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Old 06-01-2020, 12:41 AM   #1
ninjagazz
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Rob Allen Inverted Roller

Hi Guys,

On my coral sea trip a few guys had inverted rollers, I never saw these in action but i know guys were shooting great fish with them (the divers using them were also awesome spearos).

When i got back my curiosity was stoked, I had a 1600 Rob allen tuna, so i cut it down to a more manageable 1100 and fitted a Roller head. I got hold of a inverted roller head by MVD but It wasn't compatible with pulleys so I put back on the normal roller head but set it up as an inverted with pulleys.

*I used 3mm dyneema(stiff) as the line as i didn't want it jumping off the rollers, i also found this line easy to grip. I started with the same pulleys as mannysub but decided to go with some ronston ones with bearings and a swivel.

*I used 2 pairs of 16mm rubber with a stretch of 300% (left over from my salvimar hero 135). But one is reactive and the other is progressive (although identical in appearance?). There was some pretension but only about 10 to 15%

*I am using a 150cm 7mm Salvimar pacific shaft.

The gun was easy to reload (Comparable to loading a standard with a tight 18mm band, probably due to the progressive rubber), i could load it with all rubbers at once no problem. Reloading was easier than expected. There was minimal recoil.
But the shot was not strong, The shot didn't have any noticeable pull at the end of the range, my riffe euro 110 shoots much harder and my airguns would blow this out of the water. The gun was also bloody heavy! It wasn't a sinker but it wasn't far off, it would be terrible for snapper snooping.

I will try stronger rubber, max the pretension, and use softer dyneema.

I am wondering are these guns over rated? How in the world does mannysub inverted shoot a 8.5mm spear?

Do the pulleys kill performance?

I was also concerned about the pulleys rotating the line and causing twisting. There seemed to be some evidence of this.

I would appreciate your thoughts.

https://www.youtube.com/watch?v=lZ0BK6I-B08







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Old 06-01-2020, 01:07 AM   #2
popgun pete
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Re: Rob Allen Inverted Roller

Inverted roller side pulley halves the tension in the wishbone cable because the other half goes to the cable muzzle anchor, so you need two bands to replace one to get the equivalent of one band. Ditto for loading it as in a sense you are loading the gun with the assistance of a block and tackle. Piggy back bands added on lift the available grunt.
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Old 06-01-2020, 09:14 AM   #3
Marco
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Re: Rob Allen Inverted Roller

If it is too easy to load, my logic says it won't shoot strong enough. Unless you load in phases.
The bands must have pre-tension at the end of their run, otherwise, you're loosing the principle of rollerguns, which is to push the shaft all the way.
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Old 06-01-2020, 10:54 AM   #4
Diving Gecko
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Re: Rob Allen Inverted Roller

Since you can "load it with all rubbers at once no problem" you basically just have a one-banded gun albeit with longer band pull and recoil-cancellation.

I don't actually know, but I would think if Mannysub only has 2x2 rubbers in the band battery then they must load them separately to end up with any real power. Whereas you load it all in one go, I think they divide the effort. This way they can run way shorter bands/more preload than you. The first band to load via the wishbone could be cut very, very short - as you have double the power to pull with so to speak. And then the second band would be cut as hot as you would normally cut a classic band. That way, you do end up with more power than just a single banded gun.

See if you can find any videos or ask any users if they load their Mannysub guns in one or two gos. If it is indeed two, you need to find an easier way to anchor your second band at the rear of the gun and, of course, cut at least the first bands hotter. Perhaps put a beefier one as the first one, too.

Also, is that little piece of rubber or plastic tube there when shooting? If so, I would think that would be seriously draggy.
[EDIT] Just peeked at your video and yep, it's a load assist but it's there permanently. I would def loose that.

Last edited by Diving Gecko; 06-01-2020 at 11:16 AM.
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Old 06-01-2020, 02:31 PM   #5
musubi
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Re: Rob Allen Inverted Roller

Quote:
Originally Posted by ninjagazz View Post
Hi Guys,

On my coral sea trip a few guys had inverted rollers, I never saw these in action but i know guys were shooting great fish with them (the divers using them were also awesome spearos).

When i got back my curiosity was stoked, I had a 1600 Rob allen tuna, so i cut it down to a more manageable 1100 and fitted a Roller head. I got hold of a inverted roller head by MVD but It wasn't compatible with pulleys so I put back on the normal roller head but set it up as an inverted with pulleys.

*I used 3mm dyneema(stiff) as the line as i didn't want it jumping off the rollers, i also found this line easy to grip. I started with the same pulleys as mannysub but decided to go with some ronston ones with bearings and a swivel.


*I used 2 pairs of 16mm rubber with a stretch of 300% (left over from my salvimar hero 135). But one is reactive and the other is progressive (although identical in appearance?). There was some pretension but only about 10 to 15%

*I am using a 150cm 7mm Salvimar pacific shaft.

The gun was easy to reload (Comparable to loading a standard with a tight 18mm band, probably due to the progressive rubber), i could load it with all rubbers at once no problem. Reloading was easier than expected. There was minimal recoil.
But the shot was not strong, The shot didn't have any noticeable pull at the end of the range, my riffe euro 110 shoots much harder and my airguns would blow this out of the water. The gun was also bloody heavy! It wasn't a sinker but it wasn't far off, it would be terrible for snapper snooping.

I will try stronger rubber, max the pretension, and use softer dyneema.

I am wondering are these guns over rated? How in the world does mannysub inverted shoot a 8.5mm spear?

Do the pulleys kill performance?

I was also concerned about the pulleys rotating the line and causing twisting. There seemed to be some evidence of this.

I would appreciate your thoughts.

https://www.youtube.com/watch?v=lZ0BK6I-B08







As Diving Gecko mentioned, most definitely lose the rubber/plastic tubing as that's causing a lot of drag on the shot.

In my opinion, inverts are more under rated than anything, but you need it properly setup.

While I haven't experimented with many invert setups, the following is mine on my 110 cm:
- 3 x pairs of 14 mm bands. They have an inch of pre-stretch and are stretched to 360% when loaded.
- 7.5 mm RA shaft. I ran a 7 mm, but I think my shaft was whipping a little as my shots weren't as consistent.
- I'm using the MVD handle, so all of my bands are loaded on the bottom, not the sides. I don't think it matters where, but I'd recommend either locating them all on the bottom or the sides, not a mixture. You're shooting line will tangle and shots will be off.

Recoil is very low, but with this setup, my shots have been very powerful.
I calc-ed out approx. exit velocity speeds and the shaft is shooting a faster (about 13.5%) than my two banded wooden 110 cm, with 14 mm bands at 330% stretch. Not that speed is everything and I realize there are issues with reaching terminal velocity, but I'm not reaching them here. It's been a good setup landing me amberjacks, GT's, large millkfish, etc.

I'd say add another pair of 16 mm (or 14 mm) to your setup.
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Old 06-01-2020, 03:35 PM   #6
popgun pete
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Re: Rob Allen Inverted Roller

A problem with that handle for adding another band anchor at the rear and under the barrel is the line release under the grip. On a simple rollergun it is OK as the shooting line keeps away from the rollers and bands by running up the middle. However a piggy back band set along the bottom of the barrel will interfere with the run of the shooting line. Inverted rollerguns usually have a side mounted line release that runs the shooting line wraps outboard of the band system.
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Old 06-01-2020, 03:50 PM   #7
musubi
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Re: Rob Allen Inverted Roller

Quote:
Originally Posted by popgun pete View Post
A problem with that handle for adding another band anchor at the rear and under the barrel is the line release under the grip. On a simple rollergun it is OK as the shooting line keeps away from the rollers and bands by running up the middle. However a piggy back band set along the bottom of the barrel will interfere with the run of the shooting line. Inverted rollerguns usually have a side mounted line release that runs the shooting line wraps outboard of the band system.
I agree, MVD's setup isn't good for inverts. I got tangles all the time running the shooting line where the underside bands are. I gave up on inverts because my shots were all wonky with the line running like that. I ended up inserting another line wrap pin at the muzzle and changing my line wraps to the side, completely away from the unsderside bands. That solved the issue. Otherwise I really like the MVD handle which moves the reel to the trigger guard and the molded in line anchor.
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Old 06-01-2020, 07:22 PM   #8
musubi
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Re: Rob Allen Inverted Roller

Quote:
Originally Posted by ninjagazz View Post
Hi Guys,

On my coral sea trip a few guys had inverted rollers, I never saw these in action but i know guys were shooting great fish with them (the divers using them were also awesome spearos).

When i got back my curiosity was stoked, I had a 1600 Rob allen tuna, so i cut it down to a more manageable 1100 and fitted a Roller head. I got hold of a inverted roller head by MVD but It wasn't compatible with pulleys so I put back on the normal roller head but set it up as an inverted with pulleys.

*I used 3mm dyneema(stiff) as the line as i didn't want it jumping off the rollers, i also found this line easy to grip. I started with the same pulleys as mannysub but decided to go with some ronston ones with bearings and a swivel.

*I used 2 pairs of 16mm rubber with a stretch of 300% (left over from my salvimar hero 135). But one is reactive and the other is progressive (although identical in appearance?). There was some pretension but only about 10 to 15%

*I am using a 150cm 7mm Salvimar pacific shaft.

The gun was easy to reload (Comparable to loading a standard with a tight 18mm band, probably due to the progressive rubber), i could load it with all rubbers at once no problem. Reloading was easier than expected. There was minimal recoil.
But the shot was not strong, The shot didn't have any noticeable pull at the end of the range, my riffe euro 110 shoots much harder and my airguns would blow this out of the water. The gun was also bloody heavy! It wasn't a sinker but it wasn't far off, it would be terrible for snapper snooping.

I will try stronger rubber, max the pretension, and use softer dyneema.

I am wondering are these guns over rated? How in the world does mannysub inverted shoot a 8.5mm spear?

Do the pulleys kill performance?

I was also concerned about the pulleys rotating the line and causing twisting. There seemed to be some evidence of this.

I would appreciate your thoughts.

https://www.youtube.com/watch?v=lZ0BK6I-B08







Reading your post again, I wanted to bring up a few of my thoughts. First is a question. What did you mean that the MVD invert roller head wasn't compatible with pulleys?

I'm using the Harken 16mm forkhead block on a couple of my inverts. They're nice because of their small size and weight for its loading capacity and application to invert guns. That said, I do believe the size and weight of the pulleys can affect performance negatively especially if they're larger and/or have more mass.

I've never felt my pipe invert guns to feel heavy unless I tinkered too much on the ballasting. Are the rubber plugs for the barrel too far in?

In my larger invert, I shot an 8.5 mm Hunt shaft while target practicing. I had 4 pairs of 14mm bands with about 350% band stretch and I needed more power. Shaft shot straight, but the shaft was too heavy and start shooting low at further distances. I shoot a 7.5mm out of that gun now (with the 4 pairs of 14mm), but if I had to do a setup with the 8.5 mm I might try 16mm bands instead. I'd also upgrade my pulleys to one with more capacity. The Harken's max working load is 250 lbs and with 4 pairs of 16mm I think I'd be exceeding that for one of the pulleys. Another thing I thought about was that MVD doesn't recommend a setup with 4 band pairs. Ultimately I tried to double check as much things as I could, like the max shear load for the bolts for the invert wheels.

So far I've never had an issue with the pulleys rotating on me. One thing I do with the bands is I color which pair I should load first, just so I'm consistent and the pulleys are loaded the same way.

I wouldn't consider loading my invert super easy, however I do find loading it easier than my classic banded guns.
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Old 06-01-2020, 08:41 PM   #9
ninjagazz
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Re: Rob Allen Inverted Roller

Some great reply's,

I will definitively loose the big load assist, maybe try a hand held one.

I will increase pre-stretch to 150% and maybe source a bit of 20mm rubber.

I can do 3 pairs rubbers see attached, but 2 will be easier as even having the side mounts makes it difficult to attach bands when loading the secondary bands, i might try the option below. I want to keep this as simple and easy as possible.

The MVD muzzle was not designed for pulleys but for the original inverted design where there was normal roller wheels were near the handle as well. The small wheels keep the line against the barrel so when the pulleys approach the muzzle during loading they get jammed against the barrel causing a lot of friction and limiting how close the pulleys can get to the muzzle.

The Plug was put in so there was minimal gap between the it and the muzzle. I did fill the muzzle with resin, to stop water getting in. I hate the way water gets in behind the muzzles and handles of RA. There is no evidence of the barrel leaking. it just heavy. I got offered a floater by pathos, but it was interfere with the pulleys.

I have been very interested in your setup Musubi, thanks for your replys. What distance did the 8.5mm shaft get to before loosing trajectory?

I would like the RAM style muzzle, i will invest in that setup if i can get this to work.

Mannysub uses a 20mm pair and 2 pairs of 14mm rubbers to throw a 8.5mm spear. Not sure of the pre-stretch.

Muzzle Comparison


3 Rubbers Config


2 rubbers config, with one being 20mm


Pulley details
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Old 06-02-2020, 07:47 AM   #10
diveincanada
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Re: Rob Allen Inverted Roller

I know there's a lot of hype around rollers. I'm been building guns for just about a year now and having a blast doing it just for fun, just for my personal use. I've been wondering about building a roller but at the same time, I like the simplicity of a standard speargun.. When I set up my stuff, rig my gear, I always try to Keep It Simple... And to me, a roller seems like so many more elements that can go wrong. When you spend your money for a nice spearfishing trip you want your gear to work. Seems to me a simple band fail on a roller will be a pain.. Then again, I dunno how much better they shoot.. So like I said, I will probably build one soon ;-)
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Old 06-02-2020, 01:51 PM   #11
musubi
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Re: Rob Allen Inverted Roller

Quote:
Originally Posted by ninjagazz View Post
Some great reply's,

I will definitively loose the big load assist, maybe try a hand held one.

I will increase pre-stretch to 150% and maybe source a bit of 20mm rubber.

I can do 3 pairs rubbers see attached, but 2 will be easier as even having the side mounts makes it difficult to attach bands when loading the secondary bands, i might try the option below. I want to keep this as simple and easy as possible.

The MVD muzzle was not designed for pulleys but for the original inverted design where there was normal roller wheels were near the handle as well. The small wheels keep the line against the barrel so when the pulleys approach the muzzle during loading they get jammed against the barrel causing a lot of friction and limiting how close the pulleys can get to the muzzle.

The Plug was put in so there was minimal gap between the it and the muzzle. I did fill the muzzle with resin, to stop water getting in. I hate the way water gets in behind the muzzles and handles of RA. There is no evidence of the barrel leaking. it just heavy. I got offered a floater by pathos, but it was interfere with the pulleys.

I have been very interested in your setup Musubi, thanks for your replys. What distance did the 8.5mm shaft get to before loosing trajectory?

I would like the RAM style muzzle, i will invest in that setup if i can get this to work.

Mannysub uses a 20mm pair and 2 pairs of 14mm rubbers to throw a 8.5mm spear. Not sure of the pre-stretch.

Muzzle Comparison


3 Rubbers Config


2 rubbers config, with one being 20mm


Pulley details
Ah, I understand now about the muzzle. The new RAM muzzle seems better, but my pulleys still touch the barrel. I don't see any scraping against the barrel or much drag if any for what it's worth.

If I recall correctly, after 10 ft from the tip of my gun the shaft would start dropping. At 15 ft, it was dropping to 4 inches below center shot. I repeated this a few times with the same result. I did not test penetration since I don't currently have a setup for that.

I have a 7.5 mm in my 4 band pair setup now and it's worked well on penetrating wahoo and big mackerel tuna.

Quote:
Originally Posted by diveincanada View Post
I know there's a lot of hype around rollers. I'm been building guns for just about a year now and having a blast doing it just for fun, just for my personal use. I've been wondering about building a roller but at the same time, I like the simplicity of a standard speargun.. When I set up my stuff, rig my gear, I always try to Keep It Simple... And to me, a roller seems like so many more elements that can go wrong. When you spend your money for a nice spearfishing trip you want your gear to work. Seems to me a simple band fail on a roller will be a pain.. Then again, I dunno how much better they shoot.. So like I said, I will probably build one soon ;-)
That's definitely one of the cons about the invert gun. It's complicated enough to where it's harder to replace a band if it breaks. I'm always checking my gear and making sure I replace anything that's starting to look worn out. I'm taking day trips only to spearfish, so if something should happen, I have my three-prong spear as backup and wouldn't be too bummed for the day.
If I was planning a trip, I'd for sure bring a classic setup reef/BW gun as backup (along with repair parts for the invert).

The two main pros for me with the invert is the clear line of sight and the super low recoil. The low recoil affords me to shoot at odd positions and angles without having my arm or wrist locked out.
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Old 06-02-2020, 04:25 PM   #12
popgun pete
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Re: Rob Allen Inverted Roller

The real benefit of an inverted roller is that it can enable the construction of a cable gun. A cable gun has exposed cables and a hidden "engine" in the gun. Kosta's gun (Seal) achieved this set-up by burying his bands in the gun profile when the gun was cocked which improves the gun's hydrodynamic shape. Another cable gun will be the "Dreamair", if it ever hits production. Inverted rollerguns with bands exposed don't have this advantage unless the bands lie flat against the lower deck once cocked. Standard band guns are more impulse weapons than long stroke drivers. In a rollergun unless it uses preload the final push on the shaft is rather weak even though the power stroke is long. Preload means the gun stores more energy than it actually uses for the shot.
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Old 06-18-2020, 12:57 AM   #13
ninjagazz
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Re: Rob Allen Inverted Roller

I have updated the gun by shortening the rubbers and adding a pair of 20mm rubbers. I took the gun to a container pool setup as a underwater range today.

The gun shot a lot better than before. I did have a bridle snap under load so the guns isn't under powered.

In this configuration the gun had exactly the same penetration as my riffe euro (But i had to load 3 bands not 2).

Pretension was about 120%

Rubbers were stretched to about 330%.

There is room for improvement here with a slightly shorter line thus more stretch. But my riffe euro could do with some better, shorter rubbers as well instead of its elcheapo ones.

I am still not sure how a gun like this shoots a 8.5mm shaft. (ie mannysub inverted roller)

The gun was knocked out of the comp after the first shot, The 2 guns which stood out were my 4 rubber midhandled cannon made of merbau and a modified Salvimar vuoto 115. Both were fully penetrating the max thickness targets made of 3 inches of HD foam, 4mm of rubber and a bodyboard. We need to get new targets and a longer range.

On a side note the Cressi seatta pro is a stunning speargun. A step up from the Salvimar predathor vuoto.





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