Posts by Guest

I've been playing with the "lost wax" approach to carbon fiber molding for a little while on a small scale, and I finally have something to show for my efforts. There's still lots of work to do, but with the stock complete, I feel like the hardest work is behind me. So here are a few progress shots of my first attempt at a gun. It will end up as a small cross section, 52" long enclosed track gun for two bands and a 9/32" or 5/16" shaft. It's intended to be sort of an enclosed track CF euro design, with a butt extension for easy hip loading. I'm trying not to get too carried away with the actual design, while I work the bugs out of the construction process.

I found that the easiest way to cast the wax was to cast it into an oversized brick, let it shrink on top like it wants to, and then cut it to shape. The steel rod in the center reinforces the wax, so it doesn't crack during handling. It will also support the gun later when I'm melting out the wax.

This gun will be about 52" long when done. the rear 22" is carbon fiber over teak, so I have a solid core for mounting the trigger mech, handle, etc. The forward 30" is CF around wax, and will be hollow when everything is done. The two pieces are joined with a short CF sleeve.

Next post, getting the wax out . . .

Quote from Ihab

Thanks Tin Man...just a quick note...I've just read your question about the quality & polishing issue of the Nile-Tec mech....let's just say what you see is what you get.

Nice touch.

Quote from Ihab

. . .so I think I should send you the long awaited sample...about 4 days from today...how about that.

Thank you, that is very generous of you. I look forward to playing with it.

Quote from Ihab

Oh, before I forget, no the rubbers are not replacebale & I like your idea better....maybe I will use it in the future...if you do not mind.

We are seldom as clever or original as we think we are, so I'm sure that someone else did it years ago (and Don Paul probably knows who). But from my end, anything I post is for anyone to use however they can. If you get rich on it, remember me! <img src= " height="23" srcset="https://spearfishing.world/forum/images/smilies/emojione/1f606@2x.png 2x">

Glad you're back Ihab, and thanks for the silencer explanation. Is the rubber piece replaceable?

Dan - I noticed that Ihab was registered here, and I have encouraged him through PM to post his new products here, but so far it seems that he has chosen not to.

His handles and handle frames are available at Scubasworld, so presumably that is where the triggers will eventually be available. They are listed at $55 on his Nile-tec website.

Providing spearfishing locations AKA spots IS NOT the purpose of Spearfishing World forum. Our members freely share information about spearfishing equipment, diving techniques, hunting techniques, spearfishing regulations, and many other things, but should keep their spots to themselves. Knowing where to dive is the part of spearfishing where everyone has to pay their dues, going out and finding spots by themselves, or contributing to the forum for a while and making friends who will then invite you to their spots. Simply being a member here for a few days is not any reason to be given spearfishing locations.

New members may ask for locations this way: I want to go spearfishing out of ***** where can I go? Or, I read that there there are reef lines when diving from ***** how long of a swim is it to first one? In response to such questions the member should be politely directed to this post.

Some of you may think this is a harsh policy. Then perhaps you haven't seen depleted sea areas. Being a public forum anyone can read the posts. Do you want to continue getting fish from your spots? Then support the forum's policy of not giving out information about specific spearfishing locations online. Being a member puts you under no obligation to share this information with another member, never mind the thousands of people you don't know about who will read your posts. If you feel you really want to share a location with a person you hardly know, why not do it in a pm? Maybe you think that it doesn't matter because everybody already knows about a certain area, or maybe you know it's dead and don't even dive there any more, how do you think it got that way?

In particular, I would like to see how the top line release and his silencer work. I made a silencing screw for an Alexander trigger a while back, but I don't know which of Chad's guns it ended up in, or whether he is still using it. It was just a stainless machine screw, with a hole drilled through the middle and a small piece of rubber inserted, but it seemed to do the trick. I was just wondering if the Nile-tec works similarly, or uses a different approach.

On a more general note, I'm just curious if your overall impression is of a well made mech, especially the pieced together housing. Is everything really polished as it is in his photos?

Quote from greekdiver

. . . NOW GET WORKING ON SOME GOOD REELS! <img src= " height="23" srcset="https://spearfishing.world/forum/images/smilies/emojione/1f606@2x.png 2x">

<img src= " height="23" srcset="https://spearfishing.world/forum/images/smilies/emojione/1f606@2x.png 2x">

Ihab's Nile-tec trigger has the spring positioned higher, very similar to my Neptonics mod. He has recently been working with Kitto to tune the design, and the test data for trigger pull vs. band load is pretty good.

http://niledivers.com/shop/pro…b09f5d2e3d48325960bf9a54f

He says The Nile-Tec trigger casing is 0.52" wide x 1.18" high x 2.83 " long, so it would NOT be a drop in replacement for other mechs. I just thought I would add it here since it accomplishes the same end result as my modified Neptonics trigger, with far less effort. However I have NOT tried one of these trigger mechs myself, so I would be interested to hear an evaluation from anyone who has.

Quote from ladvr

Jeff,
Could you make the mold (plug) out of aluminum instead of wax and use a release agent to pop it out?

Yes, and no. That is the technique that seems to be the most common if the tubular shape is of constant cross section, especially circular. It works fine on a circular section, because you can twist the mandrel to help break it loose, and as you withdraw it.

The problem is that if you have an enclosed track, or a square shape, or anything else that keeps you from twisting the mandrel, it can be much harder to remove. At least, that's what I've been told. And obviously the mandrel approach won't work if you have something in the middle of the gun (like a high mount handle) that would be a geometric impossibility to remove if the core is one solid piece.

Hau - Take heart! I have found that this gun is giving me some trouble at the high mount handle, and the flaired butt section. But the straight section is a piece of cake. It should work very well for a Euro barrel.

The wax actually worked very well, once I learned to conrol the shrinkage, and how to remove it easily from the mold. One of the nice things about wax is that the properties can be tailored across a wide range of hardness, melting temp, etc, and it's reusable. But even the cheap parafin works well, and $10 at the local grocery got me all I needed for this gun.

I'll start a thread soon, when I'm done laying up the CF on this gun.

Aye.

Thanks Derryck. I did consider the foam / acetone approach, and even played with it a little. I wasn't satisfied with the results, but I probaby didn't stick with it long enough, nor was I aware of the fine grane foam that you referred to.

On the gun that I am laying up now, I poured the wax with a piece of steel rod inside the mold, which made it exceptionally strong and stiff. I have had no issues with heat from handling or machining softening the wax so far. One thing that I particularly like about the wax is that it is easy to repair samll chips or dings if you damage it. Not sure how that would be handled with the foam?

Do you have any pictures of the foam process that you could post? I would really like to see how that is done, and what a typical part looks like!

I should have the CF stock for my "concept gun" ready to show in a couple more days, if all goes well.

GR,

Have you tried cable? I've been using 1/16" 7x19 cable that is very soft for a while now and can't remember the last tangle. It has it's drawbacks (hard to cut, needs to be changed when kinked, heavy) but with a single wrap it probably won't make too big an impact on your shots.

I have a bunch. Let me know if you want to try some.

Quote from Don Paul

. . . I swam back to the boat and switched back to my 17/4 wishbones and after thousands of shots never had the issue again.

Love to see some pics and specifics of how you do your hard wire wishbones.

Never once had this problem on my old slide ring JBL . . .

That might be an interesting comparison. Which configuration is hydronamically "cleaner". A shark fin with an upward arcing loop of shooting line as it begins to move forward, or a slide ring that pulls the line relatively straight from the front of the muzzle? Not a JBL slide ring, but something like the slide ring for a slip tip.

GR,

What are you using for shooting line?
How long do you cut your wishbones?
How many wraps?
If 2 wraps, do you alter the wrap direction?

I recently tried using a stiff spectra line for my shooting line and it failed miserably - got stuck in the bands approximatley every 10th shot. This stuff tended to get a kink in it when twisted.

Bill used a closed muzzle rob allen railgun for years as his primary inside the rig gun and would get tangles pretty regularly until he started changing out his cable as soon as it got kinked.

I think that the tangles happen when the shooting line is kinked, or somehow slightly messed up while it is passing through the area where the bands are spread out after releasing their energy.

In my mind, minimizing wishbone length and doing everything possible to ensure that the shooting line comes off cleanly and isn't a material that is prone to kinks and tangles is about all we can do unless a bottom line release is an option.

I know that Merlo's site advocates a bottom line release to keep the shooting line on the bottom of the gun, away from the bands. He says that he has never had a band/shooting line tangle using this system. I'm thinking about using it on some future big guns which will won't utilize reels.

I just read your post in the reel thread and wonder how you route your shooting line (through the line anchor, or straight to the reel?) I like running it straight to the reel, just to keep one more thing out of the band area. As you know a float isn't an option many times on the rigs, and we usually don't have a bottom, so this is a subject that is particularly significant to me.

Sometimes I am asked to make camera mounts for home made guns that may have all kinds of goofy profiles on the stock. Generally, I decline, because it's just too time consuming.

I came across this strap mount, though, that might work for SOME applications, and it's cheap at just $20.

http://www.andrespearguns.com/…P-D68LAmJ4CFZla2god-BFwlg

The quick release feature might be nice, but I don't know how secure the strap mounting would be, especially on a relatively lightweight gun with a kick. Just wondering if anyone had seen or tried it?

Quote from greekdiver

Tin Man,

What is the best way to make the reel as light as possible?

I would guess that you could either use minimal amounts of strong (but heavier) materials, or use larger pieces of materials that are closer to neutral buoyancy. Not to mince words, but neutrally buoyant is more important than "light", right? Do we really care about how much it weighs in air, as long as it is neutral in water? Provided of course that it doesn't get so large as to be bulky.

Just some quick numbers:

The density of aluminum is 0.1 lbs/cubic inch. Delrin is about 0.055, solid carbon fiber about 0.058 (for my low tech efforts), and UHMW about 0.034.

Subtract the density of seawater (about 0.037) to get the effective density for each material when submerged. Of course the mass is still there (in terms of tracking resistance or recoil absorbtion), even if it feels neutral in water.

Any thoughts on the spool being partially enclosed (like Greekdiver's post 18), or open (like post 17)?

Thanks for the detailed explanation Davie. It sounds like the dentex system is very similar to the drag that is built into the spool of a spinning reel (for H&L fishing). That makes sense, since you don't want a fighting fish on H&L gear to either increase or decrease the drag.

I do get the point that the amount of drag is much less important, and the fact that it stays relatively constant more so.