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Speargun project
- Thread starterwhitey180
- Start date
Thread Status: Hello
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Well maybe, but that depends on how you look at it and if there are some wanted design reasons for it..
Will be a lot less if you use a longer spear...
Jégwan
I always have about 400mm of spear out past the muzzle. Next I tune up the gun along the same principle as tuning archery gear. An bow is never tuned so that an arrow comes out "centre". If it did then any variation or weakness in an arrow would case it to bend into the weakness & be different with each shot, 360 different directions. Bows are tuned so an arrow points out slightly from centre. This means that the arrow will always bend into the arrow rest when released.
Spearguns are much more simple & we are shooting much shorter ranges in a denser medium than archers, still there are some basic principles I like to follow.
First if your gun deflects or bends when loaded, think what will recover first when the trigger is slapped, the rubber or the barrel? Bendy barrels are bad. Next of your track is higher in the middle, even a fraction higher is bad (the more power the worse it becomes), the spear will bend in the middle in an upwards direction & porpoise out of the gun. If the gun is dead straight the spear can bend in any direction from 9-3 o'clock. I like to have the centre of the spear groove a mm or two below the muzzle & trigger. This means the spear always bends down into the gun & this is consistent. I use blobs of 5 minute two pack epoxy as needed in the spear groove to tune the gun. I can do it by eye & use silicone as a release on a larger spear shaft & a few pieces of paper as shims to hold the spear in place till the epoxy sets. I'm pretty fussy about accuracy & expect all of my guns to shoot instinctively & from muscle memory.
Hope this helps.
You've got me interested in what you're going hunting for with the breakaway rig?
Cheers Sharkey
Spearguns are much more simple & we are shooting much shorter ranges in a denser medium than archers, still there are some basic principles I like to follow.
First if your gun deflects or bends when loaded, think what will recover first when the trigger is slapped, the rubber or the barrel? Bendy barrels are bad. Next of your track is higher in the middle, even a fraction higher is bad (the more power the worse it becomes), the spear will bend in the middle in an upwards direction & porpoise out of the gun. If the gun is dead straight the spear can bend in any direction from 9-3 o'clock. I like to have the centre of the spear groove a mm or two below the muzzle & trigger. This means the spear always bends down into the gun & this is consistent. I use blobs of 5 minute two pack epoxy as needed in the spear groove to tune the gun. I can do it by eye & use silicone as a release on a larger spear shaft & a few pieces of paper as shims to hold the spear in place till the epoxy sets. I'm pretty fussy about accuracy & expect all of my guns to shoot instinctively & from muscle memory.
Hope this helps.
You've got me interested in what you're going hunting for with the breakaway rig?
Cheers Sharkey
Wow. Okay so once you get the blobs in the right spot you then epoxy the whole track with the spear in to make a perfect fit? Or am I reading it wrong?
I'm using a breakaway for a few reasons, where I hunt ( more in winter than summer ) can sometimes hold kings upwards of 30kgs. Even marlin have been caught there. I've also seen a few tax collectors and feel safer if my pants aren't around my ankles after I shoot a fish lol.
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I'm using a breakaway for a few reasons, where I hunt ( more in winter than summer ) can sometimes hold kings upwards of 30kgs. Even marlin have been caught there. I've also seen a few tax collectors and feel safer if my pants aren't around my ankles after I shoot a fish lol.
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It depends on the gun, sometimes only one dab (25mm in length) of epoxy at the front, is enough to lift the spear & overcome a hogsback in the barrel, sometimes three or four down to the trigger are needed.
I have never used a breakaway for marlin or tuna or kings. I just attach the gun straight to a bungee (no speed rig) if I'm chasing large fish. I'd rather keep things simple & breakaways may be ok for tea bagging, but if things become exciting & you need to load or reload quickly, or your being picked up by the boat to be dropped off beside your mate, who has a school around a fish he's speared & holding them about for you to get one too, etc, etc, then breakaways are more trouble than they are worth.
Below is a small black (31kg) taken at the entrance to Sydney harbour that showed up when I shot a king. I wouldn't have even been able to reload & get a shot at this fish if I'd been using using a breakaway.
A Sydney King (bigger than 30kg), single rubber, no breakaway, no problems.
Keeping things simple can be difficult with so much gear to choose from, but remember if it ever fails in practice, it will fail when you need it. Even for really large fish, I'm yet to be convinced in the benefits of a breakaway rig.
Keep us posted on tuning your new gun.
Cheers Sharkey
I have never used a breakaway for marlin or tuna or kings. I just attach the gun straight to a bungee (no speed rig) if I'm chasing large fish. I'd rather keep things simple & breakaways may be ok for tea bagging, but if things become exciting & you need to load or reload quickly, or your being picked up by the boat to be dropped off beside your mate, who has a school around a fish he's speared & holding them about for you to get one too, etc, etc, then breakaways are more trouble than they are worth.
Below is a small black (31kg) taken at the entrance to Sydney harbour that showed up when I shot a king. I wouldn't have even been able to reload & get a shot at this fish if I'd been using using a breakaway.
A Sydney King (bigger than 30kg), single rubber, no breakaway, no problems.
Keeping things simple can be difficult with so much gear to choose from, but remember if it ever fails in practice, it will fail when you need it. Even for really large fish, I'm yet to be convinced in the benefits of a breakaway rig.
Keep us posted on tuning your new gun.
Cheers Sharkey
Nice fish indeed! And thank you for your replies so far mate. So the epoxy is to lift the spear up off the barrel so that if barrel flex exists it does not cause the spear to porpoise. Can I ask exactly how you work out where to put what? I'm keen to learn I'm only new to gun building and what you're saying makes a lot of sense.
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Sent from my iPhone using Tapatalk 2
I'm looking forward to seeing some nice fish from yourself.
You don't want the barrel to flex at all, because if it does you can bet it will recover before the rubbers do, so the spear will not get the best start.
I work it out by eye. I look down the spear & if its too high in the middle then I'll raise the front & maybe some at the back. If its too low in the middle (not common in most guns I've seen) then some epoxy in the middle. I'm only talking 1 or 2mm, but when the spear wants to bend into the barrel not away from it you'll get consistent results. Also once you know how to tune your guns, you can have then all shoot the same & have the confidence to pick up another gun if its needed. No more "this one shoots high" or "this one shoots low", they should all shoot straight.
Cheers Sharkey
You don't want the barrel to flex at all, because if it does you can bet it will recover before the rubbers do, so the spear will not get the best start.
I work it out by eye. I look down the spear & if its too high in the middle then I'll raise the front & maybe some at the back. If its too low in the middle (not common in most guns I've seen) then some epoxy in the middle. I'm only talking 1 or 2mm, but when the spear wants to bend into the barrel not away from it you'll get consistent results. Also once you know how to tune your guns, you can have then all shoot the same & have the confidence to pick up another gun if its needed. No more "this one shoots high" or "this one shoots low", they should all shoot straight.
Cheers Sharkey
Awesome to see it in action! May I ask, why is your line (ripe) so thick? That causes a lot of drag in the water. Try a 320% setup if your using a 7.5mm shaft. Next time practice on a target so your know where your shooting too, itll help a lot solve your troubles
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Shooting line is 1.8mm thick just mono. That's the normal around here. I had every intention today on setting up a target in the river but couldn't resist the urge with the amount of fish around. Nothing to write home about but dinner and targets none the less. For the first time in three dives with the gun I shot 3 in a row, and all by doing one simple thing. Imagining my gun was an extension of my finger and taking my finger off the trigger and pointing it at the fish. Bang three in a row. Before that it was none for at least 15. So chuffed lol
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It's not as simple as the thickness of the rubber. Its the relationship between the stiffness/spine of the spear, its length & how much energy is transferred (from the rubber/rubbers) when the trigger is slapped. Eg, a 1.8m X 7mm spear will be much softer than a 1.5m X 7mm spear so a longer gun requires better tuning than a shorter one. Folks also like to add extra rubbers to long guns which compounds problems if the gun isn't tuned, or the rubber power, spears stiffness, & gun weight, rigidity & barrel/rail aren't in balance.
When the trigger is slapped the spear goes from being relaxed to being put under instant force starting from the rear. We want the back of the spear to push the front as smoothly as possible without it wanting to overtake it. Its a compromise between the rubbers, & the length & stiffness of the spear. Spears can be made stiffer by increasing the diameter but this is a compromise & adds weight to the gun.
There are some "sweet" combinations which are easy to tune, but once folks start to overload their guns strange things can happen with accuracy. Eg, just the slightest bend in a spear will cause it to bend into that weakness & cause accuracy issues which were unnoticeable at slightly less power.
Just for some discussion.
A "compound" speargun will be able to "in principle" shoot a spear much thinner & with less spine/stiffness more accurately than a standard rubber powered gun. The reason being is that the spear starts slowly (50% power) & isn't subjected to the sudden burst of energy like a rubber gun. In a compound, the full energy is transferred to the spear after its already moving, so there is less stress or flex in the spear. A analogy is, a standard rubber gun is like starting to drive bike in forth gear & when you are moving then shifting gears down to first. A compound speargun reverses the power stroke & is like starting in first, & working your way up through the gears as you move. Much better use of energy. I'm surprised that we haven't seen one on the market already. If anyone is interested, take a look at compound bows & how they work. If trying to make one, get the largest "round" (not cam) eccentric's you can find & remember that the pull stroke will only be 20 or 30 cm, so something similar to the front of roller guns will need to be installed this distance in front of the trigger. Rubbers will only need to be 30mm in length but a couple of leaf springs (like small bow limbs) may be a maintenance free option & do away with rubbers completely.
Cheers Sharkey
A
artiz
Guest
Great thread whitey180... some top advice from everyone too... very inspiring... how are you getting on with your second attempt and are you happy with your first one yet?
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A few people have been asking how do I tune all my guns & get them all to shoot accurately & to the same muscle memory even though I have so many different sizes, lengths & combinations? I thought I would bump this thread as it explains a little on how. The simple answer is, I create a slight bend down into the spear channel (not straight, a straight spear could go anywhere). This is usually only a couple of mm, but by doing this it means that the spear wont whip like it could on a perfectly straight one. I have been doing this for about three decades now & never got caught up in the craze of enclosed tracks, my comment when they first appeared down here in the early 90's was "stone age men understood more about ballistics than the folks making those". Its interesting now to watch fashion change again & away from enclosed tracks, but I still dont see gun manufacturers following the same concepts that archers have understood for 10 000 years.