# Hole spacing

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• posted on August 20, 2011, 5:46 pm
My math skills are non existent beyond basic math, and I'm trying to figure out how to space holes evenly along a center line in an area. Let's say I have a rectulanglar block, 6" long ,less 1/4" on each end for a border and I want to evenly space 6- 3/4" holes. How do you figure that? My daughter-in-law says you can do that in one of those cheap home design programs. That would be ideal for me. Anyone use one of those programs that knows if they can be used for that? Thanks.
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Paul

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• posted on August 20, 2011, 6:00 pm
On 8/20/2011 12:46 PM, Paul wrote:

This will do the same thing for you:
http://www.e-woodshop.net/files/SlatCalculation.xls
I wrote this one to give me slat/spindle spacing for Arts and Crafts furniture projects, but it will work for holes, and fence posts if necessary.
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• posted on August 20, 2011, 6:13 pm
On 8/20/2011 1:00 PM, Swingman wrote:

I forgot to mention: In Excel, right click on C7|Format Cell| and choose your desired fraction. I use 1/16
The last time it was used before it was uploaded years ago, someone obviously changed the fraction denominator.
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<%-name%>
• posted on August 20, 2011, 6:05 pm
On 8/20/2011 12:46 PM, Paul wrote:

"Evenly spaced" how, precisely?
6"-2*(1/4") - 6*(3/4") --> only 5.5"-4.5" = 1" total space left between holes...is that what you really intend?
An even number evenly spaced would be half the distance from the middle to each of the first; and odd number would have the midpoint of one in the middle of the length.
It's not difficult but need more definition of the actual layout desired methinks; this doesn't sound like a useful arrangement even having no clue what the application is...
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• posted on August 20, 2011, 6:15 pm
Paul wrote:

Overkill. Easy if you just draw 6 holes on a piece of paper, just basic math.
6 holes = 7 non-hole spaces needed
6" - (1/4 + 1/4) = 5 1/2" for holes after accounting for 2 outside non-hole spaces
6 * 3/4 = 18/4 = 4 1/2" of space occupied by holes
5 1/2 - 4 1/2 = 1" of non-hole space of the 6 holes
1"/ 5 remaining non-hole spaces = 1/5 inch between holes.
So...
1. Draw a horizontal line
2. Mark a hole center at 1/4 + (3/4/2) which = 5/8
3. Mark additional centers at 3/4 + 1/5 from preceding center mark
4. Drill holes
Note: with dimensions like that it is unlikely you will wind up with 1/4" as a border for the last hole.
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• posted on August 20, 2011, 6:52 pm

I hate math. :-)
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Bill
In Hamptonburgh, NY
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• posted on August 20, 2011, 7:59 pm

The proper conclusion to draw from the above is "I hate Imperial measurements." This problem is absolutely trivial with metric measurements (see my other post in this thread).
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• posted on August 20, 2011, 9:07 pm
On 8/20/2011 2:59 PM, Doug Miller wrote:

I agree ... further compounding the problem is it's unclear whether the OP really wants to:
"evenly space (six)6- 3/4" holes" in 5 1/2" between the borders.
It that is truly the case, my spreadsheet is correct:
http://www.e-woodshop.net/files/SlatSpreadsheetProofinPudding.jpg - or 3.571875mm between each hole and the borders.
If he want the edge of the circles to touch the 1/4" borders on either side, he wants 13/64" between the circles with the edges touching the 1/4" borders:
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• posted on August 20, 2011, 7:26 pm
On 8/20/2011 1:15 PM, dadiOH wrote:

Using my spreadsheet will get you within 1/64". Which should be well within "not visually objectionable" range.
Due to the displayed granularity/rounding error of Excel spreadsheet:
Format Cell C7 = "as hundreds"
S= 5 1/12" W= 3/4" n= 6 x= 14/100 or roughly 9/64"
Starting with the left edge of the first hole at 9/64" from the left border, you will be 1/64" off, or 5/32" between the right edge of the sixth hole and the right hand border.
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• posted on August 20, 2011, 7:33 pm
On 8/20/2011 2:26 PM, Swingman wrote:

^^
S= 5 1/2" NOT 5 1/12"!! Damn typo fingers!

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• posted on August 20, 2011, 7:57 pm

Well, this *is* basic math: all you need is simple arithmetic (addition, subtraction, multiplication, and division). What complicates this one is the use of a measuring system that's approximately a thousand years old.
You have a total of 6" less two 1/4" borders = 5 1/2" to put the holes in.
Six 3/4" holes take up 6 * 3/4" = 4 1/2" of that 5 1/2", leaving 1" for spaces between the holes.
Since there are 6 holes, there will be 5 spaces between them. You have 1" total to make 5 spaces, so each space will be 1/5".
The distance between the centers of the holes will be 3/4" (the width of the hole) plus 1/5" (the spacing between holes) -- this will be difficult to measure with tapes or rules marked in inches.
I suggest you choose one of the two options below instead.
Option 1 ----------- Increase the size of the borders by 1/32" to 9/32". This will leave you 5 7/16" to put 4 1/2" worth of holes in, leaving 15/16" to divide among five spaces between holes.
15/16" divided among five spaces = 3/16" per space -- and *that* you *can* measure easily. This gives you a distance between centers of 3/4" + 3/16" 15/16".
So mark the center of the first hole at 9/32" (the width of the border) plus 3/8" (*half* the width of the hole) = 21/32" in from one end. (3/8 = 6/16 12/32; 9/32 + 12/32 = 21/32)
Subsequent holes are centered every 15/16" from there: 21/32 + 15/16 = 21/32 + 30/32 = 51/32 = 1 29/32 1 19/32 + 15/16 = 1 19/32 + 30/32 = 1 49/32 = 2 27/32 2 27/32 + 15/16 = 2 27/32 + 30/32 = 2 57/32 = 3 25/32 3 25/32 + 15/16 = 3 25/32 + 30/32 = 3 55/32 = 4 23/32 4 23/32 + 15/16 = 4 23/32 + 30/32 = 4 53/32 = 5 21/32
Option 2 ----------
Redo everything in metric. It's SO much easier.
A number of years ago, I was in Toronto on business. Having utterly failed in my attempts to find a metric tape measure at home, I asked one of the guys I was working with where I could find a hardware store. He wondered why; I told him -- and he asked in honest bewilderment what on earth an American would want with a metric tape measure. My answer was that I'm a woodworker, and solving problems such as this is FAR easier with measurements in millimeters, rather than fractional inches -- as you're about to see, too.
It's much easier to find metric tapes in American hardware stores now than it was in the 1980s. So go buy yourself a tape measure that has dual scales (inches and millimeters). That will make it easy to see the relationships between the two systems.
Then remeasure. You will find that: - your block is 152mm long. - you want a 6mm border at each end. - you want to evenly space six 19mm holes.
152mm less two 6mm borders leaves (152mm - 6mm - 6mm) = 140mm.
Six 19mm holes occupy 6 * 19mm = 114mm
You have (140mm - 114mm) = 26mm available for the five spaces between the six holes, so there will be (26mm / 5) = 5.2mm between each hole. Ignore the point-two millimeters; you can't measure that fine anyway.
The holes will be centered every (19mm + 5mm) = 24mm.
The first hole should be a distance of 6mm (the width of the border) plus 9.5mm (half the width of the hole -- round it off to 10mm) = 16mm in from one end of the board.
Subsequent holes are centered every 24mm after that: 16mm + 24mm = 40mm 40mm + 24mm = 64mm 64mm + 24mm = 88mm 88mm + 24mm = 112mm 112mm + 24mm = 136mm And looky there: the last hole is (152mm - 136mm) = 16mm in from the end, same as the first one.
Isn't that a lot simpler?
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• posted on August 20, 2011, 8:06 pm
Doug Miller wrote:

No he doesn't, he wants 1/4" and 6mm doesn't equal that. Close but no cigar, so much for metric unless you can measure 6.35mm on that tape :)
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• posted on August 20, 2011, 8:53 pm

Do you *really* think that 0.35 millimeters (less than 14 thousandths of an inch) is going to be noticeable? Or are you just trying to be argumentative?
Had enough of that from SWMBO this past week, don't need it from you too.
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• posted on August 20, 2011, 9:33 pm

My guess is he wants them about "this far in" holding fingers apart about 1/4" or 6.35mm or 4.115 parsecs
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• posted on August 20, 2011, 11:10 pm
Doug Miller wrote:

Just pointing out that metric isn't the be-all and end-all :)
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• posted on August 21, 2011, 1:21 am

No, but it sure makes the calculations a LOT easier. Reduces the risk of error, too, because you're always adding either integers or decimals -- not mixed fractions.
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• posted on August 21, 2011, 12:27 pm
Doug Miller wrote:

Sure. Tell that to the group that engineered the Hubble Space Telescope where confusion over metric/proper measurements resulting in the launch of an almost worthless instrument.
And consider these two standards:
"Meter = 1/10,000,000 of the distance between the North Pole and the Equator measured along the Prime Meridian." (Alternative definition: "1,650,763.73 wavelengths of the orange-red emission line in the electromagnetic spectrum of the krypton-86 atom in a vacuum.")
vs
"A pint's a pound the world around."
Now I ask you, which is more practical for your average woodworker?
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• posted on August 21, 2011, 12:36 pm
wrote:

Metric rules. Just like US measurements, if you grew up using one, it takes a while to get used to the other. STill good to know both, since otherwise how would you know why plywood comes in sheets of 244 x 122 cm ...
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Best regards
Han
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• posted on August 21, 2011, 2:34 pm

I'd rather have the pint.
R
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• posted on August 21, 2011, 4:54 pm

Huh? What did MKS/FPS have to do with Hubble's mirror shape?

Strawman. An inch is defined as 2.54cm.

The one the tools use. The problem is that we now have both. I can work with either but where both is required is where the mistakes are made.