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How far to sand

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Old 01-28-2019, 06:04 PM
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Ozzy37
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Default How far to sand

So my 4 * 40 got some hangar rash on the last 3 inches of the horizontal stab. Gonna replace the horizontal/vertical stabs plus the elevator and rudder. Question is how far down into lite ply that forms the base that the horizontal stab rests on should I have to sand to get back to a glue able surface. Originally I glued it with 30 minute epoxy? Any guess out there?
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Old 01-28-2019, 06:48 PM
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speedracerntrixie
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I would suggest removing all the old epoxy. A heat gun and an xacto chisel blade works really well for epoxy removal.
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Old 01-29-2019, 04:54 AM
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I rarely use epoxy in the tail and when/if I do, I use it sparingly. Adds too much weight. But since you already have it in there, just take the epoxy down to the top layer of the wood. There will still be epoxy in the wood grain but that's OK. The important thing is the platform is smooth, straight and properly aligned. Then use epoxy sparingly when gluing the new piece in. And if possible, clamp it.
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Old 01-29-2019, 07:25 AM
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+1 on Appowner's comment. Two things to look for are a stable surface for gluing and proper alignment of the part. Getting back to the top layer of wood will do that. Sanding with a coarser grit may be your friend here since if the wood grain is sealed with old epoxy this will provide more tooth for the glue to bind to. At times where this has been a concern I have even stippled the gluing surface with a pin to make small holes for the glue to wick into.
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Old 01-29-2019, 07:58 AM
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Originally Posted by speedracerntrixie View Post
I would suggest removing all the old epoxy. A heat gun and an xacto chisel blade works really well for epoxy removal.
I second this suggestion. I have used heat to release epoxy joints on several aircraft rebuild/restorations. I will use either a heat gun or covering iron to warm the epoxy releasing the glue joint. A quick wipe with a paper towel and alcohol usually leaves a glue ready surface.
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