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Old Jun 01, 2009, 12:06 AM
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Not much in the way of building today. Which is a good thing because a pretty lady prepared a picnic lunch for the lake.

I did get some time in to bring the right wing panel completion up to the left.

Al Offt,

Building the ailerons into the wing and then cutting them free is pretty easy. I included one pic of the wing profile at the aileron and a few pics of the aileron being built.

As far as the jigs (fixtures) I have the Convenience of a woodworking shop. The sanding jig for the aileron ribs were knocked-out in short order from scrap wood and a piece of 120 grit spray-glued on.

EJWash
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Old Jun 01, 2009, 07:18 AM
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Boston, MA subburb
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EJ,
Thanks for the extra pictures. I now see what you are doing at the hinge line.

Alan
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Old Jun 01, 2009, 10:43 AM
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Kingston, Tn
Joined Apr 2009
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Looking good still EJ. I have figured out something, my kit and yours are actually different, just slight differences but they are different. If you look at the plans and instructions for the fuselage, it shows a piece of 1/8 x 1/4 stringers at the bottom, going from the doubler to the tail....my plans does not have this showing anywhere on it. I'm beginning to think my kit was made sometime in the middle 70's if not earlier right after they changed the airfoil on it from the symmetrical to clark-y setup.
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Old Jun 01, 2009, 12:27 PM
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BillyP,

Thanks. The plan has a copyright date of 1986, and the manual 1987. There is a note on the plan that states that the manual is updated more frequently than the plan.

That 1/4" X 1/8" stringer appear to be in place to give more covering surface area at the bottom sides of the fuselage. They are tapered to draw a line from the fuselage stringers. I would certainly install them if your plan does not depict them.

EJWash
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Old Jun 01, 2009, 08:15 PM
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Began the wing mid-section. Things start off with laminating (2-pieces of balsa each) front and rear internal spars. Titebond is more than enough for this job. The power of joinery is in even spreading out a nice consistent layer of glue and clamping pressure. I use a paint brush to spread out the glue on the workpiece like a coat of paint.

The first thing I do before glueing and clamping is to lay out all the tools and materials I will need within my reach.

When I clamp-up a component, I place hard and straight scrap wood on either side of the workpieces. This does two things. First, it distributes clamping pressure more evenly along the glue joint. Second, it eliminates clamp jaw marks on the workpiece.

When the clamps are applied (in this case spring clamps) you know when you have enough glue and pressure when you get tiny beads of glue squeezing out of the joint. This takes a little practice. Be very careful to avoid crushing soft balsa. Clamping time is :30 minutes, but for "feel good" reasons, you can leave a piece clamped-up overnight.

While the spars dry, I'll be shaping the leading edges and top spars.

EJWash
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Old Jun 02, 2009, 12:16 AM
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Laid out the basics of the wing mid-section. The outer ribs of the mid-section are set at a 2-1/2 degree angle to seat the inboard ribs flush with them a provide 1-1/4" dihedral at the wing tip. The build manual has a printed dihedral gauge to set the 2-1/2 degree outer rib angle.

Modern technology is a nice thing. I printed two copies of the dihedral gauge, cut them out, and spray-glued them to 1/16" plywood, which I sanded down to the outline. This allowed me to set the dihedral angle of the ribs in two places along the outer mid-section wing instead of just one.

More work tomorrow, if I can hide...

EJWash
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Old Jun 03, 2009, 12:20 AM
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More work on the wing mid-section.

Like the wing spar ribs, the mid-section ribs slide over the mid-section spars. This makes it difficult to apply pressure to the joint. Added to this, the front die-cut openings in the ribs were slightly larger than the spars. I ended up mixing up a batch of West System epoxy with high-strength filler mixed in. Using the trusty syringe (with the tip cut shorter to provide a larger bead) the epoxy/filler was pressured into the corners of the rib/spar joints. The epoxy/filler set very hard. Those ribs aren't going anywhere...

I put the wing mid-section aside to set overnight.

I spent some time planing and sanding the leading edge and the top and bottom spars to the shape of the ribs. An additional leading edge is glued in place, and then top and bottom sheeting is applied along with rib cap strips. I used a small block plane to take off most of the excess material. I then used my Great Planes Easy-Touch sanding bars with first 80 grit and then 150 grit sandpaper.

I find in planing and sanding that the trick is knowing when to stop. It is also important to take your time and use a light touch. If you apply too much pressure, you'll rock the sanding board and end up with rounded work. When planing, I take the material down to fingernail thickness. I then use the 80 grit to just a hair above where I need to be, and then the 150 grit to flush.

More on the wing mid-section tomorrow.

EJWash
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Old Jun 03, 2009, 07:01 AM
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Traverse City, Michigan
Joined Dec 2005
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Looking good, EJ. Nice, neat work, and everything glued in straight.

I like your GP sanding bar. I have something similar, but different.

While at this year's Toledo Show I picked up some of this company's wares. http://www.bvmjets.com/Pages/Catalog/permagrit.htm

While initially more expensive, these tools should last me for years, negating the costs.
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Old Jun 03, 2009, 10:31 AM
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Tom,

Thanks!

I ordered several Perma-Grit tools last year. Great stuff! Their hole saws literally sand their way through wood. No need to touch-up the hole, just the facing surface.

Here are a couple of shots of fuselage formers using the hole cutters.

EJWash
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Old Jun 03, 2009, 12:36 PM
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Tom,

I forgot to mention the GP sanding bars.

I tried one out at my LHS a while back. I liked the way it felt in my hand, and being metal is not subject to twisting, unless I use it for something it wasn't made for...

I made many a web search to find an extruded shape close to the GP sander, but didn't find anything. My thought was since I wanted several lengths of sanders, buying a long bar and cutting it myself would be cheaper. The closest I came was aluminum 'T' bar, which I could mill wooden handle sides the same shape as the GP sander. Even that method was really close to the GP sander cost. So I saved time and went GP.

EJWash
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Old Jun 03, 2009, 09:30 PM
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Sanding and shaping the wing panels and wing mid-section today. Made a dry-fit of the wing mid-section and the right wing panel. So far, so good.

Sig calls for 1-1/4" dihedral at the next to last wing rib at the tip. Cleverly, they provide wing tips blocks that measure 1-1/4 tall! Gotta love it...

EJWash
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Old Jun 04, 2009, 12:06 AM
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Laid-out the clamps, epoxy (30 minute) and glueing doublers in order to join the right wing panel to the wing mid-section.

Even though I used 30 minute epoxy, the excess in the mixing cup set up in only about ten (:10) minutes! Good thing I had the part in place and clamped.

I'm letting it set clamped overnight. I'm going to glue the left wing panel early in the morning when the temperature in the shop is only in the 80's...

EJWash
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Old Jun 04, 2009, 11:09 PM
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Glued-in (with epoxy) the wing mid-section filler and doubler, which is one piece of 3/8" X 1-1/4" X 8-1/2" balsa. The wing mid-section is joined to the two wing panels at three areas: the rear internal spar, the forward internal spar, and the top and bottom spars.

EJWash
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Old Jun 05, 2009, 01:13 AM
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France, Auvergne, Lapalisse
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building pins

the build looks good can i ask what are the pins you are using and ware i can get sum they look easy to use.
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Old Jun 05, 2009, 01:56 AM
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dpot,

The red capped pins are made by Midwest (http://www.midwestproducts.com/item_...p?item_id=526). They are very thin and more adapt to dealing with thinner balsa. I like them because they dont split or abuse the balsa as much as even the smallest T pins. I founds these at Michaels crafts stores (USA). They are also available at Tower (http://www3.towerhobbies.com/cgi-bin...I=LXRRG8&P=ML).

The T pins you see in the pics are of the smaller sized, and have been with me for a very long time.

EJWash
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