Building a speargun

Don,
You should give the open vs closed track discussion its own thread. Lots of good info.

Quote from tufual

quick question , how much of the gun's accuracy is down to the shaft like the flopper , geometry of the tip vs the track on the gun , i would imagine the barrel isn't as important as the projectile .:confused1:

A lot... here's some of what counts: hydrodynamics, duration of of thrust of the projectile (rubber pull) cross section of the projectile, payload the projectile (in the case line wt and drag) and here's the big one...speed of the shaft through a liquid the density of salt water.
More rubbers after a point don't equate to more shaft speed on long shots....more mass of the projectile retains more energy down range.

I'll save more comment for another thread sometime on dynamics.
Now I'm just drooling over the history of this fine teak.:thumbsup2:

Cheers, Don

Here we go....Enclosed VS Open.
Its quite difficult to state for sure that ET does have a -ve effect on spear projectile/speed.......its really depends on several factors.
- Type of Track
- Clearance inside track

I think the "vacuum" effect is a bit overstated....the shaft at all times is surrounded by water and if there is adequate clearance around the spear; the vacuum effect will be extremely minimal if any...just a slight decrease in wishbone length alone can tack care of it.

I'm blessed with testing guns in a pool almost every weekend and have not noted any effect of an ET....and to an extent...there is no difference except when it comes to overpowering and loading...actually the ease of loading an ET lets you focused more on the fish during shaft loading as opposed to OT where the shaft may slip out of track and you know the rest.
At times with an ET, I shot fish without rigging the mono as there was no time ( I know its not very safe) and this could be quite difficult with OT....and I was very glad I have this option...otherwise I would have lost some nice fish.

The only advantage I see in OT is that its easier to build..and have the choice of using notched shafts ...I prefer sharkfin shafts for several reason but that's another story.

If its a must, I would go with DEEP open track.

Ihab

Looking like some nice wood!! Gonna have some sweet mojo in these guns!

I had .5" of wood between holes. probably overkill, but better safe than sorry. I was also planning for 5/8" bands though. Been a couple years and haven't had any issues.

"My blank is just a touch over 1.5" tall. I'm using a Neptonics reef mech with the auto reset tab and it's a mid-handle so things are going to be tight down at that end of the gun but I think it will work. First lesson learned is make a taller blank when using that mechanism."

1.5" is tall enough if you use a handle frame with a flat recessed base. Personally, I prefer to set it up kind of high in the blank and use a bent push rod, but I know some guys don't like them bent. I have found that the rod doesn't flex if there is nothing binding it, but with 2-5/8" bands recoil won't really be a problem. Whichever way you go, if you use a flat based handle frame make sure it's recessed into the blank enough to be flush.

Deanmc:thumbsup2:

I was referring to the handle frame. The higher up into the blank you can recess it, the less the muzzle "flip" or "jump" will be. Of course, adding weight to the muzzle helps, but you can only do that to the extent you need weight forward for trim.

The build's looking good!

Nice work on the blank. Thats the only part I have yet to do myself. And nice quick work on the major cuts.

Looking really awesome :thumbsup2:, very nice shaping on the handle. May I ask you what lead you to decide to go with epoxy? I did a similar back and forth on my last gun and ultimately went with oil. So far im pleased but it hasnt gotten enough use for me to form a decision on how much I like it. My first gun was matte/penetrating epoxy and I must say im not really a fan of how it wears. Its sort of the worst of both worlds, not enough epoxy to protect the wood, but not easy to buff out a scratch and slap on a new coat with a rag like teak oil. It was however easy to get a beautiful finish at first with just a foam brush, something that seems impossible with regular epoxy coatings.

It all scratches I would say, the question is how the scratches effect the gun and what effect it has on the gun long term. Im not a coating expert but heres my 2c.

A thick glossy epoxy coating scratches easily and looks worse the more scratches it gets, but it can be refinished in a way akin the teaspon shallows KES speargun thread without ever even really getting into the wood to fix up damage. The big downside to these coatings its its effing impossible to get it perfect (even most of the amazing sexy coatings you see people doing online arent so perfect in person) , it gunks the entire gun up and makes things not fit anymore, and refinishing the gun is a major ordeal requiring getting that perfect coat once again.

A thin penetrating epoxy matte coating scratches easily and looks worse the more scratches it gets, but these scratches reach the wood since the epoxy is "soaked" into the top layer of wood and not a thick layer. You can refinish by slapping on another coat of penetrating epoxy and it looks pretty good afterwards, but to me the idea of touching up a gun by mixing up a batch of epoxy, coating it, and then praying it dries evenly and without bugs etc in it is way way more maintenance then slapping on a coat of oil. And it would need to be done often to keep it looking good

Here's an example of scratches in my penetrating epoxy coated gun.

Oil coating scratches easily but looks the best when it gets scratches, it also looks the best before it scratches imho. Much better then matte epoxy. The huge trade off here is the scratches are 100% directly scratching into the wood with pretty much no protection against anything except water. Removing a scratch means removing wood. But they are hardly noticeable compared to epoxy. The other downside is needing to oil the gun often, but its not much of a downside imho. slapping a coat of oil on is extremely simple and quick. Pretty much looks perfect regardless of what you do. And for me is kind of enjoyable. Just a few minutes with a rag and youre done. No timing, no mixing, no thinning, no heating. If it didnt kill me to know how beat up my smooth edges will eventually become oil would be a no brainer for me.

Maybe one or two comments on the "Penetrating" epoxy. I use thinned regular epoxy, not some "special" formula, and I don't use just one coat. If you like the matte finish that looks like oil, apply the epoxy, then wipe the excess off with a dust free rag. Repeat, repeat, etc. while you build up many thin layers of matte epoxy. No bubbles. I've also used cross linked poly urethane as a top coat (actually MANY top coats). The beauty of it is that after the epoxy is down and sanded smooth, the urethane goes on really smooth, whether it's sprayed or brushed (I prefer sprayed).

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