Making a 70.6 cut on miter saw

[mjmwallace]

Can't quite wrap my brain on how to tackle this.

I could make a template on my TS with my Wixey and then use it on the miter.

The miter only has 1 degree increments.

Suggestions?

MJ

[Robert Bonomi]

Just the 'obvious' one -- use a shim to wedge the stock a an angle to the 'reference plane' (presumably the _back_ of the miter bed), such that it is "mumble point 6" degrees off 'true'. Then set the miter saw to the appropriate number of whole degrees, so that the comination gives the desired 70.6 angle.

Note: depending on which way you swing the blade, you may need to set the shim wedge angle to "mumble point 4" degrees.

[Ed Pawlowski]

Set it for 71 and give it a tap, or the left handed version is to set it to

70 and tap the other side. 1/10th of a degree is important for a moon shot, but I doubt you're going to tell it on anything in wood. What is the humidity today? Tomorrow?

[Lew Hodgett]

--------------------------- Any reason to limit yourself to the table and miter saws?

Consider the following:

tan70.6 = 2.8396 or 2.84 for wood working purposes.

Lay out a triangle using trig function above with a vertical of 2.84 and a horizontal of 1.0.

Strike a line connecting the two points (hypotenuse) then cut proud of this line with a hand saw (circular, saber, etc), then follow up with a straight edge clamped in place and a router with a pattern bit.

You now have a triangle with 70.6 degrees as one internal angle.

Use triangle as a gauge to set angle needed.

Lew

[Chris Friesen]

Some more options:

1) Lay out the angle using geometry, set a bevel gauge to it, use that to set the saw.

2) Take a bevel gauge, set it to 70.6 using the wixey and your tablesaw top. Use the bevel gauge to set the saw.

3) If your stock isn't too wide you could stand it on edge and use the bevel angle and your wixey.

4) Lay the saw on its back and zero out the wixey on the fence, then use it to set the angle.

5) Buy an angle gauge. $5 for a plastic one, $25 for a digital one.

Chris

[Nova]

At 70.6 degrees halfway between 70 and 71 would be close enough for me.

[Leon]

Put your wood on the mitersaw 90 degrees to normal, adjust miter setting to

19.4 degrees.

[Swingman]

Bingo!

Or, graphically speaking:

[Lew Hodgett]

Keeps life simple.

Time to get a beer.

Lew

[Swingman]

No beer until you take the time to make the "70.6 triangle" first, which is apparently not that easy for some, according to the OP.

[Lew Hodgett]

--------------------------------- You could always layout the 70.6 line on a sled, then tack in a cleat on the line.

Simple fast, but doesn't leave a permanet record if you need to repeat the process down the road as a triangle does.

A $10 scientific calculator is in the same category as a dial vernier caliper in the shop IMHO.

Both are very useful.

Lew

[mjmwallace]

Want to thank all of you who responded to my question.

After consideration, I've decided that the "close enough" effort (half way between 70 and 71, with a SLIGHT bump to 70) is good for me.

As much as I would love to deal with a geometry question, my math interests are more towards the theoretical these days (Riemann Zeta Function anyone?), which can cause many hours of brain freeze.

It's interesting that a set of plans would have such an odd angle to cut, when no tool that I know of, would allow you to make a precision cut like 70.6 degrees.

Hmm,

MJ

[Swingman]

Depends upon the size of your project. 1/10 degree of angle will put you around 1/64+, at 12"; 3/64*" off at 24"; and 5/64+" at 4'; mas or menas.

That could be unacceptable for some projects.

I routinely use my digital angle gauge and the table saw to cut angles to .1 degrees, cut a reference angle in a piece of scrap, and use it to set up any other tool, miter saw, etc.

Or, you can set a bevel gauge to the angle of the table saw blade/reference piece and transfer it wherever.

We all know it's woodworking, but it never hurts to endeavor to be as precise as possible at every step because error becomes cumulative down the road and around the corners.

Attention to detail is the difference between mediocrity and supremacy.

[Lew Hodgett]

---------------------------------------- Simple, the answer is 1.

The only challenge is to define the units.

BTW, use trigonometry not plane geometry if you truly want to minimize errors.

Lew

[Nonny]

Bull. . . something between 65 and 75 degrees plus Bondo works well for me.

[Swingman]

When the sun's over the yardarm, there is such a thing as close enough.

[Morris Dovey]

Are you sure we wouldn't be better off using SketchUp?

;-)

[Lew Hodgett]

-------------------------------------

I specialize in SketchDown.

Lew

[Tom Dacon]

You don't consider an accurate protracter a tool?

Tom

[blueman]

If you solve the Hilbert problem, I will trust that you also know basic plane geometry & trig... ;)