Spear Notches for dyneema

[parra]

Hi,
Just purchased my first speargun a Undersee Terminator railgun and have a couple of questions.
First of all the rubber has a double dyneema bridel but they are not the same length, so when placed in the spear notch only one is touching the spear, is this normal?
The other problem I have is the spear notches were super sharp, and each time i loaded the gun the dyneema was getting damaged. I lightly filed the notch, now the dyneema keeps slipping out.
Does it sound like the spear notches aren't deep enough?
Any help would be great Thanks

 

[parra]

Hi,
Just purchased my first speargun a Undersee Terminator railgun and have a couple of questions.
First of all the rubber has a double dyneema bridel but they are not the same length, so when placed in the spear notch only one is touching the spear, is this normal?
The other problem I have is the spear notches were super sharp, and each time i loaded the gun the dyneema was getting damaged. I lightly filed the notch, now the dyneema keeps slipping out.
Does it sound like the spear notches aren't deep enough?
Any help would be great Thanks

After searching through a couple of older posts it seems I've been supplied the wrong notch style spear, and my dyneema wish bone will need to be replaced.

 

[Mr. X]

Hi parra,
Firstly, it could be that the second line of the dyneema wishbone is your spare, in case the first wears through. That would make sense to me, especially given the state of your notches. One is usually enough (mine are single 1.9mm Dyneema). Having a back up thread is quite a good idea. Another option is to have a loop project out of the end of each of the rubber, so that the wishbone can be tried between them for easy replacement - usually on used on spearguns equipped for thicker wishbones though.

Secondly, I am shocked that a railgun - which are normally equipped with Dyneema wishbones - would be shipped with a spear that has regular, unsmoothed notches, intended for a "bladed" metal wishbone. Rob Allen make good spears for railguns, their notches are carefully grooved & smoothed to work well with Dyneema wishbones - visit their website & use the image there as your guide (they also offer some other options, such a pinned fins now too).

All is not lost though. I converted my Omer XXV from a metal articulated wishbone to Dyneema wishbone & so needed to smooth the notches - as you will need to do (although you might first want to complain to the supplier first - they should have provided you with an appropriate spear IMHO and may wish to correct this mistake). I tried various tools (needle files, chainsaw files, Dremel-like tool) but the only one that really worked well (on my stainless steel spear) was a cheap set of diamond coated needle files, which were ideal for this task. Once the notches are smoothed (use images of Rob Allen spears as your reference), they should also be polished - this can be done with a piece of string or shoe lace and some kind of abrasive paste, such as metal polish (e.g. Aldi's generic version of Autosol), Brasso, green or white "compound" - at a push, something like toothpaste or Ajax might work.

 

[parra]

Thanks Mr.X
I will be contacting the supplier. After searching the same gun on here I found one with photos and our spear notches are completely different. I will get the dyneema wishbone changed, shouldn't be a problem. One of the two notches is deeper so I'm just going to use that one until I sought it out. Thanks again for your advice, If i have any trouble with the supplier I guess I'll be filling and polishing away until its perfect.

 

[Mr. X]

Hi parra, I just saw your second post which must have been posted as I was typing my response. Sounds good, most suppliers are reputable and like to keep their customers happy - otherwise they tend to loose their reputation/customers. Let us know how you get on

 

[parra]

Checked out out the other range of undersee spearguns today. Found all the guns with stainless steel spears had metal wishbones and the black steel spears had dyneema wishbones. After checking the specs with the supplier we found the terminator gun was supplied exactly as in the item description. Quick fix was to change the rubber over with a metal wishbone type and all good. Also found out with the double dyneema wishbones the second one is only for a spare ( as Mr X said"). Eventually I will go back to the dyneema type, but will wait until I damage the spear then replace it with a mini shark fin style.


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[Mr. X]

Sounds good. It seems that folk usually stick with the wishbones they start with. i.e. most folk that start with Dyneema prefer it and stick with it and those who start with metal articulated wishbones prefer to stick with those.

 

[parra]

Probably right I didn't mind using the articulated wishbone, only found it vibrates a lot when traveling in the water.


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[Mr. X]

I also always worry about my fingers with articulated wishbones, mine are like knife blades. However, on spearguns designed to use them, I suspect they may be more accurate: when I retro-fitted a dyneema wishbone to my XXY 75, I also had to remove the the front bridle support so that the rubbers pulled the dyneema wishbone securely it the notches -- which would also likely pull the backend of the spear down onto the barrel. I haven't noticed any problems with that - more of a theoretical issue than an actual problem. This would also not be an issue for railguns designed to use dyneema wishbone - as they have a rail! Most/all also have a muzzle designed specifically to position & align the (bulk) rubber appropriately for the dyneema wishbones