Riveting Seat Backs – 1.5 hrs

Monday Oct 31, 2011

Since it has now been more than 48 hours since I painted the seat back parts and it has had time to cure I began riveting the seat backs tonight. Because of time limits I only riveted those I could do with the squeezer along the sides and the lower edge. I’ll have to set up a clamping system to shot the rest with the gun and a bucking bar tomorrow.

I wanted to put the universal heads on the front side for cosmetics and for a smoother surface for upholstery but after squeezing two rivets it was clear that the shop head was distorting the thin seat back material preventing a tight joint. So I drilled those two out and riveted them in the “correct” way with the universal head on the side of the thinner material. The joint closed right up. For the hinges I put the universal head on the hinge side because the hinge aluminum seems to be a softer alloy than the seat back.

Seat Brace Holes Cut – 4 hrs

Sunday Oct 30, 2011

Well I finally solved the problem of the wobbling hole cutter. I went to Ace Hardware and picked up a 2-1/4 inch bimetal hole saw and pilot drill. On the new drill press this thing cuts a clean hole in the seat brace in about 10 seconds. No more wild shaking and wobbling. Here you can see the first brace with one of the hole plugs that came out of it.

I cut the holes in the other brace in a few minutes and proceeded to deburr and scuff these parts for priming and painting. While I was at it I did the same for the two upper stringers on the aft fuselage and the triangular doubler plate for the upper aft skin.

More deburring and preping of the aft top skin to get it ready for priming inside along the rivet lines.

And just to finish up a detail that I skipped over weeks ago I riveted the F710 bulkhead to the aft deck.

Painted Seat Backs – 6 hrs

Saturday Oct 29, 2011

An optional feature of the seat back braces is four 2-1/4 inch holes to reduce weight. I’m all for light weight so I pulled out the hole cutter to get this job done but it did not start out too well.  I set the hole cutter for 2-1/4 inch but when I tried to drill out the hole the work piece shook all over the place. So after scoring a circle on the part I aborted and resorted to the manual method of drilling a ring of small holes, cutting out the core with a rotary tool, and grinding the ID out smooth with a sanding drum. Very tedious. That is one of eight holes.

Knowing that my drill press chuck has way too much runout that causes long drill bits to wobble quite a bit I assumed that was the major cause. So after a trip to Home Depot I came home with this new 10-inch Ryobi drill press.

Well this one definitely has less runout than the old delta drill press but I was disappointed to find that the hole cutter still shakes the part like crazy. Conclusion: my hole cutter from Harbor Freight is a piece of junk. Now I need a plan B and to decide whether I should take the Ryobi back or not.

So I moved on to other work on the seat backs. I drilled all holes to final size of #30.

Then I got to work preping parts for priming and painting. Here you can see some of the parts laid out in the paint booth after deburring, scuffing and cleaning.

I put a coat of Spray-Fill primer on first, then about a hour later I sprayed Jet-Flex. The weather was perfect today for painting; warm, calm and <15% humidity. Late in the day I riveted this little tunnel cover together from the finished parts.

I also cleco’d the seat backs together.

After dinner I deburred and removed vinyl from the top aft skin. This part will have some exposed surfaces inside the cabin so I will paint those areas also.

2nd Seat Back Assembled – 1.5 hrs

Tuesday Oct 25, 2011

Tonight  I finished up the adjustable back brace for the right seat. In this photo you can see I marked the flanges of the brace for trimming according to the dimensions on the drawing. The material is .040 aluminum and is too thick to use the snips so I just ground the material off using the belt sander. It only took about 10 minutes for each side.

Here you can see that I drilled the hinge to the brace and have mounted it up for a check of the fit. Looks good.

Now both seats are assembled but not quite done yet. I still need to drill all holes to final size (#30) and drill the lightening holes in the braces. My drill press is not up to this job because it has too much runout. When I insert a long drill bit or the hole cutter it wobbles like crazy. I tried to fix it but it seems to be a flaw in the chuck which is about $60 to replace. I either need a new drill press or a hole saw for 2-1/4 inch.

2nd Seat Back Catching Up – 2 hrs

Monday Oct 24, 2011

Unlike yesterday I took more photos of the assembly of the 2nd seat back. First I had to drill the hole pattern in the side rails. I had to lay that pattern out by hand on the first seat back but this time I could just match drill using the pattern drilled into the rails from the first seat. I just clamped them together back to back and transferred the hole pattern.

Then I aligned and clamped the side rails, lower hinge and lower angle piece to the seat back and drilled all the holes through the seat back. You can’t see the lower angle in this photo because it is on the back side of the seat below the hinge.

That put one hole through the lower hinge on each end. Then I took the hinge piece out and measured and marked all the holes between the two ends and drilled those. Then it was simple to cleco the hinge back to the side rails and drill all the other holes through the seat back and the lower angle.

Next I inserted the upper angle with the rounded corner and clamped it at each end. Then I flipped it over and match drilled through the side rails and the upper angle for the end holes. I took the upper hinge piece I cut to length earlier and aligned it relative to the sides and centered the hinge flange relative to the end holes.

I drilled the end holes first, then I took the upper hinge off the left seat back and transferred the hole pattern to this hinge.

That’s it for tonight. I still need to make the back adjustment brace and drill the rivet holes through the upper angle between the end holes.

One Seat Back Almost Done – 4 hrs

Sunday Oct 23, 2011

I am dragging a bit because I have other family business to attend to this weekend but I got a couple hours in early this morning and another couple of hours later in the afternoon. This seat back is taking longer than expected because none of the holes are pre-drilled and it takes time to measure and lay out the patterns accurately. But I got everything drilled and assembled on the left seat except for final drilling all holes for 1/8 inch rivets and cutting out the lightening holes in the back support brace. Sorry I didn’t take more pictures. I’ll try to fill in some of the blanks on the right seat back.

Finished Tunnel Cover, Building Seat Backs – 4 hrs

Saturday Oct 22, 2011

The tunnel cover plate is a bit tricky because it hangs out over the front end where it bends upward to lay flat on the front floor cover. If you add up the dimensions on the drawing for the lengths and the hole spacing it does not seem to add up correctly. I did not want to drill the holes in the cover only to find out the edge distances were not good so I started by bending the front edge up 1/4 inch per the dimensions on the drawing. Then I placed it on the brackets to see how it lined up. First I noticed that I had to squeeze the brackets together to get them to match the width of the cover – but apparently everybody else has to do that too so it’s not a big deal. I used a couple of clamps to hold them in place.

Then I made sure the cover was flush on the front flange and measured the positions for the holes. To my amazement the hole positions shown on the drawing work just fine as far as edge distance goes except the aft most holes. They were only 1/16 inch less than perfect so I just shifted those holes 1/16 forward to maintain edge distance. The aft edge of the plate extends about 1/8 inch beyond the brackets but that might be as designed. I’ll find out later when I put the flaps in but if not, I can trim that 1/8 off easily. I match drilled the holes through the cover and brackets. I still need to countersink the holes in the cover then these parts go into the pile to prep for priming and painting.

Then I went back to work on the seat backs where I had cut and trimmed the ends of the vertical stiffener angles. These angle overlap the lower hinge pieces and require notches .040 deep to lay flat. Some people use a vixen file for this but I used my belt sander. It cuts much faster than a file so I knocked these two out in about 20 minutes going slow to make sure I didn’t overshoot.  It’s not a clean as an end mill job but who has an end mill in the garage. Not me.

Next I cut two pieces of 3/4 x 3/4 x .063 angle to 16 inches as additional stiffeners for the left seat. One of these pieces needs to have the corner edge rounded to fit within the inside radius of the upper edge of the seat. Again I used the belt sander (an indispensable tool for this project) to knock off the corner and then I buffed it smooth using the scotch-brite wheel.

Started F-741 Tunnel Cover – 1.5 hrs

Friday Oct 21 ,2011

Tonight I started making the F-741 tunnel cover that fits right between the two seats. It starts with cutting a couple of pieces of Z-extrusion to length and trimming the ends to shape – one right and one left side. Then there are two holes on a flange of each part that are drilled for #8 screws. Gotta be careful measuring here because those holes are not match drilled and they need to line up with the nut plates in the seat ribs.

Then I installed the brackets temporarily on the seat ribs.

Then I began studying the plans for the cover plate. This one is a little tricky. I’ll have to study it more tomorrow.

Aft Seat Floors Riveted In – 1.5 hrs

Tuesday Oct 18, 2011

Lots of LP4-3 pop rivets! That’s how you rivet the Aft Seat Floors to the seat ribs. That’s what I did tonight. I also got the nutplates ready to rivet along the center tunnel but ran out of time before I could finish those.

Seat Hinges Riveted – 2 hrs

Monday Oct 17, 2011

The objective tonight was to get the hinges riveted onto the seat floors. When I looked at it closely I became convinced that I could really make a mess of this with the AN470AD4-4 universal head rivets, especially riveting solo. If you can’t bear down firmly on the gun it is easy to make smiles on the rivet heads. What I needed was a way to clamp down the seat floor rigidly so I could apply firm pressure against the rivet gun while I held and watched the bucking bar. Fortunately I had four large clamps so I clamped a piece of 2×4 to the work bench and then clamped the first seat floor to the 2×4 right next to the rivet line. That way I could push with firm pressure against the gun and the 2×4 on the other side gave me a shelf to put the bucking bar on to steady it. You can see the set up in the photo below. In this shot I have completed the first hinge piece and I am working on the second.

All done! It worked great. Not a single smile or mushed-up rivet head. That includes both seat floors for a total of 60 rivets. Tip: Put tape over the holes you don’t want to rivet. No, I didn’t rivet those holes in the heat of the moment but I could have very easily.

Then I dimpled the holes for the nutplates along the center tunnel in both the seat ribs and the seat floor pans and cleco’d the seat floors in place. These are ready to rivet in place “permanently”.