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Finding the Center Point

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Forum topic by codysmith posted 1938 days ago 3275 views 1 time favorited 19 replies Add to Favorites Watch
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codysmith

8 posts in 1960 days


1938 days ago

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

bob101

170 posts in 1953 days


#1 posted 1938 days ago

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

DaveH

399 posts in 2281 days


#2 posted 1938 days ago

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

93 posts in 1942 days


#3 posted 1938 days ago

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

93 posts in 1942 days


#4 posted 1938 days ago

Try this link to see the center point tape measure.

http://www.rockler.com/product.cfm?Offerings_ID=1256&TabSelect=Details

-- Randy, DeKalb, Illinois

View juniorjock's profile

juniorjock

1930 posts in 2268 days


#5 posted 1938 days ago

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

View codysmith's profile

codysmith

8 posts in 1960 days


#6 posted 1937 days ago

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 2316 days


#7 posted 1937 days ago

+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, http://uppercutwoodworks.com/

View codysmith's profile

codysmith

8 posts in 1960 days


#8 posted 1936 days ago

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

View OttawaP's profile

OttawaP

89 posts in 2229 days


#9 posted 1929 days ago

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

ryno101

373 posts in 2167 days


#10 posted 1909 days ago

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

CharlieM1958

15547 posts in 2721 days


#11 posted 1909 days ago

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

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

View Kindlingmaker's profile

Kindlingmaker

2653 posts in 2029 days


#12 posted 1909 days ago

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

Grumpy

19079 posts in 2354 days


#13 posted 1909 days ago

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

Rob

197 posts in 2170 days


#14 posted 1908 days ago

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

jm540

150 posts in 1922 days


#15 posted 1908 days ago

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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