Enclosed track speargun

    Quote from hau

    Tin Man---IMO, tapering the bands does make a difference.
    1. I cut and grind the ends of my bands as much as is possible. I do not know anyone that trims their band ends as small as mine.
    2. IMO, another item that is important to spear speed and flight and accuracy is the shooting line itself. I think that how much the line effects the spear becomes very evident the first time a spearo freeshafts. I know that freedivers do not freeshaft, but I was just mentioning freeshafting to illistrate factors that effect spear flight. This is just my opinion and not to advocate that freedivers or anyone else freeshaft.


    Your on it mate.:thumbup:
    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.

    Quote from Dan

    So it's a simple round CF tube right? Could you please keep track of how many hours it takes you to do the work.


    So far, I have about 4-1/2 hours into the full sized barrel. Three hours to cut the tube to length, bore each end to the correct ID, and sand the entire length down to a perfectly smooth finish without the lines and minimal lumpiness that it started with. Then another hour to partially machine the black G10, and 1/2 hour to epoxy it to the tube.


    It's cold in the shop tonight. I have my halogen work lamps to keep everything a little warmer, but I'll still give it a solid 24 hours before I machine the track.


    The black track, with the smoothed barrel, looks much better than the green test piece. No pics though.


    One of the reasons behind Sporasub's new band setup. Threaded bands have 2 main problems:
    1 - muzzle holes need to be BIG to allow plastic fittings to pass through.
    2 - when bands under load, plastic caps act as cups (drag issues you mentioned)



    The sporasub bands have nice tapered ends, but still offer an adjustable rigid wishbone to create an open line of sight:






    I don't think the "thick rope wishbones" are nearly as much of an issue. For the acceleration phase of band release, the wishbones are oriented close to parallel with the shaft and hide mostly behind the cros-section of the bands. Sure, one may argue that every little bit helps... but the comfort in loading longer bands (when you have to grab the wishbone) is worth any minimal drag lost.




    I also agree that there's a popular misconception of throwing more HP at spearguns. The whole muzzle flip phenomenom makes perfect sense to us, but it's easy to see how counter-intuitive it is to beginning divers... "hmm, gun is shooting low, it must need more power."

    Quote from Dan

    Hey! that actually turned out very nice. Great work Jeff. Hau's going to be stoked.


    I'm a little concerned about the notch hitting the back of the track.


    What's the total labor time now?


    Thanks Dan. Funny, I noticed the back of the track as well, but not until I was uploading the photos. I plan to sand a more gradual taper on it before I send it.


    Total labor was about 12 hours.

    Maybe. I was worried about removing too much "meat' from the existing handle. Also, that is a regular Riffe shaft for the pics, so I don't know where the tabs will fall out on his shaft. If the first tab were just 1/2" forward, then I don't think there would be a potential issue with the wishbone hitting the end of the enclosed track. Of course, that would give up 1/2" of band stretch, so . . . another compromise.

    Quote from Tin Man

    Thanks Don. It's 47.5" long.


    It look's a lot longer in the first image, at 47.5 Hau should have no problem indexing the shaft on reload.
    One thing that helps as well is a 157 degree angle at the front of the ET. This will rotate and help index
    the shaft as the wing meets it on reload.
    My beach gun has a 49'' rail barrel and is a greet all around shooter. You are one cool dude man !
    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.

    Quote from Tin Man

    Maybe. I was worried about removing too much "meat' from the existing handle. Also, that is a regular Riffe shaft for the pics, so I don't know where the tabs will fall out on his shaft. If the first tab were just 1/2" forward, then I don't think there would be a potential issue with the wishbone hitting the end of the enclosed track. Of course, that would give up 1/2" of band stretch, so . . . another compromise.

    It will be a bigger problem if a rounded notch shaft has to be made out of a square notched shaft. A piece including the old notch is going to have to be cut off the back of the shaft which will bring the tab even closer. I'm not even sure if the shaft in your pic is engaged in the mech? If it isn't that will bring the tab back too far already.

    dan why do you think its going to be a problem, wont the bands pull on the shaft (still being so strong since at that point the bands are at about full extention) keep it straight enough. and if not it seems like even if it catches for a breif moment the bands are still going to have plenty of pull to shoot the spear out with plenty of force, since where it "may" catch is so far back,,

    Scupper Pro Gives You Wings!

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