Lots of questions about spearguns.

[SknDvr12]

1)Planning to switch a single rubber to two smaller rubbers. right now i have a 20 mm euro band and i am wondering if two black 9/16 bands would be stonger, weaker or equal?

2)How much bands can a 7mm shaft handle assuming the trigger can handle it?

3)How do you find out the trigger capacity of a gun? i recently bought a Sporasub Instinct Pro 100 and at first band i used was hard but i think i want more power from it. it think it is a 20mm. I hear the trigger is not that good on these guns, well so someone said, and i hear too much band power can damage the trigger mechanism, so i was wondering how to find out the capacity for the trigger mechanism, to get the optimal amount of power from the gun, without braking it.
I was thinking of adding an additional band rather then get one really big one. so I'll have the 20mm euro band and then add a second band, thinking a black 9/16.

and the last question...

4)What is the pounds equivalency to rubber size, (ie. one 9/16 =100 pounds?(not right but my example)) Because i hear some tiggers can only hold so much. i think the sporasub is 200, if im reading the info right, thanks.

 

[Marwan]

hi, i wont be able to answer questions 3&4 ( too technical for me , i just want to catch fish ),
question 1: i think the 9/16 bands (14mm) would be weaker than a single 20 mm band. i would always advise to use a single band, much easier/quicker to load. If you find it hard to load or an verkill for th type/size of fish you hunt, use an 18mm or 16mm single band
Question 2: depends n the gun, most euros would handle 2 bands only, but the US type models like riffe etc. could use up to 3 or maybe more bands on a 7mm shaft.
where do you hunt, what type is your gun (sporasub?), what is the length? what type/size fish?

 

[Pastor]

3)How do you find out the trigger capacity of a gun?

Dude there 2 ways of doing this:
1) email sporasub

2) clamp gun in strong vice, attach strong wire cord to spear in gun in such a way that pull of wire is in line with spear shaft and then around a single pulley to run vertically. To the end of the wire cord attach a weight carraige. Now add weight in small known increments untill the trigger expoldes; then you'll know
EDIT: Oh yeah, when you do this stand to one side as otherwise when that trigger goes the spear will be travelling in your direction. Ever thought of the Wong railgun? trigger tested to 600lbs, lifetime guarantee and made in your neck of the woods

4)What is the pounds equivalency to rubber size

This is a bit like asking which cars are fastest, red or blue. This depends on the band, its quality etc etc. There is some really powerfull 14mm out there that length for length will pack more punch than a crap 16mm

 

[SknDvr12]

thanks, and i got a sporasub pro 100, questoin 1 is kinda just a question my friend had. i reef dive in hawaii. and the fish are all sorts of sizes.
i also hear that two band are better then one, for velocity reasons. I'm fine with the 20mm as of now, it has been pretty damn on target, in my tests. but i figure if the velocity is better then i could get fast reef fish as well as the nice uhu i see swimin round.

I never really heard about band quality, all i know is the red is softer then black, i dont know of any band brands. SO i cant be too picky. But what i was wondering is how much pounds of force is given from a certain band. like how much pounds of thrust will a 5/8ths band have, i hear 100 adn 150, big differance.

 

[sickbugs]

different band makers, different quality bands.. if you are good with the 20mm, why change it? 2 bands take longer to load than 1 (not bad if you have the extra time) but i do think that 2 bands will offer more power, once they are good quality 16mm bands. however, if it isnt a good strong shaft, you might get shaft whip (does the gun have a rail?) which will affect accuracy, kind of like throwing a rock vs using a slingshot...sure u can hit with the rock, but its a lot more accurate with a slingshot


if a gun is shooting well, leave it how it is, its hard to get a gun to shoot properly, and really easy to get it to shoot badly, if you want a stronger gun with more bands, why not get a second gun? your probably going to want one in the future anyways. if i may be as bold as to make a suggestion for one, aimrite railguns are super accurate, pack a great punch, have a trigger that is about 5 times as strong as you will need your trigger to be, and have a lifetime warranty.. and buy one for me too while your at it

 

[SknDvr12]

i got a 7mm shaft.
i have not gotten to take it into the ocean yet, but i guess ill test it there befroe any real mods to the gun.
i hear that flattening the barb can help increase accuracy, but i wont mess with that just yet.

 

[spaghetti]

Hiya ;-)
Not a techinical answer, but I remember that the Hawaii Skin Diver Magazine tested the Instinct with two bands and reported a good performance and accuracy with that set-up (two 9/16 bands).
You can find it in this thread:
http://forums.deeperblue.net/showthread.php?t=63318&highlight=instinct
hope it helps

 

[SknDvr12]

Do you know what issue that was in?

 

[bloos]

I find that if the gun bigger than a 140 then 2 rubbers needed as it is hard to load especially if you have a short reach.
Go single if you can with good quality rubber ;-)

 

[SknDvr12]

ya i got a stock 20mm euro band, i guess it is good quality.
some dont like the euro bands, why is that? i noticed that the wishbone gets caught in a stange position sometimes but thats it, other then that i like it. no problems, but i have not used a normal band.

 

[miles]

Hiya

SknDvr12, many spearo's prefer dyneema wishbones as opposed to the standard articulated wishbone. What often happens is that the wishbone "jumps" out of the spears notch when incorrect loaded and then the articulated wishbone CAN seriously damage your fingers!! Similarly, when unloading your gun, should the rubber jump out of your hand, you're likely to hurt your hand!!

Changing to dyneema is very easy. How-ever, your spear's notches WILL have to be made SMOOTH, or else it will simply cut the dyneema.

Regards
miles

 

[Spaniard]

I remember reading, in a Spanish issue of Apnea, a comprehensive test on the major European Manufacturers of screw in rubbers; Cressi, Picasso, Sporasub, Beuchat etc. etc. and the 16mm Sporasub bands did very well in all areas. I'll see if I can dig up the magazine and if so i'll summarise findings.

 

[spaghetti]

I remember reading, in a Spanish issue of Apnea, a comprehensive test on the major European Manufacturers of screw in rubbers; Cressi, Picasso, Sporasub, Beuchat etc. etc. and the 16mm Sporasub bands did very well in all areas. I'll see if I can dig up the magazine and if so i'll summarise findings.

Spaniard, were they still the Dessaults or not?
SknDvr12: I don't know what issue of Hsd magazine it was. Ask Mark, who posted the scans in that DB thread.

 

[Spaniard]

Spaniard, were they still the Dessaults or not?
SknDvr12: I don't know what issue of Hsd magazine it was. Ask Mark, who posted the scans in that DB thread.

Yes as far as I remember they were the Dessault bands.

 

[SknDvr12]

Does anyone know how to fit the shaft to use the dyneema?
Is it simple filling?
I have noticed the danger part, it happend twice to me, it sliped and if not for my gloves would have chopped a good cut into my hands, second time, felt like it cut me throught the glove, thank god it didnt.
I guess i'll try the dyneema if i can customize my shaft, and while i am at it i guess ill change to two 9/16s

 

[Dobs]

Does anyone know how to fit the shaft to use the dyneema?
Is it simple filling?

A fine file or sandpaper will do the trick. Some use a kind of abrasive paste used for car engines if I remember correctly. I use only sandpaper and it works just fine.