Lower Left Wing - Wing Walk Plywood Glued On

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I expected more spring back after forming the plywood.  The wing rib capstrips had more spring back.  In this first picture the plywood is just laying on the rib.  The lightest clamping holds it in place so nailing the plywood down should get a good glue bond.

The first step is to layout where glue goes on the plywood.  This is easily done with the plywood clamped in place. 

I use a mechanical pencil all day, every day, but for tracing around the wood members a regular wood lead pencil works better.  You do need a pencil sharpener.

You need to layout the topside as well to know where you can place nails.  It can all be done with a straight edge.

Because I bought plywood too short to do the walk in one piece I need to make a 10:1 splice.  I'm locating it at the aft spar, where the bend in the plywood is the least.  It also works out nice for clamping the joint since the aft spar is 1 1/4" wide and a 10:1 splice in 1/8" plywood is also 1 1/4" wide.
The plywood was cut 12" wide and I want an accurate joint. The first step is to square up the sander table and level the saw table to support the end of the plywood, 48" long.

I placed a straight edge along the face of the belt sander and drew an extension line on the saw table.  I placed the table where I could conveniently make a 3" rise to a 30" run for my 10:1 angle.  I drew a line for the angle and clamped a guide block on the back of the line for the plywood to rest against controlling the angle.  You've got to love math and geometry.

The start point is marked on the sander table for locating the edge of the plywood.

I drew a 1 1/4" line on the plywood as a check on how even the sanding is across the board.

I cut a piece of 2x4 as a push block and square it to the sander so it can rest on the table while gently pushing on the plywood. 

The long edge needs to be sanded smooth.  The wood is being sanded very thin and slight bumps in the block will affect the straightness of the finished grind.

To keep the plywood tight against the angle guide I clamped a block on the table.

The block just has to be snug.

You can see it held the plywood against the guide just fine.

A very gentile touch is needed.  As you grind you want to watch the edge of the plywood and put slightly more pressure at either end to keep it straight across the board.

The grind is finished when the edge is just feathered.  I cut the aft section of plywood to length after grinding and fitting it all on the wing so I could experiment with this grinding process if needed

After doing the aft portion I used the same process for the forward section.

I did the direction of the splice so the aft portion is on the bottom and glues to the spar.  The forward section is on top.  The idea was that the aft portion is in tension if you step on it so it needs a firm grip to the rear spar to help take the tension load.  The aft end of the forward section just needs to stay down.  Hopefully the joint is well enough done that it also carries some of the tension load.  I'm also going to mark most of the aft portion as no step to reduce the chance of someone breaking it with a heavy step.

The 2 pieces were clamped in place so the aft portion could be marked for cutting to length.

To clamp the joint while the glue sets I've ground a slight curve on a piece of 2x2.  The ends are about 1/32" below the center so the center will be pressing tight on the joint while clamping near the ends.  You can see that if you clamp one end the other end has about a 1/8" gap.

Glue must be applied to both the frame and the plywood.  I mixed up 24 grams of glue for each section.  It worked out about perfect.  I did 2 separate batches so it would be as fresh as possible for each.

I used my long and short spring clamps along the trailing edge where I couldn't nail.

The clamp block at the joint worked well.  I got a very even amount of glue squeezed out along the length of the joint, indicating even pressure.

Every where I could 3/8" nails were paced about 3/4" to 1" apart.  Using the Great Neck Brad Nail Driver really speeded up this process.  I worked from the trailing edge forward nailing.  As I nailed I placed clamps at each end of the support members to assure the plywood was tight.

The nail pattern at the leading edge blocks is tighter and I clamped the edge to help assure it stayed tight while the glue set.  I know,  the wood was a perfect fit so why all the stress, that's just me.

This was one of the most satisfying projects on the wings.  It really went well.  It took about 2 1/2 hours to do all of this.  Once the glue is set I have a little trimming on the edge of the plywood.  I must not have had the rib perfectly flat.  It's very close.

I'm really happy with this.

Wing Rib Gusset Glueing & Nailing

Now that the Christmas rush is over in the embroidery shop I'm back to building wing ribs while working on other projects. I've realized there are some things which could use some more explanation.


When mixing the glue I've found that mixing by volume vs by weight is the easiest. I've also found that the amount of glue needed to put all the gussets on 2 sides of a rib is exactly the amount using 4 teaspoons of Liquid Resin with 3 teaspoons of Powdered Catalyst. I've found that clear plastic drink cups work great. Recently I got some shallow clear plastic pill dispensing cups, they're even better, harder to spill. I use a metal teaspoon since it's easy to level the catalyst with a popsicle stick. It's also easier to wash the metal spoon clean after measuring each ingedient to make sure the unused portion in the can is not contaminated. One of the nice things with Resorcinol is that it washes up with water until it cures and becomes waterproof.



I measure the catalyst into the drink cup and the resin into the pill cup. The drink cup is easier to poor from slowly while mixing in the pill cup. The 3rd cup in the picture is a gauge to double check whether I've put in the correct amount of resin.



I reuse the cup for the Catalyst so I've drawn a line on it as a double check in case I get interrupted while measuring.

That doesn't work as well with the Resin since I use that cup to mix the glue. Since the cups are clear I have a cup which I can set the Resin cup into to check that the correct amount of resin was measured. I also have a line on it for the volume after mixing which is less than the 7 teaspoon total.












I've made 2 little videos to help explain how to install gussets.

The first covers applying the glue, just to the areas needed.





The second covers using the nailer.




These methods seem simple and obvious but they reduced my time to build assemble and nail both sides of a rib from 2-1/2 hours to 1-1/2 hours. With so many ribs to build it's a big savings over holding the nails with pliers and using the tack hammer.

Great Neck Magnetic Brad & Nail Driver

I found this nail driver on line from a tip I picked up at the antique fly-in in Iowa this year. It's the Great Neck model BD1. I was not impressed when I first got it because I expected it to be spring operated like a one handed center punch. After some experimenting and building a rib with it I realized some minor improvements would make it into a great tool. It's primary attribute was a price of less than $5.00, but now I will use it for all my rib building, etc.

The first change was to buy a 1-1/4" chair foot at Lowes. I mixed a little epoxy and filled the foot about 1/4 full. Then I stood the handle of the driver in it and left it to dry over night. Next I used my belt sander to grind off the ridges to make a nice palm face. The last thing was to rough up the end and install a short piece of heat shrink tubing to allow me to more easilly slide the sleeve down if I want to see if I have a nail in the holder.



Using it is easy. I have a shallow bowl of nails I can pick up with my right hand, to the right of the gusset I'm nailing. Yes I'm right handed and not even sure I could pick up a 1/4" nail with my left hand. With the nailer in my left hand I drop the nail head first into the magetic holder.







Next position the tip of the nailer where you want the nail. I've marked my jig with a red felt marker at each nail location. It helps me know where the nails go and as a quality check when I'm done to verify I did not miss one, or serveral as the case may be. Now hold the nailer vertically and gently press down until the nail contacts the gusset.







A light slap with your right hand on top of the nailer will drive it home. If you leave one a little high just finish it with a tack hammer. When I'm done nailing I run my finger over every nail. Any that feel high I touch up with the tack hammer.

This thing is way better than needle nose pliers and a tack hammer.