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All About Guns What's your weapon of choice, and why? Discuss the beloved speargun here! |
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06-19-2014, 02:54 AM | #16 |
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Join Date: Jul 2011
Posts: 647
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Re: Custom Speargun 1.3m Euro
I have been trialling rare earth magnets that are 5mm and 8mm. The 8mm are by far better. 2 work great. You can turn the gun upside down without the shaft falling but give the stock a bump and it will drop.
If I put something over them like carbon they lose a lot of attraction. Just making sure they don't rust. I have been countersinking them below the surface and filling with epoxy to ensure no contact with salt water but I am not sure how long this method will last so I am getting it wet as often as possible. |
06-19-2014, 10:58 AM | #17 |
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Join Date: Feb 2009
Location: Weston, FL
Posts: 1,594
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Re: Custom Speargun 1.3m Euro
Very nice!
What type of bit, if you use a router bit, do you use to cut the recessed areas adjacent to the track
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Jose G. ---Dive Safe--- |
06-19-2014, 11:01 AM | #18 |
Sunrise
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Re: Custom Speargun 1.3m Euro
Use those magnets quite a bit Darren. So long as it's encased in epoxy, you should have no issues. I haven't seen one yet on any of my guns anyway.
That black gun and handle look amazing. |
06-19-2014, 11:04 AM | #19 |
Snorkel Master
Join Date: Dec 2011
Location: Lower Keys
Posts: 5,588
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Re: Custom Speargun 1.3m Euro
THATS IT, can you please stop with these awful photos. All the guns look terrible and need to be mailed to me ASAP so i can dispose of them properly...
On a much more serious note, I've never considered selling my kidneys to buy a custom speargun, but you are making me consider it. Gorgeous doesn't begin to describe, Id love to see that in person. |
06-19-2014, 12:16 PM | #20 |
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Join Date: May 2009
Posts: 3,292
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Re: Custom Speargun 1.3m Euro
I use magnets on almost every gun. I love them as I can avoid having a line guide and wrap the line over the shaft ... instead just have a small groove to the front of the muzzle and the line lays on that. I also find they have zero impact on velocity if you have just one point of magnetism. If properly encapsulated the rare earth magnets will easily outlast the gun, I remember reading somewhere about a Neodium magnet being tested after 15 years and no measurable loss of magnetism was noticed. If not done properly they will rust very very quickly, so best is to plasti dip or epoxy dip the magnet first let it dry and then encapsulate it with epoxy in a recess just under the shaft (I also agree 8mm is the perfect size).
Very nice gun by the way and that black CF finish really looks great! Are you using CF sheets or sleeves? I can't imagine a wood gun that thin and long working without CF to stiffen the stock. What setup do you plan to have for that? I am thinking of doing something similar for a 130cm band stretch and 150cm @ 7.5mm shaft using 2 x 17.5mm bands. The only thing I worry about is that the gun will not have enough flotation since it would have much less wood and the CF would weigh it down. But the advantage of being able to swim easily (especially in currents) and for a long time with such a low profile gun is a huge plus! Last edited by spearq8; 06-19-2014 at 12:26 PM. |
06-19-2014, 03:49 PM | #21 | |
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Posts: 647
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Re: Custom Speargun 1.3m Euro
Quote:
Thanks for the info on the magnets guys, much appreciated. As advised previously I found once covered in carbon they lost well over 50% attraction so its drilling them in post wrapping. I use a combination of carbon but finish with a sock. I have to do this in multiple stages to ensure the carbon is adequately saturated with epoxy prior to vacuum bagging. The muzzle received extra treatment (as you would expect) because it is really narrow. I supported this gun by the very ends and then stood on it. With 90kg of weight it had no noticeable deflection. I am sure with more scientific measuring there would have been some. This is where the cost jumps considerably. Each time you vac bag there is a good amount of sunk costs in consumables. But for me to explore the design possibilities is worth it. This gun is now wearing a new custom timber handle (similar to the one pictured on the previous page but with Padauk instead of Purple Heart). Mech is a reverse wide throat Euro. The shaft is a 7.5mm straight shaft. Twin 16mm with space for a third if required but I am not expecting that will be necessary. It has a space for a reel and after testing may be fitted. |
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06-20-2014, 12:14 AM | #22 |
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Join Date: May 2009
Posts: 3,292
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Re: Custom Speargun 1.3m Euro
I need to get myself a vacuum bagging kit. I was wondering if the track will and other curves and crevices (like the band slots) will pack ok? From the picture it looks like you have a rod in the track? Or is that an optical illusion and the bag is actually going in the recess? Personally I think with the very nice CF results you are getting, it is worth the extra costs of vacuum bagging, and for sure the stiffness of the stock will be dramatically improved.
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06-20-2014, 01:25 AM | #23 |
Pacific Spearo
Join Date: Jul 2007
Age: 62
Posts: 3,358
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Re: Custom Speargun 1.3m Euro
would it be possible to show some more pics of that gun? also, more detail about your shaping? also more detail about your CF process? and anything else I might like to see
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06-20-2014, 03:25 AM | #24 |
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Join Date: Jul 2011
Posts: 647
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Re: Custom Speargun 1.3m Euro
Just advising I will be absent for a week. Will post something on my return. Cheers guys.
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07-05-2014, 01:25 AM | #25 |
Reluctant User
Join Date: Sep 2013
Location: Santa Barbara, CA
Posts: 729
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Re: Custom Speargun 1.3m Euro
Well, it's been two weeks...
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07-05-2014, 01:37 AM | #26 | |
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Join Date: Jul 2011
Posts: 647
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Re: Custom Speargun 1.3m Euro
Quote:
Tight radius's can be problematic for carbon fibre. In my experience the carbon does not like to conform neatly in the track. I use a 8.5mm rod that I have polished and use release agent on in the track to have the straightest track I can (without machining) Any tight radius or change in shape offers new challenges. The vac bagging system is very good. Another really interesting system in moulds with inflation tubes. I will be making some of these in spring just for fun. Sorry for the later reply, its winter here and I do not like sitting down in winter, have to keep moving |
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07-05-2014, 01:41 AM | #27 |
Reluctant User
Join Date: Sep 2013
Location: Santa Barbara, CA
Posts: 729
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Re: Custom Speargun 1.3m Euro
You don't have to apologize mate - I was just stirring the pot.
But, if you happen to have any more pics of that latest carbon gun... |
07-05-2014, 02:00 AM | #28 |
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Join Date: May 2009
Posts: 3,292
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Re: Custom Speargun 1.3m Euro
Take your time and thanks for the tip on the rod, I was actually planning to do the same exact thing and think it might even be possible to build an enclosed track by pinning a 1 caliber larger than will be used rod and then before the final CF sleever, two choices ... one is to carefully lay a straight tape on each side leaving a 3 or 4 mm gap for the shark fins, the other is to go over the shaft and then hope you are able to cut a clean track after the epoxy hardens.
With regards to vacuum bagging ... I think I have come up with a perfect idea but not sure it would work. I saw a commercial on TV about food vacuum bagging to store food in a freezer. It really would be an amazing thing to have around the work shop. One use would be to seal rubber bands and rubber material. And in the commercial they show a long row of tin cans that get squished very dramatically. I really don't know what the vacumm pressure achieved by those machines and they probably vary, but if it can crush a 2 long rows of tin cans then it would seem perfect. The great thing is that you can buy rollsl of the plastic material. So you choose a thin roll that allows for your gun to go in comfortably ... you heat seal one end and pull out a long roll enough for your gun. You put the release nylon and breather fabric on the gun and then pull the vacuum and it seals it! Can't see why that would not work except that maybe the vacuum power might not be strong enough .... but sure looks interesting and I certainly am going to give it a try. I thought about the heat shrink tubing but feel it allows too much extra epoxy on the stock which can add more weight and can cause a problem in ballasting. Another thing I liked is that you can boil stuff with the bag ... so maybe you can even use hot water dip to cure harden the epoxy if you can control the temperature properly. Not sure what the cure hardening temperature is for epoxy but it must be below boiling temperature. Anyone try this idea? |
07-06-2014, 06:55 AM | #29 |
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Join Date: Jul 2011
Posts: 647
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Re: Custom Speargun 1.3m Euro
Giving the challenge of an enclosed track some thought, if I were to make one I would fist seek a carbon fibre tube and install it into the blank and then wrap the whole gun. I would then cut out the fin slot. I feel confident i could make it providing I could get the tube I needed.
I have a couple food vacuum set ups I used for my fish. I could make a little dummy blank and try it if you would like. My suspicion is it will not work as it does not draw enough of a vacuum. My pumps are 2 and 3 HP motors. These are cheap pumps that are readily available. If you would like a link I can PM it to you. (I don't want to advertise products). Regarding heating, I just bake mine a few days after coating. I do need to make a better oven though. |
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