Riffe MT0 Roller?

[Fondueset]

Well, I plan to go diving xmas day, or new years - but the air temp here has been mostly in the teens (F) with strong winds and fairly heavy snow. This makes it hard to get in the water without allready being half frozen. Consequently the mind, which is like a room full of dominos falling onto mousetraps - boogies. In such an environment I thought 'why not have an idea!?'

I've been reading a little about roller guns - and they seem pretty cool - particularly for small guns.
I'm thinking it would be neato to design a roller kit for the Riffe Mt0. I'd like it to be made with maybe nylon rollers - as small as possible - built into a mount that will fit firmly into the band space on the mt nylon muzzle. I also think it would be interesting to mount two of these - a double band roller gun. Then of course I'd want to secure the longer bands somewhere along the bottom of the gun. I'm assuming you determine band length by measuring the stretch from where the wishbone rests with the band pulled taught but not stretched - to the last fin on the shaft - then get a band that has that distance for it's optimum stretch and take up the diff along the bottom.

Any ideas for materials, sources etc. Also general comments on the efficacy of roller guns. It seems like these would be more accurate than just adding more bands because of more gradual acceleration along a longer distance.

 

[PhilLJCA]

just out of curiousity what is a roller kit and what is its purpose?

 

[Mr. X]

just out of curiousity what is a roller kit and what is its purpose?

Roller guns have been around a long time (maybe 50 years or more)...not sure what the advantage is -- perhaps a lot of power in a short gun? Seatec (which I think belongs to the founder of Omer, Valerio Grassi?) currenty produce the one below:

<http://www.spearo.co.uk/shop/g3uu3dcw5woz/cgi-bin/commerce_pro/commerce_pro.cgi?page=seatecgun.html&cart_id=2381312_18692>
http://www.spearo.co.uk/spearo.htm

 

[icarus pacific]

Yeah, it's a neato idea, but what's your time worth? And for what? Carp and the odd pike? Then again, if I lived back there in the Winter, I'd do it for lack of something to do.

Seriously, a roller allows you lengthen the bands rather than adding thicker bands and it makes the recoil less, increasing your accuracy.

Scot Merlo offers a roller, but get in line and have the coin ready.

Materials-wise, you'd do well to have the thing made from UHMW, Delrin or the like. Common woodwork and metals machining gear will handle it.

 

[Fondueset]

I leave the carp alone

But then we have only the old fashioned carp here - not the invasive monstrosities they have over in Wisconsin.

It's 19f here right now - it's not the dive - it's the walk!

And what's so odd about pike?

 

[Cingene]

How far are you from Petoskey, Fondueset? My daughter lives there. (I wonder how cold the water is in the Great Lakes...brrrr)

 

[PhilLJCA]

ok thanks for the replies but im still not quite clear: does the shaft exit the gun by rolling along the track. does it use ball bearings? does this reduce friction? btw nice pic Fondueset.

 

[Fondueset]

philljca - if you do a search in this forum on 'roller' theres alot of info - which I discovered AFTER I posted this question The roller design only effects the way the bands work. My Idea is that it would be cool to make a kit that is easy and quick to install and would fit right into the existing Riffe Muzzle.

Cingene - I'm about 70 or so miles south of petoskey. If you look at a map of Michigan - Traverse City is right at the base of the two long bays that define the 'little finger'. I haven't been in since mid-november and it has been unusually cold since the first snowfall shortly after that so I'm guessing low 40sF right now. I'll let you know when I do my new years dive if not before

 

[Mr. X]

Seriously, a roller allows you lengthen the bands rather than adding thicker bands and it makes the recoil less, increasing your accuracy.

Are you sure about the recoil being less? This came up in a thread on recoil recently -- I don't recall the discussion reaching a definitive conclusion though. I think there may be a related issue (muzzle flip/kick?).

The main aim of rollers seems to be allowing a shorter gun to use longer bands and/or have a longer draw, thus providing easier loading and/or more power (more power in a less massive gun would usually cause more recoil rather than less). Having more rubber doesn't equate to more power though -- spearos sometimes cut their rubbers short to increase the power (which makes loading harder). Presumably increasing the draw length is the important factor for increasing power(?)...not sure if it is just draw length or draw length (stretch) relative to relaxed band length; probably the latter.

 

[Fondueset]

It makes more efficient use of the length of the gun - more power - fewer bands and less abrupt acceleration. It is logical that there would be less recoil when the shaft is accelerated more gradually over a longer distance and, based on the threads I've seen where divers have described using them this appears to be the case.

 

[Mr. X]

It makes more efficient use of the length of the gun - more power - fewer bands and less abrupt acceleration. It is logical that there would be less recoil when the shaft is accelerated more gradually over a longer distance and, based on the threads I've seen where divers have described using them this appears to be the case.

Interesting...less acceleration but over a greater distance producing, potentially, a greater final velocity when the spear is eventually released. Yes, I suppose that would produce less recoil (Newton2: F=ma, Newton3: F = R) and, also, a spear with more energy (1/2*mv^2) and momentum (mv).

 

[seaman]

Take a look of the gorgeous looking roller gun of Scott Merlo..

www.merlospearguns.com

 

[Cingene]

Those Merlo guns are beautiful!

 

[Fondueset]

I like the grip he uses - also how it is attached.

 

[seaman]

Yeah, you are right, is inspired in a S&W pistol grip, same as aimrite handles that are very similar to the colt 1911, great handles by the way

 

[Mr. X]

If you like wooden grips, there is an Italian guy and a Greek guy that posted images of their DIY guns in the equipment forum that look amazing. The Greek one looks like a work of art -- especially the carved handle that partially wraps around the hand.

Another interesting looking wood gun on P10 of the Merou catalogue -- nice grip: http://www.europeanspearfishingsupplies.com/downloads/Merou 2005 catalogue.pdf

 

[seaman]

Wow man, there is something about wood that really turns me on, sexy uuh?

 

[khel]

Sounds like a fun project. Any progess on it?

I think that it'd be great if someone made a roller-muzzle for euro guns (something like hammerhead muzzles)

 

[spaghetti]

Roller muzzle for euro guns is exactly what Seatec did with its smart but unfortunate "Roller sea magic". That gun's been developed by Valerio Grassi from a project of Oreste Vacondio, the italian national champion of UW target shooting. It's different from other roller guns because it has a "power reductor" device: if you must shoot into a rocky cave, for example, and you need a less powerful shot, you may shorten the effective portion of the bands by pulling a leverage (that's the "magic").
Unfortunately, production had to be stopped due to patent issues.

 

[khel]

Roller muzzle for euro guns is exactly what Seatec did with its smart but unfortunate "Roller sea magic". That gun's been developed by Valerio Grassi from a project of Oreste Vacondio, the italian national champion of UW target shooting. It's different from other roller guns because it has a "power reductor" device: if you must shoot into a rocky cave, for example, and you need a less powerful shot, you may shorten the effective portion of the bands by pulling a leverage (that's the "magic").
.

That's interesting, I hope they'll come out with new version soon.

p.s. the only info I found on "roller sea magic" was that picture