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Thread: Grain direction of bookmatched top/back

  1. #1

    Default Grain direction of bookmatched top/back

    Hi, i'm currently on my first ukulele build, i had jointed and joined the backplate and top plate together before doing thicknessing (they were about 3mm thick at the time) and was planning on thicknessing (using a hand plane) after they were joined. There were a few scratches and dings on the "show" side of the walnut back so i decided to do the thicknessing on that side of the back plate. It was when i was planing around the centre when my plane dug into the grain and ripped Out a few substantial chunks out of the centre of the board. I realised that the grain of the 2 halves of the plate were running in opposite directions, making it incredibly difficult for me to thickness with a hand plane. Or at least in the way i'm using it.

    I'll be tossing the back and starting again but i would like to know of any way to avoid this problem. Do i thickness the plates before joining them? Or am i limited to sandpaper after joining? Or did i just screw up somehow since i can't seem to find anyone with the same problems as me on this or other forums and discussions.

    Any and all input is greatly appreciated, thanks guys.

  2. #2
    Join Date
    May 2015
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    You might try planing across the grain.

  3. #3
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    Dec 2008
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    The problem will increase if the runout is too great. Some runout can be handled by planing across but most important is an extremely sharp plane iron. Are you good with a scraper?
    Building blog - http://www.argapa.blogspot.com
    Music and atrocities - http://www.goodcopbadcop.se

  4. #4

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    I do have a scraper but i'm having difficulty sharpening it to an acceptable degree, i usually just take out dust and the occasional shaving. Any tips for getting a good edge on a scraper? Thanks

  5. #5
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    central CA
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    There are a bunch of sharpening videos on Youtube. I think Stewmac has one too.
    My Real name is Terry Harris

  6. #6
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    Apr 2009
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    New Zealand
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    Quote Originally Posted by TheHappyWombat View Post
    I do have a scraper but i'm having difficulty sharpening it to an acceptable degree, i usually just take out dust and the occasional shaving. Any tips for getting a good edge on a scraper? Thanks
    I file the edge flat then burnish it with a tungsten burnisher ( a nail punch works just as well ) to turn the edge over forming a hook which does the cutting. Lots of vids on Utube. Once you get the hang of it it is a quick and simple process.
    Kind Regards
    Dennis

    dpophotography@yahoo.co.nz
    Southern Cross Instruments
    New Zealand

  7. #7
    Join Date
    Mar 2012
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    Napa Valley
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    Try planing on a 45 degree angle off the grin you will have much better luck. And start saving your quarters for a thickness sander you can get a small 10-20 for $300 used.

  8. #8
    Join Date
    Oct 2014
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    [QUOTE=TheHappyWombat;2039384 i can't seem to find anyone with the same problems as me on this or other forums and discussions.[/QUOTE]

    What you are encountering is the perennial problem of thicknessing your timber. In my opinion, this is the most difficult part of the building process. Yes you can plane the plates and yes they are going to chip and tear out. My advice: get it reasonable close with a smoothing plane and take it down to final with a hand held orbital sander. Your aining for about 0.80 inch or so. Good luck

  9. #9
    Join Date
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    As mentioned by others above, many years ago my first guitars were made using the technique outlined in William Cumpianos book: Plane at 90 degrees and 45 degrees across the grain from both directions and follow up with planing with the grain runout in opposite directions for the two halves of the board, taking great care near the centre line not to run over it. Repeat the sequence as required. As you approach final thickness a sharp, well adjusted plane is ever more essential and I always skewed the cut (angle the plane across the direction of travel). Even then chipout was an ever present issue and I eventually bought a No.112 scraper plane for finishing rosewood.

    Thankfully an investment in a thickness sander means all this is now history!

    Just remembered the other Cumpiano tip - use a toothed blade for the cross grain cuts in particular. Then take off the ridges with the standard blade. This also helps maintain an even thickness. I had an old Stanley No 4 that was pretty useless in the conventional sense, so I ground teeth into the blade and kept it for that purpose. If you only have one plane it might be a tad wearying changing out the blade though! I never had to try hand thicknessing a ukulele top/back/sides set and since there will hardly be any room for clamping down, it doesn't sound like much fun! I suppose a vacuum clamping system is the answer?
    Last edited by Wildestcat; 02-06-2018 at 10:17 PM.
    Cheers
    Paul

  10. #10
    Join Date
    Jan 2016
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    24

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    First off make sure you have plane that is true, sharp & well tuned...I cannot stress how important this is!
    There are lots of youtube videos to help you do this. If you are just picking up a plane that you bought at a garage sale or even some of the cheaper brand new handplanes out there, they may not be flat enough. So if you have not seen to all that start there. You want it to be really sharp, the blade to be making a very light cut and even from side to side. Take the time and set it up right after each sharpening.

    I made a simple bench hook with a 1.8mm strip to hold my plate in place while thicknessing. I would then thickness each half in rotation until I was getting close to my target. Then I joined and finished with a scraper (or orbital sander if you cannot get a proper burr). Of course you have to be more precise with your join so as to make certain there is not a whole lot to take off. In other words make sure your join is flat and that there is enough meat to clean everything up.

    I did just fine thicknessing across the grain exclusively but I also am careful about not dipping towards the end and being very methodically even about everything. Take your passes with the plane at a slight angle across the grain, rotate, take your passes again and then do the same to the other half. Even strokes, take your time, check thickness often. I also found that I had better results by planing some off the other side as well as it help with the wood drying at an even rate and therefore not cup (but I live in the desert and things react quickly here). After you get it all done keep weight evenly across it to allow it to dry straight.....This is especially important if you have humidity swings. I sticker all my wood and place weights on them just to be sure.

    It is hard to describe all this in words but it is very doable and even enjoyable if you like this sort of thing. I just love the curls of wood coming off. It is so satisfying. Hardwoods are actually pretty easy.

    I sure hope this helps....Don't give up!

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