Need basic math help

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Mark Mandell - Gone Round In New Jersey

Mark line a for each bowl section at 7-13/16" intervals. The center of each section will be 3.91" or about 3-31/32. Using that as a center point for your holes you'll be about 1/100th of an inch off dead center. Ain't mil-spec but close enough for govment work.

dividers

Jack Guzman from Maine

I use dividers for all such calculations. Exact and foolproof.

Re: Need basic math help

Carlos

(30 3/8 - (5 1/2 * 4)) / 5 = 67/40 = 1 27/40 = 1.675

Each of the spaces between bowls and at the ends is 1.675".

The center of the first bowl from the edge is 1.675 + (5 1/2 / 2) = 4.425".

The center of each succeeding bowl is 5 1/2 + 1.675 = 7.175"

So center of second bowl is at 11.6" from edge.

Third bowl is at 18.775 from edge.

Fourth bowl is at 25.95 from edge.

I think that's right but somebody check my math.

Re: Need basic math help

Joe Bradshaw

Your board is 31 3/8 inches long. multiply the dia. of the bowls by 4. This gives you 22 inches. Subtract from 31 3/8 inches and you get 9 3/8 inches. Divide by 5 and you get 1 7/8 inches. Add 1/2 bowl(2 3/4 inches) dia. to this number and you get 4 5/8 inches. Measure from both ends and mark. Add one bowl dia. and 1 7/8 from your first two marks and you have the location of your second and third holes. Hope this helps.

Joe

Do it in metric

paul in AZ

Use metric measurements rather than struggling with fractionals. It then becomes simple arithmetic.

Re: Do it in metric

John in NM

Haha - I haven't struggled with fractions since the 5th grade

Its all what you're used to.

Many of us are used to fractions through woodworking in the US - the idea of switching to either decimal imperial or metric is hard to imagine.

But imagine switching our money to fractions where the base of calculation was one of division by 2 rather than by 10. Money is basically metric in the US, and we can't see doing it any other way. Ironic, isn't it?

Re: Need basic math help

John McGaw

Close but no cigar -- you started out with the wrong overall length of the board. I used an almost-identical method (which is perfectly sound) and find the space will come out to 1.88" I didn't bother to convert to fraction so that is left as an exercise. (OK so it would be 1" + between 56 and 57 64ths.)

If I was doing it I thing I'd just find a nice round number and, if possible, cut the board a hair shorter to make it work out painlessly. Anyway, It is doubtful that anybody will be coming by later with their digital calipers to check the work.

I agree with Joe

Lee Schierer in McKean, PA

I agree with Joe, mark your board 4-5/8 from each end, then 9-1/4 from each of the 4-5/8 marks.

Lee

You have a misconception about mil spec

Joe shelton

Just for starters, it IS gummint work...

Me, too.

There was a saying at Caterpillar

Dick Coers

When asked how many people work at Caterpillar, the answer was "half". "The rest are doing some kind of guvment work."

Re: Do it in metric

paul in AZ

The most ludicrous currency was used in UK for some 900 years until 1971.

A pound had 20 shillings. A shilling had 12 pence. Pence were divided in two for half penny and again for a farthing [1/4 penny].

And a guinea was 21 shillings.

Imagine being a book keeper in that system.

A UK pound now has 100 pence. Whew!

Not

Mark Mandell - Gone Round In New Jersey

Talking about APC's, just wood

Re: Need basic math help

Don Stephan

I could see cats being that attentive to spacing, but dogs?

A little different take...

Jason Roehl in Lafayette, IN

The math has been covered ad nauseum above, however, I think the spacing is a bit off. When spacing items like that along a length, sometimes it looks better for the end spacing to be half that of the spaces between items. So instead of dividing (board length minus sum of bowl diameters) by 5, divide it by 4 to get the between-bowl spacing, then halve that number to get the space at each end.

Just my $0.02.

Jason

Re: A little different take...

William Duffield

I agree. I would use the same "two pair of dividers" method that works so well for laying out hand cut dovetails. Of course, for this exercise, you would also like to have a third compass set to the radius of the dog bowls so you cn get a feel for what the layout it will look like when finished. No math and no rule necessary.

Re: Need basic math help

AZ in Colorado Springs

I know Joe didn't ask about this, but when there's a little odd bit leftover, I make the center space wider by that much. Everything still looks balanced, and as you pointed out, (almost) no one will measure and make a fuss.

Re: Need basic math help

William Duffield

But what do you do if you have an odd number of dogs?

Re: Need basic math help

AZ in Colorado Springs

I have one (1) dog. Her water bowl sits on the floor, and so does her food dish, at "suppertime" as Snoopy thinks of it (also at breakfast).