Friday, October 31, 2014

Firewall Forward Parts Repainted

Wednesday, prior to the plunge in temperatures, decided it would be a good idea to revisit the firewall forward parts that were painted earlier in the summer with VHT white gloss ceramic engine paint.  Frequent readers of the Blog may recall I was less than satisfied at the results. Decided to sand down the imperfections with 320 grit wet or dry sandpaper and have another go at it.
Parts in the bin ready for recoating with paint after sanding and cleaning with solvent.

The red paint I sprayed on the spar pins the other day was also VHT paint and the spray nozzle from that can seemed to spray somewhat better than the spray cans I used previously … so the nozzle was removed from the red can and was used to re-spray the parts. I still contend the spray nozzles supplied with the VHT paint are far less than stellar, but this time a better finish was obtainable. Overall the finish is still not as nice as I was hoping for, but far better than it was, so I won’t powder coat the parts. Because of the falling temperatures, a second light was added to the bottom of the paint drying box to generate more heat. This will likely be the end of spray painting for the year.
Firewall forward parts re-sprayed with VHT gloss white ceramic paint and placed in the drying box.

Tuesday, October 28, 2014

Canopy Frame & Parts Painted with JetFlex

Monday the weather held out long enough to provide a good day for painting canopy components with JetFlex interior paint. Prior to painting, decided it best to finish work on the C-1203A&B attach angles. The C-1203A&B attach angles require fluting to conform to the curve of the canopy frame. The object of the fluting is to insure the inside edge of the attach angles follows the bow of the canopy frame. The flutes were placed between the previously drilled rivet holes and did their job of curving the attach angles to match the shape of the canopy frame. The flutes need to be placed upward so the attach angles will remain sitting flat on the canopy frame.
About to place the first flute in the F-1203A forward attach angle. Note the curve of the canopy frame on the left … this is the amount of curve the fluting needs to induce in the attach angle.

Starting at the forward portion of the F-1203A attach angle a flute is placed where the attach angle no longer parallels the edge of the canopy frame. The fluting will pull the metal inward bringing the edge of the attach angle back in alignment with the inside edge of the canopy frame. This process is repeated placing flutes between the remaining rivet holes until the attach angle precisely follows the curve of the canopy frame.
After fluting, the F-1203A forward attach angle conforms perfectly to the inside curve of the canopy frame. The area requiring fluting is the span between my fingers.

The same process was repeated for the F-1203B aft attach angle for the left side and then again for both the F-1203A&B attach angles for the right side of the canopy frame.
F-1203A&B forward and aft attach angles fluted and ready for JetFlex paint.

After fluting the F-1203A&B forward and aft attach angles was completed, the canopy frame and all the remaining small canopy parts were cleaned with Acetone and subsequently sprayed with JetFlex interior paint.

Sunday, October 26, 2014

Routing Of AOA Tubing Finalized

The parts primed with Akzo Friday dried nicely in the heat box. One thing I wanted to do with the wing’s spar pins is spray paint them with a bright red paint … since they are indeed a safety item. Prior to priming the spar pins, the portion of each spar pin that goes through the spar pin bushings was masked off with painters tape … so it was an easy task to spray a little red paint onto the handles over the Akzo primer.
Spar pins painted bright red and placed in the heated cardboard box to dry.

Attacking the routing of the Angle Of Attack tubing ... over the last couple of weeks a lot of thought went into finalizing the routing of the Tygon tubing for the Angle Of Attack indicator. For those builders installing the Tygon tubing for the AOA, there is plenty of room to route the tubing down the center tunnel to the tail cone unless you have installed a static air tube, as is the case with the DOG Aviation RV-12. Unfortunately, with the static air tubing installed, there is really no room left over for the Tygon tubing. An alternative routing for the AOA tubing without going through the now very crowded center tunnel all the way into the tail cone was necessary.  My main concerns were for serviceability and not drilling additional holes …. the later I finally gave up on.

Without going through the center tunnel, running the tubing through outboard lightening holes in the bulkheads was the next choice … but that would require drilling supports to keep the tubing off the metal. So since drilling was required anyway, decided to just drill a hole in two of the three bulkheads and place the holes adjacent to the outboard lightening holes … the third bulkhead already had a tooling hole which was the right size (3/16") for a small SB-178-2 snap bushing.  Another consideration was to support the Tygon tubing without using wire ties because once the side skins are riveted in place, there will no longer be access to cut wire ties ... and therefore no way to replace the Tygon tubing should that become necessary in the future.
Drilling a #40 lead hole into the center channel’s forward bulkhead below and inboard from the lightening hole.

The #40 hole was stepped up to 3/16" to accommodate the SB187-2 snap bushings. The center channel’s aft bulkhead, seen to the immediate right in the above photo, was also drilled to 3/16" to accept a SB187-2 snap bushing. The holes were deburred and the snap bushings installed. This will provide a straight run from where the wing mates to the fuselage to the tail cone. A wire was fished through the snap bushing in the center channel's forward bulkhead and under the seat pan to the area of the electrical connector. The tubing was slipped over the wire and carefully pulled back through the snap bushing. Of note: A special 3/16" threaded collet was necessary to be able to use the angle drill with a 3/16" drill bit … and even so, the drill bit shank required being mostly removed with a cutting wheel so there would be enough clearance to get the angle drill between the center channel's bulkheads.
Mike lending assistance by feeding the Tygon AOA tubing underneath the seat pans as I carefully pull the wire back through the snap bushing bringing the Tygon tubing along with it.

The Tygon tubing for the AOA was pulled under the baggage flooring and there was an existing 3/16" tooling hole in the bulkhead that supports the aft wing spar that was used for the third and final snap bushing. The bulkhead that had the existing hole can be seen just in front of my right hand in the photo below.
The Tygon tubing run for the AOA can be seen just above my fingers.

At the baggage bulkhead the Tygon tubing was routed through the large lightening hole. I think this will be OK because after the tail cone is mounted to the fuselage, believe the wires, pitot and static air tubing will be above the lower level of the baggage bulkhead lightening hole allowing the Tygon AOA tubing to ride on top of the bundle. If it turns out that the bundle ends up being below the lightening hole, it will be easy to drill a hole in the baggage bulkhead and add another SB187-2 snap bushing for the AOA tubing.
The tools used to drill the bulkheads for the Tygon AOA tubing. The 3/16" collet and shortened 3/16" drill bit is attached to the 90 degree drill attachment. The snap bushings are SB187-2.

Mike and I did verify that just in case it was necessary to replace the Tygon tubing at some point in the future, it could be easily replaced. A #52 drill bit proved ideal to use for splicing the ends of the tubing together. Slipping the ends of the tubing over a #52 drill bit provided enough friction that the tubing would not easily pull apart, yet it did not increase the diameter of the tubing … so the tubing was easily pulled through the grommets.

Return from the future: Decided to edit this post for those interested in the AOA routing to the left wing so the information would be mostly in one place. The Tygon tubing for the AOA was routed to behind the blue electrical connector on the left side of the fuselage. A 3/16" hole was drilled into the F-000032 side cover just aft of the blue electrical connector so a SB-178-2 grommet could be installed. The Tygon tubing passes through the grommet and receives a Luer Lock quick disconnect. The AOA hardware including the Luer Lock quick disconnects was talked about in the following post:

A 3/16" hole was drilled into the F-00032 side cover aft of the blue electrical connector and a tiny SB-178-2 grommet was inserted so the Tygon tubing would not ride on the sharp edge of an aluminum hole. The one half of the Luer Lock quick disconnect can be seen here.
Tygon tubing at the left wing root with Luer Lock quick disconnect attached along with a protective cap. After this photo was taken, a wire tie was used to support the tubing in place of the pull string it is currently on.

Saturday, October 25, 2014

Backup UMA Steam Gauges Arrived

Yesterday, the weather was warm enough and winds light enough to finish priming the unprimed parts from the last primer session ... plus the parts made within the last week or so. The temperatures were at the low end of the Akzo recommended temperature range, so a light bulb was placed at the bottom of a large tall cardboard box to make a warm place for the wet parts to dry. Three rows of wire were strung from side to side to hang the parts from …. this worked out quite well and got the temperature up to 78 degrees inside the box.
A tall cardboard box with an incandescent bulb at the bottom was used to make a warm paint drying box.
While attending AirVenture at Oshkosh two years ago, I spotted a company that makes 2 1/4" instrument gauges for experimental aircraft ... UMA Instruments. I spoke with Sharon Rathburn, a UMA sales and customer service representative, and discovered one of the nice touches UMA is willing to provide a builder is marking the airspeed indicator’s face with correctly colored speed tapes. UMA silk screens the speed tapes onto the face of the instrument as opposed to using vinyl sticky tape as some companies do ... which can lift and peal over the years.

This year while at AirVenture, I decided to look for Sharon so backup steam gauges could be purchased for the DOG Aviation RV-12 … ultimately a 2 1/4" altimeter and airspeed indicator was ordered. A page was copied from the RV-12 POH manual which showed the operating speeds and Sharon wrote down all the information so the correct speeds could be marked onto the airspeed instrument's face.  Some would say this is total overkill for a small daytime VFR aircraft and to a certain degree, I would tend to agree. However, having a background in electronics I know displays can go lights out at any moment and typically when it the least convenient ... so the DOG Aviation RV-12 WILL have backup.
The UMD Instruments 2 1/4" altimeter and airspeed indicator with custom silk screened speed tapes.
I’m very pleased at how nice the silk screening looks on the airspeed indicator. Clicking on the above photo to enlarge it will reveal the nice silk screen job on the face of the airspeed  instrument. UMA did a nice job and the customer service was great … thanks Sharon.

Sunday, October 19, 2014

C-1203B Angles Drilled & AP Servo Pushrods Fabricated

After verifying both C-1203B aft attach angles were bent to 90 degrees, the same procedure was used again to drill both. One angle was marked and center punched then both C-1203B aft attach angles were clamped back to back and a tiny lead holes were drilled then enlarged to #40.
Clamping both C-1203B aft attach angles back to back for simultaneous drilling.
Both the C-1203B aft attach angles were clamped back to back and drilled to #40.
Both the C-1203B aft attach angles after being drilled to #40.

Fortunately, I remembered seeing another pushrod tube in a bag of autopilot servo parts which will also need priming … so went ahead in the plans to investigate. The tube is used to fabricate two pushrods for the autopilot servos. The F-1291 roll servo pushrod is cut to 3 1/2" and the F-1292 pitch servo pushrod is cut to 4 1/2". As with the control stick pushrods, the tubes are drilled to #3 at both ends and tapped to 1/4-28 threads. Figured may as well go ahead and fabricate the autopilot servo pushrods now while the shop is set up for making pushrods so they can get airbrushed with primer as well.
The F-1291 and F-1292 autopilot roll and pitch servo push rods after being cut to the proper length.

When drilling the F-1291 and F-1292 servo push rods, the same method was used as covered in the previous post using one layer of duct tape placed over the tubing prior to clamping in the V blocks and using the drill press to drill out the tubing at both ends to #3. If you have a lathe it is the tool of choice here.

While tapping the F-1291 and F-1292 push rods … to prevent twisting in the vice, some duct tape was wrapped around the tube and a small vice grip was used to prevent the tube from twisting.
Tapping the F-1292 autopilot pitch servo pushrod to 1/4-28 threads. Duct tape under the small vice grip prevented scoring and the vice grip prevented the tube from twisting in the vice.

Now that there are a bunch of small parts to prime, am hoping the weather cooperates long enough to break out the airbrush and spray some primer. We have had rain and high winds the last couple of days plus the daily high temps here are at or slightly below the minimum recommended temperatures for the Akzo primer. To get around the temperature issue, am planning on using a large cardboard box and placing a light bulb inside to generate some heat while the primer cures.

C-1203A Attach Angles & F-1264 Remade

As mentioned in a previous post, the C-1203A forward attach angles were reordered because at the time the rivet holes were drilled to #30 instead of # 40. After ordering replacement pieces, looking further forward in the plans, it was discovered ordering new parts was really not necessary because the rivet holes are eventually get drilled out to # 30 after some fluting to match the angle of the canopy frame. Since the parts were already ordered, decided to go ahead and remake them anyway.

After verifying both C-1203A angles were bent to 90 degrees the same procedure was used again to drill them. One angle was marked and center punched then both C-1203A attach angles were clamped back to back and tiny lead holes were drilled then enlarged to #40.
Both the replacement C-1203A attach angles were clamped back to back and drilled to #40.

Originally when drilling the F-1264 control stick push rods each pushrod spun a little in my clamping fixture when the drill bit was deep inside the tubes. This placed small score marks on the outer surface of the tubes which I dressed smooth. Then while tapping the 1/4-28 threads each tube twisted in the vice as well, creating additional scoring. Since I was making a parts order decided to order the tubing and remake these pieces again and strive for better craftsmanship. This was really not necessary but it bothered me … more of a pride in workmanship based on available tools knowing I could do better. Admittedly, making any of the RV-12 pushrods that require internal threads is a perfect job for a lathe … period.  The drilling can be spot on and the tap can be held perfectly centered with the centering cone while making the threads.  Sadly, the DOG Aviation shop is without lathe, so one has to make due.

When drilling the replacement F-1264 control stick push rods, the same method was used as covered in a previous post with the exception of one layer of duct tape placed over the tubing prior to clamping in the V blocks. The V blocks sunk into the duct tape and the adhesive prevented the tubes from spinning while being drilled out to #3.  Worked great!
Drilling an F-1264 control stick push rod to #3 on the drill press … if one zooms in on the photo the single layer of duct tape can be seen protruding above the V blocks. This prevented the tube from spinning when the drill bit got deep inside the tube.

While tapping the F-1264 control stick push rods … to prevent twisting in the vice, some duct tape was wrapped around the tube and a small vice grip was used to prevent the tube from twisting. This worked much better and resulted in the tubing not twisting while tapping both ends of the tube for 1/4-28 threads.

Friday, October 10, 2014

Clever At Twice The Price

After a long week away from the RV-12 project due to feeling under the weather, work resumed for what turned out to be a short and depressing work session.  The primer sprayed last week looked OK considering a considerable portion of the spraying was done after dusk.
WD-1219 canopy frame and some miscellaneous parts after priming.

Of the few small pieces that were not sprayed (because of running out of mixed primer), the C-1203A&B forward and aft attach angles required drilling ... so thought it would be best to get that task out of the way prior to mixing up some primer and using the airbrush to spray primer on the small handful of remaining parts.  Plus, by having holes drilled into the attach angles, it makes it easier to secure them with wire while spraying so they won’t fly around.

The short side of the C-1203A forward attach angles receive 9 equally spaced holes which take a fair amount of time to mark if one is striving for accuracy. Thought I would be clever and save time by only marking one of the two C-1203A forward attach angles … figuring since the holes are evenly spaced, the second C-1203A forward attach angle could be drilled at the same time if the two pieces were clamped back to back. A flat metal plate was used to insure the parts were flat and Cleco clamps were used to hold positioning for drilling.

After clamping the two C-1203A forward attach angles back to back, a small drill bit was used to drill lead holes in the two angles. With the two angles clamped back to back, only one angle had to be marked for hole locations but both could be drilled simultaneously saving time. Once a lead hole was made it was enlarged to #40 then onto #30. Discovered I should have stopped when the holes were at #40.
Drilling a lead hole through both of the C-1203A forward attach angles.

Being clever and drilling both C-1203A forward attach angles at the some time worked out great … however, a costly mistake was made in that the holes are supposed to be drilled to #40 and NOT #30. So although the idea to drill both angles simultaneously was good, it resulted in two pieces being trashed when I enlarged all the holes to #30. Guess I can’t complain too much, fortunately throughout the project the screw ups thus far have been minimal and the replacement parts inexpensive … but it sucks to have to wait for the two replacements.
Once lead holes were drilled, the holes were enlarged to #40, then out of habit onto #30. Note: Do not make the same mistake as I did by drilling these holes to #30 … they need to be drilled to #40.

After discovering I needed to order two replacement C-1203A forward attach angles, all motivation was lost and it was time to leave the scene of the crime.

Saturday, October 4, 2014

Remaining Finishing Kit Parts Primed

Although not having made any posts for a few days, progress was made on the RV-12. A few more small parts were fabricated and the canopy frame along with the majority of remaining finishing kit parts (except fuel tank components) were primed. By the time all the parts were prepped and ready for priming, it was early Thursday evening and actually dark by the time the job was finished. Fortunately, all the priming was completed well ahead of the cold snap which now has DOG Aviation in its cold wet grip.
After filing the rough edges down, a 1" Scotch-Brite wheel was used to finish deburring of the WE-1219 canopy frame. The borrowed generator worked great powering the air compressor but it is noisy … hence the ear protection. Thanks again for the generator Pat & George.

The two C-1210 outside canopy lift handles were fabricated from angle stock. Care must be taken because a left and right need to be fabricated as mirror images of each other. Each lift handle receives one #30 hole the second hole will be match drilled later to the canopy frame.
Running a C-1210 canopy lift handle through the band saw.
C-1210-L&R canopy lift handles fabricated and ready for primer.
WE-1219 canopy frame and a host of other miscellaneous parts ready for Acetone cleaning, a Scotch-Brite scrubbing followed by another Acetone cleaning in preparation for priming.

Sadly, I ran out of mixed primer before all the parts were sprayed … so there are a couple of small parts remaining to prime. I’ll prime the remaining few pieces later with the airbrush and let the parts dry in a box with an incandescent light to keep the temperature warm as the parts dry.