overcome the force of the stationary shaft and contract as fast as they can then the cable on the shaft tab will have to move close to twice that speed, because it has double the distance to travel?

In my mind, being a mechanic. It is kind of like classic band guns are at 1:1 or 4th gear direct drive. This is like changing to overdrive or 5th gear. Your car won't like it at slow speed and may stall, but at faster speeds, where your engine has the torque to push the car, you get a higher road speed to engine speed ratio.

phil herranen 11-26-2016 11:49 PM

Re: Alemanni Demultiplied Rollerguns
 
Quote:

Originally Posted by Tim.G (Post 2124993)
Ok, do I understand this correctly.

If the below bands have enough force to overcome the force of the stationary shaft and contract as fast as they can then the cable on the shaft tab will have to move close to twice that speed, because it has double the distance to travel?

In my mind, being a mechanic. It is kind of like classic band guns are at 1:1 or 4th gear direct drive. This is like changing to overdrive or 5th gear. Your car won't like it at slow speed and may stall, but at faster speeds, where your engine has the torque to push the car, you get a higher road speed to engine speed ratio.

Yes ,but it's like starting from a dead start in 5th gear and the power profile goes from the highest at the start and then tapers quickly

Tim.G 11-27-2016 12:31 AM

Re: Alemanni Demultiplied Rollerguns
 
Quote:

Originally Posted by phil herranen (Post 2124994)
Yes ,but it's like starting from a dead start in 5th gear and the power profile goes from the highest at the start and then tapers quickly

This is why the booster band is needed? To give more of 1:1 ratio from the dead start.

popgun pete 11-27-2016 12:32 AM

Re: Alemanni Demultiplied Rollerguns
 
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The band stretch diagram is shown. There is no "booster band" here, just because that idea is repeated at length it does not mean that it is true. I have not bothered showing band group 5 for this very reason.

Note that this gun shoots a 10 mm diameter shaft to obtain the most from its "band battery" system, so not surprising that it contains lots of bands!

Diving Gecko 11-27-2016 02:24 AM

Re: Alemanni Demultiplied Rollerguns
 
Quote:

Originally Posted by popgun pete (Post 2124992)
The split pulley drive is not a speed multiplier as Phil pointed out, it will only drive at the velocity that the bands are capable of moving the spear. Interesting to see wishbone 2 on band group 5, my guess is that loads first to steady the shaft on the sear tooth. That way when you are hauling the main act back with all four band groups opposing you the shaft tab will not rock or move around as you try to hook the wishbone on the tab. There are only two moving sub-pulleys, but they are shared by the band groups, that is why I show four on the diagram to indicate their half main wishbone travel power stroke.

Wonderful workmanship in producing such clean and symmetrical surfaces, this gun is a work of art almost too good to take diving.

There are some pool videos of Mr. Abellan loading and shooting his guns on youtube if the order in which the bands are loaded need studying.

gspearguns 11-27-2016 07:37 AM

Re: Alemanni Demultiplied Rollerguns
 
Quote:

Originally Posted by popgun pete (Post 2124996)
The band stretch diagram is shown. There is no "booster band" here, just because that idea is repeated at length it does not mean that it is true. I have not bothered showing band group 5 for this very reason.

When on position from picture all the bands are in preloaded stage. This is just for taking photo. In slack stage bands are shorter.

Diving Gecko 11-27-2016 12:50 PM

Re: Alemanni Demultiplied Rollerguns
 
Quote:

Originally Posted by popgun pete (Post 2124996)
The band stretch diagram is shown. There is no "booster band" here, just because that idea is repeated at length it does not mean that it is true. I have not bothered showing band group 5 for this very reason.

Can you elaborate?
So, from an technical standpoint the booster doesn't make sense?

I could understand if the force on the wishbone was halved by a pulley that a booster band could make sense. But if the force on the band side is doubled, I guess it all pretty much evens out?

popgun pete 11-27-2016 01:18 PM

Re: Alemanni Demultiplied Rollerguns
 
1 Attachment(s)
Quote:

Originally Posted by gspearguns (Post 2125004)
When on position from picture all the bands are in preloaded stage. This is just for taking photo. In slack stage bands are shorter.

From the website. I always read everything before I do the diagrams as they take some time to prepare and this photo is pretty self-explanatory. My experience is that the hardest pull is when you jerk the wishbone back to the rearmost tab on a shaft, and it seems to have plenty of urge when you drop it in as if it doesn't then it can nearly tear your gloves off.

popgun pete 11-27-2016 05:01 PM

Re: Alemanni Demultiplied Rollerguns
 
2 Attachment(s)
The "X2" gun seems to be very similar, but a much simpler gun than the "Vela 135 Special". This gun can shoot smaller diameter shafts down to 6.5 mm diameter and up to 8 mm diameter. When I started diving 8 mm diameter (5/16") was considered small and a "real gun" used 3/8" diameter! Not long before that Dinosaurs ruled the Earth and high performance automobiles used "Big Block" engines.


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