Thread: Drawing Arcs (Ellipse)

Nice write-up. That might be usefull one day.
Thanks.
Graham.

Niki brilliant as usual

spring must be in the air and warming your shed a little

Xcellent - don't know where you get them [ideas] from but I like them - could have used it a while back when I was fiddling with string and nails to make a curve - not as easy and had some wobbly lines.

Thanks mate,
Bob

Good writeup & clear pics niki

I've done ovals in the past and all I used was a pencil, a peice of string and two nails.

I had to think back to high school maths... about the only thing I've used it for since!

Thank you so much

When I posted it on the Italian forum one of the guys noticed that...

I have a mistake...

The method to draw the second arc is incorrect...actually, I'm drawing two circles (or arcs) of the same radius or diameter and that, will never give me consistent width along the arc...

To get same width all along the arc, I had to change the circle diameter while still using the same center point for both circles...

Sorry for my mistake

Here are some new pictures for the correct way
niki

Very well explained Niki, I will print it out for future reference
les

Niki, nice to see you back, it seem that while it gets warmer where you are, it gets cooler here. Today it was a balmy 35degrees C instead of the normal 40+.

I like your simple way of scribing curves. I normally plot it from the computer and tile print, stick the pages together and then cut out the pattern and then trace to board and so on. Your way seems so simple.

I shall certainly file this away for the next curve.

Robert

Than you so much Les and Robert

Now, if only I could put my router bit instead of the chalk....but I don't think that it can be done...

Regards
niki

Niki,
I have seen a web article that described using your "compass" clamped to a router table top with a straight bit at the angle where your chalk goes. Two brads are driven into the workpiece and these ride against the legs of the compass. Unfortunately I can't find the link now but I thought it might have been on this forum or possibly one of the American ones.

It can be done Niki. I have a jig I made after seeing a commercially available one. It is a bit rough and ready but I am sure you could refine the idea in your own inimitable way. Here are a couple of pictures of it. It uses dovetail sliders for the motion and the arm pivots on top of each of the sliders. the centre can be screwed or held with double sided tape and the elipse is set by a combination of positioning the router along the arm or the width of the sliders.

Thank you so much

George
I would like to see this website if you can find it


Hi Mailee, nice to meet you here
I know the commercial one;
http://www.microfence.com/pages/Ellipse%20Jig.html
http://www.woodweb.com/knowledge_bas..._Ellipses.html

Mailee, as you know, I'm very bad in math so please tell me...

If I want to make an arc for a garden gate or alike....
I want the arc to be 2M (2000mm) long (between two poles - NOT Poles ), now...
You can make the 2M arc in many radiuses...
In my case (on the pics), I just measure the distance from the base line (the line connecting the nails) and the arc center without any calculations draw and...if I like it - ok....I don't like it - I move the center up or down till SWMBO says "that's it"...

With your jig (or the commercial) do you need some calculations or special settings to cut the same length of arc at different radiuses ?

Thank you
niki

Hello Niki and I am afraid my maths are as poor as yours if not worse. I usually just adjust the length of the arm for a larger radius and adjust the sliders until I have the correct ellipse. The wider apart the sliders are the flatter the ellipse is, if you can understand my meaning? Basically I just fiddle about with the jig until it scribes the ellipse I require. I do this by placing a pencil in front of the router before cutting anything. HTH.