Finding the Center Point

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Forum topic by codysmith posted 12-30-2008 12:40 AM 4534 views 2 times favorited 19 replies Add to Favorites Watch
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8 posts in 3481 days

12-30-2008 12:40 AM

I was wondering what techniques LJ’s are using to find the center point of the end of a board accurately. I am trying to mark the dead center on the end of some 1×4’s to make some tenons in a Leigh FMT jig. Sometimes I measure and mark it right on the money and other times I am off just enough to be frustrating.

I’ve noticed that some of the boards vary from the standard 3/4” x 3-1/2” by as much as 1/8”. Is there a tool or technique I could use to find the center and speed up the process rather than wasting time cutting and then making adjustments?

19 replies so far

View bob101's profile


321 posts in 3474 days

#1 posted 12-30-2008 12:49 AM

You could start by planing the boards to be exactly the same which would be easier, But it sounds like you are using dimensioned stock from the store, if this is the case I would just use a good rule and measure twice, and hope for the best.

-- rob, ont,canada

View DaveH's profile


400 posts in 3803 days

#2 posted 12-30-2008 01:42 AM

You would think for $800 bucks the jig would find the center for you. Draw an X from corner to corner.

-- DaveH - Boise, Idaho - “How hard can it be? It's only wood!”

View Randy Moseley's profile

Randy Moseley

113 posts in 3463 days

#3 posted 12-30-2008 02:39 AM

Try this. Take a ruler and tilt it until you have an exact even amount of inches. Example, a 2×4 is approx 3.5” wide. Tilt the ruler until it “measures” 4 inches and the halfway point is 2”. Easier than all those 1/16ths and 1/32nds.

I also bought a center point tape measure several years ago. One side is the measurement, then find that measurement on the other side and that’s the middle. Works neat.

-- Randy, DeKalb, Illinois

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Randy Moseley

113 posts in 3463 days

#4 posted 12-30-2008 02:42 AM

Try this link to see the center point tape measure.

-- Randy, DeKalb, Illinois

View juniorjock's profile


1930 posts in 3790 days

#5 posted 12-30-2008 04:23 AM

There’s lots of ways to do it. But I do agree with DaveH. That is if it’s practical for your application.

View codysmith's profile


8 posts in 3481 days

#6 posted 12-30-2008 08:38 PM

Thanks for all of your suggestions. I really appreciate and will try all of them, especially the center point tape measure.

View Matt (Upper Cut)'s profile

Matt (Upper Cut)

264 posts in 3838 days

#7 posted 12-30-2008 09:12 PM

+1 on Randal’s idea of just skewing a nice ruler. That’s the way the old guys did it. Need to mark a 7 inch board into thirds? Well, skew the ruler until it spans from 0 to 9, then mark at 3 and 6. Your board is now in thirds. Need to mark it in half? Skew the ruler until you’re at 8, and mark at 4. You can do this for any number of sections.

-- Matt Gradwohl, Upper Cut Woodworks,

View codysmith's profile


8 posts in 3481 days

#8 posted 01-01-2009 12:34 AM

I totally agree with the ruler skewing method. I can’t believe I never thought of that before. Thanks Randal.

View OttawaP's profile


89 posts in 3751 days

#9 posted 01-07-2009 03:11 PM

The thing about the FMT is that it does not need to be “perfect” centered as long as you reference the tenon and mortice on the correct side when you place them in the jig your joint alignment will be 100% perfect.
The FMT is an exceptional tool to use. I just used it to install 4 corner dowels into a big old newel post. I made a matching template so I could drill out the stair tread and the post and dowels just slid in nicely.

-- Paul

View ryno101's profile


388 posts in 3689 days

#10 posted 01-27-2009 10:31 PM

My technique, for what it’s worth (I do a fair amount of turning…) is to use a “center finding rule” to find the center point of all faces, connect the lines, then use the “corner to corner” method to connect the opposing corners… what results is a box, the center of that box is the true center of the piece.

-- Ryno

View CharlieM1958's profile


16275 posts in 4243 days

#11 posted 01-27-2009 10:40 PM

Here is a thought…. simple to make and foolproof.

-- Charlie M. "Woodworking - patience = firewood"

View Kindlingmaker's profile


2656 posts in 3551 days

#12 posted 01-27-2009 11:13 PM

CharlieM1958 is right on target but use a 5mm mechcanical pencil so as the lead line is always the same width.

-- Never board, always knotty, lots of growth rings

View Grumpy's profile


23997 posts in 3875 days

#13 posted 01-28-2009 05:21 AM

I use a jig similar to Charlie but more often then not I use an adjustable square as CessnaPilotBarry does.

-- Grumpy - "Always look on the bright side of life"- Monty Python

View Rob 's profile


216 posts in 3692 days

#14 posted 01-28-2009 07:25 AM

I’ve made that dowel jig a few times but I’ve never gotten it to be that accurate. I tried again tonight and found it off by 3/64ths. But I suppose you could run it both ways giving you two lines to gauge the middle by, much like using the combo square. I’ve tried to make a jig that works on the principle of the Starrett’s centre finder but couldn’t get it dialed in. I wanted it for finding the centre of circles which I find very difficult. I’ll have to try again sometime unless I just break down and buy one. Anyone have the Starrett? And if so, how is it?

View jm540's profile


150 posts in 3443 days

#15 posted 01-29-2009 03:59 AM

i just divide mark from both ends and split the difference. I have used the tilt method it works but I cant convince my self to trust it. I also use a slide square

-- jay Rambling on and on again

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