I am going to make some spars from carbon fiber plate. What tools what I use to make long straight cuts of the carbon fiber? Thanks,

Jay

NC water jet. Seriously, it's a pain. A diamond saw blade is about the next best thing. You can get diamond cut-off wheels from Harbor Freight and build a mini "table saw" for your Dremel.

This is a main reason why people use tow for spar caps.

-David

I remember Markus saying he used some sort of carbon plate and then he just cut his spars for his planes from this carbon plate... I am hoping he chimes in too...

Jay

Oh... do you mean carbon-faced shear webs? Those you can cut with a razor blade (and many, many passes).

-David

Originally Posted by davidfee

Oh... do you mean carbon-faced shear webs? Those you can cut with a razor blade (and many, many passes).

-David

Yes, that's what I meant. I just assumed they were the same thing. I have some carbon plate and cutting it with a razor blade seems nigh impossible. Also cutting it accurately would seem to be difficult..

speaking of these carbon faced shear webs, are they faced on just one side, or both?

Jay

It depends. If the wing is pretty thick, they can be faced with glass (both sides). As the wing gets thinner, the shear forces get larger... so you put carbon on one side and glass on the other... but when you get to the 6-7% F5B/D wings, both sides are faced with carbon (+/-45deg).

Solid carbon plate IS basically impossible to cut with a knife if it's more than, say, 0.02" thick. If it's just a layer of carbon facing on a shear web, you can lay a straight edge down and slowly make passes with the blade until it cuts through. Solid stuff needs a diamond cutter, as I mentioned before (other cutters will dull rapidly).

-David

I personally chew through it. gave up on knives and cut off wheels long ago. :P

Rhett

Carbon plate is several layers of woven carbon fiber cloth epoxied together. I have a 0.06 plate that I can cut with the Dremel cut-off wheel but it is slow and best done outdoors. The carbon fiber faced sheer web is a sandwich of balsa with carbon fiber laminate on either side like an Oreo cookie. A fine tooth razor saw will cut it but it will ruin the saw in no time.

Another thought would be to buy some carbon fiber cloth, cut a few layers to the length and height you want and then vacuume bag it. Custom carbon spar and not too messy.

Hope this helps,
Wayne

high speed carbide router bit designed for fiberglass and CF. (rasp bit) turning 20k-30k cuts CF fairly well using CNC setup. it is much easier to cut cloth.

Attach it to the bench with double sided tape or 3m.
Cover the cut line with masking tape.
Use the straight edge with double sided tape or 3M to keep from moving.
Score the beginning of the cut or nick it for the start and use many light to medium pressure scores along the straight edge until you get through it. The masking tape will kind of collect all the little carbon shards and save you some grief.
On thin plates it is sometimes possible to get it started and tear it off along the grain in equal widths if the layup was good, just try not to delam it as you tear off the pieces. Good luck. (Snap off knife works good, replace the blades often and be careful not to slice off your fingers etc.)

http://groups.yahoo.com/group/SALglider/message/7145

http://groups.yahoo.com/group/SALglider/message/7139

http://groups.yahoo.com/group/SALglider/message/5084

I glue a wood "fence" to the side of my bandsaw for the plate to slide along. The bandsaw cuts pretty quickly and leaves a nice cut, but it will dull the blade fast.

Dan

In case you haven't seen it before, wear a good mask when machining CF (and when cleaning up the dust). The fibers are very small and will cause problems later.

Yup... otherwise your snot will be black for a day or two. That's enough to creep anyone out. Wear a mask! You don't want that stuff in your lungs.

-David

Originally Posted by davidfee

build a mini "table saw" for your Dremel.

Hi, do you think you could explain, pics, diagrams e.t.c.?
Just I want to be able to cut CF sheet, but I know its quite tricky.

Thanks, Duane