FHB Logo Facebook LinkedIn Email Pinterest Twitter X Instagram Tiktok YouTube Plus Icon Close Icon Navigation Search Icon Navigation Search Icon Arrow Down Icon Video Guide Icon Article Guide Icon Modal Close Icon Guide Search Icon Skip to content
Subscribe
Log In
  • How-To
  • Design
  • Tools & Materials
  • Restoration
  • Videos
  • Blogs
  • Forum
  • Magazine
  • Members
  • FHB House
  • Podcast
Log In
Tips & Techniques

A Simple Jig to Draw an Ellipse

Issue 204
  • X
  • facebook
  • linkedin
  • pinterest
  • email
  • add to favorites Log in or Sign up to save your favorite articles

Arched openings add a nice touch to a doorway, an alcove, or even a piece of built-in furniture. Architects and builders typically choose the easy-to-draw, equal-rise- and-run section of a circle for this application. Just swing an arc, and be done with it. But sometimes an arc doesn’t look right because the curve wants a softer transition to the intersecting wall. That’s when you need the harder-to-draw unequal-rise-run ellipse. The drawing shows a simple way to solve this layout problem.

Start by measuring the baseline. For an arch at the end of a hallway, for example, the baseline is the distance between the walls. Divide this number in half to get the run of the ellipse. Next, determine the height of the arch in relation to its intersection with the wall. That’s the rise of the ellipse. On a sheet of plywood, lay out the baseline, run, and rise of the ellipse, as shown in the drawing. Now drive 10d finish nails at points A, B, and C. Next, square a line from point B the distance of the rise to find point D. Drive a nail into it. Now take two strips of plywood, overlap them as shown in the drawing, and nail them together so that they are in contact with the neighboring nails. Remove the nail at point D.

To draw the ellipse, place a pencil at the intersection of the two strips, and slowly slide the strips, always in contact with the remaining nails, as you move the pencil from point A to point C. Repeat from point A to point B to scribe a perfect ellipse.

Watch Chuck Miller demonstrate how to draw an ellipse.

Click here to enlarge the illustration.

David Kalin, Kaneohe, HI

Edited and Illustrated by Charles Miller

From Fine Homebuilding #204

Sign up for the Fine Homebuilding Tip of the Day and get daily tips and special offers delivered to your inbox.

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters
×

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

New Feature

Fine Homebuilding Forums

Ask questions, offer advice, and share your work

  • X
  • facebook
  • linkedin
  • pinterest
  • email
  • add to favorites Log in or Sign up to save your favorite articles

View Comments

  1. George1234 | Aug 24, 2016 08:09pm | #1

    Great tip and a great video link demonstrating the process. Another not so elaborate method is three nails and a piece of lattice on edge. Two end points and the rise and you're good to go. This is useful for long arches you might find on cornice assemblies.

  2. Suburbanguy | Nov 08, 2018 07:14pm | #2

    Not a true ellipse. Much, much easier to simply use the string method. You can use math (an "a", "b", "c", and an equation), like I taught my students, OR...
    The length of the string is twice the width of the hall. Put a nail at the top of the ellipse. Now put the string around this nail and one finger on each hand (forming a triangle in the string), gradually moving those fingers out along the width (from the centerline) of the hallway. When the string is tight, put a nail where each finger is. These are called the focii. (Hopefully your two stretched-out arms are long enough to make the string tight.) Oh, and make sure each of your nails are the same distance from the centerline of the hall.-but I guess that just makes sense.

  3. AitchKay | Nov 08, 2018 10:32pm | #3

    Yeah, it's not an ellipse. But that technique is an excellent way to draw an arc of a true circle, without having to find the center of that circle (a lot of the time, who cares what the radius is?)

    For instance, if you're trimming out an arch-top window, trying to guess the radius and playing around with trammel points can take forever..

    Instead, you can simply hold a straightedge across the window from spring line (where the curve leaves the vertical side and starts its arc) to spring line, and measure the distance to the top of the arc.

    The width of the window and the distance to the top of the arc tells you where to place your three nails.

    Bingo! You're there!

    But it ain't an ellipse, it's an arc.

Log in or create an account to post a comment.

Sign up Log in

Become a member and get full access to FineHomebuilding.com

More Tips & Techniques

View All
  • Precut Bottom Plates in Doorways
  • Prevent Paint Bridging With Picks
  • Stop Cracks at Corners
  • Sticker Smudge Solution
View All

Up Next

Video Shorts

Featured Story

Ducted vs. Ductless Heat Pumps

Choosing the right heating and cooling system means finding the best fit for your home's size, layout, and climate—and balancing trade-offs in efficiency, comfort, and cost.

Featured Video

A Modern California Home Wrapped in Rockwool Insulation for Energy Efficiency and Fire Resistance

The designer and builder of the 2018 Fine Homebuilding House detail why they chose mineral-wool batts and high-density boards for all of their insulation needs.

Related Stories

  • Prevent Paint Bridging With Picks
  • Mortising a Hinge without a Router
  • Cedar-Roof Shingling Guide
  • Lightweight Miter Clamps

Discussion Forum

Recent Posts and Replies

  • |
  • |
  • |
  • |
  • |
  • |
View More Create Post

Highlights

Fine Homebuilding All Access
Fine Homebuilding Podcast
Tool Tech
Plus, get an extra 20% off with code GIFT20

Video

View All Videos
  • Podcast 454: PRO TALK With Greg Palese of Klein Tools
  • Angle Your Drywall Knife for Best Results
  • Must-Have Hand Tools for a Remodeler's Kit
  • Cutting Out Drywall for Doorways
View All

Hand Tools

View All Hand Tools Articles
  • Lightweight Miter Clamps
  • Gazebo-Layout Template
  • Lightweight but Functional Pry Bar
View All Hand Tools Articles

Fine Homebuilding Magazine

  • Issue 331 - June 2025
    • A More Resilient Roof
    • Tool Test: You Need a Drywall Sander
    • Ducted vs. Ductless Heat Pumps
  • Issue 330 - April/May 2025
    • Deck Details for Durability
    • FAQs on HPWHs
    • 10 Tips for a Long-Lasting Paint Job
  • Issue 329 - Feb/Mar 2025
    • Smart Foundation for a Small Addition
    • A Kominka Comes West
    • Making Small Kitchens Work
  • Issue 328 - Dec/Jan 2024
    • How a Pro Replaces Columns
    • Passive House 3.0
    • Tool Test: Compact Line Lasers
  • Issue 327 - November 2024
    • Repairing Damaged Walls and Ceilings
    • Plumbing Protection
    • Talking Shop

Fine Home Building

Newsletter Sign-up

  • Fine Homebuilding

    Home building tips, offers, and expert advice in your inbox.

  • Green Building Advisor

    Building science and energy efficiency advice, plus special offers, in your inbox.

  • Old House Journal

    Repair, renovation, and restoration tips, plus special offers, in your inbox.

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters

Follow

  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X
  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X

Membership & Magazine

  • Online Archive
  • Start Free Trial
  • Magazine Subscription
  • Magazine Renewal
  • Gift a Subscription
  • Customer Support
  • Privacy Preferences
  • About
  • Contact
  • Advertise
  • Careers
  • Terms of Use
  • Site Map
  • Do not sell or share my information
  • Privacy Policy
  • Accessibility
  • California Privacy Rights

© 2025 Active Interest Media. All rights reserved.

Fine Homebuilding receives a commission for items purchased through links on this site, including Amazon Associates and other affiliate advertising programs.

  • Home Group
  • Antique Trader
  • Arts & Crafts Homes
  • Bank Note Reporter
  • Cabin Life
  • Cuisine at Home
  • Fine Gardening
  • Fine Woodworking
  • Green Building Advisor
  • Garden Gate
  • Horticulture
  • Keep Craft Alive
  • Log Home Living
  • Military Trader/Vehicles
  • Numismatic News
  • Numismaster
  • Old Cars Weekly
  • Old House Journal
  • Period Homes
  • Popular Woodworking
  • Script
  • ShopNotes
  • Sports Collectors Digest
  • Threads
  • Timber Home Living
  • Traditional Building
  • Woodsmith
  • World Coin News
  • Writer's Digest
Active Interest Media logo
X
X
This is a dialog window which overlays the main content of the page. The modal window is a 'site map' of the most critical areas of the site. Pressing the Escape (ESC) button will close the modal and bring you back to where you were on the page.

Main Menu

  • How-To
  • Design
  • Tools & Materials
  • Video
  • Blogs
  • Forum
  • Project Guides
  • Reader Projects
  • Magazine
  • Members
  • FHB House

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Popular Topics

  • Kitchens
  • Business
  • Bedrooms
  • Roofs
  • Architecture and Design
  • Green Building
  • Decks
  • Framing
  • Safety
  • Remodeling
  • Bathrooms
  • Windows
  • Tilework
  • Ceilings
  • HVAC

Magazine

  • Current Issue
  • Past Issues
  • Magazine Index
  • Subscribe
  • Online Archive
  • Author Guidelines

All Access

  • Member Home
  • Start Free Trial
  • Gift Membership

Online Learning

  • Courses
  • Project Guides
  • Reader Projects
  • Podcast

More

  • FHB Ambassadors
  • FHB House
  • Customer Support

Account

  • Log In
  • Join

Newsletter

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Follow

  • X
  • YouTube
  • instagram
  • facebook
  • pinterest
  • Tiktok

Join All Access

Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features.

Start Your Free Trial

Subscribe

FHB Magazine

Start your subscription today and save up to 81%

Subscribe

We hope you’ve enjoyed your free articles. To keep reading, become a member today.

Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine.

Start your FREE trial

Already a member? Log in

Privacy Policy Update

We use cookies, pixels, script and other tracking technologies to analyze and improve our service, to improve and personalize content, and for advertising to you. We also share information about your use of our site with third-party social media, advertising and analytics partners. You can view our Privacy Policy here and our Terms of Use here.

Cookies

Analytics

These cookies help us track site metrics to improve our sites and provide a better user experience.

Advertising/Social Media

These cookies are used to serve advertisements aligned with your interests.

Essential

These cookies are required to provide basic functions like page navigation and access to secure areas of the website.

Delete My Data

Delete all cookies and associated data