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GeckoSub Mirage Evo - And Adventures in 3D Printing Speargun Parts

popgun pete

Well-Known Member
Jul 30, 2008
3,851
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Just bumping this thread as for anyone thinking of a souped-up pneumatic this is the way to go as you can load it relatively easily even when using a high start pressure. Although carbon fiber tanks look cool, if you are using a cylindrical tank then you may as well use an alloy tank as no sealing problems with nose cone and rear handle connections. If you want a bulged pressure tank, such as the Pelengas Max, then carbon fibre is a good alternative, but expensive.
Pelengas rear handle and reel carbon model.jpg
Pelengas Carbon pneumatic gun.jpg
 
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Diving Gecko

Diving Gecko

shooter & shooter
Jun 24, 2008
1,619
403
188
Shanghai
Island Mode - A New Grip (The Trigger Guard)
I've been stuck on an island in the Philippines for the longest time and lately I have begun thinking about taking this gun out for a spin. But I also wanted to do a bit of work on it. Specifically I wanted to do a better grip. Back when I "built" this gun, the plan was always to make a grip out of my special mix of chopped carbon fiber and micro balloons like the one I did for my Pathos:


But I only had time to do a Polymorph grip so that's what's been on the gun until now:


The carbon and micro balloon mix is super light and pretty easy to shape, but I don't have any of my composites stuff with me here but a friend of mine had a small set of epoxy resin with a bit left over and I figured there would just be enough to make the new grip if I mix it with saw dust. It will be more ghetto, or rather island work than normally but that's fine with me.
But I also wanted to raise the handle as much as possible this time.

First step was to remove the old Polymorp grip which was easy. Just dunk the whole handle in hot water for a few mins and then pull it off:


You might notice that this Poly grip is actually a bit higher than the one in the first pic - once I had a bit of time on my Indo trip that the gun was made for, I took a Dremel to it and got rid of as much of the black plastic above the middle finger as I dared at the time. Well, time has made me braver since then so now, I wanted to take off material all the way up the underside of the trigger:



As you can see, I have chopped off the original trigger guard. Before this, I had actually tried to heat, bend it and epoxy it in place in its new location but I couldn't get a good hold with the glue and finally the whole thing snapped cuz I was too impatient when I heated it. So, now I had to make a new trigger guard. Also, the reason the build-up of epoxy + saw dust in the pics above is fairly large is because I cut quite a lot off material off in that area when I wanted to bend the original guard.

Luckily, my friend with the left over epoxy also had some carbon fiber. It was bought for a failed attempt to repair some cracked fins but they had bought UD fiber which is not my favorite, but beggars can't be choosers and as I said, this is an "island build" so having any CF is lucky in the first place;)
To make a "plug", I used some very cheap epoxy putty from the local fishing supply store (they use this to glue their local banca outrigger boats together so you can get it everywhere and it's like USD 2 for 500g or so):


And then, importantly, I fixed the handle to a chair with packing tape - the fixation, not the chair nor tape is the important part;-):

(Might be hard to see, but the plug is covered in clear packing tape for an easier release of the CF)

Whenever I can, I like to wet up the CF on a film or piece of glass before placing it on the part:


(To the left you can see that I did place UD in both directions)

After each strip (13 in all) was wetted out and placed on the handle, I used electricians tape for compaction. This is where having the handle firmly fixed in place paid off as it made it a whole lot easier to get proper - and even - pressure on the tape as it was pulled down on each side:


Pro Tip;-)
Do NOT wrap the tape around the part like you would wrap bicycle handlebars or a tennis racket - there's a huge risk of the laminate shifting to one side without you noticing. Instead, cut loads of strips of tape long enough to wrap around the part and latch onto itself. This way, you can keep even pressure side to side on the laminate so it will stay put and also, since this type of tape really only sticks well to itself it's important that the are strips long enough for the tape to "reach itself". Also, wipe the handle down with acetone after the layup and even a few times while you do the taping as the tape really doesn't work if just a bit of resin gets on it.
(Full disclosure; the reason I am adamant about doing it this way is that this is actually the second trigger guard I made... When I did the first one, I wrapped the tape continuously around the handle and the CF shifted under the tape and while the guard came out almost alright, it was a whole lot thinner on one side).

But basically, just keep putting strips of tape on the part:



When done, the gimp can sleep...;-):


In order to not have to do much sawing or sanding it's a good idea to cut the excess laminate off while the resin is "green" (not so hard enough that you can't cut it with a knife but not so soft that the CF will move around, either):



Here it is after having fully cured, a bit of sanding and after I knocked off the plug again:


I had to cut a slot for the trigger to be mounted through as the guard will be epoxied in place (the original also has such a slot):

(I later went to my friend's freedive shop to drill out the ends of the slot but for some reason I don't have any pics of the guard mounted before I started working on the grip).

I have to say that the CF guard came out better than I thought - after I learned the taping trick of only using strips and not doing one continuous wrap - and I am quite surprised with how good compaction I got on the laminate just by using tape. No visible voids at all and the part is very, very stiff.
 
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Diving Gecko

Diving Gecko

shooter & shooter
Jun 24, 2008
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Shanghai
Island Mode - A New Grip
Making the grip itself, I decided to do two rounds of wood dust putty - btw, I got the wood dust from a local furniture maker, they just let me fill a bag and then I dried it out in the oven. Looks and smells like mahogany:




But sadly, when mixed with the resin the looks resemble something altogether different:


Anyhow, as always, remember to wear your spearing gloves when you make custom grips. I don't use fingerless gloves but these were so worn out and the tips were shredding so had recently cut them off. Wont impact the shaping of the handle:


Here it is, after the first round:


The idea was just to get the very basic shape done and then after curing, finalize the grip with a second round of putty. But I messed up... Despite having worked with epoxy resin a lot on boats in my youth and now, on my gun projects for the last few years I made the most rookie of mistakes. I had mixed the very last batch of epoxy left:


I knew it was a bit hot but I had my timer on and thought I still had around 15 mins of working time but because I had bundled the putty up and the ambient temp was running high, too the whole thing exothermed on me in the time it took me to change to a new set of plastic gloves...!:(
When I reached for it to start putting it on the grip, it was already hard, way too hard to work with and all I could do was to break it up in these chunks:


So, now I have a grip half done and I have run out of resin...:-(
I have asked around and there might be one guy on the whole island who has some he can part with. Still waiting to hear back.
 
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Diving Gecko

Diving Gecko

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Jun 24, 2008
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Island Mode - A New Grip (The Missing Pics)
Definitely a bit rough around the edges but for an "Island Mod", I am more than OK with that. Also, for my own curiosity I wanted to push the grip up as high as possible. I got probably have gotten it 4mm higher near the trigger guard, but since I am lifting the hand up really high near the pump inlet valve, I think that makes up for it.
A few pics:


It looks stubby and short if you just look at the grip - which makes sense as I chopped about 20-25mm off the bottom of the grip. But it's made up for as the whole hand moves up on the grip. Now, a pic of that would be nice but I will get some in a day or two of me holding it.

I mentioned I had a failed first attempt at making the CF trigger guard but that the laminate had shifted a lot, leaving one side much thinner than the other. Once I trimmed it down and made it quite narrow it was actually a nice enough part - but I wanted to see if I could still make it work with a better use of the tape (strips instead of continously wrapping in the same direction). So, here are two pics with the discarded guard:



Not 100% the same angle on these two shots but the scale is matched quite well but just to give you a rough idea how much I have been able to raise the grip:
 
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Diving Gecko

Diving Gecko

shooter & shooter
Jun 24, 2008
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Why do you even post in this thread? I know how your gun looks, it already has its own thread but this thread - as I have told you so many times before - is specifically about a gun that can be loaded at about 50kgf and the modifications I am making to it. In this thread, we learn nothing from you showing your gun time and again - a gun which you wont even sell to the West.
You are polluting, please stop - for the greater good of the World.
 

Vlanik

Well-Known Member
Jan 19, 2009
128
6
58
Sothi
This is not a picture of my gun, but a hint on how the handle should be in my hand ...
Since you did another stupid thing ...
 
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Diving Gecko

Diving Gecko

shooter & shooter
Jun 24, 2008
1,619
403
188
Shanghai
This is not a picture of my gun, but a hint on how the handle should be in my hand ...
Since you did another stupid thing ...
Sorry, thought it was your gun.
But please do elaborate Mr. Russian Oracle... How was moving the grip up on my handle a stupid thing? It aims to do exactly what your pic showed - get the grip closer to the shaft. Or perhaps, once again, you have decided not to listen to the premise of this thread and instead think the only solution is to change to a different gun.

If you don’t already know, you actually never really provide any answers. If one was to look at all your posts here they would soon realize that you criticize other people's guns, work and ideas but not in a constructive way. You just say it is idiotic. You rarely say why and almost never share ideas for improvements. (A pic or mentioning of your gun does not qualify as meaningful in most of these cases).

As a result, the part of me that respects what you designed has long ago been superseded by the part that find you extremely disrespectful, egocentric and trolling. You probably don’t care but I know of at least a few people who are so turned off by your personality that while they would really like to own a gun to your design, they can’t get themselves to give you any money. Lucky for you, your compatriots seem to not mind paying a guy who insults people left and right for no reason at all.

This forum is literally one of the best in the world exactly because the vast majority of its members don't behave like you and that in that regard you are indeed special. So, congrats on that.


Sent from my iPhone using Tapatalk
 
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Diving Gecko

Diving Gecko

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Jun 24, 2008
1,619
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Shanghai
Ah, I see you almost attempted an explanation there. Well done on the progress.
But it also seems like you have an unexplained "rule" that dictates having the trigger finger angled down is wrong. I find your view dogmatic. Granted, I am compromising in my grip - in order to get my hand higher up, the price I have to pay is that the trigger finger has to be angled down. But I truly believe that it's a very small price to pay. In terms of improved recoil control, it doesn't matter much where the trigger finger is, it matters more how high up you can get the palm of your hand.
Then again, I am on path learning about how to really power up airguns and shoot heavy shafts - so, recoil control is something I think about. Your guns shoot shafts much, much lighter than this, so I don't think a "recoil grip'' is as needed there.

I should add that I have made other grips with the trigger finger angled down and they have worked well and some wood gun builders have really pushed this idea - and as you know, band guns have way more recoil than air guns.
So, we will just have to disagree on whether it is idiotic or not to have to angle your trigger finger down in order to achieve better recoil control.
 
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popgun pete

Well-Known Member
Jul 30, 2008
3,851
965
203
Australia
Small tank diameter gun with a pull rod on a forward latching mechanism, so of course the handgrip can go further up, but the guns we use have bigger diameter tanks, so nothing to be learned from that gun. The Airbalete family put the handle behind the tank, but then lost a lot of working course of the piston and were not well thought out in other areas.
Evolusion gun parts.JPG
 
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Diving Gecko

Diving Gecko

shooter & shooter
Jun 24, 2008
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Shanghai
Glue!
Since I am pretty much treating this gun as a platform for various experiments, I thought I would try something that in theory might work but may very well not work in reality: Glueing a reel onto an airgun...

I am glueing the reel mount/adapter directly onto the CF reservoir and the reason why it could work is that high end epoxy adhesives like the 3M-DP460 I am using has strengths of up to 30MPa which means that in ideal conditions it can hold a load of app. 300kgf/cm² which is kinda nuts! But that's with a perfectly prepared surface and a strong material. On weaker materials, the substrate (the parts being glued) will fail before the glue itself. 3M says when glueing fiber reinforced plastic it fails around 70kgf/cm². I would think the surface of the adapter is around 4-6cm², so that would give me +280kgf of max theoretic hold if the surface prep is perfectly done.

Now, in reality perhaps an off-angle knock might undo the whole thing right away, but as said, it's an experiment;)

I'll let the pics do the talking from now on:








Many epoxies, this one included, likes a post cure at elavated temps so I left it in the tropical sun with the rest of the gun covered by some wet towel and clothing:


The reel is a super cheap Chinese offering. Not too shabby for the price once deburred.
"Pro tip": The "wheel" is a two-part thing which is a bad design as the line on it will often expand once it gets wet which will force the wheel apart leading it to easily jam. Glueing them together solves that - I have one I use as a belt reel, hence why I know;).
And yes, I probably overloaded the reel and will cut off a bit of line after an outing or two:


I'll also tie a piece of "safety lanyard" from the reel to the trigger guard just so I don't loose the whole thing if the glue joint fails.
Lastly, my tinker OCD is really hurt by the gap between the guard and the reel - but I wanted to be able to pop the reel on and off without having to depressurize the gun and pull off the handle.
 
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Diving Gecko

Diving Gecko

shooter & shooter
Jun 24, 2008
1,619
403
188
Shanghai
I am glueing the reel mount/adapter directly onto the CF reservoir and the reason why it could work is that high end epoxy adhesives like the 3M-DP460 I am using has strengths of up to 30MPa which means that in ideal conditions it can hold a load of app. 300kgf/cm² which is kinda nuts! But that's with a perfectly prepared surface and a strong material. On weaker materials, the substrate (the parts being glued) will fail before the glue itself. 3M says when glueing fiber reinforced plastic it fails around 70kgf/cm². I would think the surface of the adapter is around 4-6cm², so that would give me +280kgf of max theoretic hold if the surface prep is perfectly done.
Just for the fun of it, I modeled the reel adapter/mounting plate so that I could measure its surface area:


I also did a measurement not counting the slightly countersunk areas :


The theoretic holding force of the glue joint should be a whopping 412-496kgf.

I can tell you that there's no way, the surface prep was 100% perfect. Just the fact the I masked of the reservoir with electrical tape is a no-go if you really want to follow protocol - the reason being that as you sand, you actually contaminate the sanded area with plastic and possibly even glue from the tape. Also, I don't know how pure the acetone is that I used or the tissue for that matter. So many tissues have softeners in them these days and those are often silicone based which is pretty much the worst contaminant for an epoxy adhesive.

So, let's see how long it stays on in real life:)
 
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Diving Gecko

Diving Gecko

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Jun 24, 2008
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Shanghai
How is the reach to the trigger with your hand in the new position?
A bit long though it's not too bad. I was going to take an angle grinder to the front of the metal trigger and cut it back to win me a few mm but didn't get around to it. Might do it next time I depressurize the gun. The reach on that handle was always a bit longer than is ideal for my hand - I think a smidge over 70mm.
Had I had access to my 3d printer, I would probably have printed a new trigger to give me a shorter reach. I think it would have worked alright.
 
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Diving Gecko

Diving Gecko

shooter & shooter
Jun 24, 2008
1,619
403
188
Shanghai
Island Mode - A New Grip (The Trigger Guard)
I have to say that the CF guard came out better than I thought - after I learned the taping trick of only using strips and not doing one continuous wrap - and I am quite surprised with how good compaction I got on the laminate just by using tape. No visible voids at all and the part is very, very stiff.
Here's a closeup of the cut-out from when I made the slot in the trigger guard. I sanded it a bit with #600 grit sandpaper to help show how well the laminate ended up looking:


Just a few small pin holes, no big voids at all. For an island hack that's more than an acceptable result to me:)
 
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