Already zoomed out as much as possible. Need a wider test tank. <img src= " height="23" srcset="https://spearfishing.world/forum/images/smilies/emojione/1f606@2x.png 2x">
I think I need to crop more before the "good" part. Even though it's only a second or two, it seems like an eternity at 1000 frames per second. Baby steps!
Display MoreI had a chance to test fire this a few times in Wood Guy's test tank today, and I learned a few things:
1. Wood Guy's high speed camera is freakin' COOL for this kind of stuff!
2. The roller gun design works nicely. It was easier than expected to load, the wishbone arresting pins worked well, and I had no issues with the bands jumping off the roller.
3. This gun has surprising power compared to a standard band setup. One of the advantages to this build was that I could easily replace the roller muzzle with a standard muzzle and a single band with the same stretch ratio.
In Wood Guy's tank, we were shooting at a foam archery target that's about 12" thick. With the standard muzzle, my shots were hitting about 4" low (10' to the target) and penetrating about 7-1/2" into the foam target.
With the roller muzzle, the shots were dead on vertically, and protruded 4"-5" through the back side of the foam target. I like this setup a lot, and I am excited to tinker with it more. I think it would have plenty of power for what I want to do, even if I shorten it a bit more from the current 42" length.
Wood Guy shot some really nice video of both the roller and standard muzzle, which shows the shaft moving forward with measured marks in the background to calculate shaft speed. He'll post it as soon as he has it ready.
Success, albeit clumsily! 
I made it: Film the video with new hs camera > download to new computer > edit video with computer software > Get u tube account > upload video to u tube > download video to forum. This makes building spearguns look easy!
This is a shot of Jeff's new rollergun muzzle as the gun is being fired. The pin(s) you see sticking up are the "arresting pins" that grab the wishbone as it nears the end of the barrel. It was shot at 1000 frames per second, then most of the time was edited out. More to follow. The process is clumsy right now, but after some tweaking with the camera set up, and some improved operator skills, this is going to be one awesome anylitical tool.
New camera, new computer w/ new operating system, new software- still working on it. Baby steps!
:thinking:
Nice streamlined shape, and very nice woodworking. Do you have any pictures of it rigged?
Bill, I'd love to see the video.
I plan on shooting more video and posting details of the "Koi Racing Training Tank" upgrade in another thread soon.
I think there is also less muzzle jump. When I shoot my little rollergun it just recoils straight backward. I shot some close up nigh speed video of it and the video shows the gun just pushing straight backward out of the frame- no upward movement at all. I think it's also more than a "little" more powerful than a conventional gun of equal size- like maybe 50- 75% more, depending on preload.
Can't wait to see it shoot (and shoot it)! <img src= " height="23" srcset="https://spearfishing.world/forum/images/smilies/emojione/1f606@2x.png 2x"> maybe we could do some target penetration tests and see just how much more powerful it is. compared to the gun rigged the conventional way- food for thought.
I would suggest having the bands pull slightly down from the top of the shaft (assuning you have sharkfins , not slots n your shaft). While that force doesn't contribute to propelling the shaft through the water, it does serve to hold the shaft against the bottom of the track. Even with an enclosed track this shaft lifting to the top of the track can affect accuracy on a long shot. With an open track the spear can actually lift from the track, causing erratic shots that go every which way. The energy lost doing this is very small, like 1-2%, but if you don't hit what you're shooting at, power doesn't matter.
The aluminum used is not anodized, since I would have to do that after all the machining is done- and I seem to never finish making changes! <img src= " height="23" srcset="https://spearfishing.world/forum/images/smilies/emojione/1f606@2x.png 2x">
I'm not sure what "aircraft" grade aluminum is. The aluminum I'm using is just 6061 schedule 40 pipe.
Interesting concept. Why pins instead of screws? When the gun is fired, the bands will rotate forward and try to keep going. The pins will need to hold the rounded plate from tearing off. Seems like screws would hold better, and allow for removal of the plate if you wanted to remove bands without re-tying them, or wanted to use solid wishbones. Pins are also strongest when they are in shear, and at 45 degrees their retaining strength is reduced significantly. Without some kind of head (like a rivet), the ss end piece could just pull off the pins fairly easily.
Nice clean lines- I like that! How about some more pics?
Lunker Buster, we can cycle your trigger in this one me and my friend built 20 years ago, and I can promise the plastic bits will get recycled into picnic forks and spoons.
;)
Me and my buddy John go by the rule ''Expect what you inspect'' You should hear the noise this baby makes when cycled at 1000 lbs.
Cheers, Don
Not to derail the thread, Don, but could you explain how it works, how you calibrate it, and maybe show a few more pics? Maybe a separate thread or a PM would be more appropriate so as not to derail this one. Thanks!
The Permatex I used was Permatex Black Adhesive Sealant #81158. It's a silicone based sealant, so it is relatively flexible, and it's waterproof. The black color blends right in with the butt pad, so it doesn't show.
Sorry for the deleted photos in the first post. I was reorganizing the photos and didn't realize what I had done. These are some from Xan's gun that show the line release in an "exploded" view. Note the line release lever is baackward in the photo- I didn't notice it until after I had shipped the gun!
Here are some from the original post.
Very nice handiwork, there, Rich. What kind of wood is the stock, and what size/ number of bands do you plan to use?
Thanks for sharing, Don. I look forward to the additional pics.
Bill
How does the lever work? Do you attach the bands to that so you'll have more slack to load on the topside, then turn the gun upside down and pull the lever and latch to get the remaining band strength?
Looks amazing. I always enjoy seeing hi-tech gear.
In the uncocked position, the bands are relaxed with the lever toward the muzzle. To cock the gun, you move the lever toward the muzzle of the gun, then cock it using either one or two of the 5/8" bands (I take one off if I only want to use one). Then you just move the lever toward the handle until it locks down on the catch just forward of the handle. You then shoot it as you would a "normal" gun.
The extra stretch from the preload gives the gun a lot of power for it's length, since it's really band length and stretch that give the gun it's power. In this case the band length is an additional 50% because of the additional band under the gun. An additional advantage is that due to the preload, the shaft is accellerating all the way down the length of the gun, compared to the "normal" gun, where the band is relaxed when it is about 1/3 back from the muzzle. Makes for a very powerful gun for it's size. Once you get used to it, it cocks almost as fast as a conventional gun.
I have the bands cut so the elongation is 250% with the preload. It's a lot easier to cock using the compound leverage for the last part of the cocking, so it would work well for anyone who has had an injury, or is otherwise unable to cock a gun to the full 250% elongation.
The concept certainly isn't new. I think it was Jack Prodonovich (sp?) that built a lever rollergun in the 30's. He didn't have the materials and equipment available then that we have now, but the concept is pretty much the same on my rollergun as on his.
I need to shoot it some more in the test tank, then the next one (there ALWAYS is a next one) will be a midhandle rollergun with a remote trigger about 42" or so- maybe with a stock made from some of that sexy colored plywood. :thinking:
It didn't stay in the sun long enough to get warm! <img src= " class="smiley" srcset="https://spearfishing.world/forum/images/smilies/emojione/1f606@2x.png 2x" height="23" width="23" loading="eager" data-tooltip="biggrin" aria-label="biggrin">
Always good to have some nice heini around! :toast2:
Even if you don't like the look of trashcans on your boat, you might want to consider this. It can be used for midhandles or Euros, with or without reels. I laid it out to hold 7 guns, 3 on one side, 4 on the other (well, 7-1/2 if you count the rollergun stuck in the corner). It's held in place in the boat with bungies, so I just take it out of the boat, put it on my cart, and haul the whole thing up to the house for rinsing and storage. Per Tin Man's suggestion, I'll add a 1-1/2" piece of pvc pipe in one or two corners for spare shafts.
Maybe the best part is the price: $35 at Home depot for the bin (Rubbermaid Slimline), $5 for the tarp bungies. I used some aluminum I had laying around for a heavier duty version, but holes and slots in the plastic would work as well, since it's pretty heavy duty plastic. If anyone is interested in building one, I would be happy to provide the spacing and layout I used.
A lead ingot the size you mentioned would weigh a little over 11 Oz. Big enough unless the gun was pretty big. It would be easy enough to just downsize it to get it exactly right. Maybe the best thing about it, however, is how easy it is to change if you add / take stuff off the gun, like a camera mount or a reel. You could even make more than one ingot, depending on how the gun is configured for a particular day of diving. Suweeet, Jeff 
