On Tuesday, September 15, 2020 at 11:00:45 PM UTC-4, 2G wrote:
On Tuesday, September 15, 2020 at 4:49:45 PM UTC-7, wrote:
On Monday, September 14, 2020 at 5:57:17 PM UTC-4, wrote:
On Thursday, September 10, 2020 at 8:14:05 PM UTC-4, wrote:
On Thursday, September 10, 2020 at 7:22:57 PM UTC-4, wrote:
On Wednesday, September 9, 2020 at 5:08:11 PM UTC-4, Chip Bearden wrote:
On Wednesday, September 9, 2020 at 3:50:55 PM UTC-4, John Sinclair wrote:
On Wednesday, September 9, 2020 at 11:29:22 AM UTC-7, Chip Bearden wrote:
What UH said. He allowed me to supply a huge number of hours of work when we refinished my ASW 24 a few years ago. With two guys in the workshop (sometimes three), it was actually enjoyable sanding and talking soaring. But it takes a long time. I'm sure there's an easier way but I haven't talked to anyone over the years who's found it.

I recall there were spots--areas, actually--especially on the fuselage, where the gel coat just seemed a lot harder to sand than in other spots. And it was unrelated to whether it was over a seam where you would expect to encounter a slightly different gel coat/hardener ratio. Maybe it was where the factory had patched defects in the gel coat coming out of the molds?

One other thing--and I'll defer to UH and JJ on this--is that I wouldn't have started with the stab and elevators. The elevators and ailerons were the touchiest surfaces for me to sand, both removing old gel coat and finish sanding PU. The narrow chord combined with slightly concave surfaces meant it was really easy to sand through. And, of course, due to weight/mass balance considerations, we couldn't just spray on a whole bunch of stuff and sand some of it off. The sharper leading edge of the stab and the tight compound curves around the fairing for the rudder are a little fussy, also.

I had done some contouring/profiling on wings in previous years but was otherwise a rookie. If I were approaching it again, I would do it the way UH did. The first winter we did the fuselage (sans horizontal tail). The surfaces were big and relatively easy to sand and the consequences of slight imperfections were smaller. The compound curves, especially on the forward fuselage, were less of a problem than I had thought. In all, it was a good project on which to learn some technique.

The next winter we did the wings and tail. We were very careful with the wings because I think I have a "good" '24 and didn't want to have that little edge disappear in the dust. So we pulled leading edge templates from one wing and used those when applying the filler/primer. UH also wielded the grinder when we did the "B" leading edge mod and then we used templates to profile the outer portion of the wings where that applied (the leading edge is less sharp on the ASW 24B on the outer wings).

Sanding the big surfaces--fuselage and wings--went faster than I thought. My biggest mistake was not wanting to swap in new sandpaper often enough. It was still cutting but just not as fast. UH will laugh or be moved to tears for all the times he encouraged me to change paper and I declined.

It was a therapeutic, educational, and rewarding experience.. And the glider still goes great and looks like new. We even did a few upgrades: e.g., UH's fuselage vent and filling in the factory water dump ports on the wings.

Chip Bearden
Roger on changing sanding pads often .........they’re expensive, but nothing compared to what the labor is costing. Also a good idea to weigh the controls before starting and check and record the trailing edge weight (balance). Easy on the prime and paint on all control surfaces. I have had to sand off and repaint controls that didn’t check out after painting. Use a respirator when spraying AU! If you smell the stuff, your killing brain cells!
Enjoy!
JJ
Agreed, JJ, although UH might argue that my labor cost was pretty low. Or high, depending on whether he still recalls what a PIA I was worrying about tinkering with the airfoil.

We took it VERY easy on the control surfaces and actually came out a little to the good, IIRC, when measured against factory specs. The downside was more than one sand through. IIRC, he finally finished off the last elevator and winglet when I was at my real job one day rather than take a chance on another sanding/spraying/sanding cycle with me on the job! My hat is off to you guys who do/have done this full time. It's a huge amount of work and a few seconds of inattention can result in hours more.

UH did the spraying but I hung around to watch a bit. Respirator, of course, and he was wearing the full positive pressure treatment. I also wore a pretty effective dust mask when dry sanding (old gel coat). I had one left over that I tossed in my toolbox. When the 'Rona first hit, I went downstairs and checked: sure enough, N95. I haven't been able to find any more since then, though.

My one physical effect was "trigger finger" from clutching sandpaper on rubber sanding blocks with all the finish sanding I did. It took over six months to go away from the fingers of both hands.

JB
Well the end is in sight, I am spraying the final coats of primer and sanding down to a super smooth and blemish free surface prior to spraying paint. I should be finished this weekend and work toward balancing the elevators and then on to sealing and a final check. I am trying to find the balance specs on the 24, if anyone has them it would be greatly appreciated. Bob
Elevator Mass- .64 to .79 kg
Elevator moment- 1.4 to 1.8 kg-cm
Section 5.4 of maintenance manual
UH
I did a pre paint balance evaluation and things looked very good. I concluded that by applying the paint I will be within the good margin. I did spray the topcoat of paint and tomorrow I will re check to determine my precise number. Thanks for the info. Bob
I am right on the numbers, these elevators turned out beautiful, maybe the best paint job that I have ever done. My friend at the gliderport told me they shined like a diamond in a goat's ass, wow, that must be really good, just wait until they are polished. Bob
What paint and equipment did you use?

Tom
Tom, I did things a bit differently, I have restored many antique cars and have worked with many paint and filler systems. Acrylic urethane is the only way to go, because of many properties of the chemistry and the ability to repair, buff, and durability. I do like epoxy primer as my second coat, a good filler prior to the epoxy primer is a must, it really helps the finish process. Once you get down to the fiberglass , after the removal of all the gel coat it would benefit you to seal the surface prior to the epoxy primer, I found this out the hard way.
The process continues until you have bloody fingers from sanding and sanding and sanding, I am very critical of my work, so I might just expect more than some. Spraying Acrylic Urethane is not difficult, just time consuming and once yo have learned the tricks of the paint you will develop your own application methods that work well for you.
My preference for paint is Nason, 2k single stage, it if from Axalta, or previously Dupont. Don't get too hung up on different paints, there are only about three manufactures that make them all. Transtar 2 in 1 primer filler is a great product, works well and compatible with most all paints.
Mika abrasives are very good, I even used them wet with great results. I tried many combinations of abrasives and found that each has a special need. Do not be afraid to tackle your own projects, you may be surprised at your finished product. Bob