I used a vacuum bagging technique to attach the wing skins to the foam core . Now I have to make the channels for the servo wires and retract pneumatic lines in the wing.

a) I was thinking of cutting out a strip of about 1/2 wide balsa skin then routing the channels for the servo wire but leaving a shelf so I can reattach a piece of balsa where I removed it.

Do you think this will weaken the wing severely?

b) Alternately I can bore a hole using a brass tube with one end cut like a hole saw teeth . However this is quite difficult to do because the tunnel I need is quite long ( about 14 inches ) . I can make a jig so it drills straight. I have done this before but on a much larger and thicker wing .The current wing half is about 22 inch and only 1 1/2 inch thick at the root and it tapers to 1/2 in at the tip.

One other question I have is whether it makes any difference to wing strength whether the cable channel is bored approx centered in the wing core or making the channel adjacent to the wing skin .

Would appreciate comments. Any other methods?

Thanks

Yikes! You want to do all that stuff before you glue the wing skins on, e.g. the retract gear mounts, wheel well, air line channel, servo mounts and servo wire channels.
http://www.rcuniverse.com/forum/m_39...11/key_/tm.htm

Cutting the holes in the foam for the air lines and servo leads with a sharpened tube would be best at this point.

The reason for making the servo wire channels after the vacuum bagging process is because the vacuum tends to crush the balsa skins where the cannels are cut .

I see. After I cut the channels I fill the top gap with a glued in strip of 1/6� balsa so the wing is support well.

Hope your rain stops soon!

I read in another thread a clever way to do this. Cut a 1/2 in wide strip of balsa skin for the channel but angle the cut so that you remove a V shaped piece ( balsa skin + some foam) Now route or hot wire the bottom of the V groove for the cable. The V shaped piece that was cut can now be glued perfectly back due to the V shape !

We try to fly between the rains

Tks

I use a heated piece of music wire, I drill a hole the size of the wire in a scrap piece of wood sheeting, this is screwed to the work bench at the elevation that I need the hole. Heat the wire with a propane torch and slowly turn the wire into the wing core, I use a variable speed drill to turn and push the wire into the core. Don't overheat the wire as in will melt a large hole in the core.
Tony Hallo

Just last week, I used a sharpened brass tube (1/2") to cut a hole about 10" into foam wing halves. It worked great using the shucks to keep the wing aligned with a jig. The jig is simply a block of wood with a V groov cut along its length. I rolled the tube in the V as I pushed it into the foam. Just clean the foam from the tube every couple of inches and it cuts fine. I even pushed a rocket body tube into the opening to help prevent collapsing from the vacuum.

I also use the hot wire method. But I don't do anything fancy, I just heat the wire (5/32 or 3/16" Music wire) and run it down by hand. You will need to re-heat the wire several times, and it really doesn't matter if you get sloppy. It's all under the sheeting, and you're really not taking away any strength.

If the plane is not a rocket or a wild 3D, the wing groove and re-cover are no big thing.

Tape or sanded Glass cloth will do.

Its a 45 in span Bob E Cat with Midifan so its not all that fast. I will take the easy route of using the wing groove method. Tks