Angie's New Rollergun

Back in May, Angie Anderson's brother Will posted a thread about his sister Angie. Angie has a medical condition that prevents her from being able to hip or chest load a conventional speargun. Since she grew up around the water and loved to spearfish, this was devastating for her. Tin Man first pointed out the thread to me, and he and I started discussing what kind of gun might work for her particular situation.

At first I thought a lever action rollergun similar to what I had built before might work, but after looking at it in more detail I realized that no matter what I did, she would be unable to load the top half of the band. After talking to Tin Man, we both came to the same conclusion: what would be required would be a miniature winch with an appropriate sized crank handle to stretch the band. The winch would be located under the gun, in front of the trigger guard. One end of the bands would hook to the sharkfin on the shaft just like a normal band, but the other ends would be hooked to lines that would run over the rollers, under the gun, and back to the drum on the winch.

With this as the concept, I began design of the winch. It took about 3 weeks to get a design I was fairly confident would work. Then, I build an aluminum working model of the winch. I used aluminum because it's much easier to work with than stainless, and I knew there would be a lot of changes that would be made along the way. Sure enough, I had to go back and redesign quite a few components of the winch. After several iterations, when I figured the aluminum model would actually work, I built a pine mock up of what I thought the gun would look like.

Then I mounted the aluminum model on the mock up gun so I could begin checking ergonomic issues. Back to the cad program again! I realized for the first time that, even though this was an aluminum version and couldn't take the stresses of the final version, I would have to design in some safety features. This would have to be done while keeping the design as simple as possible. I had discarded two previous versions of the winch because they were too complicated, and as I designed in the safety features the latest version was going down that same road. I finally came up with a design that incorporated the features I needed: It was small: 2" long x 1.25" high x 1.25" wide. It was powerful: Using a 6" crank I could make the 44" gun more powerful than a 55" gun with 2 - 5/8" bands. It was corrosion resistant: All stainless except for the sleeve bearings, which were bronze. It was light: It weighed in at about 2.25 x a typical trigger mech.

I made 2 guns. The first one I would shoot, the second would be Angie's. I made mine first so I could see how everything would come together before I made Angie's. After testing mine for 2 or 3 dive trips, I began hers. That's when she contacted me and said she was going to be taking a dive trip in August. Yikes! I finished everything on her gun except the winch, so I took the winch off my gun, mounted it on hers, and shipped the gun last Tues. When I get another winch finished, I'll either send it to her or just mount it on my gun.

More in the next post.

Here's what I ended up with for the winch prototype. I stopped counting the parts, and subsequent versions will have fewer parts and a few more standard parts like sleeves, etc. Still more complicated than I wanted. The sprocket looking part is actually the ratchet, and it keeps the handle from unwinding when you load the gun. The lever is the pawl, which engages the ratchet and holds it in place. The lever on the pawl allows the ratchet to be released so the gun can be unloaded or reloaded after it has been shot. The small button next to the pawl can be slid down to prevent the pawl from releasing, up to allow the pawl to operate normally as in loading the gun, or up and forward to hold the pawl in the released position. All of the parts are stainless steel except for the bushings which are bronze, and the crank knob, which, for this winch, is delrin

Once I got the winch working the way I wanted, I started on the gun itself. The gun itself isn't all that different from other rollerguns I've built, except that it is heavier because of the winch. My plan was to use the winch as ballast, and trim the gun the way I wanted by removing wood until I got the buoyancy I wanted. More about that later.

I made a delrin enclosed track and installed it, then got some good news from Tin Man. I had used one of his recently prototyped reverse mechs on the prototype gun I made as I was making Angie's gun, and he provided another reverse mech for Angie's gun. There are only a few of these out there for testing right now, and I have to say this is the smoothest mech I have ever shot, bar none. It has a cross bolt safety like a shotgun, which can be removed easily if not preferred, and shoots more like my Ruger 270 than a speargun. When this mech comes on the market, I won't be shooting anything else. The takup is crisp and short, and the honed sear and trigger contact surfaces make the thing a joy to shoot. Most of you know Tin Man is my son, but it wouldn't matter - I'd still be shooting this mech, even if he wasn't related.

I made the delrin rollers and used a 1/4" diam. standoff as the axle. After experimenting with the mock up I found I needed to make the rollers a little larger so the end of the bands could "crawl" over the top of the roller and under the gun. I ended up with 1.5" diam. rollers. I made them 3/4" wide to accommodate either a 3/4" or 11/16" dia. band. The pic is of the rollers I started with, not the 1.5 dim. ones. I also installed a 3/16" wide aluminum muzzle reinforcement that is installed in a slot under the gun. This strip serves two functions: It carries the load from the rollers back into the solid, stronger part of the gun, and it serves as a shooting line anchor. Even though I've got enough support on the outside of this gun, the strip allows me to thin down the thickness of the wood on the outside of the rollers without sacrificing support for the rollers.

I used a Tin Man handle for both the prototype and Angie's gun. I like everything about this handle. No reason to move the mech further back and use a pushrod on this gun since the winch is strong enough to stretch a 3/4" band to a 4:1 ratio. This way it's also easy for Angie to customize the grips to fit her hand.

I had been saving another piece of teak from a yacht. This seemed like the perfect time to use it. In the next post I'll show you how that worked out.

Things are shaping up, it's starting to look like a speargun!

This is the piece I started with. I'm not sure exactly what part of the yacht it's from - almost looks like inside trim. I do know it's some damn fine looking teak! I sawed off the wood that wasn't teak, then planed it down until I had all good wood with no cracks, as shown on the right. Later, I would remove additional wood to get the right ballast by tapering the bottom and narrowing the width. Next post I'll show you how it turned out.

This gun turned out to be more of a challenge than I had anticipated, and I view the gun not as a finished product, but rather as a work in process. I wanted to get the gun in Angie's hands this summer, so she will shoot it this summer, then I'll make any necessary changes (I'm sure there will be many) over the winter. I've had a chance to kill a snapper with the prototype, and, typical of rollerguns, it shoots straight, smooth, with little recoil. I will probably drop down from a 3/4" band to a 11/16" band on my gun, since for my hunting I just don't need all that power. Another nice thing about the winch is that it truly is a variable power gun. One revolution of the crank stretches the band 2 inches, so you can adjust the power on the spot just by turning the crank.

The weather was overcast and rainy when I took these pics, and I was in a hurry to get the gun to Angie, so I couldn't wait for better weather.

All in all, I think the gun turned out pretty well. Angie will hunt with the gun next week, and I can't wait to see how it works.

Shoot 'em up, Angie, and let's see some pics!