Laying out evenly spaced holes

I'll try to describe this, maybe someone else can do a diagram.

It's not too hard to divide a 12" piece of stock to have evenly spaced holes every 2".

But what if you have a square piece of stock 17 11/16" that you want to divide into 7 equally spaced holes? That's a little harder math.

The answer is a diagonal of a known length.

Start at the bottom edge of the piece (17 11/16"). Measure a diagonal of a known length that divides evenly by the number you are trying to lay out.

Since we are looking for 7 equal increments, I'd use a 21" diagonal (because it divides easily by 7).

I'd put zero on the bottom left corner of the stock. Then align the ruler so 21" touches the right hand edge, whatever angle that takes. Mark every 3" along the diagonal.

Use a square to project the 3" increment marks back down to the bottom edge of the piece.

You have now divided 17 11/16" by 7 even increments. I have no idea how long the segments are, but they are all perfectly equal.

I'm having a hard time visualizing this.

Of course, after doing this you'll have 6 evenly spaced holes so you'll have to go back and do it again with a 24" diagonal and 8 segments.

Another option: the metric system.

Woody wrote: I'm having a hard time visualizing this.

He's basically dividing the hypotenuse of an arbitrary right angle triangle (chosen for easy math), then projecting those marks down on to the base of the triangle. I can see this being in the bag of tricks of a carpenter, just like the 3-4-5 right angle trick. Guys who do stuff like this for a living have a bunch of great shortcuts, and you may have learned some of them in primary school when you were introduced to geometry.

Or you use the metric system.

The really easy way:

Fan spacer

should be withing a 64th of 2 17/32" space from center to center

how i came up with that;

convert 1/16th of an inch to a decimal: .625

so 11/16 to a decimal format: .6875

add 17" to that: 17.6825

divide by 7 2.527"

.

easier method;

convert 17 11/16" to MM: 449.263

divide by 7: 64.18mm

convert to inch: 2.5267717

BTW google will the convert for you.

Keith Tanner wrote:

Woody wrote: I'm having a hard time visualizing this.

He's basically dividing the hypotenuse of an arbitrary right angle triangle (chosen for easy math), then projecting those marks down on to the base of the triangle. I can see this being in the bag of tricks of a carpenter, just like the 3-4-5 right angle trick. Guys who do stuff like this for a living have a bunch of great shortcuts, and you may have learned some of them in primary school when you were introduced to geometry. Or you use the metric system.

Right.

I shouldn't try to explain stuff like this when I'm tired.

Don't remember where I learned this, but when I saw the title to the thread, I knew what SVreX was going to post. I have used this method many times over the years.

I've never had any need for this … but it makes sense … thanks