# Need Assistance With Sliding Compound Miter Saw - Small Planter Box



## LGLDSR73 (Jul 24, 2013)

At the onset I apologize if this is the incorrect forum to post this….please feel free to move at will.

I am relatively new to woodworking with a recently acquired a DeWalt DWS-779 Sliding Compound Miter Saw. I've gone through an unknown quantity of hours with scrap wood and have a good deal down pat. Scrap wood is all gone at this point.

My wife recently asked me to make her a small Planter Box for her flowers and in scouring the Web I've basically come across designs that produce a product that is simply too large. I.e., at minimum 6'L x 3'H x 2+' W.

I am simply looking to make a Planter box that is perhaps 2'L x 7"'H x ~7" W. Will likely make it out of Cedar. I'd like the ends beveled ~30 degrees (and sides?) to add some design to it. Compound cuts where possible would be ideal.

While I've found some plans the authors have made assumptions that I'll know whether or not to lay the board Horizontal or Vertical for any given cut. Or use vague instructions such as "Swivel the blade 30 degrees". Miter or Bevel? Flip the board after first cut or change saw direction from left to right?

In other words, I need guidance…"Compound Miter Saws for Dummies". I've watched more videos on YouTube than I can recall.

Any assistance would really, really be greatly appreciated. I'm retired (yeah, right) and we're raising our three Grandchildren so money is tight. Every new board I screw up is money out the window. Not good.

Thank you,

Lyman


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## Loren (May 30, 2008)

Do you have a clue how to mark out joints? you can draw what you want on the wood and if there's material left on the ends make test cuts to see if they're at the angles you want your final cut to be. When comprehension of the geometry involved in woodworking fails, I go to the drawing board. If you work things out on paper a few times they start to make more sense.

I would expect "swivel" would apply to the protractor at the base of the saw controlling miter angle.


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## MadMark (Jun 3, 2014)

30° is *steep*. Try 5° instead.

Sketch the desired object (freehand ok). Using that as a basis sketch end and side showing angles and bevels. You only need one end and one side since object is (or should be) symmetrical.

Now you can compute angles and such or try to draw it to scale. If you draw it accurately you can use a bevel gauge to pull the angle off the drawing and transfer it to the wood/saw for cutting.

Computing saw angle setting requires calculator and trig. Side angle swings from 0° (vertical) to 90° (horizontal).

Layout tapers first. Don't cut *anything * until all angles and bevels have been computed as SCMS cuts *both at once.*

Start at, say, 5° from vertical. Base width is set. Measure from one corner of board at 5° to opposite side and mark. Measure over base width and mark again. Using bevel gauge measure across board at 5° away from end and mark. This defines one edge.

Since angles are reciprocal end cut on 1st piece is same-same as 1st cut on 2nd piece. Measure over base width from last mark and again mark 5° angle across board away from end. At this point you should have three 5° lines crossing the board that will yield both ends. Layout for sides is same.

Now you have to bevel as well as taper. Bevel needs trig. Sine function goes from 0 at 0° to 1 at 90°. Cosine is inverse starting at 1 at 0° and reducing to 0 at 90°. Bevel angle on rectangle (90° sides) is 45° expanding to 90° (no bevel) when flat. (This is really hard to explain without drawings!) So 1/2 the bevel angle (2-1/2°) winds up being *added* to the cut. So instead of a 45° you'ld cut 47-1/2°.

Edges (ideally) are beveled as well as corners. Math is same but subtract 5° from 90°. These are rips that need a table saw to cut, not an SCMS.

I *think* this has been explained correctly, but anyone feel free to check/correct my math.

The angles are independent of the widths/lengths so build a small version out of scrap first to validate everything.


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## RichT (Oct 14, 2016)

If you're planning to simply attach the end pieces to the front and back pieces, then you'll be cutting the front and back at 30º on both ends (swivel the arm). You'll want to cut the top and bottom of the side pieces at 30º as well, so they are flat. That would be a bevel cut with the saw blade tilted.

If you want to do a miter joint in the corners, then you'll be doing compound cuts on the ends of the front and back pieces, with the saw swiveled 30º and the blade tilted 45º. The sides would have a 90º cut with a 45º bevel.

If you want all four sides to be at 30º, then you'd do that compound cut on all four corners.


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## LGLDSR73 (Jul 24, 2013)

Everyone, thank you for your invaluable input and the time spent. It's a learning curve on this end.

Rich, thanks for hitting the nail on the head!

Best,

Lyman


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## RichT (Oct 14, 2016)

> Rich, thanks for hitting the nail on the head!
> 
> - LGLDSR73


Happy to help.


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## cebfish (Jan 15, 2011)

google compound angle calculator


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## LGLDSR73 (Jul 24, 2013)

> google compound angle calculator
> 
> - cebfish


Will do, thank you!


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## cebfish (Jan 15, 2011)

jansson.us/jcompoud.html save to bookmark bar it comes in handy all the time for me. compound angle calculator. sorry I should have put this in my reply last time


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## LGLDSR73 (Jul 24, 2013)

> jansson.us/jcompoud.html save to bookmark bar it comes in handy all the time for me. compound angle calculator. sorry I should have put this in my reply last time
> 
> - cebfish


No problem! Thank you for taking the time to add that information!

Best,

Lyman


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