Refinishing ASW24

Removing gelcoat is a real bear, but it shouldn’t take that long! We use an electric DA, like RIDGID with 60 grit pad to remove 50% Down to where the underlying cloth starts to show. The remaining gelcoat is much softer. Works best on flat surfaces like the a stab.
Be very careful on concave surfaces like the underside of the elevator. If memory serves me, it should take something like 24 hours to completely strip a 15 meter bird.
Hope this helps,
JJ

On Monday, September 7, 2020 at 6:18:16 PM UTC-4, John Sinclair wrote:
Removing gelcoat is a real bear, but it shouldn’t take that long! We use an electric DA, like RIDGID with 60 grit pad to remove 50% Down to where the underlying cloth starts to show. The remaining gelcoat is much softer. Works best on flat surfaces like the a stab.
Be very careful on concave surfaces like the underside of the elevator. If memory serves me, it should take something like 24 hours to completely strip a 15 meter bird.
Hope this helps,
JJ
60 grit is like using Charmin on the underside! This thing laughs at 36 grit, and yes the electric tools have been used, Mirka 40 wet does a bit of removal.

On Monday, September 7, 2020 at 3:51:27 PM UTC-7, wrote:
On Monday, September 7, 2020 at 6:18:16 PM UTC-4, John Sinclair wrote:
Removing gelcoat is a real bear, but it shouldn’t take that long! We use an electric DA, like RIDGID with 60 grit pad to remove 50% Down to where the underlying cloth starts to show. The remaining gelcoat is much softer. Works best on flat surfaces like the a stab.
Be very careful on concave surfaces like the underside of the elevator. If memory serves me, it should take something like 24 hours to completely strip a 15 meter bird.
Hope this helps,
JJ
60 grit is like using Charmin on the underside! This thing laughs at 36 grit, and yes the electric tools have been used, Mirka 40 wet does a bit of removal.

We have found that 36 grit mostly rides on top, but 60 grit is fine enough to start removing the top hard coat and get down to the softer underlying stuff. Dual action (DA) is a must and it greatly reduces the risk of digging in.

On Monday, September 7, 2020 at 7:04:27 PM UTC-4, John Sinclair wrote:
On Monday, September 7, 2020 at 3:51:27 PM UTC-7, wrote:
On Monday, September 7, 2020 at 6:18:16 PM UTC-4, John Sinclair wrote:
Removing gelcoat is a real bear, but it shouldn’t take that long! We use an electric DA, like RIDGID with 60 grit pad to remove 50% Down to where the underlying cloth starts to show. The remaining gelcoat is much softer. Works best on flat surfaces like the a stab.
Be very careful on concave surfaces like the underside of the elevator. If memory serves me, it should take something like 24 hours to completely strip a 15 meter bird.
Hope this helps,
JJ
60 grit is like using Charmin on the underside! This thing laughs at 36 grit, and yes the electric tools have been used, Mirka 40 wet does a bit of removal.
We have found that 36 grit mostly rides on top, but 60 grit is fine enough to start removing the top hard coat and get down to the softer underlying stuff. Dual action (DA) is a must and it greatly reduces the risk of digging in.
I have used many Abranet grit pads and custom made blocks. The best so far is the Mirka 80 with the cushion pad beneath the Adranet pad, this is used in a very slow rotation of the sander, speed seems to cut less than a slower rotation. Speed also increases your risk of gouging and also heats up the surface much to my dislike. Fiberglass Supply Depot in Ft. Pierce , Florida has the best supply of abrasive supplies and tools one would ever need, check them out online, great people and huge supplies of products. Bob

On Tuesday, September 8, 2020 at 2:19:07 AM UTC-4, wrote:
On Monday, September 7, 2020 at 7:04:27 PM UTC-4, John Sinclair wrote:
On Monday, September 7, 2020 at 3:51:27 PM UTC-7, wrote:
On Monday, September 7, 2020 at 6:18:16 PM UTC-4, John Sinclair wrote:
Removing gelcoat is a real bear, but it shouldn’t take that long! We use an electric DA, like RIDGID with 60 grit pad to remove 50% Down to where the underlying cloth starts to show. The remaining gelcoat is much softer. Works best on flat surfaces like the a stab.
Be very careful on concave surfaces like the underside of the elevator. If memory serves me, it should take something like 24 hours to completely strip a 15 meter bird.
Hope this helps,
JJ
60 grit is like using Charmin on the underside! This thing laughs at 36 grit, and yes the electric tools have been used, Mirka 40 wet does a bit of removal.
We have found that 36 grit mostly rides on top, but 60 grit is fine enough to start removing the top hard coat and get down to the softer underlying stuff. Dual action (DA) is a must and it greatly reduces the risk of digging in.
I have used many Abranet grit pads and custom made blocks. The best so far is the Mirka 80 with the cushion pad beneath the Adranet pad, this is used in a very slow rotation of the sander, speed seems to cut less than a slower rotation. Speed also increases your risk of gouging and also heats up the surface much to my dislike. Fiberglass Supply Depot in Ft. Pierce , Florida has the best supply of abrasive supplies and tools one would ever need, check them out online, great people and huge supplies of products. Bob

80 grit has more rocks in contact and, from my experience, gives a quicker and better result. I use random orbital and Mirka Gold 80 grit sticky back paper with soft backing pad.
"there must be an easier way".
Nope
Stick with it Bob.
UH

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
JB

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

On Wednesday, September 9, 2020 at 2:29:22 PM UTC-4, 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
JB
Chip, the therapeutic part of this comes from me not listening to the wife complaining about not being able to fly her glider. The educational part derives from my approach to spending more time doing things than required, but they are done correctly. The rewarding part of this ordeal is that I know P1 would be happy to see the old girl looking great again.