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All About Pole Spears & Slings What is it about that traditional method of the early hunter/gatherers under the water? These devices are indeed interesting and effective.

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Old 06-16-2017, 01:46 AM   #31
Diving Gecko
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Re: Help Needed, DIY Jap Style Polespear

I did do some calculations on the displacement, mass and resulting buoyancy but that was on paper. I think I mentioned the results a few posts up.
The CAD could definitely do most of it as I can specify the density of each different material and then it will tell me the mass and volume, then I would just need to adjust for the density of saltwater.
I do have the mass of the metal parts but didn't make the full assembly in the CAD yet, but it is doable.

As for the finish, this is only the renderings out of the CAD part of the program. I haven't even been inside the CAM part yet - but they do have it, and supposedly it is really good, too. So, the finish is just some preset that I picked (Stainless for the steel part and then they had a pattern for carbon fiber, too).

The pole's outside diameter is 16mm, btw.

But at the end of the day, I might have drawn up something that is not really practical to machine with a lot of fillets vs. chamfers and perhaps some other things that my engineer will change just to make life easier in the machining part. E.g. that inside little tail end with a hole in it is just for the "safety lanyard" running between the connectors in case the carbon snaps. The hole is 3mm, so I can use 2-3mm dyneema and honestly, no one will ever see that tail end, so if it is much easier to machine in a different way instead of this nicely rounded fillet it had now, then of course that is fine. Even with a normal chamfer it would still be fine as the dyneema wouldn't need to hold up to much chafing (it would only ever be of use for hauling in one fish in case the pole had snapped).
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Old 06-17-2017, 08:09 PM   #32
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Re: Help Needed, DIY Jap Style Polespear

I has making a joke about the surface finish in CAD. (engineering humor)

Mass calculations are pretty good actually in most of these programs.
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Old 06-18-2017, 06:01 AM   #33
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Re: Help Needed, DIY Jap Style Polespear

haha, I did consider that for a moment, but you know I am "the in-between generation" who disliked smileys to start with and now, I can hardly write a sentence without them. So, since there was no winking smiley, I wasn't sure if you were joking or not, haha. Such a pity how I have come to rely on those little faces...

Anyways, I have spent a decent amount of time watching tutorials on Fusion 360 and supposedly, the CAM is really good and resides within the same program, too. You switch seamlessly between the two, so if you need to go back and change something in the CAM, it should update the CAM automatically. I don't really know much but it does sound like a real world time saver.
It is free for a year, at least, for start up companies or maybe also for small enterprises(?)
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Old 06-20-2017, 12:50 PM   #34
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Re: Help Needed, DIY Jap Style Polespear

Bands - Slim and long or Fat and Short?
I touched upon this earlier on in the thread but no bites yet.
So, let's try again:-)

I have some Primeline Small ID bands in many different sizes and would like to rig the spear with just one band (not a loop).

From a quick test I did a while back, I figured out I could pull around 44 pounds. Let's call it 40 pounds for the sake of simplicity.
Now, the thing is, you can obviously set up bands in many different ways to get you to 40 pounds. Like a fatter band stretched less or a thinner band stretched more.

E.g. going by the Primeline force calculator I compared these two:
13mm small ID rubber stretched by a factor of 4 = 41 pounds of force
14.5mm small ID rubber stretched by a factor of 3 = 39 pounds of force

Let's call it an even 40 pounds for the two. Am I right in assuming that a thinner band stretched more would be advantageous? I am thinking that since it would be cut shorter, it will have more "efficient band stretch" and push the spear over a longer distance before it goes slack?

I don't mind if the band's life expectancy is shortened by stretching it longer.

Here's the Primeline force calculator numbers for Small ID bands, btw:

Last edited by Diving Gecko; 06-30-2017 at 06:25 AM.
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Old 06-20-2017, 12:53 PM   #35
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Re: Help Needed, DIY Jap Style Polespear

Quote:
Originally Posted by Diving Gecko View Post
BANDS - SLIM OR FAT?
I touched upon this earlier on in the thread but no bites yet.
So, let's try again:-)

I have some Primeline Small ID in different sizes here and would like to rig the spear with just one band (not a loop).

From a quick test I did a while back, I figured out I could pull around 44 pounds. Let's call it 40 pounds for the sake of simplicity.
Now, the thing is, you can obviously set up bands in many different ways to get you to 40 pounds. Like a fatter band stretched less or a thinner band stretched more.

E.g. going by the Primeline force calculator I compared these two:
13mm small ID rubber stretched with a factor of four = 41 pounds of force
14.5mm small ID rubber stretched three times = 39 pounds of force


Let's call it an even 40 pounds for the two. Am I right in assuming that a thinner band stretched more would be advantageous? I am thinking that since it would be cut shorter, it will have more "efficient band stretch" and push the spear over a longer distance before it goes slack?

I don't mind if the band's life expectancy is shortened by stretching it longer.
[/quote]

I personally would rather run larger ID and less stretch in the case that I need more punch.
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Old 06-21-2017, 09:35 AM   #36
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Re: Help Needed, DIY Jap Style Polespear

In preparation for the assembly and rigging of the spear (waiting for parts) I did a test of some of my Primeline Small ID rubber. I know that I can pull about 45lbs and hold it - that was on a tube with no grip, so maybe I can hold more. But I am aiming at this for now.

I hooked up a short piece of 14.2mm Small ID rubber on my test bench and pulled it to various lengths and found out that this particular rubber gives me 45lbs at 3.4 stretch ratio. So, I will cut one rubber to that ratio and then cut a 13mm rubber at a higher stretch but same 45ish lbs load and bring both, plus possibly some extras.

Also, I will try to eliminate as many steel connections as possible and make the "band stretch" as long as possible. I will go with a hand strap, so I loose some band length and efficiency there but getting rid of shackles and swivels and just tying short wishbones with slip knots will help. It should also make the spear less noisy.

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Old 06-21-2017, 09:53 AM   #37
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Re: Help Needed, DIY Jap Style Polespear

Quote:
Originally Posted by Ren View Post

I personally would rather run larger ID and less stretch in the case that I need more punch.
Oh no, Ren. I was hoping you'd say the opposite, haha.
I do think the math is for thinner bands (same power at longer stretch) as they will have more "travel" at which they can exert force on the spear before they go slack. Anyways, I can probably only really verify this by shooting penetration tests at thick foam and I am not going to waste my time doing that in Japan. So, I will cut one thick band and one thinner one and see how they feel;-).

Also, as mentioned above, I will try to rig the band so I don't waste any unnecessary band stretch. Spearos are going that way with reverse triggers and shafts with shark fins further back on their guns. On a polespear with a much longer band stretch missing out on a few inches has less of an impact, but it still feels weird to me when I see super long wish bones on many commercial spears.

Anyways, I have most of the bits and bobs, just waiting for the metal parts to show up.
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Old 06-25-2017, 08:53 AM   #38
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Re: Help Needed, DIY Jap Style Polespear

Hand Strap V1
While waiting for my connectors, I set out to make the hand strap.
A lot of this stuff, e.g. nylon webbing, is dirt cheap in China, so I ordered a few different sizes and settled on a strap 30mm wide. I am a sucker for black, grey and red - even to the point where I am considering ordering red Primeline rubber, just for the sake of it;-) (but I wont. Well, at least I think I wont... but it might, haha)

Anyways, onto the strap.
I'll just post some pics and add some comments, it's all pretty self-explanatory:

50mm was too wide, even 38mm I think is too much, so here are some strap material in 30mm width:


I had this idea that I wanted to use semi-hollow, tubular rivets so ordered some of those in 4mm - in stainless 304 - but it turns out they are so damn tough I can't even set them properly with a hammer. I would need a hand press and that is 30-50 bucks I don't feel like spending on a one-off. The pic shows two test rivets after a whole lot of hammering. They are just not being shortened enough that I can use them:


As mentioned I am trying to gain band stretch, so trying to not even use a D-ring. Instead, I am threading the wishbone dyneema through this short tube of 304 stainless steel:



The tag end of the line runs through a hole that I burned in the strap and will then attach to a plastic wishbone inserted into the band:



For the strap itself, I superglued it just to hold it in place while I burned the holes for the 'screw posts' or 'binding rivets' that I had to go with instead of the tough 304 SS rivets mentioned above:




I put the whole strap on my test bench and it held 50kg/110lbs of pull - which is over double of what I can hold in my hand. The dyneema did get cut where it exits the steel tube in the strap but I think it will be fine once I smooth the edges, so I am not too worried about that.
I even wet the strap to see if the nylon slider would still hold the strap properly and it did. Now, I have read that nylon can swell when submersed for a long time, so it may still break or give. But I'll make a strap without a slide as well since it is not really needed once I dial in the correct size:


Next up is to add a resting hook to the strap. Could be a table spoon as they have a suitable size and thickness. I may also make a version with Tinman's 'dyneema trigger' but not exactly sure how well it works in real life.

Last edited by Diving Gecko; 06-30-2017 at 08:41 AM.
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Old 06-27-2017, 06:39 AM   #39
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Re: Help Needed, DIY Jap Style Polespear

I actually managed to cut the dyneema twice on the sharp bend in the SS tube which wasn't too surprising given that I had not deburred the drill holes at all. So, I used some abrasive string and followed up with #320 and #2000 grit polishing paste on a piece of nylon line. Now, no issues at all. I pulled the strap with about 128lbs on the bench and no cutting or fraying of the line this time.



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Last edited by Diving Gecko; 06-30-2017 at 08:42 AM.
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Old 06-30-2017, 06:12 AM   #40
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Re: Help Needed, DIY Jap Style Polespear

Resting Hook and Finalized Hand Strap
I made a resting hook so the first strap is done now.
Didn't go with a spoon, though I think it is still an easy option. Instead, I found some stainless hooks on the main Chinese equivalent to "Amazon". Again, cheap, cheap (about 50 cents/ea). I ordered one each in the sizes of 50, 60 and 80mm and ended up using the 60mm size.

I used ordinary hand tools to cut and bend and a power drill and Dremel to sand and polish the hook:




Mounted on the strap and polished all the way to #2000 with polishing paste after having first ground and sanded it to shape with a rotating grinding stone and sanding disk on the power drill:


Here's the backside showing the binding rivets I used earlier on, too. They get pretty beat up when I put a vise grip on to screw them together, bit I polished off the burs, just so the don't mess with my clove too much:


As before, I threw the strap on my test bench for a quick check, pulled it to 35kg/77lbs and it all held up nicely:


All in all, I am quite happy with this first strap. I will make 1-2 more in the next few days, possibly without the nylon slider to simplify things a bit.
Hand straps are definitely not rocket science and there are a ton of ways to make these. You do loose quite a bit of band stretch, though and if I was using a looped band on a shorter pole, I would probably have a go at making a harder sort of custom shaped "hard glove", perhaps with a tube to route the band through, to better spread the load on the hand whilst not losing band stretch.

Last edited by Diving Gecko; 07-01-2017 at 04:02 AM.
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Old 06-30-2017, 06:18 AM   #41
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Re: Help Needed, DIY Jap Style Polespear

Grip
I also received some heat-shrinkable grip. I think it is used for fishing poles and I have seen some of the Japanese spearos use it, too. Again, for about two bucks for each meter/yard, it is affordable:


I might also try the self-fusing tape. I have some both in silicone and rubber (the blue one is silicone, though I ordered red, haha):


From left to right, silicone tape, rubber tape and the heat shrink (with o-rings):

I can't actually tell that much of a difference in the "stickiness" of these grips in the dry. Possibly, the rubber and silicone is slightly grippier than the heat shrink.

[EDIT]
I did a new shower test with the three grips shown above and PU coated working gloves. Sounds fancier than it is as I just took the test poles with me in the morning shower;-).
The most grippy was the black rubber (3M and cheap local brand was the same), then silicone and heat shrink.

But I actually think the best thing I can do, once I know exactly where I want my grip, is to add a layer of carborundum. I have it already in some different grit sizes for a few custom grips I did on my spearguns not long ago:

Last edited by Diving Gecko; 07-04-2017 at 11:22 PM.
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Old 07-02-2017, 12:26 AM   #42
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Re: Help Needed, DIY Jap Style Polespear

that heatshrink grip + Orings is cool!!

maybe when this economy roll of silicon self-amalg tape runs out I'll try something neat like that

the carborundum'd be neat, and low profile, but rips the hell out of skin/gloves/wetsuit no?!
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Old 07-02-2017, 04:54 AM   #43
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Re: Help Needed, DIY Jap Style Polespear

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Originally Posted by kavachi View Post
that heatshrink grip + Orings is cool!!

maybe when this economy roll of silicon self-amalg tape runs out I'll try something neat like that

the carborundum'd be neat, and low profile, but rips the hell out of skin/gloves/wetsuit no?!
Can't take credit for the heat shrink thing at all, I have seen it on Japanese polespears (except they don't seem to use o-rings) but it could be the easiest way to do this and the grip with PU gloves seemed pretty good in the shower:-)
But the self-amalgamating silicone tape had even better grip, I think, though it seemed a bit fragile. Just the behavior of silicone; it's not very resistant to cut and tears. I haven't tried the rubber yet. Again, these things are cheap out here at 1-2 bucks per roll. But even if it is 5-10 bucks for a roll, it is probably worth it. I think there is about 5m (or yards) on a roll and since you stretch it as you roll it on, I think you could probably re-wrap 5-10 times per roll, depending on your grip length.
As for carborundum, I think the wear depends on the grit. The first speargun grip I did with this was with a very low grit (#24, I think) which does eat up gloves for breakfast. The latest one is #80 and it seems from other posters that #60-125 is a good range and a little gentler - but of course less gentle than the rubber tape or the heat shrink.

As a side note, it is interesting who came up with what though in the different "schools of polespear thoughts". It seems some ideas were hatched there, and made it to the US. Some might have been in the US first (10-15 years ago), then made it to Japan, before coming back to the US.
E.g. Headhunters' slip-tips looks pretty much exactly like Japanese slip tips (small tip, big barb and smaller in length). Their rubber band retaining system is similar, too. Though it is more beefed up and I like the simple HH "quick release" of the shooting line.
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Old 07-02-2017, 06:01 AM   #44
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Re: Help Needed, DIY Jap Style Polespear

one of those gangster Okinawa GTs is gonna see that sexy carbon fiber and its going to be ON!!
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Old 07-03-2017, 11:07 AM   #45
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Re: Help Needed, DIY Jap Style Polespear

Quote:
Originally Posted by Diving Gecko View Post

As a side note, it is interesting who came up with what though in the different "schools of polespear thoughts". It seems some ideas were hatched there, and made it to the US. Some might have been in the US first (10-15 years ago), then made it to Japan, before coming back to the US.
E.g. Headhunters' slip-tips looks pretty much exactly like Japanese slip tips (small tip, big barb and smaller in length). Their rubber band retaining system is similar, too. Though it is more beefed up and I like the simple HH "quick release" of the shooting line.
I don't think any Japanese style spears or gear have made it this way. Their style of diving and pursuing fish is unique to them. The gear they use are copies of what came back from Hawaii and the US. I know, I've had a hand in some of what gets considered as Japanese style.

Started using the "X" heatshrink style grip 10yrs ago. The non X style form the same manufacture works better. I use transfer tape then wrap 200-250lb mono then the grip. You wrap different for left handed shooters. If its a spear that is under 3/4" I dont use this type of grip as it doesn't offer any advantage in holding power. If I can get away with it I use no Mono, orings, wire, tuna cord, trimmer line etc under my heatshrink, or wrapped grips.
Less is more when you are gong for range. Big bulky grips slow the spear.

I like to take 3/4" wide sand or rubberized grip tape and with 1/2" to 1" spacing warp if down the spear to make my grip. I either will wrap this with amalgamating tape or leave as is. On all my grips I will take either heavy 2" pc of heatshrink tubing or quality electrical tape and place at front of spear. Shooting fish wreaks the grip and this helps prolong the life of the grip. Unless im going over 80lb of band pull I leave my grips plain.

. Ive made a ton of custom stuff over the years and these designs are on just about every spear out there now.

First time I seen a Manny knot on a spear was in the 80's. SCUBA pole stickers would use this design to slip over their hand so not to lose the spear.
Grips are nothing new and always remember my dad making different types of grips for our spears.

Started using 1/2" band material in '91. My Dad started with some amber speargun 1/2" even earlier.

At one time fiberglass polespears were well built and very strong. Manufactures mainly used solid fishing rod blanks. Most had gelcoat. Look for older Sportsways, Aquacraft, Healthways, AMF, Aqua Lung 1-pc and rarer 2-pc also Dacor etc.

Ok im rambling.
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