rainedave

My Feedback: (1)

Beautiful work Andrew. I've always liked "bowed" ribs, but I haven't used them since building rubber powered stuff.

David

KidEpoxy

Nice stab with the bowed ribs.
Are the LE & TE laminated to get that shelf for the ribs bows to end on?

Cause that would be where I'd put 1.2oz of elmers
I dont see how 3m77 would spray such a narrow stick to lam it.... wont I end up wasting 80% of the spray as it misses the target? I've tried using CA, but all it takes is for me to get the tip near a piece of balsa, and it will wick half the bottle all over the wood [:@]. I find myself holding the work up in the air & trying to keep the CA bottle at or near horizontal to fight the Wick & Drain

jetpack

My Feedback: (1)

I have a 6" (i think) metal draftsman compass that accepts an Exacto #11 blade and is a solid tool that would be perfect for cutting larger diameter holes. I found it in an art supply store, and have only used the blade end to cut masking but would work well on balsa.

jetpack

My Feedback: (1)

I have a 6" (i think) metal draftsman compass that accepts an Exacto #11 blade in an interchangable head, and is a solid tool that would be perfect for cutting larger diameter holes. I found it in an art supply store, and have only used the blade end to cut masking but would work well on balsa.

GrahamC

Well done CP. Very reminiscent of other shop made circle cutters. Two of note come to mind (for others who might wish to pursue the idea)

http://www.modelenginenews.org/ed.2005.05.html#tt3

http://www.modelenginenews.org/techniques/punch.html

Both on Ron Chernich's model engine web site (and for those who have been around the hobby for some time will recognize Bert Steigler's name ie Ebenezer).

I have an Olfa circle cutter I use occasionally for cutting holes in balsa or gasket material. Works but is not the greatest as it lacks the rigidity I would like in such a tool. I will have to make my own and CP's design and picture has given me an idea.

cheers, Graham in Ottawa

Andrew

KE -

The LE and TE are 3/16" stock. I pinned the LE and TE down, then used 1/16" scrap spacers (gray) to set the shelf height. I butted the 1/16" shelf against the LE and "tacked" with CA between the spacers. When it set, I pulled the spacers and finished gluing along the butt joint.

I use teflon (PTFE) spaghetti tubing from [link=http://www.mcmaster.com/]McMaster-Carr[/link] (catalog page 793). You can get it in IDs as small as .012 for $0.10 to $0.12/foot. Five bucks gets a lifetime supply. I cut about a 2" piece and then cut one end on an angle. I'll trim the end of a CA spout just enough to push the angled end of the tubing in about 1/4" - a good friction fit is all that is needed. The tubing lets me reach a lot of joints and due to the small ID, I can control how much CA I use. Since it is teflon, if I get a ball in the end, it just pops off. When done, I drop both the tubing and cap into a tub of acetone and cap the CA bottle with an uncut spout. When I get ready to use the cut spout and tubing again, the acetone has dissolved any remaining CA and both are clean and ready to go.

Use "spaghetti tubing" in the product search words.

Jim Thomerson

I still have a supply of "Hotstuff' tubing. For Titebond, get a bunch of cheap watercolor brushes at the craft store and use the appropriate size to apply the glue. Wash up with water or discard.

KidEpoxy

"I butted the 1/16" shelf against the LE and "tacked" with CA between the spacers."


OMG! I cant believe something as simple as Tacking was the step I was missing.
I was going over in my head what kind of traetment I could give the spacer to avoid having it glue to the shelf.... duh, tack where there aint spacer.

This might unstall a project or two hanging on my wall.

Thanks Andrew

Andrew

I had used the Hotstuff tubing before and liked it, but being frugal (OK, OK, maybe cheap), I looked for another source. We use McMaster a lot at work and they have many products that we use in the hobby, but in bulk pricing. At the time, I think I paid 8 cents a foot, so I bought a lifetime supply.

If you don't have access to tubing, I've found that by heating the middle portion of those plastic shaft cotton swabs over a candle until pliable, then stretching, you can draw it out to a very fine tube. Cut it where you want it, heat and slip the other end over the CA spout and you have a quick and dirty applicator.

Bipe Flyer

I use forstner bits. I put the balsa on a piece of pine and cut through it with no problems. In fact, I've used them to cut through balsa sheeted foam. Just go really slow.

glydrjocky

I was trying to figure out a simple way to make holes through my ribs to route servo wires and came across some some empty .44 magnum pistol shells on my reloading bench. They were perfect! I simply used my dremal tool with a stone to chamfer the inside edge. I then took a knife edge needle file to put a number of notches (serrations) along the cutting edge. This helps keep from tearing the wood as the brass twists through the other side. I then drilled and tapped the primer pocket for a 1.5" 10-32 screw and lock nut. The extension screw allowed me to cut the hole in a rib under the center section sheeting since the routing of wires was a bit of an afterthought on one project, this also required the grinding down of the cartridge rim so it could pass through to the next rib bay. The nice part is that pistol and rifle brass comes in many "calibers" I'll set up a .357 and .45 long colt next. I suppose a spent .22 magnum might cut nice small holes.

I usually twisted the cutter through a few ribs, then cleared the wood plugs from inside. Very happy with the results and it worked in a pinch.

Now I suppose if a person was really good and you used a sharp edged "wadcutter" bullet, you could just lay the wing panel on its side, line everything up and just shoot out all the ribs in one shot (using a safe backstop at all times)...........

I of course dont own a horse named "Trigger" so I just stuck with the one at a time method.

Necessity is the mother of invention!

T

Yuu

That's a Great idea!! Take the hollow base wad cutter...say, 150 grain... and cut a sharp edge inside the base of the bullet. Then load it backwards in the case, and fire it into a stack of ribs for a tapered wing. As the 'tip' cuts each rib, the 'base' would expand a little, making the next rib have a larger diameter hole. If you shot from the wing tip [small end rib] towards the Root rib, each hole would be a little larger in diameter, and each rib is a little larger too!! Neat idea... of course, you'd have to make another 'hole cutter' for the other side of the wing..... not cheap, but... F A S T !!!!

KidEpoxy

You guys dont just cherry up a cigar & burn your way thru the rib?

Bipe Flyer

You could "honeycomb" the balsa with a shotgun.