Need help with sanding

Discussion in 'Fiberglass and Composite Boat Building' started by Msalvatore47, Dec 15, 2009.

  1. Msalvatore47
    Joined: Oct 2009
    Posts: 6
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    Location: Texas

    Msalvatore47 Junior Member

    I own a Rigid 6" D.A. random orbital sander....electrical.
    question numero uno...
    1) Do i need to wet sand my boat? (i'm completely restoring this boat and it has alot of spider cracks)
    2)If i do need to can i do so with my currently owned sander?
    3)If i buy a pneumatic sander, how big of an air compressor do i need??
     
  2. Kay9
    Joined: Oct 2006
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    Location: Central Coast Oregon US.

    Kay9 1600T Master

    Your planning to re-shoot the Jel-coat then?

    I would think your 6" DA would be just fine.

    K9
     
  3. TeddyDiver
    Joined: Dec 2007
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    Location: Finland/Norway

    TeddyDiver Gollywobbler

    1. Depends what you going to put on the sanded surface. Check instructions..
    2. I'd rather wetsand by hand if the material ain't very hard.. allmost as fast and better quality
    3. Big.. atleast double the sander air consumption .
     
  4. alan white
    Joined: Mar 2007
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    Location: maine

    alan white Senior Member

    The random orbit sander will take you to 220 grit. Be thorough. Follow the R.O. with wet/dry by hand (some will recommend power-wet-sanding but I haven't tried it yet). You may go through 80 grit, 120,180,220,320,400,600. and 1000 grits but the surface you get is worth it. I'd guess about 6-8 sq ft per hour.
    Then machine compound. Spider webbing is too deep to remove. You have to live with it or redo the gelcoat.
     
  5. pescaloco
    Joined: Feb 2006
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    Location: so. california

    pescaloco Senior Member

    Yes you can wetsand with your electric. (you know water and electricity don't mix so be carefull) I use a spray bottle and mist the surface with water use a GFI cord or adapter)

    Use velcro backed sandpaper with no holes in it, if your sander has a dust collector try to block the port off. You can actually get some 5 or 6 inch wet paper at a higher quality tool supplier it is usually used for wet stone polishing I use 600 , 800, 1200.

    As for an air compressor, if you have the place to use it and plan on more restoration work it will be the best tool investment you ever make. I think a 60 gallon tank is bare min for running air tools. Sanders really eat up a lot of air and you end up overworking the compressor. 80 or 100 gallon tank would be prefered.

    Spider cracks have to ground or groved out completely, determine if they are just superficical cracks in the gelcoat or do they go deeper into the glass, either way they need to be removed. For the cracks you will need to use heavy paper and work out to fine like Allen and others have suggested.
     
  6. Msalvatore47
    Joined: Oct 2009
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    Location: Texas

    Msalvatore47 Junior Member

    thanks everyone. man i got myself into a real big hole with this thing and dont know how i'm gonna get it done by april.
     

  7. Herman
    Joined: Oct 2004
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    Location: The Netherlands

    Herman Senior Member

    Checking for spider cracks: Mix some ink in water (1:2), and wipe the surface. The ink will creep in the cracks, so they are better visible.

    There are also spray cans with a similar mixture in it. (might be easier)
     
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