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how to find the center of a board?

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Forum topic by Belg1960 posted 05-24-2012 11:50 PM 2592 views 0 times favorited 22 replies Add to Favorites Watch
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Belg1960

833 posts in 1819 days


05-24-2012 11:50 PM

Topic tags/keywords: question

Guys, I saw a video somewhere on how to use a set of calipers to measure the exact center of a board that you want to resaw/rip. Does this ring a bell with anyone and could you share a link or the method?

-- ***Pat*** Rookie woodworker looking for an education!!!


22 replies so far

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Mickey Cassiba

312 posts in 1786 days


#1 posted 05-25-2012 12:03 AM

I’ll try…
an old method is to lock your caliper at a distance slightly larger than half of the width of the object. Scribe an arc.
drop to the opposite side and scribe another arc. the intersection of the two arcs will be the center. Obviously this will be more accurate if the arcs are struck from a line perpendicular to one edge. to elongate the line, repeat the procedure from another point on the object. The line indicated from the two intersections will describe the center line of the object.

-- One of these hammers oughta fix that...

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rodman40

163 posts in 1081 days


#2 posted 05-25-2012 12:17 AM

http://www.youtube.com/watch?v=UXgRixVhcp4 See if this helps you out.

-- Rodman

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rodman40

163 posts in 1081 days


#3 posted 05-25-2012 12:23 AM

http://www.youtube.com/watch?v=inEs_C3fzEI&feature=related Here’s one using measurements.

-- Rodman

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bandit571

7527 posts in 1437 days


#4 posted 05-25-2012 12:32 AM

When I need the center of a board, like a drawer front bing fitted for a knob, I just use a straight edge.. Long enough to reach both ends of the board. I go from ‘upper’ corner to “lower” corner at a diagonal. Eye ball near the center make a short faint line. Repeat from the other direction. Where the two faint lines cross, that is the center. This can also be used on the ends of a board. Just make an “X”, center of the “X” is the center of that board.

-- A Planer? I'M the planer, this is what I use

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Dallas

3219 posts in 1241 days


#5 posted 05-25-2012 12:33 AM

You can always use a piece of paper to find the center. LOL.

-- Improvise.... Adapt...... Overcome!

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Belg1960

833 posts in 1819 days


#6 posted 05-25-2012 12:41 AM

Guys, really appreciate the help, but I want to do this on the 3/4” end of the board with such a small surface these layout tricks have let me down. Even the smallest movement when making the marks leads to one rip being thicker or thinner then the other. The method I’m talking about uses the wood to set up the tablesaw and takes into account the thickness of the blade as well. So the search still continues. I “believe” the guy that showed the method was of Asian decent but its been soooo long that I could have this confused with the hundred or so videos I’ve watched to try and get better.

-- ***Pat*** Rookie woodworker looking for an education!!!

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waho6o9

5304 posts in 1331 days


#7 posted 05-25-2012 12:56 AM

Then, 3/4 equals 6/8. Minus 1/8, blade thickness, then you have 5/8.
2 and a half eights one side, 2 and a half eights the other side. The blade will be in the middle.

Or 5/16, 1/8 for the blade,5/16 will be left over.

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Dallas

3219 posts in 1241 days


#8 posted 05-25-2012 01:10 AM

http://sawdustmaking.com/Center%20Gauge/centergauge.html

-- Improvise.... Adapt...... Overcome!

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Infernal2

104 posts in 951 days


#9 posted 05-25-2012 02:03 AM

The trick I use is to take a ruler (you can do it with a tape measure but its a pain) and put the one corner on one side, then with the other side, move the ruler up and down so that an even number mark rests on the other side of the board. So for example, if you have a board around 7 inches and you move the ruler down slightly so that the corner rests in the left corner and the eight rests somewhat lower, then the exact difference mark will be the center of the board, in this case, the four will rest in the center.

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CharlieM1958

15822 posts in 2973 days


#10 posted 05-25-2012 02:49 AM

Are you really just trying to rip a board into two pieces of equal width?

I just set the fence to a smidge less than half the board’s width, make the rip, the send the offall piece back through the saw without moving the fence. Presto…. both pieces are identical. The only downside is 1/16th or so more waste than if you made the cut dead center on the first pass.

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

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TopamaxSurvivor

15090 posts in 2430 days


#11 posted 05-25-2012 04:59 AM

I do it like Charlie does. Get as close as I can and send the biggest through again.

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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bluekingfisher

1107 posts in 1734 days


#12 posted 05-25-2012 07:15 AM

Pat, I don’t know the caliper method but a marking gauge is how I would do it. Set your gauge to just a hair less than half the board thickness. Then, scriibe the edge about a 1/2” long from one face side then the other. This will give you two paralell lines on the board edge. The centre is between the two lines. You could even sneak up so the scribe lines when scribed from both sides to line up exactly. However, if you have a gap the width of your saw blade bewteen the lines then that will be good enough, just center the blade between the two lines.

-- No one plans to fail, they just, just fail to plan

View Belg1960's profile

Belg1960

833 posts in 1819 days


#13 posted 05-25-2012 01:01 PM

Guys, a few excellent points.
David, I like the idea of using the marking gauge it will really help center the blade.
Charlie, Topomax being as ANAL is I am,(LOL) I try to do everything in as few moves as possible. This is the method I have been using right now and feel there has to be a more “scientific” way to move ahead.
Dallas, buddy I will make a few of these types of marking gauges. They will come in handy. I didn’t get the paper tip or was that just you being funny. Just went over my head I guess. LOL
Infernaln2 the method you describe is really closely related to 1 of the links in the earlier post.

Many thanks men very much appreciate the support. If someone does find the method with the calipers plz post it here.

-- ***Pat*** Rookie woodworker looking for an education!!!

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ChuckV

2489 posts in 2281 days


#14 posted 05-25-2012 01:57 PM

I usually use Charlie’s method for ripping into two equal widths.

But sometimes I use a ruler/pencil or marking gauge that is set to be close to half the width (by a quick measurement or eyeballing). I make a mark from both edges of the board. Whether I am set a tad over or under the exact target width, I end up with two marks close together and centered on the board center.

I set the fence to put the center of the blade in the center of those two marks and make some test cuts. If my actual board is over-length, I will do this right on the end. I just flip it over to put the other edge against the fence to check.

I often use this two-mark method to locate the center of the width of a board for reasons other than ripping – say locating a drawer handle. I also do this on the edge of a board to find the center of the thickness so I can set the fence on my bandsaw when resawing.

-- “While the world with closed eyes sleeps, The sky knows and weeps - steel rain. ” ― Nathan Bell

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dhazelton

1288 posts in 1051 days


#15 posted 05-25-2012 02:27 PM

Yes, math never lies. You want to rip a 1×4 in half say, it is 3 and 1/2 wide. Subtract 1/8 for a kerf and you have 3 and 3/8. Divide by two and you have 1 and a half plus 3/16, or 1 and 11/16.

If you wanted you could make yourself a set of spacers that when set against the blade will set your fence to width depending on what width board you are cutting. Make a 1 11/16 spacer and write “1X4” on it. Add a half inch and cut another one that says “1X5” on it. Make a whole set an drill a hole in them and hang ‘em on a hook somewhere.

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