Build Your First Speargun - A Beginners Primer By Sven Anderson
Bio Of the myriad pursuits that both freedivers and SCUBA divers enjoy, spearfishing is right up there on the list. Though there is a like myriad of commercially available equipment to the aspiring and experienced "spearo", the act of providing for the table with a speargun of your own construction, a design refined with your experience and equipped to your exact needs is one of unparalleled pride.
So what's to stop you?
Most speargun manufacturers offer their parts individually or in kit form that will include the trigger mechanism, line release, handle, butt pad, line anchor and fasteners. Hit up their websites for the particulars.
The space available here is certainly not enough to give you a line by line set of instructions, but rather an overview to whet your appetite. It's also not within the scope of this article or site to teach woodworking and tool safety either, but a very modestly equipped hobbyist will have the tools necessary to do any operation necessary. For the most part, working with wood is more familiar to the average "afficianado" so we'll concentrate on a wooden-stocked gun, though there are certainly great designs utilizing metal and composite plastic tube barrels and even combinations utilizing all three materials.
You can look in the threads here on the site's forums for discussions on the varieties of wood appropriate for speargun construction, but it pretty much comes down to Teak or Mahogany. Teak's oily and beautiful grain resists the watery environment well, has built-in bouyancy and you can't beat the look of a finely finished teak stock. It get's pricey so take your time in choosing a straight, tight grained piece free of knots and defects. What looks good as a highly figured piece of furniture is not what you want in a speargun.
The barrel or stock of a wooden gun is most often a laminated stack of thin strips cut on the table saw and planed smooth and of equal thickness, giving the wood additional strength and resistance to twisting. Of great importance and patience-trying is the "seasoning" or drying/stabilizing of the wood, where the wood is brought indoors and allowed to reduce it's moisture content. This will help your finished product stay straight, aid in construction and fill your room with an exotic aroma not to be missed. The strips are alternately reversed in their grain's direction and glued together with epoxy and left to stabilize again for an unbearably long time, often 3-4 weeks.
Following the scraping, rough trimming and truing of the blank stock, the maddeningly fun part starts- the layout of the hardware. A good ruler and decaffeinated beverages are mandatory here. Happily, most if not all difficulty associated with this step is lessened by just taking your time and marking everything with masking tape and pencil. Making shallow cuts to your final depth(s) will let you catch any errors and minimize tool and temper wear.
The shaft's track is usually the operation that puts off most first-timers, needlessly. The idea of having to cut a perfectly straight groove is daunting, but attainable. It's machined with a solidly mounted router equipped with a cove bit slightly larger than the shaft's diameter, from the eventual muzzle end to the location of the trigger pocket. Clamping straight edges as fences on either side of the stock will ensure you a straight and true track for your spearshaft. Make multiple passes to ensure a straight and true track. Feel the fish's fear yet?
The trigger pocket is next, essentially a rectangular hole slightly shorter than the depth of the stock, depending on the trigger's size, track depth and the amount of wood you designate as the butt-end of the gun, drilled out with a drill press and some careful work with a sharp chisel. Take your time here as a mis-mounted trigger mechanism will frustrate you with jamming and an uneasy feeling when you go load that bazooka of yours for the first time. A good tip here is to have your spearshaft handy to aid in setting the depth and aligning the trigger mechanism with the track. Go slow, keep your fingers intact and take your time- the fish are only getting bigger...
If your trigger incorporates a line release, your newfound expertise will make it's installation a breeze. It's a slot cut alongside the trigger mechanism's body that lets the fin of the release swing with the motion of the trigger sear letting go. Take care here as it's free operation is critical to your line coming off with your shaft correctly. Making the slot a tad oversize and the hole for it's retaining pin or screw a mite tight, won't hurt anyone except the fish.
At this point you can stand back, brush off the sawdust and admire what resembles nothing more than a stick with some holes in it. Let's make it resemble something in the store windows by tapering the stock on the table saw or a solidly held jig saw, leaving most of the material intact at the rear or butt end to help absorb recoil and let you add ballast while removing a goodly chunk at the muzzle-end to reduce the mass of the barrel making it easier to track your dinner. This will now let you drill out the slot for the bands and the hole(s) for the line anchor and breakaway plug. A little additional carving underneath will position your handle where you want it and if you are building a "mid-handle" style gun, this is the time to mill out the pushrod slot. A little more carving will let you attach the butt pad to the rear of your stock with a stainless screw or the freshly flattened area can receive the patches of wetsuit you've glued up for that purpose. Don't glue it to the stock yet, because now's the time to make it all pretty!
Chuck up your roundover bit in the router and ease all the edges so it feels like it's made for you- because it is! Some judicious use of sandpaper and a file will separate the hack jobs from the true piece of art. Time spent here will show and reward you. At this point, attach all the hardware to the stock and check for proper operation. Doing it now will save you from a lot of grief later when you're gouging up the fine finish you painstakingly applied. If everything's smooth and it's warm out, get to the finishing. Strip all hardware from the stock one last time.
And what of the finish? Teak fairly screams for a hand rubbed oil finish, though you'll get a lot of admiring glances from a glossy epoxy finish as well. Leave the red semi gloss for the bedroom... Reinstall the hardware one last final time, glue or screw on the butt pad, install your homemade or store-bought bands, put a tip protector on the speartip and head for the safe confines of an uncrowded cove or vacant pool for some tests. Don't be surprised if after all the time and patience you've expended that it works exactly like it was made for you- because it is!
Happy and safe hunting.