double roller build

    Hey guys. Just wanted to show the work I have in progress. I still need to clean it up a bit more and then put some protective coating on it. The primary goal with this build was to try and prevent things from getting snagged. It started out as a double roller single action but with the difficulty I had trying load the bands, it needed to be a double action. I didn't see any other way to solve that problem.

    Have you thought of different angles between the two rollers with taper to achieve a more ideal band alignment? I see some power loss to friction @ the band/ roller plate.


    Cheers, Don

    "Great mother ocean brought forth all life, it is my eternal home'' Don Berry from Blue Water Hunters.


    Spearfishing Store the freediving and spearfishing equipment specialists.

    Not quite sure what you mean here, Don? Is this due to the bands making contact with one a other? The rollers are off the shelf from WM and I can not do much with them. They are narrow and is the reason I used them. The wood that's between the rollers are 3/4" wide and I wouldn't be comfortable with anything less. All that said, the muzzle on these rollers can get pretty wide and I was trying to keep it as tight as possible. I guess something has to give.


    I was hoping that the bands would lay a little differently on the bottom but no matter which bands I load first, the results seem to be the same. So I adjusted it with varying the wishbone length. Will water help lubricate the friction between bands?


    Thanks,
    Randy

    very nice work!!! i like the use of what i assume is either delrin or uhmw to keep weight down in the front. the rollers look to be a good size for the application (do you have a link or any info on them?) and the rest of the gun looks very well made.


    rollers can get really complex and they go against my "keep it simple" principal but i also like to tinker with things so i cant help myself.


    what don is suggesting is staggering the rollers to keep the rubber from rubbing against each other but that does make the muzzle really wide. i have been thinking of doing an inverted double roller like the one in the pic, as you can see the advantage of this design is, the mass is in the rear of the gun and the muzzle can be made thinner. it really kills my "keep it simple" theory but like i said, i cant help myself.

    Man my head was spinning after looking at that picture. I had to google it and saw the yotube vids. It looks like he uses lines underneath the gun and comes back up to load on the shaft. Basically a 4 roller set up. Wow, very impressive.


    I'm like you Steve, trying to keep it simple.....but the challenge....well, that's just fun. Ofcourse I have limited tools- hand tools, drill press, saw and router table- and that adds to the challenge as well. delrin is very user friendly and I was concerned about having too much weight up front. My pevious roller design was a single roller single action.


    I built the same band retainer for another diver on his roller gun and heard that the lines got tangled somehow as he was shooting in a downward angle. It shoots fine shooting horizontally, but for some reason the lines got caught shooting downwards.

    If you look at this image you can see the conflicting angle that will start scuffing the inner band when things are in motion. If you slightly cut a deeper groove on the inside back roller and on the outside of the front you may gain some clearance. A tapered grove in the wood of the back band may help as well . but it is hard for me to see all the angles/clearances.


    Cheers, Don

    It also looks to me like the inside delrin spacer could be modified to give the back roller some clearance. You could do two plates in stainless instead of that thick delrin to gain 1/8 and then use delrin spacers to stagger the rollers. Doesnt seem like it would take much offset.

    Ladiver, I think this will be an effective blue water or WSB gun. It has over 70" of band pull.


    Don, thanks for the clarification. I don't think I can do anything with it at this point. The rollers are bearing rollers and are pretty narrow. They are also in line with the wood or slightly higher so routing out a track to keep them apart probably won't do any good. Definitely something to keep in mind for the next one.


    Reef, I went with Delrin to keep the weight in the muzzle in check. I wouldn't go any narrower than that. For my intended use, it will be a single band. I would only use the second one for blue water. Actually a single band and first stage for reef shooting and put it on the second stage for amberjacks or if I need a little more reach.

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