Renovating and Modifying a Mares Mirage

[Diving Gecko]

By The Skin Of My Teeth - Nose Cone Update...
I leave tomorrow for a trip to Indonesia and really wanted my long Mirage to work but the nose cone kept leaking. After spending two days trying way too many o-rings (I must have had the gun taken apart, reassembled and pumped back up at least 20 times by now) I decided to go down a different path.
Since two of my three Mirage nose cones leak by the mere sight of a pump I thought I might as well try something rather drastic.
While the wall thickness on the cone just under the pumping barrel is really thin (0.6-1.4mm) there is quite a lot of material at the front end of the hole. Since my issue is that the o-ring seat is in bad shape, I came up with drilling it out as well as making the seat deeper (protruding more forward).
It took some careful measuring and a bit of panic/courage before closing time to decide on the drilling. But on the other hand, I think this nose cone is a dud anyways.

I needed some way of mounting the cone for the drilling operation. I made a fixture which is just a rod held in a tool holder:

The cone mounts on the rod with a tight press fit:

After lining it up on the tool post, I set about drilling out the bore (Yeah, the lathe is messy, been too busy to tidy it up):

It's a bit hard to see what I did, but I drilled out a 12mm bore to 13mm and went about 3mm deeper:

This gave me a new and much longer bore to seal against. I should have done this with a reamer - the bore would have been smoother - but I didn't have any in the right size and no time to get one.
I made some new dummy plugs to test if this nose cone mod would work. Thing is, I would need to make a whole new pumping barrel to fit this new bore, so better to test first. (Black dummy plug was from yesterday when I was still trying to make the un-modified cone work. The white delrin and alu ones are specific to the modded cone):

As I have done in some other of my mods and designs lately and as the dummy plugs show, I also wanted to squeeze in two o-rings. The longer bore made this possible. And since the OD of the pumping barrel dummy is now 1mm larger I also have a deeper o-ring seat which helps keep the o-rings from pinching and extraction.
And now the drum roll... it worked! The gun has been up to 35 bar with the alu plug and it's all good.
Side note: If for some reason, I want to pull out the pumping barrel and convert the Mirage to a fancy looking Sten, I just need to leave this plug in;-)

Last step was to make make a new pumping barrel, a few mm longer, with the new o-ring groove dimensions at the front. Now, I didn't have 14x10mm alu tubing in stock but my girlfriend called a metal shop in town and had a delivery guy deliver two 1m alu tubes in 30mins for about USD 8 total (on a Sunday!). Sometimes, you gotta love China;-)
With all the time I have spent on the lathe lately I made the new pumping barrel pretty fast. My new barrel at the bottom with an original one at the top:

And second drum roll; it even held air fully assembled with the new pumping barrel in it;-). Also, the pre-pumping function is working without any leaks.

 

[Diving Gecko]

Before packing I also found time for an airflow mod. I am now almost convinced that the airflow in many oleos is restricted too much. I may do a test on that some day, but that's for another thread.
I milled out a flat on the underside of the barrel from the airspace in the power regulator bulkhead to the beginning of the trigger slot. I did this on my very wobbly bench drill but at least the chatter marks look like fish scales;-)

When I arrived in Indo and started assembling the guns I made one more air flow mod but no pics of that. I removed some material in the bulkhead to open up the area where the power regulator bushing sits in the throttled position. Since I don't really believe in the efficiency of that function on this gun I thought it smarter to try to improve the air flow even more. I'll snap a pic sometime in the future.


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[Diving Gecko]

I guess the gun works. Of the three macks just one of them are mine but I shot one more the day before:

The one from the pic above, just under my gun, made a crazy run. I didn't think macks could do this but it almost pulled my 20l float down twice.
They are not monsters but big enough for me at just above the 10kg mark. Hopefully other nice fish in the days to come.


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[Diving Gecko]

New Toys
So, there's a new toy in the GeckoSub Workshop...;-)
3D printers have come down in price and work better out of the box than ever before so I decided to treat myself to one. I went with an Anycubic I3 Mega that looks like this in a vendor's snap:

It's one of the best rated printers for the price these days. Another one is the Creality CR-10 but I didn't have a need for such a large printer, so I went with the Anycubic which has a build volume of 210mm x 210mm x 205mm.

Here's a picture of the obligatory owls that come as a file with the printer. I also printed a quick test part to see if I can actually print threads and make working parts. This is a simplified valve cap with an M14x1 thread:

And it works, the thread actually printed really nicely:

Now, it will take me a while to get to know this gadget. I will need to read up on this stuff a lot and then calibrate and tune the settings as I know I should be able to get better finishes than this.

The idea is to make or at least "prototype" certain parts for my guns. The first project will be a new and improved regulator bulkhead for my Mirages. Here's a snap of two early test pieces being printed right now. I will use them to check tolerances and dimensions:

Other working parts could be line releases, triggers, perhaps even nose cones. And for prototyping maybe handles and grips (the former not as a working part, but the latter could be).

 

[Diving Gecko]

Early Adventures in Printing
I think I am going to like this little machine

I printed another bulkhead test this morning, this time in a better PLA material (and importantly, a much nicer color, haha):

I got the position on the barrel right on yesterday's black testers but need to place the locating pegs which mate with the handle correctly, too:

They are a bit off, so I eyeballed some measurements for the next iteration:

It's pretty amazing that you can print a part, check the fit and then head back to the laptop to adjust a few measurements for the next print. And then know that the machine will print accordingly, eliminating the human error in manual machining. All this with a cup of coffee next to you.
3D printing isn't really super fast, though. The red part took a bit over an hour, but since the machine is running stable I can go and do other stuff in the meantime, so it's not really an issue.

Here is a screen shot of V3 from the CAD program (I am adding text to the test parts from now on so I can tell them apart later on):

Once finalized in the CAD, you move the file to the "slicer" which is what they call the CAM software which translates your CAD file to G-code which the printer can read:

There are a ton of parameters in the slicer which affect print quality, speed, precision, etc. Enough to get lost, so for now, I try to not change too many at a time. I did print the last red test bulkhead at much higher resolution and slower speeds to see what kind of surface finish I can get. This is important as it will need to be smooth enough to seal well with o-rings. Judging from the prints so far, I do think this will work out.

That said, I definitely need to do some calibration on this printer as it is out on one axis by 0.1-0.15mm per 20mm of travel. Could be a lot of things but for now, I will concentrate on just learning the ropes a bit more.

Finally, as an interesting aside, the Mirage handle and bulkhead are not really symmetrical - not even where it should be. Features that should be centered are ever so slightly off-centered. I suspect AMF-Mares might have made the molds in hand somehow. Even the trigger guard is slightly off-center. If it wasn't for it making my "reverse engineering" more of a pain in the bum, it would almost be charming;-)

 

[popgun pete R]

As I let my registration expire at the 25th May deadline I had to re-register just now, but apparently my old name cannot be reused as it is already "in use". Anyway it is me, "popgun pete", so I hope I can retrieve my old ID. I have been out of action for some months for reasons which I will not go into here. My "Mirage" is in pieces and while I was away it was nearly thrown out as some over zealous clearing out was taking place.

 

[Diving Gecko]

As I let my registration expire at the 25th May deadline I had to re-register just now, but apparently my old name cannot be reused as it is already "in use". Anyway it is me, "popgun pete", so I hope I can retrieve my old ID. I have been out of action for some months for reasons which I will not go into here. My "Mirage" is in pieces and while I was away it was nearly thrown out as some over zealous clearing out was taking place.

Oh, disregard my other post on your absence then. Suffice to say it's good to have you back. Just a few hours back, once again an old post of yours came to the rescue of a newish member! (https://forums.deeperblue.com/threads/2-mini-pneumatics-from-the-80s.110837/#post-978259)

 

[popgun pete R]

Actually while I have my doubts about 3D printing parts of structural parts for a pneumatic speargun, bulkheads may be a different matter and a conversion of the Mares "Cyrano 1.3" to a "Mirage Evo" could be possible. The muzzle and partitioning bulkheads are a much simpler task than the rear handle in terms of 3D printing them.

 

[Diving Gecko]

Actually while I have my doubts about 3D printing parts of structural parts for a pneumatic speargun, bulkheads may be a different matter and a conversion of the Mares "Cyrano 1.3" to a "Mirage Evo" could be possible. The muzzle and partitioning bulkheads are a much simpler task than the rear handle in terms of 3D printing them.

I agree fully. Also, a lot of the surface area of the bulkhead is supported by the reservoir. And the nose cone will be supported substantially by the muzzle, I think. A handle is another beast that I wouldn't trust to 3D print with the current technology.


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[popgun pete]

https://www.ebay.ie/itm/MARES-MIRAG...931102?hash=item3b1915d2de:g:sAkAAOSwS-Va4yiG