Two More Ways (Of 4!) to Draw Arcs

[@ericstreff5810]

Really helped me out on a portico job I’m doing with an arched ceiling

[@DirtFarmerJay]

Excellent! Glad to be of help. Best, DFJ

[@AnthonyDeGallery-lz2fq]

Very helpful tips. Thank you so much! And I appreciate the fact that you are very well spoken and speak very clearly in detail as well as the process is simplified !

[@DirtFarmerJay]

Glad to be a help.

[@richardsextro1627]

Thanks for putting this together. The first method you show (on the previous KZbin), using a flexible strip, like a metal ruler doesn't, in fact, make a true arc portion of a circle, so in some sense, it is not equivalent to the other three methods you discuss. It may be "close enough" in some uses, but I think the viewers should be cautioned that at large sagitta, it will be obviously different than a true circle arc. I think its a parabola, but I haven't worked out the math

[@richardsextro1627]

A quick additional note - I used the method described by John Thompson in his comment below for drawing an arc for the profile of some stretchers for a table I am making. And it works great and is very simple. It's essentially the same as the third method you demonstrate. All you need are two nails at the beginning and end of the chord and the height of the arc at the mid-point of the chord. The layout is two straight 'sticks' - one running from the top of the sagitta to one end of the chord and the other stick from the top to the other chord end. I drilled a hole through the stick where they overlapped and used a flat-head 1/4-20 bolt as the pivot. Once that angle is fixed by tightening the bolt, then you slide the assembly along the nails with a pencil at the point where the two sticks cross. A perfect arc segment of a circle. And now I have an adjustable 'arc maker' I can use for other projects.

[@DirtFarmerJay]

Richard, I really like the idea of an adjustable jig and the way you did it. Simple and effective. I'll give that a shot myself. Thanks for taking time to detail your approach. Best Regards, DFJ

[@robertpenoyer9998]

If running the two straightedges along each pair of nails strikes a circular arc, then using only 3 nails--the end points of the baseline and the top of the sagitta--to construct the straightedges will also strike a circular arc. Once the straightedges are built, remove the nail on the sagitta and simply run the straightedges along the end points to strike the arc.

[@squigglyverm]

This is very helpful thank you! :D

[@DirtFarmerJay]

Glad it was helpful! Keep watching squiggl. Best to you, DFJ

[@parkavenue6970]

What do I think? I am astounded! It is beautiful and amazing that such an effect, can be accomplished with training. Thank-you!

[@DirtFarmerJay]

You're very welcome. Best, DFJ

[@johnthompson1266]

An old master Carpenter taught me a slightly better way. Make the base line and mid point. Mark the height up from the mid point. Then with the two board against the end nails and cross at the midpoint secure the cross angle. Now the arc is trace with a pencil at the intersection. Just a little bit easier.

[@dicksargent3582]

I agree as a blacksmith I've used this method often for arches over gates and window grills. It's very similar to drawing circles with a framing square.

[@Robertoayon]

👏👏👏👏

[@DirtFarmerJay]

Glad to be of help!

[@TNtoolman]

Slick... Segment could be titled "The Arc of the Dirt Farmer"

[@DirtFarmerJay]

Love it. It would sound more classic that way... Best, DFJ

[@warrior4christ777]

The radius of you arc would be 24.14 inches if you to draw the whole circle risesq +1/4 arc sq ÷2× rise =24.14

[@doughambright9712]

I love what you did. Great geometry, but the term "tangent" does not belong in this discussion because a tangent is a line, in the same plane as a circle, which intersects the circle in only one place.

[@DirtFarmerJay]

Thanks, Doug. Preciseness matters. Thanks for the assist. Best, DFJ