After a short break, we picked up work again and made very good progress. If you review my sign-offs in the plans, it looks terribly scatter shot, but the logic is solid. As with the previous sections, the goal is to accomplish all final/match drilling, deburr, countersinking, and part shaping prior to priming so we can prime all at once.
Countersinking was accomplished on the E-01423L, R, & T trailing edges using the drill press and the Countersink Jig from Cleaveland Tools. The jig makes it very easy to get great results. The plans call for a tapered pilot on the #40 countersink to allow countersinking 90 deg. from the surface on each side of the trailing edges. I just used the bench grinder to shape the pilot.
Other countersink jobs are on the E-00907-1L Rear Spar where the forward half of the trim tab hinge attaches. Additionally, the E-01403 Trim Tab Spar gets countersinks on the forward flange for the aft trim tab hinge half.
Fabrication of the elevator trim tab pushrod was done by separating the parts with bandsaw, then shaping with bench grinder fine wheel and scotchbrite wheel. This makes parts E-01401A-L, E-01401B, and E-01401R. Parts L and R get countersinks on the exterior sides for double-flush riveting to form the pushrod. Riveting will be done after priming.
The other fabrication is the Trim Tab Horns which is accomplished by trimming E-917 and E-918 to conform with specifications on page 09-12. I used hand shears to accomplish the initial cut. Parts were clecoe'd and clamped together for shaping to final dimension with Scotchbrite wheel.
The Trim Tab closeout tabs were dimpled and final drilled using a #33 drill.
To get ready for priming accomplished Steps on 09-13 and 09-15 which call for marking positions of Trim Tab Ribs and Trailing Edge Ribs. The plans then specify use of 150 grit Aluminum Oxide sandpaper to scuff the rib locations to prep for future bonding with tank sealant. Parts scuffed are E-1408 Trim Tab Skin, E-01405 Trim Tab Spar, E-00901B and E-00900B Skins, E-00907-1L and E-00907-1R Spars.
Trailing edges of the skins are also scuffed to prep for taping of the trailing edges prior to double-flush riveting.
Finally, after scuffing those areas, they are all masked to protect them during priming.
Following those items we cleaned up all the deburring not already done and scuffed all the parts for priming using red Scotchbrite pads.
All the parts were then wiped clean with occasional scotchbrite to get rid of aluminum oxide as well as any other contaminants prior to priming.
NOTE: Parts are handled with urethane gloves from this point to preclude any skin oils getting on surfaces. Also, final cleaning was done just prior to prime to preclude formation of aluminum oxide on parts which would prevent good bonding with the primer wash (again, we used Sherwin Williams P60G2 Primer Wash and R7K44 Primer Catalyst Reducer). Proportion was 2 parts Reducer to 1 part Primer Wash.
Priming was done with HVLP paint gun. I got better results this time by paying attention to the pressure, but I'm going to get a regulator to go at the gun since the compressor regulator just doesn't adjust fine enough to get consistent results. It's fine now with the Primer Wash, but I will want better control down the road since I do plan to do interior prime/paint in the fuselage and cockpit myself.