Renovating and Modifying a Mares Mirage

Hi Fox,
Thanks for the link, good to see. I have indeed spent good time looking at your fab creations over the years.

The polymorph I have sourced locally in China seems a bit sweaty. It's like there is a tiny film of grease on the surface, I don't know if that's just the formulation of the plastic or if mine is tainted. I am not sure, I could get the carbon to stick well to it. Besides that, I also feel polymorph is too heavy on a gun which is already on the heavy side.

So, weight savings and better adhesion are the reasons I went for balsa. I only used the polymorph for mocking up a handle to get an idea of how to shape the balsa.

Had this been a Sten handle, with it's skeleton handle, I think things would have been easier.

Also, my handle shape is a bit less complex than yours and I hope that my vacuum bagging setup will help the cloth to lay down tighter. We will see once we get that far;-)

Ahem...
So, my wood working skills, even in balsa, are embarrassingly lacking. I wont look for excuses, but suffice to say, there's something missing in my brain - I can't transfer the shape I have in my mind to a block of wood.

I don't really know why I thought it would be better with XPS foam, but maybe because I can easier make changes to its shape it was more alluring.
So, I dropped the balsa for now. Changed to blue XPS insulation foam. Diligently filled in every void in the, much amputated, handle and glued more foam blocks on the handle to shape into.

It was going OK, but then ADHD got the hold of me again and I decided, I would just do a rough undersize shape in the blue foam and then add FIMO style polymer clay (AKA polyclay) around that core. That should be easier than filling in strangely shaped undercuts/hollows on the handle with foam.

I love how when working with the Shapelock it becomes quite easy to make a 3d imprint of your hand - basically by just grabbing the "dough" and adding material for support where needed. All in real time.
Polyclay offers the same, so I went for it.

In the beginning, I considered just adding the carbon fiber onto the shaped polyclay handle, but it soon turned out that even with the foam core, the handle would be way too heavy.
So, now, I have decided to take a molding of off the handle.
It's been messy to get this far and when I went to bake the clay, I made the very stupid mistake of not thinking of the low melting point of the XPS foam. So, of course, the foam collapsed in a few spots.

Anyways, next step will be to do a quick silicone mold of the handle shape as it is now (the fundamental shape itself is now perfect for my hand). Then I will use that mold to make an intermediate "dummy handle" in epoxy filled with microballoons or maybe just plaster. Something that I can sand and spackle easily as I will make the final shape and finishing on that "dummy handle". Once that is OK, I will do a second mold.
(Yes, I could tidy up the real handle, fill it up with spackle and so on before taking the molding, but I'd rather do it on a dummy. Eg. the XPS gets dissolved by polyester filler, which I like to work with since it is sands easily and cures fast).

If there are no tricky undercuts on the handle I can make a rigid split-mold that I can use to vacuum-bag the carbon fiber handle in. But depending on the final shape, I may have to do flexible mold instead. If it is flexible, I don't know if I can lay of the carbon fiber in it and make it stay put though. If I can't, then I could pour casting wax into the mold and once demolded, cover the wax handle with carbon and finally melt out the wax. (This way, the handle would become a few mm bigger though. Don't know if it will matter.)

Either way, once I have the CF handle skins done, I will epoxy it onto the remains of the Mirage handle and fill the hollow interior with a closed cell expandable two-part PU foam. I don't think I will make it detachable, though.

Yeah, I know, this is a very, very, very long way around what could have been a somewhat small job. But as they say, at least, I am learning... I hope, haha.

Nah, it's all good. All these materials are dirt cheap in China and I've been wanting to play around with the lost wax process as well as PU foam and silicone molds for a while.

Also, this way, I'll actually get a way to produce an identical handle for my second Mirage and perhaps for other guns, too. I might have to make 100 handles before it makes up for all the extra work it will take to make this one, haha.

End of novel, here are some pics. I really, really hope my final handle will make up for this, haha.


Here is that much amputated handle that I did not dare show earlier.


I spent a bit of time to make sure every little hollow in the handle would be taken up by the foam, so that no water could mess with my buoyancy. It was a mute point, as I will eventually get rid of this foam and fill it up with PU instead.


Shaping the foam back when I still thought I'd glass over it.


Now, this is where I took a turn - I started using polyclay over the foam core to get the best possible, personal shape to my handle. As you can see, I am adding the clay in layers. Might not be kosher, but much easier to add a bit of support/bulk where you feel it is needed.


As mentioned earlier, it is not neglible how much bigger my hand is with 3mm gloves on. So, going through the pain of making a custom handle, it makes sense to wear the gloves you'll be using most when shooting. The latex glove makes sure the neoprene doesn't stick to the clay - works wonders in Shapelock, too.




This is the shape that fits my hand like a... glove. It really does. And it seems to have good support and I feel like I have the angle very close to perfect, too.



If it was structurally strong enough (which it isn't) and didn't way a ton (which it almost does), I could keep it as is. But since I wanna try to go for some swank carbon fiber, I will take a mold of this shape. Work on an intermediate dummy handle produced from that mold to tidy the whole thing up and make the finish prettier. And then hopefully make a cool CF handle

Time for an update.

I have mentioned that I was considering making a regular, solid two-piece split-mold of the handle to then lay up the carbon fiber in, but it wont happen. It would simply be impossible with the shape of the handle to get it out of a solid mold - the undercuts would be locked in.

So, I am going with a two-piece flexible silicone mold. Once I have that I will pour casting wax into the mold and lay up the fiber onto the resulting wax handle. Once the carbon has cured, I will melt out the casting wax - which should be easy as it melts at about 65C.

That should give me a one piece hollow carbon fiber handle that I will then epoxy in place on the stub of the original Mirage handle. The void will be filled with either two-part PU foam or epoxy filled with microballons. Though microballoons (tiny glass spheres) are the lightest epoxy filler available and will still yield a positive material buoyancy wise, the foam should be much lighter. So, I am undecided on that still.

I am now doing a parallel modification with the same technique to the handle of my Seac Hunter.

Here are some pics - and even though this thread is about modifying my Mirage, I am showing the early stages of "building" the Hunter handle because ditching the foam core helped a ton. So, this is how I should have done it the first time around on the Mirage;-)

Again, it is a polyclay (AKA FIMO clay) but this time on a small core of balsa.

The handle was then baked in the oven as per the instuctions for my specific brand of clay. It varies slightly from brand to brand. And this time, since I had changed the core from foam to balsa, it actually held its shape;-)

Polyclay can be shaped and formed quite nicely and eg. Tinman has plenty of examples of how you can use it as is and make it look great. And though I think there is def not enough PINK in the world of spearfishing my intention was not to use this on the final handle;-)
For my use, on a stock pneumatic gun, it is still too heavy a material.
So, I just shaped it without thinking too much about final surface finish and such.

That said, if you are after weight savings but still want to use the clay on your final handle, I suggest you build a balsa core and just use the thinnest possible layer of clay for the final shaping.

After baking I did two quick filler and sanding jobs and then the handle should be ready for having a silicone mold taken off of it.

And now, to add to the confusion, we leave the Hunter and go back to the Mirage handle;-)

The Mirage handle underwent a similar process though the mock up handle looks pretty beat up from the core first collapsing during the first bake - and then, and I did not tell you about this, I noticed that the core of the clay hadn't fully been baked, so I thought I would bake it thoroughly one last time. You can re-bake polyclay, so that should not be an issue.
But this time, the foam core did not melt, as I thought it would have. It expanded and cracked the handle...

So, I had to glue the handle back together and then putty fill and sand it a few times.
Part of me now thinks the spirit of the Mirage, with its uniquely shaped original handle is fighting back!

But I am intent on winning, so here comes the Mirage handle in half of the silicone mold:



As you can see, there are ton of bubbles. Not that it really matters for this rough mold which will only be used to cast a wax core.

But I have used the bubbles as an excuse to whack together a rough little vacuum chamber to degas the next half of the silicone before pouring it. Remember, I have the vacuum pump already for my vacuum bag setup for laminating purpose;-)

The hose fittings are being epoxied into the vac chamber as we speak and if all goes well (which would feel like a first), I will pour the next pink batch of silicone this afternoon - hopefully bubble free this time;-)

As I said, the vacuum chamber to pull the air out of the silicone would be rock'n roll;-)
And as we all know, the most rock'n roll stuff comes from... IKEA:



Yup, I had one of those glass jars in the kitchen and I had the hose fitting and valve left over from when I put the vac bag setup together. I had actually thought of this DIY vac chamber months ago (yes, like in the cooking shows, I cheated...) and had already bought a glass drill bit.

So, I whipped up some epoxy with silica powder and for good measure, I threw in some powdered pigment - I am kinda testing colors, too, these days.

The IKEA vac chamber didn't implode when tested, so I went ahead and degassed the last batch of silicone for the second half of the mold. The silicone is quite thick, plus it's quite cold in the kitchen where I did all this, so I am not sure I got as many bubbles out as I could have if I had done it in a warmer place.




This is how it looks through the top of the jar/vac chamber:




And in the end, it does look like I have a lot less bubbles in the second pour. BTW, the specks of darker pink in the silicone is powdered pigment clumps. I might have to switch to a paste-based pigment:





As I mentioned earlier, I don't think it would have mattered at all if I had not degassed this mold as I will only use it to make a wax core. But I wanted to try degassing as the process might make sense for epoxy for, say, a top coat which will be brushed onto a finished part.

Demolding time:



The shine is from using vaseline as release agent. Silicone sticks to pretty much nothing except... silicone, so when pouring in the second half it's important that the first part is covered with a release agent.
It probably wouldn't even have been necessary to cover the handle but I did it anyways.


On the left is the first non-degassed pour and the right has the degassed silicone so it did indeed get rid of the bubbles.

Notice the cut-outs on the surface of the first pour. These were done once the first half had set and serve as keys so that the second half of the mold will be aligned properly for later on.

Just one last shot to show the smooth non-bubbly surface of the degassed silicone. The mating flange looks a bit rougher but I think it is because of the copious amounts of vaseline used. (Yep, any and all seedy jokes are def expected... haha)

Next step is casting wax.
I don't have any pics of pouring the wax, but before melting it, it looks like this. Small pellets that melt around 65C and are reusable:




And with an AA cell for scale:




The process is pretty simple, you melt, then you pour and then you wait. And since the silicone mold is not conducting much heat it takes quite a while for the wax to set.

But once it did, this is how it all come out:







Next step will be the actual carbon fiber work. I will laminate onto this wax handle and then melt out the wax once the carbon has cured.

Well, actually, the next step is more complicated than that. With the regular vacuum bag material I have, I don't think I can get my vac bag to adhere closely to all the little curves on the handle, so I am considering making a custom silicone vacuum bag that fits the handle perfectly...

To be continued;-)

Thanks for the warning, Pete.
I have a lot of trust in two-component epoxy. I might have said that I considered using PU foam to fill the void which is true but not without a proper epoxy glue joint first. Also, for the gluing-in I would not use microballoons in the epoxy but likely chopped carbon fiber.

One thing, that I haven't mentioned, but that I am aware of, is that since I am not laying laminate into a female mold, the handle will end up slightly oversized. That's OK. Making it a few mm larger all around wont be an issue.

Diving Gecko said:

[...]
With the regular vacuum bag material I have, I don't think I can get my vac bag to adhere closely to all the little curves on the handle, so I am considering making a custom silicone vacuum bag that fits the handle perfectly...

To be continued;-)

Click to expand...

As mentioned, I had an idea on how to make a customized vacuum bag for the handle. I thought of making one out of silicone brushed on to the handle which had somehow been built up to imitate the thickness of the laminate and vac bag materials. This would, in theory, give me a bag which would not have (m)any pleats and would not move around much as it set into shape during the initial vacuum pull.
But for now, I am trying something a bit easier.

I sourced some small sheets of silicone in different thicknesses and so far 0.2mm and 0.3mm seem like a good compromise between flexibility and resistance to punctures.
To seal it, I used some cheap one-component silicone out of a tube and did a quick test.

In this pic, I inflated the bag to check for leaks. There were none. The bottom is closed simply by rolling the bag a little and clamping it down with a piece of alu:



Next pic is of the wax handle in the bag under vacuum. The handle is covered in bleeder ply - as it would be if this had been a real layup. The silicone bag is not perfect but definitely better than a regular vacuum bag would have handled it:



I am slightly worried because the silicone sheet is quite tacky/sticky as it is and it kinda grabs hold of everything, so it could very well shift the laminate around once it pulls into place.

On the other hand, this was never really going to be a perfect cosmetic bling bling piece. I don't like smooth handles and I intend to either leave it matte or may even cover the handle with silicone afterwards for more grip. The main purpose is for it to be light and strong.

I am waiting for some carbon fiber but if all goes well, I will lay up the first handle before the end of the week.

Another update.
Not much laminating yet, despite having received my carbon fiber.

I am a bit unconvinced that the fabric I got is flexible enough that I can drape it over the handle. I have done a few "dry runs" and it's borderline. It depends on the thickness of the cloth and the weave type. Some weaves are looser and more pliable but I don't have that great of a selection out here and none of the most forgiving ones.

I might have a go with a unidirectional fiber for the first few layers and I am considering just putting one layer on at a time, then cure, then one more layer, etc. This way, I will have more control and less risk of the whole laminate shifting out of place.

But while I ponder these things - and while I wait for some braided carbon fiber sleeve samples (AKA "sock") which could be the solution - I set about finally making my vac pump setup somewhat more proper...

This is how it looked when I last used it:



It worked, but having 220V out in the open and sealing fittings with tacky tape (vacuum bag tape) was not a sustainable solution.
So,now it looks like this:




I mounted the pump and reservoir on a piece of wood and sealed all fittings with silicone. Also, to avoid getting electrocuted before the end of my project, I mounted the electronics in a box.
I hooked up a three way switch to give me 'off' and two different pump modes. One which is just 'full on' and 'vac' which goes by the pressure sensor and maintains a preset pressure. The first mode is good for e.g. degassing or when I just want to vac down the bag bit by bit and make sure I can adjust how the bag sets without having to constantly program the pressure sensor switch. And the sensor mode is for when the bag is where I want it to be and I want the pump to maintain constant pressure during curing.
It is not easy getting a 100% leak free setup and the sensor mode makes sure the pump turns on once in a while if there is such a small leak.

I had a small "Noga Arm" lying around that I mounted the pressure sensor switch on. It is nice for peace of mind that I can turn it to wherever I am and keep an eye on it:


The whole setup measures roughly 25x25x25cm and weighs 7kg. It's easy to move around and store when I don't use it.

The Saga Continues...

I did a quick test layup of sorts with just a bit of unidirectional fiber as that is the most pliable I have in house.



Some areas are nice, but some came out, as I feared, with some creases in the cloth:



I could sand it down and keep adding one or two layers at a time (I am targeting app. 5 layers for a 1.5mm laminate thickness). Again, this is not a cosmetic piece so that would probably be OK.
But as mentioned, I am waiting for some braided sleeve and will give that a go before doing anything else.

Had this been a simpler shape, I would have been all fine by now. The reel sleeve/camera wing I did as my last project was all done in one go - as should be the case - and came out fine because they were more straight forward shapes.

With the handle here, the areas that are less "bumpy" come out OK, as in the left hand side of the pic here which is the support of the lower palm area:


I don't really have a pic of it, but I am pleasantly surprised about how the underside of the handle turned. I thought it would be very hard to get the fiber to fold around the edge and onto the underside, but that's one thing the uni weave did OK.

More to come when the sock comes in - very fitting for Xmas;-)

Another update.
I received My Xmas Socks AKA my samples of braided carbon fiber sleeve:



It's pretty, right?;-)

I got two different sizes (diameters) and the smaller one is the one with the best range. The bottom of it, with the taped end, is about 25mm in diameter and the widest part, I guess is about three times that.

It's rather thick at 12K, so it is not a pliable as a sleeve which would be thinner. This would be great for building up some laminate thickness fast on, say, a blank or other less exotically shaped parts;-). You can get 3K and 6K sleeves, too, but this was what I could get samples of and also, the 12K is pretty good value.

But I had to test it so I can decide if I want to go down this path.

To lay down the sleeve onto the handle and keep it in place, I lightly misted the wax handle with a spray glue. Then I used a "guide tube" (just some rolled up plastic film) to help slide the sleeve onto the handle - it would not be possible without the tube as the sleeve would get stuck in the glue.

No pic of the guide tube operation but here is one shortly after I pulled out the tube:



I trimmed the ends and folded over the cloth:


Then I mixed up some epoxy and heated it slightly to get it to flow better and applied vast amounts of it with a brush. I've never laid up CF like this and was worried the resin wouldn't really want to go into the laminate from the outside, but it kinda got wicked in, so I think it's fine.

Then I wrapped the handle in peel ply and... oooops, I just realised I forgot the perforated release film... The perforated film helps control how much resin is sucked back out of the laminate and into the bleeder ply once vacuum is applied.
Without it, there is a risk you suck the laminate dry but I think I'll be fine - the laminate is very wet and I will just not put a huge amount of vacuum on it until the resin has set more.



Will leave it to cure overnight and pull it out of the bag after breakfast

foxfish said:

Good luck, I think my method if wrapping stretchy tape around the wet carbon is a lot less trouble

Click to expand...

Sure, no doubt!
But it wouldn't work with my handle as there are too many concave undercuts that the tape would not be able to put pressure down upon.
A combination of tape and intensifiers could work. 'Intensifier' is the word the composite guys use for custom shaped blocks of e.g. silicone which goes onto areas of the laminate that are hard to put proper pressure on.

This is why vacuum bagging works well for most part. This part, this handle, is just a bit too complex. It's more an issue of the (lack of) flexibility of the carbon fabric than it is about the vacuum technique.

But you are right about tape, if you have no concave areas, it is a very good option. Either over-stretched electrician's tape or even better, heat shrink tape. The latter is actually used in professional composites.

But the thing is, I like little pet projects and for years, since my aborted attempt at becoming a boat builder (the sanding, sanding, sanding killed me, haha) I have wanted to play around with CF and vac bagging. Spearfishing parts were the perfect excuse.

Anyhow, I got the handle out of the bag just now.
With all the resin cured in the bleeder ply (the cotton like layer which is there to absorb excess resin) and me forgetting the release film, it took some work getting the bleeder and peel ply off of the piece:



It looks much better, but there are still a few creases and I will have to put that down to the thickness of the sleeve. It is about three times thicker than the regular 3K sleeve.

But overall I am convinced that sleeves are the way forward. It is just so much easier to work with. It's faster and stays in place much better than using regular cloth.
Since I also have a dream project about a custom barrel for the Mirages, I think I will buy some sleeve. It's not cheap, but it will be my Xmas present to myself;-)



The tiny little squares - not the ones in the weave but the even smaller ones are fr0m the peel ply film which is a nylon release film place immediately on top of the laminate.
The idea is that for secondary bonding, like gluing or adding more fiber, you would not have to sand the surface as the peel ply leaves it clean and textured already.

Finally, a quick shot of the "guide tube" which is just some thin plastic film rolled up into a tube. It could be anything, but this is what I had on hand:


I am on hold for some days on this handle until I have ordered and receive some more sleeves. Though the thinner 3K version is double the price/weight I might spring for it since it will lay down even more easily.

In the meantime, I am working on a tool for the pump inlet valve and I still need to do a silicone mold for the Seac Hunter custom handle.