Lost wax carbon fiber molding

[Tin Man]

It's actually only two coats. The first sleeve, and all the uni-wraps are applied at the same time. After curing, sand it smooth and even (there will be some minor ripples) and then apply a nice, neat final sleeve, in your choice of color.

The key to keeping things relatively flat is to vent excess epoxy. If you are using the tape or heat shrink method, use one of these little "woodpecker" tools that you can usually find in a remote control model shop. After wrapping the tube with tape or heat shrink, run the woodpecker up and down a few times to make a bunch of tiny holes. You will see the excess epoxy ooze out.

The final finish is easy for me, because I really don't like a super shiny look. To get a really nice satin finish, sand it with 220 grit paper, brush on a coat of epoxy, and then immediatly wipe off all that you can with a clean cloth. No drips, no runs. I then rub it down with 000 steel wool to get a nice matte finish. Unlike wood, there is no need to build up a thick protective layer, since the whole thing is epoxy and CF.

 

[JCooke]

What makes you think it's lite?

With the Rob Allen horizontal reel (not shown), it's a bit over 5 lbs including a 5/16" shaft, but I'll probably use a 9/32" shaft most of the time.

So I would venture to say that it's a good 30% heavier than a typical euro of similar size and mounting two bands.

Well using carbon fiber makes me think it lite, and its hollow? I had some snowmobile parts make of CF went from 28Lbs to 5Lbs.

Jas

 

[foxfish]

I assume we want to remove or expel as much epoxy from the product in an attempt to keep it light as possible.
What happens if there is to much epoxy left, I mean will it effect the product strength or simply make it heaver?
I see where you are coming from with the woodpecker wheel, I have seen pre perforated shrink tape available or as I was intending to use, peel ply.

 

[Tin Man]

Carbon fiber is about 60% as heavy as aluminum and about 25% as heavy as steel, so it CAN be used to make an equivalent part lighter. But I also made my barrel considerably thicker. So what I ended up with was something that is a little heaver than a typical aluminum euro, but with good balance, and REALLY strong.

 

[Tin Man]

I assume we want to remove or expel as much epoxy from the product in an attempt to keep it light as possible.
What happens if there is to much epoxy left, I mean will it effect the product strength or simply make it heaver?
I see where you are coming from with the woodpecker wheel, I have seen pre perforated shrink tape available or as I was intending to use, peel ply.

Well, since we're not building an airplane, a few grams of extra epoxy usually isn't the end of the world. And you are correct that a composite is generally not quite as strong if it is too "resin rich". But again, we are talking about small differences. I don't build that close to the design edge. I recognize that my technique is far less than perfect, so I just throw on an extra layer to compensate. If strength is adequate, what matters most to me isn't weight in the air but the balance in the water, and a bit of extra mass is usually a good thing.

The biggest reason to vent the excess epoxy is that when you squeeze the assembly, however you choose to do it, the incompressible epoxy will flow to the areas where the compressive force from the tape or heat shrink is slightly less. This will leave you with little waves along the surface. The holes allow the excess to get out, which leaves you with fewer and smaller waves or bumps to sand down.

 

[foxfish]

Thanks, I am getting there slowly but surely.

 

[Tin Man]

One other thing. When I did my first tube, I let it cure for about two days and then put my weight against it to see how stiff it was. I was disappointed to notice more flex than I expected. Frustrated, I set it in the corner for a week or two until I had time to work on it again. At that time, I noticed that it was considerably stiffer than when I first checked it. So even though the epoxy appears fully cured, it probably isn't right at first.

Along those lines, a guy I trust said that I did myself a favor when I used my barbeque at about 150° to 160° to melt out the wax. He said that a cure at an elevated temperature like that will also help the epoxy reach a measureably greater strength. In my case, I did it a day or two after I formed the barrel, but ideally, it would be done right after layup.

 

[Don Paul]

I've use a deserted black suburban in my industrial complex before my friend
found a pizza oven on craigslist.
No help to you snow bound guys, sorry.
Don

 

[jtkwest]

how did you get the track cut into the mold?so perfectly? did you make that muzzle? realy nice work!

 

[Tin Man]

I cut the track using my Bridgeport mill after everything was cured, but it should be possible on a router as long as you've got a good fence. I made the muzzle as well. Nothing fancy, but I like the minimalist lines.

 

[jtkwest]

that is the nicest muzzle i have ever seen. i would love to have something like that for my hybrid.

 

[Don Paul]

that is the nicest muzzle i have ever seen. i would love to have something like that for my hybrid.

He may sell a couple if he has them.
Cheers Don Paul