Carbon Fiber Backplates?

[saxman242]

You'd still need to encase it in resin (I'm no expert on Kevlar) The glass layer is just a tell tale, if the resin is damaged but not the glass layer, you can patch up the resin. If the glass is damaged, then the underlying CF layers maybe damaged.

The Glass layer isn't structural its almost (but not) sacrificial

Kevlar is used like any other grp style fabrication method, but has much higher impact and abrasion resistance. Prevents things like chipping/shattering of the overall laminate. Isn't nearly as pretty though and can be a pain in the butt to work with. For a product that's going to see a lot of bumps and bruises though, it'd make a much better outer layer than glass.

 

[saxman242]

Product you see advertised as Carbon fibre, often just have on layer of Uni direction (the famous herring bone pattern). Its not doing much (but looks pretty)

Just to be pedantic, what you're talking about here is a 2x2 twill bi-directional weave, not uni directional carbon. Uni directional carbon does not display the herringbone pattern you're talking about.

 

[Manatee Diver]

As I said - over simplified (clearly not enough)

You argued that a bolt was a greater stress point, than cam bands I was just trying to demonstrate why in this case it isn't. I wasn't saying the material couldn't take the load, that was you.

Actually I wasn't the one arguing that the material couldn't take the stress either. I personally think that for single tank purposes all but the most shoddily laid up carbon fiber can handle it.

 

[Aviyes]

Kevlar fiber is an ugly yellow color, so not exactly the best looking for an outer layer. The sheets of bi-directional Kevlar are a pain in the ass to cut.

 

[saxman242]

Kevlar fiber is an ugly yellow color, so not exactly the best looking for an outer layer. The sheets of bi-directional Kevlar are a pain in the ass to cut.

View attachment 559031

Agreed. Kevlar sucks to cut and isn't the prettiest of things in its yellow state, however, there are dyed kevlars that don't look that difference from cf available.

 

[TheRealScubaSteve]

But I only used to design and test CF components in aerospace. If Haylc0n make them and GUE sell them, they must be okay

Just curious, what type of resin are they made with - epoxy?

You'd still need to encase it in resin (I'm no expert on Kevlar) The glass layer is just a tell tale, if the resin is damaged but not the glass layer, you can patch up the resin. If the glass is damaged, then the underlying CF layers maybe damaged.

The Glass layer isn't structural its almost (but not) sacrificial

Depending on weave, kevlar can have difficulty in absorbing resin. Outer surfaces will generally wet out pretty good, but as noted if the scratches permeate through the outer glass and scratch the kevlar deep enough, it can cut into a dry section. Then it just becomes a weak point in terms of strength but also in terms of absorption and de-lamination.

 

[saxman242]

Just curious, what type of resin are they made with - epoxy?



Depending on weave, kevlar can have difficulty in absorbing resin. Outer surfaces will generally wet out pretty good, but as noted if the scratches permeate through the outer glass and scratch the kevlar deep enough, it can cut into a dry section. Then it just becomes a weak point in terms of strength but also in terms of absorption and de-lamination.

I don't believe diving Dubai was suggesting Kevlar, that was me, and in this context as an exterior ply.

 

[TheRealScubaSteve]

I don't believe diving Dubai was suggesting Kevlar, that was me, and in this context as an exterior ply.

I don't have a strong opinion either way. I have limited experience with CF but plenty with fiberglass and E glass. It would be an interesting project to clone one of my backplates with varying laminates, but I really don't have that kind of time.

If I were to make or buy a laminated plate regardless of material type, I think my primary concern would be the trimmed edges rather than the "body." I've never seen a carbon plate, but I assume that they're trimmed rather than closed-molded without any cut ends. Any idea?

 

[saxman242]

I've never seen a carbon plate, but I assume that they're trimmed rather than closed-molded without any cut ends. Any idea?

I imagine they're trimmed and then given a bead of resin along the edge and post cured.

I've contemplated doing the same a few times and add in a few layers of titanium between plies at the mounting holes to help with bearing loads from the bolts.

 

[TheRealScubaSteve]

I imagine they're trimmed and then given a bead of resin along the edge and post cured.

I've contemplated doing the same a few times and add in a few layers of titanium between plies at the mounting holes to help with bearing loads from the bolts.

I suppose for production volumes they're probably made with pre-preg glass with a post-cure. If made with another method, I'd be surprised if they were.

Just Googled a few photos of different makes and it looks like they've put a washer between layers and included an (aluminum?) sleeve in the nut holes. Seems like a simple enough solution. Compression tubing would also be a very suitable option for through-bolted items.