When I made the blank I went to Martin's Lumber in Everett and bought several pieces of very nice, very clear, Western Red cedar, in 2"x8"x8' dimensions. This is an expensive way to do it - the wood was well over $200 as I recall. After cutting them to a better length, I ripped them into chunks a little over 2" thick and got ready to laminate them all together.
I was worried about the glue joints ending up too dry, so I coated each joining side with raw epoxy, then slathered on a layer of bog for good measure:
After all of the pieces were glued together, I then clamped it all up: 
After the bog dried, I "post-cured" it in a black garbage bag in the sun, but otherwise the blank just sat because the 3D file wasn't ready yet (hasn't been a huge priority for either my neighbor or me, obviously :). This month things were finally ready; here's a picture of the 3D model:
My neighbor first did a test board in MDF (which I test-fit in my daggerboard case) and today he cut the real board out of the blank. Here is a picture of the CNC machine in the middle of a rough-cut phase on the first side:
Here's a short video of the CNC machine in operation:
The audio isn't much :) but I think it's pretty cool to see the machine in action.
Here's a picture of the "finished" product:
Frankly it looks really beautiful; it's a shame it will all be covered up in glass, fairing compound, primer, and paint (I'm thinking of painting it yellow, for capsize emergencies). Anyway, next steps will be coating it with a sealing coat of epoxy, then starting the glass and uni layers. (And yes, we made sure to under-size the board to account for the thickness of the glass layers).
5 comments:
That daggerboard is very very nice. Looks like it belongs in a living room.
Was there any sanding required after the CNC work?
I'm also curious how much it weighs. I'm wondering if all the effort for a carbon fiber foam core board was worth the effort.
I'll bet you are going to get people asking you for the cnc g-code.
Cheers
Grant
The CNC work left a very slight ridged surface. It probably would have been fine for laminating, but I briefly sanded it down with 80grit before doing the first sealing coat. Leaving the surface with ridges was intentional; the machine can be told to produce a glass-like finish, but we didn't think it was worth it, given the risk of further cutting around some of the delicate edges (eg trailing edge).
Good question about the weight. Unfortunately I did not think about that before putting on the first sealing coat (and it's still too tacky to do it now). Even if it's a little bit heavier though, it's more than out-weighed by the extra bouyancy the boat gets from the cedar, thus holding it up out of the water a little bit more. Cedar Is Faster (tm).
I have already had a couple of folks ask me for the cnc file. However I am waiting to hear from Ian before handing it out, since I'm not entirely sure what the right policy is, legal or otherwise. At a minimum, it would be bad if I started sending out the cnc file to random folks who weren't F22 builders and hadn't payed for the plans.
Jay
Jay --
Looks beautiful. You should make a second scaled down version as a piece of art like Grant said.
Having watched the cnc process, what would you think about two sandwiched pieces of foam with a layer of glass in-between to keep it from flexing during the milling?
A note on buoyancy -- I think it is the 'upward' force caused by the volume of displaced liquid/gas and its force is related to the density of the liquid. The density of the object is part of the equation describing the forces that would oppose the buoyant lifting force. Hence, a heavier cedar has a larger buoyant vector to equal a larger gravity vector at the cost of a larger submerged surface area (has to float deeper since the shape and volume of the foam and cedar foils are identical -- since its exposed area will actually be identical, this is transfered to the hull being deeper). Any physics majors out there to add any insights?
Andrew.
I actually have a Physics PhD. No kidding, I did alot of work in early practical laser processing of materials with higher power lasers back in the 80's and early 90's. But to tell you the truth the physics of sailboat design has always eluded me. I think it is because I was put in a sailboat at age 9, and I picked it all up intuitively.
Personally, I think a well sailed and trimmed boat with either cedar or carbon fiber will outperform the other. But, is will cedar supply more buoyancy than foam? From trusty Wikipedia "when a body is partially or completely immersed in a liquid, then it experiences an upward buoyant force which is equal to the weight of the fluid displaced by the immersed part of the body." Then since both types have the same volume and are constrained to displace the same amount of water....
Grant
Wow - Andrew and Grant, thanks for your comments. I must now feel bad, and admit that my Cedar Is Faster remark was made firmly tongue-in-cheek. Sorry, didn't mean to go trolling there.
Jay
Post a Comment