Band Risers

Quote from Dude george

So I have seen many threads on the net about speargun builders looking for that perfect groove to set up their bands into a elevated and even layup against the gun as they are stretched out into the loaded position, it is touted that it reduces muzzle jump.
My question is this: is it something important, functional or even useful?

Yes.

Get the rubber to pull on the same axis of asymmetry as the shaft.....Chicks dig it.:thumbsup2: and you'll shoot straighter and get bigger fish.

Cheers, Don

In theory it is useful, as don said. The closer to parallel, the greater the reduction in muzzle lift and recoil becomes more directed into you as less making the gun jump.

That said. I see a lot of guns that do not elevate the bands they have simply added grooved areas for the bands to recess into. These are beneficial for the fact that they reduce to file which reduces drag. They do not help with the issues don mentioned. The really cool muzzles do both

The way I see it there are two separate issues you're raising here George. One is band elevators for the purpose of bringing the band pull inline with the shaft travel path, with the goal of increasing accuracy. The other is shaping the speargun stock in such a way that when the bands are stretched everything is nice and compact. To me neither of these factors is significant for better functionality of the speargun.

There's nothing more compact than a slim rectangular shaped stock (the longer side being vertical). When the bands are stretched over it the outcome is a more or less rounded profile that is easy to grip and carry.

Unless the bands are elevated directly from the anchoring point like in this style gun, IMO it won't make a difference.

If the bands are anchored lower than the track, and are raised in any number of ways, a steel rod through the stock, or wings shaped onto the stock, there will always be a point in the contraction of the bands that will cause movement due to opposing forces exactly where you want there to be no movement. Of much more significance is recoil control via manipulation of the weight of the gun and band power. If this wasn't the case none of our simple pipe guns would be accurate. Just my :twocents:

Quote from Dude george

Don so simply putting say a old shaft through the front of your gun and having the bands lay up on them will achieve this beneficial effect? If so why dont I see it more do you think?

Yes that would work providing the barrel is not weakened. I like to see wood muzzles that have this geometry factored into the build.

The euro guns do a good job with this as the muzzles are designed with this in mind.

I'm heading out to do some boat work, I revisit this thread.

Cheers, Don

I think if you need band elevators, the gun is either overpowered or poorly designed.

I like the Alexander muzzles on my Wong MGS and Ono because the band slot is the highest I've seen on a wood stock gun.

Then I got into roller guns. If the roller is placed correctly, it lines the bands up perfectly. And the minimal kick also reduces any muzzle flip.

C

To satisfy my own curiosity, I just did some quick sums on this for a gun with a 1.4m stretched rubber length.
If the rubber holes are in the centre of the stock for an 80mm deep stock, the angle of pull is roughly 1.5degrees. Assuming 4 bands and 45kg force on each band (100lbs), thats a total of 4.8kg downward force. If you move the rubbers up 10mm, the angle is reduced to 1 degree, and the downward force comes down to 3.1kg.

A pretty big reduction percentage wise, but I'm not really sure what effect this will have on the spear or the feel of the recoil, which is where real world experience comes into it I shoot mainly a single 18mm rubber on a 1.2m railgun. 5kg vs 3kg would feel pretty different on an outstretched arm I would guess.

As the shaft moves down the stock the angles increase but the forces decrease, so I think at trigger pull would be worst case. I'd be interested to see in super slowmo at what point the wishbone loses contact with the shaft. I imagine it is pretty soon after release.

I remember somebody posted once that he likes long bands, because they continue to push the shaft for a longer time, meaning past the muzzle after the shaft leaves gun

I would hate having that metal bar through the stock of the gun as pictured

Didn't know what band riser use for but now i know. Anyway i notice they add new product to neptonic system's site. A band riser that easily attach to any wood speargun. Don't know if it is good.

Check out this link:
Speargun Band Elevators

Quote from sdeisen

I would hate having that metal bar through the stock of the gun as pictured

These are not guns that you carry swimming around the reef.

Quote from Dan

These are not guns that you carry swimming around the reef.

That is a good point

Those neptonics ones look pretty cool. I feel like anything you move drawn bands across will shorten the life of your bands

The large, mid handle, open track, Riffe guns are much more accurate with the bands more inline with the shaft.

True.

Quote from LunkerBuster

Those neptonics ones look pretty cool. I feel like anything you move drawn bands across will shorten the life of your bands

The stress of laying over a band riser would be a lot less than where they do a 180 degree turn in the holes on the muzzle.....which makes a split band seem more logical..?

I thought about that. In my small monkey brain that is the band stretching without sliding or being pulled across an edge.

Well fit bands don't move around after being fired so I assume they aren't moving too much during the shot. My bands are always changed before they fail. I like short tight snappy bands.