Posts by Wood Guy

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.

Quote from Wishihadgills

Aluminum will form a very thin layer of oxide at its surface that will protect the rest of the metal underneath. Anodizing is a controlled method of increasing the thickness of this layer. Technically it is not needed to protect the metal but anodizing gives a much more uniform finish, allows for colors and provides better abrasion resistance as aluminum oxide is harder than the pure aluminum metal.

For a finished product I would say the anodizing will look better and produce a higher quality piece in the end. For areas of the spear that are likely to com in contact with rocks or other hard objects it will help protect the spear. For internals or parts that wont be seen it is probably not necessary if you are trying to cut costs but nice for longevity of the item.

Well said. I would add that you will see more corrosion from using stainless fasteners (galvanic corrosion) than you will from not anodizing. I use aluminum fasteners wherever I can and avoid mixing aluminum and stainless whenever possible. From a practical standpoint it's unlikely either will affect the polespear's performance, as long as you rinse in fresh water after using, since the actual time wet is a fairly small percentage, and for galvanic corrosion to occur the ss/ aluminum has to have an electrolyte, which is the salt water. Rinse in fresh water after using, and the galvanic corrosion all but stops. Use aluminum fasteners, and it doesn't get started.

Quote from Dan

Interesting take. But I don't think you'll achieve the same power as this 19mm band at %250, with a 16mm band even at %400, irrespective of the 19mm pulling over a shorter distance. I could be wrong, lets hear more opinions.

A 16 mm band at 400% elongation generates 144 Lb. of force. A 19 mm band at 250% generates 153 lb. of force. The 19 mm band at 250% would generate the same power at 28" as the 16 mm bans at 400% would at 30".

Just for clarification, how are you all calculating % elongation? I get the stretched to relaxed ratio is 3:1, but are you including the relaxed band length in the % elongation? In Dan's example, is it: 30 cm (relaxed) + 60 cm (stretched portion) = (90 cm/30 cm) x 100% = 300% elongation, or is it: 60 cm (stretched portion) / 30 cm (relaxed length) = (60 /30 ) x 100% = 200% elongation? :confused2:

The mechs I've used release the lever and allow it to move forward when the trigger is pulled, but have no way to actually move the lever. The tension on the shooting line does that, so if there's nothing to move the lever forward it just stays there when the trigger is pulled. If you push on the lever with your finger and the lever moves when you pull the trigger, the mech is working properly, at least with the mechs I've had experience with.

It depends on the capability of the shooter. You could keep adding preload and keep increasing the power as long as the shooter could pull the bands back on the second stage. With my lever action, you make the band length such that the shooter can just barely load the first stage because you have a mechanical advantage (for my gun it's 2:1) that always allows you to load the second stage.

For what it's worth, when I first tested my "Dirty Water Rollergun" in my test tank I took a 9/32" and a 5/16" shaft and shot them into a block archery target that was 12" thick. With the same gun, same band setup, same target I got roughly twice the penetration with the 5/16" shaft, with both one and 2 bands. Not very scientific, but it definitely supports what Don is saying. Target was at about 12' so distances were pretty close. I got the same result at 16'.

Quote from John Hanson

Thanks for the explanation and your perspective. Most everything said is all stuff I have already heard. I guess my real problem is understanding how one long band equates to 2.5 short bands. I didn't do a very good job of asking the question in my post. It may sound silly, I know I should "get it", but there is something in my mind that just doesn't seem to agree.

Like most things for me, the best way to gain any real perspective on something is to experience it. I would like the opportunity to shoot a roller gun someday.

"After all is said and done, it's about like 2.5 bands on a comparable conventional gun. so, you could take the same gun, put 3 bands on it, and the main differences would be a "better" sight picture due to 1 band instead of 3 (some would argue they actually prefer 3), and a softer recoil. For a shooter who practiced with both, there probably wouldn't be a noticeable difference in loading time. The time it takes me to load my 48" lever action rg is so close to what it takes to load a 2 banded conventional gun that it's academic if there at all."

I'm referring specifically to my 48" lever action roller here, that's why I said "it depends". For a conventional gun in that configuration the energy developed at 250% elongation with a single 5/8" band is 1664 inch Lbs. (This comes from the spreadsheet Tin Man and Jim Cuda developed from the Primeline tables and charts on the Primeline website). For the roller version of that gun, the cocked power is 3400 inch Lbs, 4100 inch Lbs, and 4900 inch Lbs. for a 5/8, 11/16, and 3/4" band, respectively. This is equivalent to 3400 / 1663 = 2 bands for a 5/8" band, 4100 / 1663 = 2.5 bands for an 11/16" band, and 4900 / 1663 = 3.0 bands for a 3/4" band. I mentioned earlier that the max power is determined by the shooter's ability to cock the top band. If he's already doing that, he can't just go to a bigger band to get more power. But with the lever he can go to a bigger band, make it the length he can just load on top, and still load the bottom because the lever gives him a mechanical advantage (in this case 2:1) to cock the bottom, which he would otherwise be unable to cock.

Like I said in an earlier post, you can put 3 bands on a conventional gun the same length and get the same power. It's not faster to load 3 bands than it is a one band roller, and the roller will shoot with less recoil if that's important to you. They can be sleek and streamlined, just as conventional guns can be, so if they aren't, it's because the builder built them that way, not something that's inherent in the concept. If shooting 3 - 5/8 bands on a conventional guns is something a builder prefers, then that's what he should do. Rollers are no more "one gun for all situations" than a pipe gun, hybrid, or pneumatic. It just comes down to what you want to shoot.

Quote from Dan

I think the freediver vs scuba diver factor may have bearing on this preference. If I remember right Bill you don't freedive? Just trying to keep things in perspective. One of the reasons I post about this is to help guys not make a costly wrong speargun choice.

I'm trying to understand what that has to do with rollers vs conventional guns, and soft recoil vs hard recoil, but I'm having trouble getting my head around it....but then, I've had a few cocktails so maybe I wouldn't understand it if you explained it! Why would freedivers prefer one over the other? If so, would freedivers prefer a roller or a conventional? Seems to me they use both, and their preference doesn't have anything to do with whether they freedive or SCUBA, but I could be wrong.

"Bill, aren't conventional spearguns built to handle a certain power configuration without being adversely affected by recoil? As long as the recoil doesn't affect the shaft trajectory, I like it. It tells me the gun is shooting hard and fast, whether the bands need to be shortened or changed. With the roller I feel like there's too much time before the shaft leaves the gun, almost enough time for changes in my grip and arm position to affect the aim."

Not trying to be cute, here, Dan, but spearguns are built the way the builders build them. Very few, if any, production guns are overpowered, but it's done with custom and home built guns all the time. Whether inaccuracy is due to overpowering or the shooter anticipating the recoil, is pretty hard to determine. It sounds like you just like the way a conventional gun feels and shoots, so like a favorite shotgun or set of gulf clubs, you shoot better with it. The first time I shot Tin Man's carbon fiber gun it felt so natural it was like I had been shooting it for years, yet the gun wasn't like anything I had ever shot before. To me, the feel of a roller is very natural, so most of the time that's what I shoot - with the exception of that cf gun! :laughing:

Different strokes for different folks - great to have choices! :thumbsup2:

Quote from John Hanson

I was never able to completely wrap my mind around the concept of the roller gun...

If more power is needed on a shorter gun, why not just add another band? It seems a much simpler and more practical solution to all the "bells and whistles".

The part I can't really seem to wrap my mind around how increased band length is going to give anymore real power. The length of the rubber still needs to be stretched to the same ratio to be effective. With that said; doesn't that translate to the same amount of power?

I think it's kind of "a consultant's answer" - "it depends".

You can always add more bands instead of having a longer band like a roller does, but for a given amount of power, a roller will shoot with less recoil. The power any gun can have is determined by the shooter's ability, in terms of strength and technique, to load the bands. That's why conventional guns need several bands instead of just one big, thick one. With a multi stage roller you can cock a more powerful band, but only to a point, since the limit is still the shooter. Enter the lever action roller. More complications, but now you can load the max of your ability on the top, and get a mechanical advantage on the bottom. After all is said and done, it's about like 2.5 bands on a comparable conventional gun. so, you could take the same gun, put 3 bands on it, and the main differences would be a "better" sight picture due to 1 band instead of 3 (some would argue they actually prefer 3), and a softer recoil. For a shooter who practiced with both, there probably wouldn't be a noticeable difference in loading time. The time it takes me to load my 48" lever action rg is so close to what it takes to load a 2 banded conventional gun that it's academic if there at all.

Are those 2 advantages enough to want to screw with the additional work to build one, or the additional cost to buy one? Depend on what you want, and what you can afford. I don't see rollers taking over, nor do I see them going away. There will be tweaks that make them better, but a conventional wood gun gets the job done easily and simply, and to me the other guns are just adaptations to fit special situations or preferences.

After all is said and done, whatever gun is being used, I think it's still more about the Indian than it is the arrow.

Quote from Dan

Judah, I do. IDK, will have to try.

George, the longer band accelerates the spear in a noticeably slower way. I felt like I was waiting for it to leave the gun, and felt the rubber passing/contracting along the rollers.

He just prefers a "slap" to a "kiss" :rolleyes1: :laughing:

Dan, I guess it isn't surprising that you wouldn't care too much for rollers since the function you mention as disliking the most is the very function that is most often mentioned as being the greatest benefit, mainly the soft recoil, which, as you mentioned, is due to the slower acceleration from the longer band.

Most of the time aluminum tanks corrode from galvanic corrosion due to dissimilar metals being used together, like an aluminum tank with a brass fitting or stainless screws. The actual pitting isn't necessarily next to the dissimilar metal, and could well be in the welds because of small stresses set up when the welds were made when the tanks were built. Moisture from moist salty air in the bilge becomes the electrolyte, and the corrosion begins, usually resulting in pits, then lots of pinholes. In fresh water, since there's no salt, the tanks last indefinitely. In salt water, 8 - 12 years, depending on whether the bilge is allowed to completely dry out between trips, since the corrosion stops when the moisture completely evaporates. Aluminum can be successfully used in a salt water environment if brass or stainless fittings are isolated from the aluminum with a nylon bushing, and aluminum fasteners are used instead of stainless.

A poly replacement tank will give years of service if not exposed to the sun, which in the bilge it wouldn't be. Make sure the metal attached to the tank is grounded, however, since the gas sloshing around generates a lot of static electricity. The downside of a poly tank is that you may not find a custom shape that is an exact replacement for the aluminum one, and you might give up some capacity with the new tank.

What do you plan to do with the fuel soaked foam?

I would call it a rear handle + as well as a very nice first build! :thumbsup2: Nice clean lines. I can't see it very well, but is the handle frame recessed into the wood? If not, you might want to consider doing that. Two 3/4" bands is enough power to be a concern if you're depending just on the mounting screws to handle the recoil forces against the handle.

"I may not end up tapering the gun and recessing the handle as I expected. With the blanks 2.5 x 1.25 profile I am not sure I will have as much height to work with as I originally planned."- ReefChief

Raising the handle will help reduce muzzle flip more than almost anything else you can do to a gun (except maybe adding more mass at the muzzle), and with the handle that far back, won't really weaken the gun, so I would recomment raising the handle, even if it's not as much as you were hoping for. It's more effort, but you won't regret it.

Im not sure from your statement whether you were going to recess the handle frame into the bottom of the blank, but it isn't just about aesthetics, however, since it allows the frame to transmit load directly to the wood instead of depending on 4 - #8 screws to carry all of the load from the recoil. The screws should just hold the handle in place. A nice fitting recess, especially on the front of the frame (try to stay focussed here :laughing:) will transfer the load from the gun to the handle the way it should, and not depend entirely on the screws. On a long, fairly powerful gun like this, I wouldn't consider not doing it.

Looking good. That first gun will always be special, and the first fish you kill with it will be the best fish you ever tasted. :toast2: What is the exact width of the mech you're using? Thought they were pretty much all .5" now.

I've used both the Tung and Teak oil. I don't really see all that much difference. To me, the most important part is the presanding. I use 320 grit before I oil. First coat is applied very liberally and rewet until it stops soaking in. I let stand about 30 min, then wipe excess off. Let dry, preferably in a/c, for several hours but overnight is better. Hand polish, do it again. After 3-4 coats you will get that hand rubbed luster that makes teak look so awesome. Lots of right ways to do it - teak with oil is VERY forgiving.

Here's how it turned out. I'm pretty pleased with it so far (After just shooting it in the test tank). Just like the other rollergun postings, it has a nice soft recoil, and is very accurate. With Tin Man and Jim Cuda's spreadsheet, it is really easy to do "what if" cases without doing all the calculations to design. Thanks guys, but I wish you had come up with it a couple of months ago! It's easy enough to have a light band for dirty water hunting around small wrecks in the bay, and a more powerful band for the gulf wrecks. The spreadsheet also is handy for comparing guns. If you have a gun that has just the right power, it's now easy to configure a different size gun with the same power. I'll shoot the gun for q while, and if I'm happy with it the next one will probably be a 38" mid handled version of the "Dirty Water Rollergun" that got me started with rollerguns in the first place.

I added a couple more items. I installed 2 pins to help keep the shooting line in place. (Note the gun is inverted in the photo)

Then I made a delrin light holder and installed an LED dive light on the lever, which was really the only place it could go. If it works for shooting in holes it will be great. If not, Im just out some delrin and some time making the bracket.

And, finally, I also added one of Josh's safeties. I use it mostly when I"m making changes to the gun and need to test it in my shop. In the water when I'm hunting with the gun, I'll use until the gun is cocked, then hunt with it in the "fire" position.

As I looked at the larger pics, I realized I had already made some modifications to the gun after some of the pics shown were taken. The safety latch, for example, is a little different. Originally, it was like this with a solid end cap.

I had the lever come off the safety latch when I was testing the latch, resulting in the lever moving forward with enough force to actually bend the 3/4" (Actually .830" outside diam.) aluminum pipe. While a testimonial to the strength of the pinning and installation of the aluminum side pieces that hold the lever pin, it was a little scary. So, I modified the end of the lever to incorporate a secondary catch, similar to what the latch on my original "Dirty Water Rollergun" had. Now, if the latch is bumped and releases the lever, it gets caught by the second catch filed into the end of the lever, and has to be manually released with my finger before the lever can be released. After the gun is fired it's a simple matter to do both releases and after you shoot the gun a few times it's second nature. If you want to unload the loaded gun you just reverse the loading procedure, uncocking the lever first, then unloading the band on top. The force unloading the lever is very managable if you're expecting it since you're working with the 2:1 mechanical advantage because of where the band is attached to the lever.

Here's what I ended up with.

I also realized that the length of the wishbone loop where it connects to the lever was important. Too small and it won't roll over the button easily, too large and it comes off when the band is relaxed. A small "o" ring over the loop solved that problem.