Rectangle Centre finder for all you non-squares.

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Project by LittleBlackDuck posted 03-27-2017 11:46 PM 1079 views 3 times favorited 9 comments Add to Favorites Watch

G’day all. While preparing my Small Circle Cutting Jig article, I found that I had to resort to using a particular jig far too many times as I kept stuffing up the video and consequently having to follow that up by marking out more sacrificial pieces of MDF.

The aforementioned jig is my “Rectangle Centre Finder”. I’m sure most of us have one of those proprietary centre finder gizmos or made one ourselves,

Let’s face it, all us woodwoekers know how to cut that perfect square… in the shape of a rectangle.
I’ve found those gadgets great for small squares and circles, however, you don’t have to mark and drill too many pieces before you finally realise that the mark was not centred for rectangles… I kept thinking I inserted my drill bit off centre (and for my new drill press that was a no-no).

I challenge anyone to get the ruler on both the opposing corners of a rectangle perfectly alligned in less than 10 attempts (and I may be generous there).

My jig is made out of pine, though hardwood would be more robust. I prototyped it out of pine and as it worked so well I saw (no pun intended) no reason to redo until it eventually breaks or wears out.

It’s held together with a couple of ¼” bolts just snugged up tight enough to stabilise it but not so tight to stop free movement. The secret of the whole operation is the use of 2 Australia Post rubber bands. They seem to provide the best tension and do not break down in the atmosphere like most cheapo rubbers. Just goes to show Autralia Post is good for something else other than paying their CEO $5,000,000 per annum, just to deliver overpriced postage… I deliberately post myself letters, not because I like my scintillating conversation, but just to get more free rubber bands.

For successful operation, it is imperative that the slide is held tight against the corner blocks to ensure a centred line. I found this easier to implement using the AP rubber bands, after abandoning the idea of using springs in many failed and impractical combinations.

A close up of the corner blocks, hardware and bungee (and the top of the saw table) as I had some film left over in the camera,

As I was already wearing my video director’s cap, I zipped together a quick video of it’s use here, and of course the SketchUp model is downloadable here. Note: The rubber band is missing out of the SketchUp model… it kept flicking off the screen.

And for the double pose,

Thanks again for reaching The End.

-- If your first cut is too short... Take the second cut from the longer end... LBD

9 comments so far

View BobWemm's profile


2370 posts in 1799 days

#1 posted 03-28-2017 01:33 AM

Great idea.


-- Bob, Western Australia, The Sun came up this morning, what a great start to the day. Now it's up to me to make it even better. I've cut this piece of wood 4 times and it's still too damn short.

View crowie's profile


2174 posts in 1824 days

#2 posted 03-28-2017 05:21 AM

Very clever thank you Alex…

-- Lifes good, Enjoy each new day...... Cheers from "On Top DownUnder" Crowie

View Scott Oldre's profile

Scott Oldre

980 posts in 3304 days

#3 posted 03-28-2017 12:37 PM

Makes total sense to me. Thanks for sharing. Doesn’t look too difficult to make either.

-- Scott, Irmo SC

View JoeinGa's profile


7732 posts in 1880 days

#4 posted 03-28-2017 02:09 PM

Hmmmm. Got me to thinkin’ (yeah, yeah. I know. Dangerous!)

I just might need to make me one of these.

-- Perform A Random Act Of Kindness Today ... Pay It Forward

View helluvawreck's profile


29723 posts in 2739 days

#5 posted 03-28-2017 05:24 PM

It looks like a well thought out jig. Nice work.

helluvawreck aka Charles

-- If a man does not keep pace with his companions, perhaps it is because he hears a different drummer. Let him step to the music which he hears, however measured or far away. Henry David Thoreau

View majuvla's profile


11477 posts in 2740 days

#6 posted 03-28-2017 05:27 PM

Sometimes it’s very helpfull.

-- Ivan, Croatia, Wooddicted

View woodbutcherbynight's profile


3744 posts in 2282 days

#7 posted 03-28-2017 09:32 PM

Thanks for the post, another jig for me to get cracking on. Good idea!

-- Live to tell the stories, they sound better that way.

View BurlyBob's profile


5147 posts in 2138 days

#8 posted 03-29-2017 05:53 AM

That’s a real interesting jig Idea. I’m definitely going to give it some thought.

View dannmarks's profile


420 posts in 454 days

#9 posted 03-29-2017 11:01 AM

Love it.

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