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Old 04-19-2017, 09:48 PM   #31
Fat Larry
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Re: А fling to the classics

Back to my Jokers set up.

After configuring the rubbers and line guides i rigged it up only to find that the shaft had a curve in it when it was rigged and secured.

Turns out the groove on the head that the spear rests in is about 3mm out of true to the rest of the rail... which in its self has a pretty substantial chicane shaped curve in it around the middle of the gun.

Looks like if i ever want this gun to shoot straight i'll need to true up the rail track with filler and sanding etc... Should be doable but it's pretty disappointing to see in such an expensive gun.

Anyone else ever noticed this or did i get a lemon..?
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Old 04-19-2017, 11:45 PM   #32
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Re: А fling to the classics

When I did my muzzle mod, I pushed the line over shaft pin forward ... thus when I wrapped the line the shaft would bend down as there was no support in this new area. Actually that is a critical point in any gun build ... you need to support the area where the line over shaft happens as the line will push the shaft down. I also had to do that in my Pathos Sniper mod. It is an easy fix ... just get the shaft that you shoot ... put two layers of electric tape on it. Now add some epoxy with filler mix (with graphite to keep color black in a small area where it will provide support, and lay the shaft over it and let it harden. I usually tape up the gun before and after the location I want and thus you get only about 1 or 2 cm of support. That is all you need. This ensures that your shaft comes out stable without jumping up once the line release lets go of the line.
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Old 04-20-2017, 12:01 AM   #33
seal77
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Re: А fling to the classics

Quote:
Originally Posted by Fat Larry View Post
Back to my Jokers set up.

After configuring the rubbers and line guides i rigged it up only to find that the shaft had a curve in it when it was rigged and secured.

Turns out the groove on the head that the spear rests in is about 3mm out of true to the rest of the rail... which in its self has a pretty substantial chicane shaped curve in it around the middle of the gun.

Looks like if i ever want this gun to shoot straight i'll need to true up the rail track with filler and sanding etc... Should be doable but it's pretty disappointing to see in such an expensive gun.

Anyone else ever noticed this or did i get a lemon..?
Actually the C4 concept doesnt support verry much the need of a proper track.Their first models didnt have a track at all,wich is a premise to bend the shaft when push it under pressure with all lines.But they was still shooting good with proper setup.I think the joker has a partial track.Actually the first euroguns- simple pipes without a rail was becoming like bananas when load them and they was shooting good for the standarts these times.
For present shooting standarts and long guns its good to have a full shallow track I think.But I believe that if the shaft is good positioned on the body of a shorter gun with thicker shaft,you dont even need a track
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Old 04-20-2017, 07:16 AM   #34
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Re: А fling to the classics

Quote:
Originally Posted by Fat Larry View Post
Back to my Jokers set up.

After configuring the rubbers and line guides i rigged it up only to find that the shaft had a curve in it when it was rigged and secured.

Turns out the groove on the head that the spear rests in is about 3mm out of true to the rest of the rail... which in its self has a pretty substantial chicane shaped curve in it around the middle of the gun.

Looks like if i ever want this gun to shoot straight i'll need to true up the rail track with filler and sanding etc... Should be doable but it's pretty disappointing to see in such an expensive gun.

Anyone else ever noticed this or did i get a lemon..?
The Joker muzzle can be moved to different extension lengths on the gun, any chance that the misalignment is due to this adjustable muzzle in terms of how it is being secured? As for the wiggle in the track at the back, you would think that it would be made straight originally, but your gun is second-hand and maybe it has warped in some way. Guns stored leaning up against a wall can bend out of line, especially if they get hot, such as the plastic Panther guns from Scubapro. I would have thought carbon fiber was dimensionally stable over time. Is it possible that storage conditions have affected its shape?
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Old 04-20-2017, 07:16 AM   #35
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Re: А fling to the classics

Fat Larry, are you talking about a curve left to right or up/down? My guess is the track is straight left to right. A lot of Euro builders have strange track set ups. I had an Alemanni in here the other day and though there was a full shallow track on the gun, the track was lower than the natural plane of the shaft resting so it was only touching at the mech and the muzzle. Had an almost Cantilever feel to it when aiming. You know how these things go.. Enclosed Track becomes the robber of velocity so no track must be the opposite.. My guess is that if you set that gun up with 2 x 14.5m or 14mm bands and a 7.5mm (19/64") with a few inches of Overhang it should work out. Not sure it would be a good match for an 8mm.

Band Lay. That whole muzzle situation.. I guess the first thing I'd try is I'd take off those Metal sides and give them a sand so they were not as tall and obtrusive. Then I'd really soften those edges. Using smaller Diameter Bands and shrinking those Metal sides down might be a better combination. I guess you could pretty easily close the muzzle with just a little door of stainless screwed into place. Then you wouldn't need the sides?
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Old 04-20-2017, 06:44 PM   #36
Fat Larry
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Re: А fling to the classics

Quote:
Originally Posted by spearq8 View Post
When I did my muzzle mod, I pushed the line over shaft pin forward ... thus when I wrapped the line the shaft would bend down as there was no support in this new area. Actually that is a critical point in any gun build ... you need to support the area where the line over shaft happens as the line will push the shaft down. I also had to do that in my Pathos Sniper mod. It is an easy fix ... just get the shaft that you shoot ... put two layers of electric tape on it. Now add some epoxy with filler mix (with graphite to keep color black in a small area where it will provide support, and lay the shaft over it and let it harden. I usually tape up the gun before and after the location I want and thus you get only about 1 or 2 cm of support. That is all you need. This ensures that your shaft comes out stable without jumping up once the line release lets go of the line.
Thanks for pointing this out. Just at stock at the moment the line pulls the shaft down a few mm. I'll keep that in mind when re doing the head.

Last edited by Fat Larry; 04-20-2017 at 07:06 PM.
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Old 04-20-2017, 07:21 PM   #37
Fat Larry
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Re: А fling to the classics

So you can sort of see the deviation in the spear here, caused by the misalignment of the groove on the head. I tried to get some shots without the spear but it was to hard to see with the camera.




This is how i've set it up at the moment. The rubbers are 14mm small ID and sit happily under the rear bolt mounts when loaded. Given i'm not going with c4s shooting idea and using the sides on the head i think its going to be important to have a straight rail track.

Shaft is a 7.5mm abellan.




The track looks ok vertically aside from the drop off where the line goes over the shaft, there's no play in the extension. The horizontal deviation on the body is pretty small but its there. I'll start with the head and see how it looks after getting that in line.

Last edited by Fat Larry; 04-20-2017 at 07:33 PM.
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Old 04-20-2017, 07:34 PM   #38
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Re: А fling to the classics

Thanks for the photos, looks like the muzzle component has the twist in it as the rear view from the butt shows the lateral muzzle bosses not sitting symmetrically about the centerline. The socket entrance for the muzzle looks snug enough, so no side play there. If the gun were new then it would be cause to send it back, or at least get a new muzzle section.
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Old 04-20-2017, 07:46 PM   #39
Fat Larry
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Re: А fling to the classics

Heh yes if it was new i'd send it back.. but i like a challenge and it really is a beautiful piece of gear.

If you zoom in on this shot you can kind of see the deviation in the rail on the body of the gun.

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Old 04-20-2017, 07:50 PM   #40
Fat Larry
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Re: А fling to the classics

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Fat Larry, are you talking about a curve left to right or up/down? My guess is the track is straight left to right.
Both by the looks of things. Thanks for the suggestions, its going to be a bit of work to get it good but should be a fun and rewarding exercise.
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Old 04-20-2017, 10:24 PM   #41
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Re: А fling to the classics

Yes, I pumped your image up to 250 per cent and you can certainly see the wiggle. How it got like that is rather puzzling. Almost as if it was pressure molded, then pressure was lost too soon and it slightly sagged back in the mold leaving a dip.
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Old 04-20-2017, 10:31 PM   #42
Fat Larry
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Re: А fling to the classics

Its actually more pronounced further back where the depth of field blurs it.

Plan is to fill it with epoxy putty and then some how shape a new one into it. Not quite sure how to go about that yet any tips would be apreciated as most of my experience with glassing/composites is surfboard repairs.
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Old 04-20-2017, 11:40 PM   #43
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Re: А fling to the classics

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Its actually more pronounced further back where the depth of field blurs it.

Plan is to fill it with epoxy putty and then some how shape a new one into it. Not quite sure how to go about that yet any tips would be apreciated as most of my experience with glassing/composites is surfboard repairs.
I actually made a DIY rail a little while back (post #49 onwards).

Personally, I would probably sand the existing track quite far down and then build it up from there.
Use masking tape to protect the part of the gun you don't want to get epoxy on and to make a nice separation line. Actually, cover the whole gun as this process can get messy.

If you use the shaft as a 'plug', I think the main thing you have to make sure of is that the shaft itself is super straight and doesn't sag anywhere as that will make an impression in your new track. I thought of using a straight edge (an alu profile) on top of the shaft, but instead I made some spacers in about four different positions under the shaft (on the barrel).
If you thoroughly wax your shaft, it should release nicely though you can also just add a layer of packing tape or electrical tape on the shaft. Both should release pretty easily.

Then mix up a batch of epoxy resin with a filler. I would probably go for microfibers for added strength and possibly a bit of graphite for dying it black (and possibly it will lower the friction, too). Aim for a consistency close to mayonaise, something that will just hold its shape but not be much thicker than that.
Add the mix, sometimes called 'bog' by boat builders, to a big syringe with an enlarged nozzle, a plastic bag with a cut-off corner or a cake topping bag thingey and then use that to add the bog all along the sides of the spear.
After that, the trickiest part is to get a nice shape to the outside of the filling (the inside will match the shaft). Try different shapes of spatulas.
Actually, google how to make epoxy glue fillets - boat builders do it a lot. It could be worth doing a dummy run on scrap wood - if you get the mix to the right consistency and find the right spatula tool, you can get really nice results with this method.

BTW, composites can warp if they reach temps higher than the TG (glass transition point) of the resin. This is the temp where the resin goes soft again. Normally, they resume their shape and stiffness when cooling down unless the item is physically kept in its warped shape as it cools down. But the TG of C4 guns should be pretty high as I think they use prepregs (preimpregnated cloth) which already need higher temps to cure than most regular wet layup resins. And then I think they do a post cure cycle at even higher temps - raising the TG even more. (Whether this is the cause of your crooked track, I have no idea about, though).

Last edited by Diving Gecko; 04-25-2017 at 03:05 AM.
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Old 04-21-2017, 01:08 AM   #44
Fat Larry
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Re: А fling to the classics

Really appreciate that Gecko. Thank you.
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Old 04-21-2017, 11:17 AM   #45
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Re: А fling to the classics

hmmm... though to really see in the images. One thing you can do is take a piece of string. affix it to the back of the gun centered at muzzle leveled at mid point of height of shaft, then bring forward to corresponding position at end of muzzle. When the string is taught that is your straight. (helps to have another person) then take some calipers and figure out what is going on i.e. mm deviation here or there. If this was wood it would be fairly easy. A slight slight curve you can work out with two vice grips a few pins and a Heat gun.. but composite is a different beast. The Joker system is pretty ambitious because they are not moulding their track in one piece, and there needs to be the tiniest bit of play. It might be as simple as shimming the join even the littlest bit like one coat of epoxy on one side of the join could affect. The next least ambitious fix would be to look at your measurements and then open up the track. i.e. if it's 1mm curved to the left then open up 1mm to the left and also 1mm to the right. This will allow the Shaft to determine it's straight path not the rail. The next stage of composite work would be to remove the rail.. this sounds like a lot of work.. I guess you could then get a piece of stick on rail like you'd find from JBL which normally goes on pipe guns and set that as straight..

I guess the first thing I'd do is use the string and make the measurements. you may be in luck and their might be enough play for you to sand with a length of shaft and only put a layer or two of epoxy in specific point.
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