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Avoiding rough spots when sanding down a body

Discussion in 'Tele Home Depot' started by newuser1, Oct 8, 2017.

  1. newuser1

    newuser1 Tele-Meister

    Age:
    46
    202
    Mar 1, 2017
    Toronto
    I usually sand down my bodies down to the line using oscillating spindle sander, instead of routing the outline. I use this sander:

    https://www.lowes.ca/benchtop-sande...VBWSGCh0w6gQeEAYYAiABEgJKSfD_BwE&gclsrc=aw.ds

    While I'm generally happy with the results I get, I'm trying to improve my work, and avoid rough spots on the outline of the body. Here is a poplar body I sanded yesterday and I have several rough spots after sanding it down. I tried sanding them with a flat sanding block with 180 grit but the roughness remains, no matter how long do I sand it for. I know from experience now that such imperfections will remain visible after finishing the guitar and I would still be able to feel the roughness of those spots through the paint. How do I avoid those while using the OSS and how can I fix the ones I have in my finish right now?

    IMG_1315.JPG IMG_1316.JPG IMG_1317.JPG
     

  2. R. Stratenstein

    R. Stratenstein Doctor of Teleocity

    Aug 3, 2010
    Loganville, Ga.
    That's a puzzler. Are you sure your block is perfectly flat? Maybe try a cork block ( which I prefer), or hard rubber block, and be sure your strokes are perfectly parallel with the grain. Also try raising the grain with a damp cloth--let the wood dry, then try a finer grit, 220 or so. One of those shots looks to be transitional to end grain, and sometimes end grain needs even finer grit to flatten it out, although you shouldn't have to go any finer than 320 grit. I use quite a bit of poplar, and have not had this problem.
     
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  3. TRexF16

    TRexF16 Friend of Leo's

    Apr 4, 2011
    Tucson
    The second picture of the end of the horn shows a couple flats that make me feel like it has not been well hand sanded. Poplar has a reputation for being a "fuzzy" wood sometimes, but proper hand sanding with a backed piece of sandpaper should smooth off the spots you showed. Try sanding one direction only, like petting a cat along the flow of its hair, not against.
    BUT, you do need to get rid of those flats on the horn. Try "shoe shining" across the end of the horn to help even out the flats.

    As a last resort, just shoot some sanding sealer on the fuzzy spots and let is cure. Then sand it. Lather, rinse, repeat until it's to your liking.

    Good luck,
    Rex
     
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  4. newuser1

    newuser1 Tele-Meister

    Age:
    46
    202
    Mar 1, 2017
    Toronto
    Thanks, I'll follow your advice and report how it goes.

    Do you mean spray sanding sealer over the spots? All I can find here in Canada are these and they are not in a spray form:

    http://www.leevalley.com/en/wood/page.aspx?p=63843&cat=42942

    http://www.homehardware.ca/en/cat/search/_/N-2pqfZ67l/Ne-67n/Ntk-All_EN?Ntt=sanding+sealer
     

  5. RickyRicardo

    RickyRicardo Friend of Leo's

    Mar 27, 2012
    Calgary, Alberta
    The flat spots are easy to remove with a sanding block and 120 grit. Just follow the contour. A spindle sander is great for getting to the line but not for the final finish. It creates the flat spots and that's where the manual labor comes in. I spend a good hour hand sanding the edges before saying done.

    I use this sanding sealer as well as their lacquer:
    http://www.woodessence.com/Brite-Tone-Sanding-Sealer-P4370C117.aspx

    Really nice stuff and a great Canadian company to deal with. No affiliation.
     
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  6. guitarbuilder

    guitarbuilder Doctor of Teleocity Ad Free Member

    Mar 30, 2003
    Ontario County
    I use a belt sander for outside curves and the spindle sander for the inside curves. Really, I think one needs a flat surface for outside curves. Abrasive on a hard block or an orbital sander should clean it up pretty well. One trick you learn by doing this often is to keep the wood moving.
     
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  7. Maricopa

    Maricopa Friend of Leo's

    Age:
    51
    Feb 4, 2009
    Phx, AZ
    I avoid rough spots by making sure to sand all the guitar. HTHs.... :cool:
     
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  8. reddy2300

    reddy2300 TDPRI Member

    Age:
    48
    46
    Aug 25, 2017
    Dublin, Ohio
    I agree with finer grit and less pressure with a sanding block. And stabilizing the surface with any kind of lacquer or poly wouldn't hurt. Unless you're doing a translucent finish.

    I had the same problem on my current pine build and was able to smooth it up a bit with 220 and a block. (Yes, it took a while.) I did use a little Bondo spot putty and DupliColor automotive primer to fill the lower spots as this body is getting painted.
     
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  9. Vizcaster

    Vizcaster Friend of Leo's

    Sep 15, 2007
    Glen Head, NY
    How close to the line did you saw before sanding? The photos almost suggest that there's some grain tear-out there, which I didn't think was possible with a spindle sander but that might be happening with a coarse grit?
     
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  10. RogerC

    RogerC Poster Extraordinaire Vendor Member

    Mar 30, 2011
    Oklamerica

  11. cain74

    cain74 TDPRI Member

    56
    Feb 12, 2014
    Cincinnati, OH
    Have you tried a sharp card scraper?
     
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  12. R. Stratenstein

    R. Stratenstein Doctor of Teleocity

    Aug 3, 2010
    Loganville, Ga.
    This should work very well, provided you have a card scraper and you know how to use and sharpen it. The nature of the question makes me suspect not, though. However, developing card scraper skills is always a big plus for guitar building.
     
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  13. newuser1

    newuser1 Tele-Meister

    Age:
    46
    202
    Mar 1, 2017
    Toronto
    I tried 220 and while results are encouraging, by no means is this body ready to paint.

    I used jigsaw and cut roughly about 1/4" off the line. You are right there is a low spot that looks like tear out. The grit I used on my spindle sander is 80.

    Do you know of any commercial glue size products available in big box hardware stores?

    No idea what card scraper is.
     

  14. R. Stratenstein

    R. Stratenstein Doctor of Teleocity

    Aug 3, 2010
    Loganville, Ga.


    I'd try making my own.
    (use Elmer's white glue or common yellow carpenter's glue like Titebond I)
    From the article Roger posted


    Glue size is most commonly made of a watered-down, water-based, PVA adhesive. If you do plan to make your own, try something on the order of 10 parts (or a little less) water to one part white glue. Keep experimenting if this doesn't work out right (it will vary with species.


    Card scrapers are actually one of the more satisfying tools to master and use. Not that I have yet mastered it, but I occasionally get the planets to align, and it works well.

    :http://www.startwoodworking.com/post/how-use-card-scraper
     
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  15. mtorn

    mtorn Tele-Meister

    393
    Nov 29, 2016
    Portland, Oregon
    It's hard to make smooth outer curves using a spindle sander. They tend to dig in and make divots. It helps to move your workpiece around a lot, and to use the largest spindle you have, but a better tool would be a belt sander or a disc sander.

    If you don't have either (or even if you do), a good way to get a smooth arched surface is to use adhesive sandpaper on a bendable backer. Something like a scrap of pickguard plastic, or maybe some thin piece of wood, perhaps even some heavy cardboard.
    A sponge sanding block won't work as well, since it flexes in every direction, not just around the bends. A rigid block is better than none.
     
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  16. newuser1

    newuser1 Tele-Meister

    Age:
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    202
    Mar 1, 2017
    Toronto

    How do I apply the glue size?
     

  17. R. Stratenstein

    R. Stratenstein Doctor of Teleocity

    Aug 3, 2010
    Loganville, Ga.
    Brush it on lightly, but thoroughly around the "fuzzies". Let it dry well. The goal is to stiffen them a bit, so they don't lay down, but are cut by the sandpaper.
     
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  18. newuser1

    newuser1 Tele-Meister

    Age:
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    202
    Mar 1, 2017
    Toronto

  19. RogerC

    RogerC Poster Extraordinaire Vendor Member

    Mar 30, 2011
    Oklamerica
    If I remember right, we did our projects by pouring the mixture onto a towel and slathering over the entire surface. Let it dry overnight and sand back the next day. We did that process at least twice.
     
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  20. newuser1

    newuser1 Tele-Meister

    Age:
    46
    202
    Mar 1, 2017
    Toronto
    Thanks Roger,

    Will try that tonight, and then will try resanding it.
     

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