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

[Diving Gecko]

one of the best thread in 2018 -- 2020

Thanks so much. Hope your adventures in wood are going well.

I’m stuck in the Philippines and with no idea about when I can get back to China and work, I had my apartment and all my gear packed up and put into storage. Most of my projects and improvements are only happening in my mind these days.

But once the world returns a bit more to normal, I’ll continue learning about and trying to improve my air guns. The end goal is a scratch built one but I’m not in a rush.


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[Johny Depth]

I found your article a great story.Well Presented and the challenges you faced with all the processes you under took to arrive some were on the project well done

 

[marco15499]

Hey Gecko! Did you ever try the reel?

 

[Diving Gecko]

Hey Gecko! Did you ever try the reel?

Not on that gun, no as the gun hasn’t been in the water since I added the real. It’s a very powerful gun when I run it at higher pressures - too powerful for the kind of fish I see around here now.

As for the reel, I have one of those as a belt reel. Once you glue the two halves together it works alright. Whether a quick wahoo run would melt it, I don’t know;-). But it’s a 20 bucks reel so it might be worth a try...

I might have found a place where I can go hunt for Spanish Macks in the 10kg size but I’m sure I can still shoot those on the Pathos 100 or the Predathor Vuoto 100 so not sure if I’ll even bring the bigger gun...

Acually, if I had a 7-7.5mm shaft for it, I might have brought it and used it a “normal” pressure. It’s just that I only have 8mm and for that, I need higher pressure than I can load without the pulley loader. And at higher pressures the gun starts shooting really high...
I haven’t mentioned it here as I’m still not on top of why it is and it’s very difficult to get used to. But I shot it a little bit in the pool at 5m and it shoots way high. Something like 10cm high.
My theory right now is that the exit speed is so high the barb creates lift and makes the shaft go high. I always place the barb on the underside and only did on shot with the barb on top and while it did shoot lower then, it was just one shot and not enough to make any firm conclusions.
Since then, my friend has closed down the shop and the pool is getting too dirty to test in.


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[Vlanik]

In order to reduce the toss of the barrel when firing, there are reversers ... You can also put the hood of a cobra ...

 

[Diving Gecko]

In order to reduce the toss of the barrel when firing, there are reversers ... You can also put the hood of a cobra ...

Hi Vlanik. As always, “interesting” to hear from you.
Do me a favor, please never ever change. Please continue your amazing habit of hardly ever taking other people’s thoughts into account when you post. Please just continue replying to posts you didn’t bother to fully read.

Maybe it’s muzzle lift but I specifically said that I think it’s because of the barb as the shaft shot low when I turned the shaft so the barb faced up. Now, I’ll test more at some point and let the rest of the readers here know when I have more data.

As for “hood of cobra” I’ll take a guess and say you mean “wings”. Personally, I think they are ungainly and a bandaid solution to a root problem best solved in other ways.
I am actually not entirely discounting the possibility of traditional muzzle flip caused by recoil but that’s why I modified the handle to get a much, much higher grip on it. Something you earlier in this thread, once again, talked trash about but which, in my book, is the proper way of reducing muzzle flip.

But since I raised the handle - if it’s not the barb that’s the culprit - then it could be the whole gun lifting as a result of the change in buoyancy as the heavy 8mm shaft leaves the gun.

I don’t know what a “reverser” is. Some sort of mass dampener, perhaps. Please do notice the lack of question marks in those two sentences as I really don’t need you to answer.

Good luck on your own 3D printing endeavors. ABS is a good choice for your parts and once I fully enclose my Printer I’ll start messing about with ABS and hopefully PC.


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[Vlanik]

setting one flag on the harpoon always leads the harpoon in the opposite direction ... The front rudder is more effective than the rear one ... cobra heads ... and the reversers and the cobra hood you can see on my guns ...

 

[Diving Gecko]

setting one flag on the harpoon always leads the harpoon in the opposite direction ... The front rudder is more effective than the rear one ... cobra heads ... and the reversers and the cobra hood you can see on my guns ...

I don’t look at your guns much at all - reason being simple: though they are technologically interesting they remind me of the personality of their creator which I don’t need reminding off.
Except I have to admit I saw your ABS handles and cudos on those.

I actually thought your cobra heads (cuttlefish shape) was to stop your guns from sinking and I’ve stated plenty of times, how my own preference is for guns that are neutral in the water when loaded.
Either way, of course, giving the gun more mass will make the shaft have relatively less mass out of the total and reduce the percentage wise change in buoyancy as the shaft leaves the gun. No surprise there.

 

[Vlanik]

here the reversers are clearly visible ... Previously, I made them in the form of a cobra hood, so that they clicked on the receiver

 

[Vlanik]

I used to make handles out of epoxy resin and fiberglass ... Now I print them on a 3D printer ... All the details on my guns are printed on a 3D printer ... Except for the front and back caps ...

 

[marco15499]

I love your "fights"!

Gecko: I used to have that same reel and I didn't liked it. I ended up changing it.

However, It was capable of landing a very nice mackerel. I was curious about how good it would hold to the barrell with the glue.

 

[Diving Gecko]

I love your "fights"!

Gecko: I used to have that same reel and I didn't liked it. I ended up changing it.

However, It was capable of landing a very nice mackerel. I was curious about how good it would hold to the barrell with the glue.

Haha. I promised myself countless times I’d not even reply to Mr. V but I guess I find some fun in him, too.

I’ll update here once I actually have some real world experience on that glue joint


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[doyenofcastle]

Handle Design is the main suspected factor when gun not shoot accurate or u want upgrade to to shoot bullseye if all other factors is accurate (spear ,rubber ,......etc ) , in case of wood handmade guns ,I have been struggling for long time with different guns and the solution came from a very small modification in handle ,of course the pneumatic speargun have different concepts and u need to search for that secret factor ,more test in pool with styro foam target ,I attached something from air gun shoots analysis ,it give a general guidance for me .

 

[Diving Gecko]

Hey all,
Hope you're all good.
I took a loooong hiatus from this forum but slowly coming back.

Just wanted to say that if any of you end up on this thread and are frustrated that the picture links went dead, so am I. They were hosted on a free image data base that decided it didn't wanna be free anylonger. And on top of that, I lost most of the files in a bad laptop crash.

Anyhow, I have managed to download them from said data base so if any of you have any questions let me know and I can elaborate and repost pics. Seems I can't add them back to the original posts as I can no longer edit them.

 

[tromic]

Hey all,
Hope you're all good.
I took a loooong hiatus from this forum but slowly coming back.

Just wanted to say that if any of you end up on this thread and are frustrated that the picture links went dead, so am I. They were hosted on a free image data base that decided it didn't wanna be free anylonger. And on top of that, I lost most of files in a bad laptop crash.

Anyhow, I have managed to download most of them from said data base so if any of you have any questions let me know and I can elaborate and repost pics. Seems I can't add them back to the original posts as I can no longer edit them.

I had the same painful experience with my images hosted at ImageShack..

 

[Diving Gecko]

I had the same painful experience with my images hosted at ImageShack..

Yeah, I think I went through two of these hosting services, too but I can't recall which one I used before Imgur. Maybe ImageShack, too. It would have been ok if I hadn't lost two laptops in the meantime - and while I do think I have most of these images backed up on HDDs, they are still in storage in SH.

Anyways, I was considering hosting the images myself from now on but then noticed that the image upload function on this forum is great now. Just drag and drop.

I may actually, if I find a big pocket of time ask the admins if they can reopen the edit function on some of my old build logs so I can put the pics back up. Let's see... Lots of other things I need to be doing, though

 

[Diving Gecko]

Back At It - Making The Evo Mirage Work For Real This Time (?)
I know all the pics from the last time I tinkered with this gun are gone. But in short, I was/am fairly obsessed with making a Mirage style gun work. I have had a small handful of original ones and the parts are hard to keep in working condition so this build log was about how to use a more modern handle combined with 3D printed (FDM) parts.

I learned a lot but the gun still ended up failing halfway into the Indo trip I made it for. So, I yanked out the Mirage bulkhead, dropped the pressure and used it as a classic gun for the remainder of that trip.

Since then, Covid hit and I got stuck in the Philippines away from all my belongings in China. I decided to stay based in the Philippines and just recently, I got a lot of my stuff sent here from China - amongst them my lathe and some speargun parts. Also, I now have a CNC mill and a resin printer so it was time to have a second go at this project to see if I can give it a worthy ending

Anyways, that was the background. Now, onto the resurrected build

 

[Diving Gecko]

A New - but simpler - Mirage Bulkhead
Last time around, I was intent on making a 3D-printed bulkhead with both check valves built into it. And it worked! For a while... It failed on the spearing trip - maybe something got stuck inside that tiny internal, curved bore between the check valves.

This is how it looked in a screenshot from 2017/18:

This time, I will take advantage of having a CNC mill and make it aluminium - and I will simplify it a whole lot.
The check valve that lets the air into the front part of the reservoir is gone. On the original Mirage this is done by a simple rubber sleeve valve at the rear end of the pumping barrel and I will do the same on this build.

Also, the original Mirage actually does have two check valves in the bulkhead but one is an overpressure valve in case the pressure differential between the two compartments becomes too large. Whatever "too large" is. All I know is the spring in it seems really stiff. Anyhow, I am eliminating that one, too.

So, now, the design looks much simpler:

I have also made the bulkhead a bit shorter to lower the volume of air behind it as that governs how many pre-pumping strokes I need to do to be able to load the gun when moving the shaft to the shooting barrel. I did want to keep a little bit more volume than in the original Mirage so as to have more power in the Low Power shot.

Also, the power regular piston is still 9mm in diameter as it was in the last itiration.

Next post will be about actually making this part...

 

[Diving Gecko]

Making An Aluminium Mirage Bulkhead
I started out by turning a piece of oversized rod down to size on the lathe. The lathe is not behaving too well these days so not the best job I have done, but this whole thing will also be an exercise in not overthinking things and keep them functional more than anything.

The stock is on the left, I also turned the o-ring groove while it was on the lathe.
The square part is a simple fixture to hold the stock in for the machining. I thought about soft jaws, but I needed to keep the part from rotating when it gets flipped over for the second milling operation, so this is what I went with. Set screws are for keeping it in place and some brass spacers not to mar the part too badly:

Here's the stock locked into the fixture ready for Op 1, which is the features on the forward part of the bulkhead:

I honestly don't have enough light on the machine or a new enough phone to make good pics whilst cutting, but you get the idea. This is Op 1 mostly done:

I took the part+fixture out once done for a quick sanity check. I am still very new at CNC'ing but it had gone fairly well. Only had one near crash, haha but I saved the part in time and there's just one tiny beauty mark on it. Also, forgot to chamfer the air transfer bore on top of the peg for the pumping barrel but I'll do that by hand later. But using a T-slot cutter to cut those two o-ring grooves on the peg was pretty cool and something I needed to learn to do sooner rather than later:

Some not so pretty tool marks on the floor, but still learning which strategies are best for what. On the plus side, I am weirdly proud by that rounded fillet on the forward edge. It came out sweet

Op 2 is all about the deeper features after the part has been flipped. So, hollowing out the bulkhead, leaving the locating side pegs in place and then opening up the power regulator bore plus the bores for the check valve parts. Which included thread milling an M8 thread, but while the pucker factor on this is not small, I have yet to screw up a thread milling operation and this one went well, too

The pic, sadly, doesn't really show any of the deeper work:

But here's one after it was done:

(It looks better in real life without the dirt. Actually one inside wall was close to a mirror finish which was a nice touch)

 

[Diving Gecko]

Finishing The Check Valve
I made a quick little threaded bushing for the bottom of the check valve in brass.
The manual turning was OK, except my drill only had one sharp cutting edge so it wandered off center and I got sloppy with cutting the slot for the screwdriver so that's off a bit too. Which is ironic as I did that on the CNC, though just by jogging the handwheel and eye balling it. (I don't yet have a 3D probe set up)

As an aside, I had to use a tap die as I pulled the whole change gear setup off of the lathe to install an electronic leadscrew (ELS) but it's drifting and can't start a thread in the same spot on subsequent passes. Which is the number one reason for having an ELS... I checked all the stepper pulses/pitches/encoder pulses/pulley ratios/etc and it's all good, it's just drifting.... Don't have time to figure that problem out right now, hence the hand tapping.

Anyhow, it turned out fine - as in functional. Remember, I have a new goal which is to not f*ck spiders...
Actually, in my mother tongue, it's flies, not spiders.

I made two while I was at it:

The spring looks a bit under developed, haha. But I have a bunch in various sizes and I gather, it doesn't have to be that strong for this purpose.

Here's the bushing "test inserted". Still did some deburring later on. I had actually done pretty much every chamfer in the machine which was cool, except I did the one for the M8 thread before the thread milling where I should probably have done it after.

I also made a new power regulator piston and a shorter rod for it but didn't snap any pics. I was dreading having to tap M4 and M3 thread into stainless Ø4mm rod but it went smoothly.

Did a quick test fit on the Evo handle and the fit is perfect. Well, I actually did the first test fit when the bulkhead was still on the CNC mill but yeah, it's spot on. There's also a new o-ring groove on the shooting barrel to seal against the bulkhead, but can't see it when assembled.
Also, at some point during the pandemic I made a new custom grip on this handle. Not one of my best but not too bad either.But the handle is still the same one as when I first set out on this project.

I scuffed up the outside of the bulkhead with some Scotchbrite. It was too shiny before

Oh yeah! Forgot to say, I haven't fully given up on 3D printing for this build. The nose cone is printed - more on that in the next post.