Friday, January 15, 2016

Back in black

Bring on the roll of carbon fiber.  It's time to build some composite parts.

First up was the mast tube.  I like the rocking mast tube concept that we did on the Rodger Wedges so I will do that again.  While other boats in the fleet selected to go with a slot shape for the top of the tube, I was concerned that building the mold for this shape would probably frustrate me.  Additionally, I would like to support the tube along the forward surface internally,  This is difficult when it's cylindrical and only makes contact at the tangent point.  I went with a square cross section with 1/2 inch fillets on the edges.  The mold was easy to build and the part popped out nicely.  I have a plan for ensuring that the tube doesn't point load the mast when rocked all the way forward and aft, but we'll go into that detail later. 

Here's the mold made with MDF.
I wrapped it with release film and layered on the cloth. Here's the stackup I used:

0/90 3 oz glass
0/90 carbon
30/60 carbon
-30/-60 carbon
0/90 carbon
0/90 3 oz. glass

It came out right at the anticipated .090 thickness. Yay math! Stay in school, kids.
After I wrapped it, I added another layer of release film and then clamped it up.  I probably should have bagged it, but it didn't seem necessary for this part at the time. 

With a little brute force and awkwardness the tube released from the mold.  The inside turned out nice.  There's one void, but I don't think it's going to impact performance.


Here it is after a little clean up.


A touch of sanding on the outside and this thing is good to go.

Next up was the daggerboard trunk.  Same process. 
Here's the mold:

All wrapped up and going into a clamp I built for it to cure in.


Here's the finished product before trimming.  We finally had some cold weather and I didn't have any heaters.  Stuff I added to the boat finally cured up a day later, but the daggerboard trunk was moving slow so I popped it in the oven the next morning.  It kicked after that, but I think it embrittled the film a bit or it wasn't quite done when I pulled it off, either way, the film didn't come out of the inside real nice.  That's ok.  Less marring on the board with a polyester film touching it rather than the hard epoxy, right?


3 comments:

  1. Nice job. What NACA # did you use for the CB case blank? I'm goinng to use the same process for the cedar stripped Euro.

    Bill Boyle

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  2. Hey Bill, thanks! Can't wait to see the strip planked Europe! I'm going with a NACA 0009 profile on a 9.75 chord length for the board. The rudder will be a NACA 0012, 6.000" chord.

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  3. Hey Jamey, the boat looks great! So glad you are posting photos. George A put a link on his blog so you may get a lot of visitors. Nice idea on the carbon trunk; the mast tube looks cool too. I'll keep checking to see your progress.

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