shaft size and bands???

[joker]

Hey all, well it's time for me to start building my speargun, and I am wondering how to determine shaft size and such....

I am hunting in freshwater...visibility really depends on the lake, and I will be mostly after panfish and carp..

I don't need much power for panfish, but for carp i need alot.

I was thinking getting a 5/16"x32" shaft...

but for bands i don't know how to determine this... I know for carp i need alot of power cuz they are so tough... but how should i determine what size bands to get???? How can i determine a good band length and width so that it balances good and is accurate???

any suggestions on spear length, diameter, and band width and length??

Thanks,

joker

PS. I know this is in the beginner hunting, i asked for a mod to delete it, i decided this is a more appropriate place for it.

 

[spaghetti]

So what's the gun length on your mind? (please in centimeters, or euro-peones like me won't understand inches).
Basically, an euro type gun's length refers just to the barrell length. So when I say "a 75 euro" I mean than the BARRELL is 75 centimeters long: handle and muzzle don't count.
In the case of a woody, the length in european "language" is determined this way: from the second notch of the shaft to the point where bands are attached to the muzzle/barrel's edge.
This said,
-for a 75cm barrell euro (a reasonable length for freshwater) the correct shaft is 115 centimeters long, correct 20mm circular band is 42cm long.
-For an 80cm gun, shaft 120, bands 44.
-For a 90cm, shaft 130 and bands 48
Hope this helps.

 

[joker]

ummm well i want to build a gun that is shorter than me, so one that's shorter than 157 centimeters... Umm i would hope that it would be around 75 centimeters so it is easier to hold.. Okay so I would want a 115 cm shaft, and is there a particular width of band that you need?? If so why is that?? And how do you determine band length??? Remember though, i would be shooting at carp, so it has to be pretty powerful right?? Should i mount two bands into my gun??

 

[spaghetti]

No I don't think you should mount two bands: more power reduce accuracy and the gun is harder to swing.
So my word is no gospel, but if you ask me, for a 75 euro this is a correct set up with a good power and punch:
band: one circular band, 20 millimeters thick, 42 centimeters long
shaft: single flopper tahitian, 115 centimeters long, 6,5 millimeters thick.
---
For the power thing, note that the average 75 euroguns are sold with 6 or 6,3millimeters shaft and 16 or 18 millimeters band. So if you decide to follow my humble suggestions and mount 20mm bands and 6,5mm shaft your gun will have more "punch" than the average for this category of gun.

 

[joker]

okay...

but by the way..I'm not really buildin a eurogun, I'm just building a plain wooden gun with a rear handle, and a simple rail, not a euro rail where the shaft is only supported in two spots, but a rail... so does that make any difference???

And how do you determine the length of the bands??

I'm just curious here, trying to learn all i can,

soo if i build a 75 cm gun, get a 6.5mmx115 cm shaft, with 20mmX42cm bands then??

cool thanks,

joker

 

[spaghetti]

okay...

but by the way..I'm not really buildin a eurogun, I'm just building a plain wooden gun with a rear handle, and a simple rail, not a euro rail where the shaft is only supported in two spots, but a rail... so does that make any difference???

And how do you determine the length of the bands??

I'm just curious here, trying to learn all i can,

soo if i build a 75 cm gun, get a 6.5mmx115 cm shaft, with 20mmX42cm bands then??

cool thanks,

joker

...and then you have to build the gun.
Note that european woodies have a full length rail.

 

[joker]

umm okay..what does that have to do with determining band length??

how do you determine that??

 

[spaghetti]

the lenght of a circular band is taken between the two edges were the wishbone is attached.
But if you ask WHO and WHY determined that, this is the answer: the length of bands sold with guns of each length are standards derived form testing and experience: worldwide, manufacturers found out that on 75 eurogun a 42cm band gives the best performance, that on a 90cm gun a 48cm band shoots better than any other length option, et cetera et cetera.
Now my question is, and forgive me for asking, but: how much experience do you have with spearguns? I don't mean bulding them, but using them?

 

[Spaniard]

If you are using 'screw-in' pair bands then 19cm is a good guide for a 75cm gun; that is 19cm each band.

 

[Shadowkiller]

Forget the 6.5mm shafts. A decent fish will bend them like a pretzel.

I assume you will be diving in 3-4m viz?

Make your gun ~75cm from muzzle to triggermech. Site the handle towards the middle of the gun. This will make it nice and easy to swing around. Use a nice solid shaft, 7.5mm or 8mm, 1m long, plenty of punch that way. Twin 16mm rubbers (each rubber 50cm total length, so 25cm a side) for plenty of shaft speed. If you are making your own gun, then you will probably use a bulk rubber muzzle (see Riffe guns for what I mean), which is way cheaper than screw-in rubbers which require you to buy a muzzle.

Rubber length is calculated using the 3:1 stretch "rule". So for a 75cm gun, a rubber that is 25cm will stretch to 75cm, or 3:1

And heres a gun building tutorial by the Sultan himself:
Build Your First Speargun - A Beginners Primer by Sven Anderson on DeeperBlue.net - Fanatical About FreeDiving, Scuba Diving, Spearfishing & Technical Diving

 

[Ron S]

It sounds like for what you want to build and for what you want to hunt, you're talking about something along the lines of a Riffe Comp #0 gun as far as demensions. I'd take a look at the Riffe website, (speargun.com), and look at the dimensions of the comp series of guns. It shows shaft lengths, band sizes, and band stretch for each size of gun.

I only suggest this because you first mentioned using a 32" shaft, and that's gonna be a much shorter gun than a 75cm Euro. It's hard to compare the Euro guns to the American guns in terms of sizes because they're measured very differently.

Ron.

 

[Jack101]

What kind of bands and shafts would i use for a 75cm gun in salt water

 

[Selenium]

What kind of bands and shafts would i use for a 75cm gun in salt water

You don't really read much do you ?
First decide what you are shooting, that is how you decide the thickness of the shaft
then find out where this fish lives and how you are going to shoot. It... the visibility in the area..., that's how u find out the length of the gun.... then add the overhang for the spear and now u have the spear length, spear diameter and gun size.
Now you can start thinking about rubber bands considering all this..