dw's shop tips #1: 3-4-5 rule.

  • Advertise with us
Blog entry by Don W posted 07-02-2011 02:38 PM 2901 reads 5 times favorited 3 comments Add to Favorites Watch
no previous part Part 1 of dw's shop tips series Part 2: Threaded inserts? Really. »

You want to square your project. Its to big or to small for a square. Maybe you can’t reach one corner to do a corner to corner comparison. Use the 3-4-5 rule.

The rule state simply if one side of a triangle is 3 and the other side is 4, the diagonal measurement will be 5. This can be inches, feet, millimeters, miles, arms lengths, anything as long as they are all the same.

Any set of numbers divisible by these will work. Need longer, double them for 6 – 8- 10.

Use the rule in conjunction to double check yourself.
Use it to check your square.
Use it to make your new “antique” wooden square.

-- - Collecting is an investment in the past, and the future.

3 comments so far

View Tedstor's profile


1691 posts in 3690 days

#1 posted 07-02-2011 08:06 PM

One of the most useful formulas around. I’ve done a couple of flooring proects in my home. Since I don’t own a 16 foot framing sqaure, the ole 3-4-5 rule was invaluable.

View MsDebbieP's profile


18619 posts in 5218 days

#2 posted 07-03-2011 01:28 PM

the first time I saw that used to square up a deck, I was “in awe”. Of course, I always forget what the numbers are and have to do a little math in my head :)

A great tip!

-- ~ Debbie, Canada (, Young Living Wellness )

View bigike's profile


4057 posts in 4346 days

#3 posted 07-03-2011 06:08 PM

Thanks for the reminder. I’m gonna have to use this on my next box or picture frame. THANKS again.

-- Ike, Big Daddies Woodshop, http://[email protected]

Have your say...

You must be signed in to post the comments.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics