Tear Down and Clean Up

Wednesday 27th February 2008 2 hours

Tore down the spray booth and cleaned up the shop.

I dismantled the spray booth and stowed it away. By this stage, a lot of the seams are coming apart. The duct tape turns out not to be the best solution.

I have got Dorothy to promise to sew all the seams before I put it back up again. I will take that opportunity to revise the design of the door. I want to have a long zipper to close the new door. I am looking at large frame tents where one long continuous double-ended zipper goes across the top, down one side and across the bottom. The fabric of the door then falls naturally to one side and out of the way. Only one hand is needed for the job, which is great if you are carrying a part or the spray gun in the other. Hopefully, that job will not be needed for several months until the wings are ready to be primed.

I gave the shop a good clean while I was at it. The camera has quite a wide angle lens that makes it look a bit bigger. In fact, I am worried about how I am going to build a fuse in here.

Dorothy and I are off to Madrid for a few days to celebrate our birthdays, which both fall around now. We have never been there before so we are looking forward to it.

Primer Off and On

Tuesday 26th February 2008 2hr 30min

Etched and primeed EET-602B trim servo mounts. Removed primer from trailing edge location on right elevator and rudder left and right skins

These are the very last empennage parts to be primed. Boy am I glad to get to this stage. The spray booth takes up a lot of space, making working on the benches and moving around to my storage bins and saw, scotchbrite wheel, etc very tiresome. Also, I have not found this priming very easy. I need to go over to Frank Vogels to get some training in the use of his products before I take on priming the wing parts.

The Dremel wire brushes proved to be better quality and were much slower to wear out than my Chinese originals. Still, I went through 4 of them while doing the right elevator and right and left rudder skin trailing edges. Still, its done now. I should have done more thinking before hand about where primer should go and where it should not.

Sorry, no photos this evening

Plates and Gussets

Monday 25th February 2008 2 hrs 45 min

Match-drilled E921 gusset to E-907 elevator trim sapr and E905 left elevator root rib. Deburredn adn edge-prepped it. Match-drilled ETT-602B trim servo mounts to the E-616PP cover plate. Deburred and dimpled holes in all three parts. Dimpled E-616PP cover plate for #6 attachment screws. Removed primer from left elevator skin where trailing edge wedge will be glued.

Setting up the trim servo mounts took quite a while and a lot of care to make sure the orientation and placement were correct. Some builders mention difficulty in getting the cover plate into its position when the trim servo is mounted on it. I tried it out and I believe it will go in okay. The clecos holding the mounts and servo in place make it hard to be sure but if there is a problem, I will fix it later on.

Dimpling the inspection plate introduces compound curves into the cover plate, which I simply bent out by hand. Back riveting the mounts onto it will also help flatten it.

I used the 'Dremel' (actually a cheap Chinese import copy) to remove primer from the inside trailing edges of the left elevator skin where the trailing edge wedge will go. it was easy enough and gives a good result but I went through 3 wire brush bits in less than 3 feet of edge and I still have about 12 feet to go. Hopefully, actual Dremel brand brushes will be of a higher quality.

These trailing edge wedges can't be primed as they will be glued with tank sealer before riveting. That makes them the only non-alclad part of the emp that will not be primed. I haven't seen any discussion of this on the various forums. Presumably, as the top and bottom faces are covered in sealer, it is only the leading edge that is exposed. I must research this a bit more.

On the Edge

Sunday 24th Feb 6 hours

Re-assembled the left and right elevators, match-drilled left and right trailing edge wedges and countersunk them.

The wedge for the rudder is pre-punched but those for the elevators are not. To ensure accuracy, I assembled the elevators one at a time. I cut a straight piece of 4 X 2 into which I could drill and cleco the trailing edges. I left each elevator resting on the clecos, which raises the piece 2 inches off the bench. the depth of the elevator at the leading edge is 3.25 inches so I cut the timber to 3 and 5 eights (2" for the clecos plus half the depth at the leading edge) This meant that the chord of the elevator was horizontal and I could drill perpendicular to the chord by simply holding the drill in the vertical. This method of drilling the trailing edge into a timber is demonstrated by George Orndorff in his video and differs from the method in the Vans plans, which call for a length of aluminium angle to be match-drilled and clecoed to the upper skin trailing edge to keep it straight. As long as the timber is perfectly straight (mine is), the Orndorff method is certainly easier. I found that you need to be careful about alignment of the top and bottom skins for this drilling stage. There is still quite a lot of flexibility in the structures even with all the other parts clecoed together. This flexibility dissapears when the trailing edges of the skins are fixed together but any twist in the structure at the time the trailing edge is match-drilled will be made permanent when it is riveted. From this point of view, it might be better to have the elevator skins rivetted to the bottom of the spar and ribs and lying flat on a flat table (preferably weighted) as the Vans instructions suggest. However, I am afraid that some of the flexibility would already be lost by the riveting up to that point, resulting in stresses being fixed into the structure when the trailing edge is pulled into place. By matchdrilling while the elevators are assembled with clecos, all the joints can still move to allow the skin trailing edes to assume their correct position. I felt the elevators looked perfectly happy resting on their clecos and the whole structure seemed straight and well-aligned so I think this method is better.

I removed the wedges after this process and deburred and countersunk them on both sides to take the dimples in the skins. To make this easier, I planed an angle into the edge of a piece of scrap timber to match the angle of the wedge. I then drilled and clecoed the wedge to this edge so that the top surface of the wedge was horizontal. This makes it easier to countersink the holes perfectly. As the timber was quite short, I moved the wedges along, replacing the clecos and doing about 6 holes at a time. I also deburred and dimpled the trailing edges of the skins. The wedges are supposed to be bonded in place with tank sealer before being rivetted as a means of ensuring a straight edge that won't distort during riveting. I have now realised that I forgot to mask off the area where the wedges go so these areas have primer on them. It's back to the Dremel to clean the primer off these areas. I will have to clamp a metal straight edge in place to mask off the primer that needs to stay undisturbed.

Un-masked

Saturday 23rd February 2008

Cleaned, etched and primed replacement VS-706 and trim tab skin. Sanded runs from trim tab horn parts and re-primed. Countersunk rudder trailing edge wedge, cleaned and etched it. Assembled left elevator for match-drilling of its trailing edge wedge.

Quite a lay-off - over seven weeks in total. There were a number of factors involved. Firstly I thought I would wait for the new parts to arrive before continuing with the priming operation. I want to finish with priming entirely and get the spray booth out of the way before I begin final assembly. When the parts showed up two weeks later, the trim tab skin was damaged. It had a wrinkle in the middle of the top trailing edge caused by someone putting a heavy weight on the middle of the long box in which it came while it was supported at both ends, thereby bending the box and the part. I immediately rang Vans to ask if the part was insured. However, they simply said "we better send you a new one then". Granted, the part is only $22 dollars but the shipping would be closer to twice that. Anyway, the gesture is very much appreciated. Also, I now have another part on which to practice those end-tab bends and make sure my technique is spot on before tackling the part for the third and final time.

After about another two weeks passed with no sign of the new replacement trim tab. I rang Vans to find that they had omitted to send it to me. Presumably, since it was a freebie, it did not go into the conventional order system and this caused the disconnect. They apologised and assured me it would be sent straight away. Finally, after another 2 weeks (about 6 weeks now in total), another trim tab showed up and this one is perfect.

Another delay was caused by a vacancy in a buy-to-let apartment we have down in the north inner-city. This was bought nine years ago and really needed to be re-decorated from top to bottom. We thought we could blitz the job in one weekend but it actually took three weekends with lots of evenings in between.

This time, I decided to prime the inside of the trim tab skin before doing any bending as access will be very difficult once the trailing edge bend is completed and the end tabs bent into place. I masked off the locations for the foam ribs and scuffed them with sandpaper as per instructions. This time, I had the clever idea of just cutting the blue vinyl from these locations and using the remaining blue vinyl as masking - worked reasonably well. However, I went quickly into screw-up mode by forgetting to mask the scuffed areas when it came to the 1st coat of primer. So I now had to mask off the primed areas and use a dremel with a wire brush bit to remove the primer. This left a lot of dirt on the primer. When I washed it off, some of the primer came with it so I gave it 2 extra coats after I got it cleaned and dried. All of this bother could so easily have been avoided.

The only parts left unprimed at this stage are the E-921 gusset, the mounting rails for the trim tab motor, the trim tab hinge and the three trailing edge wedges. The instructions call for these wedges to be match-drilled after much of the riveting has been done but I don't want to wait until that stage so I have decided to go ahead and match-drill them now.