Custom Carbon Fiber Grip (For Mirage Pneumatic)

This is a work in progress but wanted to get the thread started.
I have a sort of build log over on Deeperblue but it has tons of babbling so I will try to keep it a bit more to the point here.

I have fallen madly in love with Mares' old pneumatic design The Mirage.
The Mirage is a special pneumatic, with some pretty smart features. I will get into that a later point and for now just focus on one of the things I did not like about the gun: The Handle... (drum roll!).

(Here seen with a Salvimar Vuoto vacuum muzzle)

The Handle - yes, it certainly has to be capitalized since The Handle was a defining part of the gun with its ultra swept-back grip reminiscent of a target pistol. It is certainly special and some would say beautiful, but after having shot it for a while I realized the grip angle really did not suit me.

To cut a very long story somewhat short, I found that with a lot of time in the water, I could get used to the grip angle and make it work and place my shots well.
But I don't spear regularly - only on vacations - and the first few days (or on hurried/instinctive) shots, I found out I always shot high.
A side note here, an actioncam in slow motion mode is great for self-diagnosing stuff like this.
Coming to terms with this, I could see only one way forward. I had to commit gun sacrilege and chop that iconic grip off and make a custom one.

Here is where the road starting taking so many twists and turns that I will leave out most of the mishaps of the adventure and try to tell this tale in a more sober way than it was living through it;-)

I knew I wanted an anatomically shaped handle to fit my hand exactly. I find them sexy, haha! I know some people are against them as they don't work well "backwards", but this is what I wanted.

I also wanted the handle to end up lighter and/or more buoyant than stock as the Mirage is too heavy as is. Also, I like to fool around with carbon fiber, so a sort of plan was hatched.

I started out by sawing off a big chunk of the original grip and then built it up with various materials. The "various" meaning, I strayed and F'ed up a handful of times... Early on, I harbored hopes that I could just cover the custom shaped grip in carbon and that would be it, done!
But all the clay I added, even on top of a lightweight XPS foam core, made the handle way too heavy. So, I switched to an approach where I would use the custom grip I was making as a plug to have a mold taken off of.

Sawed-off Mirage!;-):

The grip was built on foam core with poly clay (AKA FIMO clay) as I still thought I might have kept it as is with a cover of CF:

When shaping custom grips in clay, Shapelock or putty remember to wear the glove, you would normally wear. I wore a 2mm one for tropical waters. Also, I wore a latex glove on top of the neoprene one as both Shapelock and the clay stick to the neoprene, but it doesn't stick to the latex:

Now, this is where I F'ed up...
The clay needs to be baked at around 135C (275F) for 30 mins (slight variations depending on the brand). But that messed with the foam which either expanded or imploded - prolly both in that order. So, I had the tab on the top collapse and I had the middle part of the clay crack wide open.

But I soldiered on and fixed those issues with some cyano glue, putty and sanding runs.
At this point, it had become obvious that the shape I would end up with would not work in a normal two-piece solid mold. The concave undercuts of the grip would simply get stuck in the mold. The solution was to make a flexible silicone mold.
But that was not the whole answer as it would probably not work to use a flexible mold to make the CF grip in. The missing piece of the puzzle was found right here on this forum from Tin Man's amazing Lost Wax barrel project.

So, now the method had become:
1). Make a plug (the custom grip)
2). Take a flexible silicone mold off of it
3). Pour a lost wax grip in the silicone mold
4). Laminate carbon fiber onto the wax grip
5). Melt out the wax from the carbon fiber grip
6). Mount the carbon grip on the handle itself

But let's get some pix up here to go with all these words.

Here is the handle after I had poured the first half of the silicone mold:

And after the second half had been poured:

And finally, after demolding:

And yes, I know what you are all thinking: There is just not enough pink in the world of spearfishing! I, for my part, is trying to do something about that:-)

PS. Some of you might have noticed that the left, lower mold half has a lot of bubbles in it while the other has none. Reason is that I de-gassed the second batch of silicone by flicking a quick vacuum chamber together and hooking it up to my vacuum pump.
(Let me know, if any of you want me to elaborate on that part or the vacuum bagging for the CF laminate.)

With the PINK silicone mold done I could get to work on the wax core.

I don't have any pics of pouring the wax, but before melting it, it looks like this. Small pellets that melt around 65C (149F) and are reusable:

And with an AA cell for scale (though it comes in blocks, too):

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:

And one with the "plug handle" and the stock handle:

After tidying up the wax grip a tad with a scalpel, it was time to actually do some carbon fiber work (finally)!

This shape is not at all easy to lay up on. Just too many abrupt changes in its lines for the fiber to accommodate, so I knew I needed the most pliable fabric I could get.
I immediately gave up on the regular plain and twill weaves and started out with some uni-directional which was barely OK.

BTW, I vacuum bagged the part as using tape or shrink wrap for compression wouldn't have worked because of the concave areas.

First pic is after the first layer of uni-directional. Not great, with some creases and slipping of the fiber but this was before I got the sleeves:

But then, just a few days before Xmas, Santa got me some pretty socks;-)

These are braided sleeve samples and immediately, I knew they were the better option, but I was still not there. The thinner 3K sample was not big enough in diameter though so I never got to use that and the thicker 12K sleeve, though perfect in size, was almost too stiff to fully follow the contours. But still, it was better than the uni, so I went ahead with the 12K sleeve.

It is so much easier to "lay up" the sleeve. Really makes a huge difference. I mist the grip with spray glue, then insert the sleeve over a tube which fits over the grip and pull the tube out as I lay down the sleeve:

Here it is in the vacuum bag:

And out of the bag with the layer of 12K sleeve:

My lamination work is not amazing by any means, I had a few places where the fiber slid and creased but structural it should hold up just fine.

After having tried the 12K sleeve, I got my hands on a sample of 6K sleeve and I think, for this part, 6K is the best compromise between thickness and pliability of the fabric. 3K would drape even better, but I would need more layers. And 12K was just a tad too stiff.

I used the same technique as before - tacking down the dry sleeve with spray glue and then adding the epoxy afterwards.
After the initial room temp cure over night, I post-cured it in the oven for 4 hours at 80C. The latter served two purposes. First, it melts out the wax and second, it makes the laminate stronger. (Check your resin system's specs for post-curing at elavated temps, as it differs from system to system).

In the oven with the wax floating out:

In all its beauty;-):

The hollow inside of the grip:

The grip weighs about 38 grams (1.34 ounces):

It is incredibly strong. I "tested" it with 70kgs on it by standing on its side and noticed no flex at all.

This is where I am at now, just a quick test fit - it is not glued in place yet:

What is left is to sand it down and give it some top coat.

Also, I have been pondering different solutions for attaching a float line to the handle.
I thought about making a tube from the underside to the orginal Mirage stub, and thread some Dyneema through there. Or attach a sort of stringer to the stub and let it exit at the bottom of the handle.
I also sourced a few SS eyebolts and I could get a U-bolt and fix either one on the flat underside of the grip.

But I think I will drop all these ideas and go even simpler.
As mentioned earlier, I am positively surprised by the strength of the CF grip.
So, the plan now is to just drill a hole straight through the rear, lower part of the handle. The inside here would be filled with chopped CF and epoxy - which I also plan to use as structural glue to secure the grip on the remains for the stock handle

I don't see the grip breaking in two even with a strong pull on the float line - the risk is the whole grip coming off the stub. But with the shape of the stub as it is, and perhaps a few strategically drilled holes in it, I am pretty sure, the grip will lock in firmly once the epoxy glue joints and core has cured.

After having glued in the grip, I will fill the empty spaces in the handle with either syntactic foam (another trick I picked up from Tin Man and Griswold) or 2K PU foam.

Dunno how I missed that, I did a search.

No way to use the attachment function and place the image in line instead of just at the end?

I ended up with a crazy merry-go-round to do this which consisted of first attaching, then saving, then copy pasting the link, then embedding the link, then saving, then deleting the attached pics and then saving...
I kinda dislike the extra step of having to go somewhere external to host pics. Also, I see a lot of old posts on various forums have lost their images cuz they were hosted elsewhere.

Shoot, I thought the pix were here - they showed on my laptop but I just cleared my local cache and none of them are:-(

Photo bucket it is then as I like the embed in between text.

[EDIT - just put them all back in via Photobucket now]

Quote from Mighty kc

Now you have inspired me to do something with the handle on my Sten.

I hate the Sten handle. I will let you know how it works out.

KC

The Sten is a good candidate - and it shouldn't be too difficult to make it detachable, either.

I have a short Sten, too, but just did the quick Polymorh/Shapelock thing on that one.

I just went through my "archives" and found some pics I had stored of a French builder's handles.
I hope Mizalo wont mind that I re-post them here for inspiration:

If Google translate serves me right, he used the white plastic as a plug and used it to make a mold for the fiber handles:

His wife supposedly did the paint jobs on the barrels:-)

I don't know if he is in business any longer, these pics are four years old, he has not been active on the forum where I got them from since 2013 and his website has been down for years. I hope he is OK, though. (Maybe Virgil will know?)

Links to where I snatched these from:
The white plastic handle

Carbon Fiber handle

Texalium Fiber (and wife's paint job)

A nice CF reel holder sleeve

It's funny, I haven't looked at these pics in years and I just realized how much I "stole"/got inspired by them - but I forgot the origin in the meanwhile;-).
Thanks Mizalo!

BTW, the white plastic in the first pic is Utileplast which seems to be the same as Polymorph or Shapelock but I don't know how he has gotten it so smooth. I reckon he must have used filler and paint before that pic cuz the Shapelock I have played around with does not have a fine surface like that.