Dirty Water Rollergun

Hi Y'all'

I finally got around to almost finishing my first attempt at a rollergun. I'm considering it a prototype, which is code for "I screwed up a lot of things but finished it anyway" Actually, there are some things that are new that I want to try, and depending on how they turn out, I'll build a "new and improved" version down the road a little.

I found the rollergun a bit of a challenge, trying and discarding ideas as I went. The final result looks a little like it was designed by a committee, but turned out fairly well, despite all the modifications I made as I went along. Not a lot out there on rollerguns. Phil H was helpful in his posts, and there were a few other rollergun builds, but not much.

Anyway, here goes:

The gun is only 30" overall, sinks with the shaft in and floats horizontally without the shaft. I built it for hunting the turbid water in Pensacola Bay, FL, where tin Man and I do most of our local hunting these days. It shoota a 9/32 or 5/16 shaft in an open track, and is designed to shoot either one or two 5/8" bands. We often get shots at decent red snapper and grouper, and I wanted th have enough power to shoot a 15- 20 Lb fish. Most shots are less than 12 feet, but if the gun shoots straight enough I might try rigging it for 14' or so.

I started out thinking I would build the muzzle out of aluminum channel, but as I got into it I couldn't get the strength between the aluminum and the wood I felt comfortable with, so I mortised in a piece of teak, and the muzzle became teak along with the rest of the gun. I stole the shooting line retainer idea from Bretto's post (I told you I would, Brett!). It's fastened with the forward roller axle and the pin you see between the two axles.

I installed 2 epoxy coated magnets under a delrin muzzle piece to hold the shaft in place.

The delrin rollers are 1-1/4" for the front, and 1-1/8" for the rear, and are tapered to make the rear bands move inboard when stretched, and the front bands move outboard. The axles are 3/8" aluminum bar stock with the ends drilled and tapped to hold 8- 32 screws with washers.

I'll continue in the next post.

The track is an open 11/32" track with a poseiden sub mech. Tin man and I installed his "rubber rivet" silencer on my last trip to Baton Rouge. The handle is aluminum with a shapelock grip. I still need to do a little more definition on the shapelock, but I can shoot it like it is (Jeff, is there a maximum number of cycles shapelock can go through before it loses it's properties? :D)

I made the handle frame a little longer than usual, and installed the line release in the front of the handle frame. A short push rod from the line release tab on the bottom of the mech operates it. Hopefully, the channel down the center of the underside of the gun will keep the shooting line from getting tangled with the bands. We'll see.

More in the next post

Originally, I had made band anchors out of aluminum channel that was screwed to the underside of the gun. I didn't feel comfortable with that, so I installed 1" x 2" aluminum pieces in the stock and pinned them with 3/16" aluminum pins, then milled out the little hooks. Since I was after a gun that could have a preload, there were 4.

The gun will be able to shoot with or without the preload feature. It sinks with the shaft in, and floats level without the shaft. Here are a few more pics.

I've still got a little tweaking to do, but I hope to shoot it next week at a target and see how it shoots. There are mor differences between a conventional gun and a rollergun than I thought, so I'll see how it shoots and go from there.

Got a few more pics today. I couldn't shoot at a target due to lack of vis at my dock, so I shot a few times into the sand and at least got to see how it fired. No shooting line entanglements, etc. I only shot from the back pin (per Phil's recommendation), but I shot from both the single and 2nd stage position. The solid wishbones worked ok, and I like the sight line they allow along the shaft. I'll probably leave them on and try soft wishbones the next time I have to change something on the bands (Phil mentioned that hard wishbones often cause the tie lines to wear quickly so that might be the first thing I need to change).

Shooting line and bands functioned well and there were no problems with the bands interfering with shooting line, in spite of their close proximity.

Once I have the water clarity I'll see how the accuracy is. I didn't see any problem with how the shaft was leaving the gun, but without high speed photography or a target I can't really tell where the gun is shooting.

The bands lie pretty good along the top and bottom, especially with only one band. I've got 3 wraps on the shooting line right now but I'll wait until I can shoot it in the water and see how much of a pain 3 wraps are before I decide whether to shorten the line or not. If the gun shoots straight and has the power, I might leave 3 wraps on it since it's so short.

Here are a few more pics showing how the bands and shooting line lay. I've got some tweaking to do on band length, but these are the first attempt. The bands are so short a little change makes a lot of difference in the stretch ratio.

If I make em small enough, nobody can see the screw-ups.:laughing3: How do you make them bigger?

Thanks. I'll re-try with the larger pics.

Made quite a few changes since I last posted on theis thread.

I wasn't happy with having to move 4 band ends to get the compounding effect after loading, so I decided to install a lever. I wanted to push the lever toward the muzzle so, by having cables run from the end of the bands through a roller and back to the lever I could maximize band length and stretch.

Here's what the underside looked like before the change:

"It's a terrible thing to see a beautiful theory brutalized by a vicious gang of facts!"- Unknown. I really should have thought it through a little better. Pushing the lever forward required placing the other hand on the muzzle over the spear shaft, which was now in the loaded position. The reversing pulley also created additional drag which made it harder to cock the lever. After visions of the pins on the shaft going through my hand like a tiny two toothed chain saw, I scrapped that idea and decided to build the gun with the lever pulled back toward the handle. Much safer. The little gun is now starting to resemble some kind of mosaic with the different colors of teak.

Of course, in order to move the cocking lever under the gun, the line release had to be relocated to the side. I used the same resetting tab at the bottom of the mech, and used the previous line release slot under the gun for a locking lever to hold the cocking lever in place after the compounding lever is in place. Whew!

Here's the handle with the original line release:

Here's the final version (side release).

More in the next post.

I used a compression spring to make the lever latch engage:

With images of the little chainsaw still in my head, and knowing I would be bumping the gun around in the test tank, I also installed a safety.

Here's how the lever turned out:

In the next post I'll show how it looks rigged out.