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IndustryArena Forum > General Manufacturing Processes > Milling > best approach for contour on solid wood part
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  1. #1
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    best approach for contour on solid wood part

    I work in wood, typically oak, ash and walnut. I'm wondering how people generally approach a setup for a simple 2d contour in a thick piece of hardwood.

    For something like the part in the attached drawing I usually rough out the profile on a band saw leaving approximately 1/8" all around before milling the contour on the CNC (img option-1.jpg). I use side clamps on the part and program the machine to mill around them.

    The other option, option 2, would be to mill the part out of rectangular stock leaving in about a 1/2 an inch on the outer perimeter and tabs to hold the part, the same way you might approach cutting sheet stock.

    The reason I favour option 1 is much less waste material, I can cut my stock out very close to the final size. With option 2 I have to leave a 1/2" for my tool diameter and then another 1/2" extra to give something stiff enough for my clamps to hold on to, so nearly 2" wider and longer then necessary. In option 1 I can also make deeper cuts with an adaptive clearing method since I can approach the part from the side using only a percentage of the tool width. In option 2 I'm afraid to make cuts much deeper than 1/8" since I'm using the full width of the tool (3hp spindle).

    Is there any downsides to option 1, would it be typical to work this way, or is the other approach more widely used?

    A few things I wonder about it:
    I get some corners chipping especially the outer corner of the curved point in the example part. I slow down the feedrate as much as possible around corners but it often chips anyway. I read somewhere that having material on both sides of the tool can help this, is this true? In this case would option-2 be favourable?

    Secondly with option-2 is there a danger in having material on both sides of the tool once you get fairly deep in the stock. I worry something could snag once the tool is buried far down in the piece.

  2. #2
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    Re: best approach for contour on solid wood part

    I’m not a fan of clamps on small parts. Using them on large sheets is ok. My two methods are option 2 in a vice but you use more wood and the cam software has to have bridges.

    My other method is a 12 inch square block about 2” high with a 7/16-14 bolt in the middle that sticks up about 7/16 above the surface. You need to clear out the back of the block so you can turn the bolt with a wrench

    So you find a place where you can drill and tap 7/16-14 in the part and lock it down. I usually put machine origin on the bolt. Make sure tool path doesn’t go thru the origin. Route the part and cut the tapped hole out later. Stock can be minimal on all sides. Nest multiple parts and cut them at the same time if you like.


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  3. #3
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    Re: best approach for contour on solid wood part

    You can always drill and tap in the part. Then either leave it or fill it in with a dowel.


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  4. #4
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    Re: best approach for contour on solid wood part

    you have been using band saw for this purpose. what about other saw options like I found here. https://sawadviser.com/

  5. #5
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    Re: best approach for contour on solid wood part

    ok so what I did today was like the images attached.
    I placed two parts in one piece of stock and like in my first option mentioned I cut out the profile first on the band saw.
    I screwed them down the middle between the two parts and programmed the cnc to lift above the screws.

    This worked well. A part of my issue was that the the little side clamps tend to want to lift the part off the table, so the screws solved the problem.

    So I'm still wondering is this a generally acceptable approach? Is it more likely to chip the wood on the corners then the other approach which leaves stock on both sides of the tool?
    Or I guess in a broader sense is there any reason I shouldn't be setting up my stock this way, or roughing out the shape first?

    @Dean448 would you by chance have an image of your second setup with the 12" block?

  6. #6
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    Re: best approach for contour on solid wood part


    The machine bed has a bolt pattern used to hold the block. This is a sample part band sawed from a much thicker part. Then the two parts were sawn in half.
    There is a locator in the center of the bolt used to set origin. Very little clearance between the bolt threads and the block so the position doesn’t change much over multiple parts.
    Again I find this a convenient way to hold parts.


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  7. #7
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    Re: best approach for contour on solid wood part

    oh i see so you bolt it in from underneath?
    The four bolts on the outer perimeter are the ones you use to bolt down on the table?

  8. #8
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    Re: best approach for contour on solid wood part

    Yes. With one obstruction, and always at the origin, it’s a safer setup in the future. No random fasteners and suitable for wood gears.


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