Double roller speargun build

The Plan:

Every Winter when the water is frigid I retreat to my basement shop where I build my spearguns. I like to try something new each Winter and this year I decided it would be an all-wood double roller rear handled gun with a "cuttlefish shape." It was during the previous Summer I decided this would be my Winter project/goal.

Late summer, early Fall I started acquiring images of this style gun from various sources and gun builders whose guns I had been admiring. Antony Bullock (Ace Spearguns), Peter Kedzo (Petar Pan), Sniper Sub and of course Alemani were just a few of the different builders whose guns I poured over before starting this build. I also researched the building process by reading through various build threads on Spearboard to learn about some of the specific design aspects. 

With a semi-clear picture in my mind of what I wanted to do I decided to dive into the process. I had been flip/flopping for a while between inverted roller or classic roller. I decided to start with the more basic classic roller design. After laying up two identical blanks made with Mahogony; (6 vertical lams) 50 inches long, 3.5 inches wide and 1 and 3/4 inches thick I started getting my parts together.

The Parts:
As far as parts were concerned, the gun would have an all-wood handle mortised into the speargun body and I'd be making that. Since I wouldn't be incorporating the trigger guard into my wood handle design I decided to use a simple stainless guard I purchased from MVD. For the trigger I went with the Neptonics Reverse Trigger Mechanism, my go-to mech for all rear handle builds. The rollers themselves I got from Emanual Bova who runs Manny-Sub in Australia. Since I wanted this gun to have two stage loading I had two 9/32" shafts made by Dean Koutras from Addiction Spears. Both shafts were made with a resting tab 20 inches forward of the trigger mechanism. Both shafts were set up with a single flopper and I decided to get two different lengths, one three inches longer than the other. I also decided to install a vertical reel I had purchased a while back from Maverick (I think it is made by Meandros) that I thought would be perfect for this gun.  All the other hardware on the gun (line guides, anchors, and loading pad) I wound up making myself out of stainless rod and flat bar I purchased from online metals.

The Process:
Once I had the parts together (I didn't have the shaft's at this point) I decided to make a 110cm gun, measured from the back of the trigger mech to the tip of the gun. The exact measurements; where the shaft engages the mech 111cm (44 inches) and; overall length of the stock, 124.5cm (49 inches).

Before doing any cutting on my blank I glued up some plywood with the same dimensions (height and width) as my blank so I could test out a few cuts and see what my layout would look like at the muzzle where the rollers would be installed. 

I wanted to make the two sets of rollers offset from each other, my dilemma was where to place the two sets of rollers in relation to the muzzle ie.; wider set of rollers closer to the muzzle or narrow set of rollers closer to the muzzle? Initially I thought I'd place the narrow set further forward (as pictured below). After doing some research I found out that putting the wider set forward would make loading easier and would limit the shooting line being trapped by the bands at the muzzle. This made sense to me so I decided to go wide at the muzzle. The downside to doing it this way is that the muzzle shape ended up being a bit wider than what I would have liked. Oh well, function before fashion!

After marking up my dummy blank with some layout lines I went to the router table and made the mortises for the rollers. It was a pretty simple process. I did one set and then moved the fence to do the other set. Cutting all the way through went pretty quick without having to raise the bit more than 3 times. You make a cut on one side, then flip and reverse the blank to make the same depth cut on the other side. You wind up breaking through somewhere in the middle.

Below is my dummy blank which was also used to practice a few other cuts in addition to the rollers.

Once I felt comfortable with the layout and design of the muzzle I set about working on my blank. I wanted to make this gun with an enclosed track so the first order of business was cutting a track with a 1/2" straight bit and then filling with epoxy.

After curing I cleaned it up by taking a very light cut off the top with my table saw.

The next thing I did was cut a pocket for the trigger mechanism and then with a ball-end bit I cut in the enclosed track. Once the track was cut I proceeded with pinning the mechanism. This is one of those parts of the build that has to be super accurate. If things don't line up correctly and the shaft doesn't engage with the mech properly you will have some adjustments to make. There are a couple of ways you can deal with this situation; fill the pin holes with epoxy and drill again, fill the track with epoxy and route the enclosed track again, or, route out the enclosed track and switch to an open track design. If it were me I'd opt for filling the pin holes with epoxy and then re-drilling.  Fortunately I got the mechanism pinned without having to make any adjustments! 

Next order of business was routing out the holes for the rollers. Again after laying out the muzzle and setting up the router table this was a simple task that didn't take more than 15 minutes to accomplish. The time consuming bit is the layout and design, lots of head scratching, erasing lines, measuring, making new lines etc... Below is the blank after routing out the roller pockets. You can also see the band recess grooves I routed with a big ball-end bit. I made those grooves after routing the narrow pair of roller pockets because the fence was lined up perfectly to do that. After routing the band recess grooves I drilled the holes for the rods that hold the rollers in place. 

Once the muzzle and band grooves were taken care of I turned my attention to the handle.  The goal is to have as little space between the handle and the actual mechanism as possible. Getting the handle up as close to the track as possible makes for a more accurate weapon. The Neptonics reverse mech bottoms out about an inch into the blank (if you want it to sit flush with the top of the gun). Knowing where the bottom of the mech is gives me an idea of how deep I can mortise in from the bottom of the blank. It also gives me an idea of how to rough out the shape of my handle. In the photo below you can see the roughed out handle and the tenon on the handle that will be epoxied into the mortise.

The tenon on the handle was made when the handle blank was still square, I did it on the table saw using a dado stack. Below is another shot of my handle setup. I decided to cut in a slot for the base of the handle to be glued to making a stronger joint. If you look close you can see a small black spot in the bottom of the handle mortise. I actually broke through to the trigger pocket, that's how little wood there is between the bottom of the trigger mech and the tenon on the handle.

Before gluing the handle in I wanted to get some rough shaping done on the blank. It needed to be tapered on three sides (all but the top), and I wanted to cut the contour you see in pencil above. I have a jig I've used with success in the past for cutting tapers but this blank was too wide and tall to use the jig. Lots of head scratching ensued and I decided to go for it using my tiny 10" Rikon bandsaw with out-feed rollers to support the blank. After installing a fresh blade I started with the taper on the bottom of the blank. I managed to cut a pretty straight taper. The blade did wander once or twice but it was nothing major. I was happy with my rough cut. Next up were the tapers on the sides of the blank. They came out decent enough but not perfect. I would later flatten and straighten everything out using a hand plane. Finally, I did a bit of cutting at the muzzle. Below is the roughed out shape after all of these cuts were made.

While I had my bandsaw out and set up with the out-feed rollers I decided to make the rest of the rough cuts along the layout lines for the shape of the gun. The two photos below are of the roughly shaped gun As you can see much refinement is needed!

double rollergun

double roller gun

Shaping up:

To get this rough shape looking pretty I used the following hand tools; standard angle block plane, spoke shave, rasp(s), 60-100 grit sandpaper and sanding blocks.

I started with the block plane and worked on getting the rough and uneven spots flat and smooth.

double roller speargun

The block plane removed  wood fairly quickly but in some of the tight spots up by the muzzle I switched over to the spoke shave which was a better tool for that part of the gun. Once the shape starts coming together I find myself switching back and forth between rasp, sandpaper and sometimes the spoke shave. Two shaping sessions later the rough shaped blank doesn't look so rough anymore.

Happy with how the gun shaped up the next step was to install and shape the handle. I glued the handle into the stock using thickened West Systems epoxy. I let it set up for 48 hours before taking any tools to the handle. The tools I use for shaping a handle are; a foredom rotary tool, rasps and sandpaper. I do probably 90% of the shaping with the foredom and various "rotary rasp" heads. Sandpaper and hand-held rasps finish up the job.

With the handle complete it was time to make up something to protect the back end of the gun. I usually make a thick rubber pad that I screw and glue on the butt end of the gun but I wanted to do something different this time. I had some 1/8" 316 stainless flat bar lying around so I decided to use that material. I measured and cut off a chunk with my angle grinder then further refined the shape with a coarse grinding wheel on my bench grinder. I decided this would be a good place to tie off a float-line, as opposed to drilling a hole somewhere through the stock so I left a small piece off of one end large enough to bore a hole for a piece of line. Here's what I wound up with.

Later I decided I might like a little padding back there as well just in case one day I'm diving with a really thin wetsuit. I decided to add a piece of rubber which I glued in place. The whole piece will be glued and screwed to the back of the gun on assembly day. The two screws are countersunk about half way into the rubber.

At this point in the build I started looking at the gun and came to the conclusion that while confident the handle was strong and would take a beating I wouldn't mind if it were a little stronger. I decided a layer of fiberglass and carbon fiber bonded to the handle and up the side of the stock would give it the extra strength I was looking for. I also felt the same way about the roller head (muzzle) and the front third of the gun which after shaping, were pretty thin. I decided I'd wrap the muzzle and the underside of the gun (about 1/3 of the length) with a layer of carbon fiber. Having never worked with carbon fiber or fiberglass (except for some surfboard repairs) this was a new to me. I of course visited YouTube to watch a few tutorials on "skinning" with carbon fiber and went at it with reckless abandon! Below is the handle after the epoxy set up on the layer of fiberglass.

After some light sanding and trimming off the excess cloth I did the same thing using carbon fiber.


All the rough edges you see in the two photos above were smoothed out with sandpaper being really careful not to sand down into the cloth. Once everything was smoothed out I hit it with another coat of epoxy. The same process was followed at the muzzle end of the gun.

In the below picture you are looking at the speargun with the carbon fiber wrapped muzzle and handle as well as the line guides and band anchors I made from 316 stainless round bar. I fashioned a jig to facilitate making the bends in the stainless round bar. All of the line anchors and band anchors are held into the gun with epoxy The gun has also been sealed with one coat of epoxy. Next I will be taping off the areas with carbon fiber so that I can paint with my airbrush the remaining parts of the gun.

My plan for the paint job was to do a fade from black to red. Below you see the gun with a nice coating of primer applied.

I finished up the paint job with Createx pearlized paints for the red and black. I then used a sheet of shelf liner as a stencil to get a dotted looking pattern (similar to carbon fiber) along the length of the gun. When I got back to where the trigger mechanism is located I switched from the shelf liner to a piece of mesh for a different pattern. I sprayed all of this with a metallic aluminum base coat paint. After that dried I went over the red with Createx candy colors "Blood Red".  Below you can see how this all turned out.

Happy with how the paint looked it was now time for the final step, sealing the gun in epoxy. I use "Phil's" epoxy which you can buy from Neptonics. After four coats of epoxy the gun looks pretty sweet. The below picture hardly does it justice. Nicer shots to come after it's fully assembled.

Assembly of the gun went well. I started with installing the trigger mechanism which is always the first thing I do when assembling a gun. I had to cut pins to length. The forward pin is also customized to serve as a line guide. I make this pin long so it sticks our roughly a quarter inch to three eighths of an inch or so. I use a file to put a small notch on the underside as well. You can see how it works in some of the pictures that follow. After the trigger mech I installed by loading pad/butt protector, just a matter filing off a couple epoxy drips and then screwing it in. Next up I needed to install the rollers. I did this very carefully as the wood on the outside of the rollers is pretty thin and I didn't want anything to get damaged while driving the pins through. The last two items I installed were the trigger guard and reel. I used threaded inserts epoxied into the stock so this was just a simple matter of screwing these guys in.  

To finish up the gun the last two items are installing the bands which I had already made up and then rig the shooting line and put some line on the reel. I left the wishbones long because I wasn't really sure how long they would need to be. They will eventually be shortened up a bit. After installing both bands I loaded the gun to see how the bands sat along the top and underside of the gun.

double roller gun

Pretty happy with how that worked out!

After putting on a double wrap shooting line and filling the spool of my reel I took a run down to my beach and had a little photo shoot with the gun!

double roller speargun

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 Testing the Gun








    Bonjour je voudrais savoir le prix d’un fusil harpon long 120

  • Dean

    Jose, I can appreciate painted or unpainted. Both are cool


    Covered or painting this gun is a crime! plain wooden its beautiful! just oiled with teak oil and go!

  • Dean

    Hello Henri, yes, just a stainless pin which serves as an axel for the rollers works fine. There is a secondary loading hook on the bottom of this gun so it’s what’s known as a “Two-stage” roller. Much easier to load than having to stretch the band which would be under tension from the start of the pull.

  • Henri Watson

    Great instructions here thanks a lot. Building my first roller right now and I have two quick questions. Are you just using a simple stainless steel pin to hold the rollers in place? If so does it work alright? And seeing that you didn’t do a bridge on the nose for raising the wishbones up, do you have a secondary band hook on the bottom of the gun? Thanks again, lots of good tips here.

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