Building a speargun

  • OK, I'm going to give this gun building thing a shot! I've been reading and rereading every morsel of information on the topic (here there and everywhere) that I could find. I've finally got things set up in my basement, have my materials and parts. I'm ready to start putting my blank together this Sunday. I've been practicing with 2X4's - the basics like the mech pocket handle recess and line release. I'll have a spare blank to use for test cuts and set up before I start working on the padouk blank I'm making. Even after all the reading, before I start glueing up the blank I have a few questions.


    Question #1
    I've got the West Systems 105 base epoxy and the 205 (fast hardener). I'm in the Northeast and my basement is typically in the 55 to 65 degree F range this time of year. I'm also going to be using the 403 microfiber filler. Does that sound like the correct recipe?


    My wood is padouk. In the shots below; the first one is the day I picked it up from the lumber yard. The other two pieces are reclaimed teak from the USS NorthCarolina that I plan on using in another build (hopefully) at a later date. The second shot is one half of that 10ft 8/4 board. After sitting in my basement for over a month it twisted quite a bit so I had to flatten it with my planer on a sled. I lost 1/2" of wood in the process but I got it perfectly flat. The third and forth shot are from earlier today after ripping some pieces for the glue up. I wound up with four 1/2" X 1.5"X 5' strips and two more slightly thinner ones. I still have half the board left for another piece that I'll use horizontal across the top so I can achieve the correct dimensions I want.


    Question # 2. These pieces I ripped are a little twisted, I'm obviously not going to attempt to joint them because of their thickness. I'm assuming they are OK to use as long as I oversize my dimensions to be straightened at a later date? What's a good rule of thumb in regards to oversizing? I was thinking a quarter inch on the width and height.


    I guess that's all I have for now but I'm sure I'll be hitting all you talented builders up again at some point. Oh yeah, the gun is going to be a mid-handle like the Riffe 44" with a 48" shaft. I do a lot of diving in murky water. I've got a Neptonics reef mech, handle frame, shaft etc. I also bought the UHMW track but I'm thinking I might make this an open track. Thoughts on that?


    Thanks in advance for all comments and suggestions.





  • Twisting is , in my opinion, the hardest problem to deal with when the lams are less than perfect. I would suggest you make sure they are flat along the top when the lam is on edge. Saw or plane them so they are, then when you glue the lams, make sure the twisting is offset to try to balance the internal forces. I would also suggest you hang the blank for a couple of weeks after it is glued up so you can tell how / if it's going to show any twisting. Normally, 1/8" on the top and sides would be enough, but the lams are showing quite a bit of twisting, so 1/4 oversize would be better.


    Most guys prefer open tracks for murky water, but I prefer enclosed tracks, so that's generally what I build. I think I'm in the minority, however, since shooting a fish too close can wreck the end of the gun if the shaft doesn't clear the track before it hits the fish.


    The Neptonics gear will serve you well - Josh sells good stuff and his service is second to none. Did you get the auto resetting mech? Not sure if you knew it, but you have to ask for it or you will get the version you have to manually reset, or install a separate auto reset. The auto resetting mech has a small tab sticking down in front of the trigger, the manual resetting one does not.


    Good luck with the build - good to see you're already planning another build. Very few builders only build one!

  • I'd go open track dude, you aren't going to be shooting enough bands or far enough to make a difference on a 48" especially in dirty water, might as well save the track for a build where an ET is going to really give you some benefit or return it. Otherwise Woodguy covered everything I could think of and more.

  • Twisting is , in my opinion, the hardest problem to deal with when the lams are less than perfect. I would suggest you make sure they are flat along the top when the lam is on edge.


    I will definitely give them a little trim job to make sure they are all lined up on top. I had planned on doing the double flip so the twisting forces would be alternating with each lam.



    Did you get the auto resetting mech?


    No I wasn't aware of the auto rest mech, I'll get that for the next one. :thumbsup2:


    Good luck with the build - good to see you're already planning another build. Very few builders only build one!


    I have the feeling this is going to be another hobby that becomes a total obsession!

  • I'd go open track dude, you aren't going to be shooting enough bands or far enough to make a difference on a 48" especially in dirty water, might as well save the track for a build where an ET is going to really give you some benefit or return it.


    Yes, that's exactly what I was thinking, the more I read about enclosed VS open the more I was leaning in that direction for this gun.

  • From my empirical knowledge and history; I see closed tracks as something to use as:


    1. A scuba free shaft tool on a gun that has a extra shaft mounted to plug a hog fish with.
    2. A design I tried in 1984 on my over powered 50'' poured graphite track gun and after extensive testing with power and range,mounted the pretty gun in a Brigeport and milled the track open...
    retested...found deeper penetration @ 20' off the tip to the target and never looked back.


    3. Used as a tool by a guy with great mind and build skills;Steve Alexander to keep the bottom shaft in his double from falling out.


    4.A marketing tool Steve then used when coming out to compete with a Riffe Blue Water gun,followed by more Scuba lovers in Florida... see #1.
    But... now the cool ''state of the art'' factor motivates guys to order guns from Steve Alexander in closed track.Jay Riffe counters with a closed Metal tech that sinks...see #1. 1990's a dive mate of mine bought one(Steve's) and could no longer make the long shots he was used to. I pool tested the gun for distance and penetration, then told the gun owner I would buy the gun from him if it didn't shoot further after I milled the track open.....it did and the gun stayed with him and served him very well.


    In conclusion; lets look at the state of the art carbon guns in Italy and Greece in 2000 to 2004...
    no ETs. because they know how to design and match the power to the gun.
    I bet under their breath their saying ''those crazy Americans will even pay $110.00 for a
    Titanium knife that cuts like a laser, but will not hold a edge''.
    So the tail wags the dog and now we even have the Greeks and Italians on board with guns that ''shoot like a laser''. :rolleyes1: But guess what... Americans will buy them along with their cross drilled brake rotors and painted calibers that they think look hot and stop better.


    Somewhere on the web Steve Alexander is asked about his closed track guns shooting further... he tells the truth saying to the effect that ''well mine don't, but when the gun is leaning up against a wall and falls the shaft stays in place''. Recently Mori was asked the same question.....guess what he replied?


    I believe owner peceived value and cool factor is what sells here, gives a guy something to talk about at the Scuba Store.


    Cheers, Don

    "Great mother ocean brought forth all life, it is my eternal home'' Don Berry from Blue Water Hunters.


    Spearfishing Store the freediving and spearfishing equipment specialists.

    Edited 13 times, last by Don Paul: need reading glass's ().

  • To me the advantages of an enclosed track vs. a deep track is that the shaft doesn't fall out of the gun without the shooting line being wrapped, and the line guide is eliminated making routing the shooting line more streamlined. For these two factors alone I prefer an enclosed track speargun. I see no disadvantages to it except not being able to use notched shafts, but I prefer tabbed shafts anyways. And the risk of shooting into a hole and the shaft not clearing the track. But to protect the track in this situation I add stainless steel plates at the end of the track. So to me there are no disadvantages to an enclosed track speargun, it's not any more difficult to cut an enclosed track than a deep track.



    I'm surprised at what Don said, that an enclosed track negatively affects energy transfer to the spear. I don't know how an enclosed track could cause this.. increased friction? But in this case an enclosed track can be powered a little more than an open track gun, overcoming any energy loss due to friction.


    You'll find the best selection of speargun trigger mechanisms at FreediveStore.com https://spearfishing.store/42-speargun-trigger-mechanism

  • The enclosed track supposedly has a vacuum-like effect on the shaft as it leaves the gun. With an enclosed track having a smaller opening on top (smaller than the diameter of the shaft), it's harder for the surrounding water to rush in and fill the void of where the shaft was sitting.. making the exiting shaft actually expend energy by sucking water into the now empty enclosed track.

  • My open track guns shoot a wider variety of shafts. I sold my ET's because they only worked well with 5/16th dia.. I do think they required less fine tuning with band power then the open track.

  • "No I wasn't aware of the auto rest mech, I'll get that for the next one". :thumbsup2:


    I'm pretty sure Josh will swap out the mech you have for an auto resetting mech if that's what you prefer, or just send you a different sear so you can change it yourself.

  • Alexander on closed track guns shoot further and why one of his guns would have more range.
    Quote:
    This is a common question that I often get asked. First let me saythat if you hunt where there are plenty of fish and you can get all you want, then an enclosed track gun is not going to help you. However, if you go home empty handed too many times because the few fish you saw were just out of range, then an enclosed track may improve your odds. I started building guns with enclosed tracks about 13 years ago simply as a means to hold the shaft in place while hunting. This was a necessity with my
    over-and-under, dual-shaft guns, especially with the bottom shaft. Then, as more and more divers, following Terry Maas’ lead, started targeting the big Tuna, I saw a need for spearguns with more range to increase the number of opportunities to hit and land these fish. Like everyone else, I tried adding more power to my gun, but it became erratic as the shaft bowed when fired
    and the recoil increased drastically. My solution was to increase the gun weight and enclose the spear track. This resulted in a gun that would shoot a 3/8" shaft powered by 6 bands, over 30ft. with consistent accuracy.


    So how much of that improvement was attributed to the enclosed track? Not very much, I’m afraid. John Warren, a part-time gun builder in S. California has made several guns with up to 7 bands that have exceptional range and accuracy with only the slightest depression on the top of the gun for a track. These guns, however, are extremely heavy. I would have to say an enclosed track is beneficial under certain circumstances, that is, if the shaft is subject to very high band tension and the diver wants the gun to be reasonably light for handling purposes. On the other hand, an enclosed track is entirely a waste of time if the shaft is not being over-powered. So, at what power level does the shaft become unstable during acceleration? That depends on many variables, such as: tip weight and drag, shaft diameter, shaft length and hardness and how straight it is. Also as previously mentioned, gun weight, especially at the muzzle end, has an effect on recoil in the vertical direction, which can destabilize the shaft considerably. Underwater testing of your particular combination is the only simple way to tell for sure, but “generally” a 5/16" x 65" shaft in a close fitting, half round track, will handle about 300 pounds of rubber tension; and a 3/8 x 72"
    shaft is OK up to about 420 pounds. Shorter shafts can take more power, longer ones less. Again you may get away with more power if the gun is very heavy.


    There is another way to increase range without sacrificing accuracy; Increase the stiffness of the spearshaft by increasing the diameter. How about a gun with a half-inch diameter shaft and nine bands that shoots 45 feet? This may seem a little extreme, but you’re only limited by how much gun weight and size you’re willing to lug around and how many bands you’re
    willing to cock! Remember, the more range you have the more opportunities you will have. SA

    "Great mother ocean brought forth all life, it is my eternal home'' Don Berry from Blue Water Hunters.


    Spearfishing Store the freediving and spearfishing equipment specialists.

  • quick question , how much of the gun's accuracy is down to the shaft like the flopper , geometry of the tip vs the track on the gun , i would imagine the barrel isn't as important as the projectile .:confused1:

    Be safe ... Happy hunting .

  • how much of the gun's accuracy is down to the shaft like the flopper , geometry of the tip..

    A lot! I made a shaft take a pronounced curved trajectory starting at 10 - 12ft by bending up the tip of the flopper, I thought at the time it would improve the deployment of the flopper. I couldn't believe how that shaft moved, I could've shot fish from around a corner, but couldn't hit anything straight on past 10ft.

  • Don, thanks for all the great information on enclosed tracks. Really good stuff.


    One of the only reasons I offered my thoughts are for other home builders that may be overwhelmed by the construction of what some guys preach i.e. 'The only way for a long gun to be built is the ET track system.' Not everyone has the skill to mill such a groove with just a drill press. Fine guns can be built with files/rasps, sand paper and planes.


    I've seen too many Tahitian marksmen as they shot their 6 foot long 6.5mm spring shafts propelled by two 16mm bands through the heads of small fish.


    Cheers, Don

    "Great mother ocean brought forth all life, it is my eternal home'' Don Berry from Blue Water Hunters.


    Spearfishing Store the freediving and spearfishing equipment specialists.

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