Speargun project

[whitey180]

Heya guys,

Have decided on going down the long road of building a gun from scratch. Been doing a lot of research and already driving the mrs mad with talk of spearguns ( I haven't even started it yet really )

Anyways I know it's very ambitious but the plan is a 90cm roller gun ( bolt on rollers ) with an ar15 pinned mid handle, reverse neptronics mech.

I have laminated together some rose gum boards and rough cut them square measuring around 50x50x1200. I cut the ends off today to have a look at the glue joints after 4 days in the clamps. I'm a little worried the glue didn't take, as I could put the timber in the vice and bit one of the laminates with a hammer and it snapped at the glued joint.

I used nuplex es180 epoxy resin and hardener for the joints. I'm not sure if I should continue with the gun on this blank or not is there any definitive way to tell if it will hold?


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[lawstraljan16]

Building my own roller too, so good luck. Not sure about the glue though as I havent glued mine together yet as Im still designing it in 3d and slowly working around the wood.

One thing about the glue process though. I was told to give the wood a sand down with some 40 sandpaper (sides where the wood is being glued together) and to clean the wood with some kind of cleaner, which I cant rememeber the name Then glue it, and with epoxy resin not to give it too much pressure either. Try that out and maybe give it some more time to dry (7days) around 24 degree celcius temperature with no humidity.

Im sure someone more experienced can help you


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[whitey180]

I glued up another blank at the same time as this one so I'll try cutting some of that and see if it breaks also. Thanks for replying to me mate, I really appreciate all the help that I can get in this as when you get down to it there seems as though there's quite a bit to think about even in the planning stage.


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[lawstraljan16]

You bet ya. Ive been 3d modelling for the past week and still come up with problems here and there. And I expect a lot more once the build starts

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[whitey180]

I'm still deciding what my final dimensions are of the stock so I. An get it squared and true before cutting tracks etc and then shape it to what I want without having to cut too much out with a table saw and stuff up the lines of the trued stock.




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[lawstraljan16]

Im working on my model now, getting all the measurements and parts so I do the exact same thing. Hard stuff, at least for us newbies haha. Post some pics when you get the chance

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[whitey180]

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[whitey180]

Blank measures about 50x50x1200


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[foxfish]

Gum tree! you should get a beautiful looking piece of that mate, any idea what sort of eucalyptus it was ?
You do occasionally get people complaining about epoxy not working very well but as a product it is the best glue available to us & generally works exceedingly well!! Most issues are about damp wood, low temp or bad mixing!

 

[whitey180]

It's a rose gum. looked up the specific gravity and it's around 7 and teak is 6.5. So should be ok I'm hoping


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[foxfish]

Once you have finished this one go for a multi laminate one like 10-15 strips & use a black glue to really show off the beautiful rose gum.
I work with eucalyptus a lot & some pieces are amazing (didgeridoos mainly)
I used about 50 1mm laminates on this one with a blue epoxy mix.

 

[whitey180]

Wow that looks unreal.

I guess having those glue lines there gives you an added benefit of being able to follow the lines when shaping to get the gun even also!


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[whitey180]

So today I managed to find somewhere to true up the blanks.

I was advised by the guy who tried them up to seal them as soon as possible to stop them warping. Is this correct ? I have both epoxy resin here and also some poly casting resin.

Is it worth sealing them now? If I do seal the blanks it might take the square away that I need to work with?


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[foxfish]

No you don't need to seal them at all, the whole point of using laminates & epoxy is give a stable blank!
I would not plunge it in water but as long as the blank is kept dry I cant see any point of coating it at this stage.

 

[whitey180]

That makes sense cheers


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[-Paddy-]

Hi,
Your project sounds a lot like the one I've made a couple of years ago.
Here are some pictures of it, maybe it will help you somehow with yours.
Good luck with it!

 

[whitey180]

That actually gives me a few more ideas looking at those pics things I had to though about.... Cool lookin gun! Can you remember the dimensions of the finished stock ? Are they 20mm bands? It looks hard to load lol


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[-Paddy-]

Finished stock is 40x40mm and 750mm length. Bands on the picture are 18mm, but I replaced them recently with 16mm and thanks to that it is easier to load it and is less recoil.

 

[whitey180]

Looks good! Never thought about recessing the bands into the gun at the bottom! What size spear? Would a single 16 of a gun this length be ok to push 7mm you think ?


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[Jegwan]

....Would a single 16 of a gun this length be ok to push 7mm you think ?

Yes, if its a roller. Use a stress ratio between 320% and 370%. Start at 300% and work you way up until you find the right compromise for you between power and how easy it is to load.
Jégwan