# Calculating precision as displayed

## Recommended Posts

In my cabinetshop I do a lot of calcuations that involve conversion from inches to millimeters.

1 inch, for example, equals 25.4 millimeters.

I would like the calculation to delete all values to the right of the decimal. I know I can change how it is displayed with formatting but I'm trying to make it change in calculating.

For example: 25.4 + 25.4 = 50.8 should read 25 + 25 = 50.

MS Excel does this with a function that converts values to equal "precision as displayed".

How would I do something like this in filemaker?

(For what it is worth we were going to maul the door on the edgesander anyway so the loss of .4 millimeter accuracy was moot anyway)

##### Share on other sites

Try the Int() function? Note that in your example the error is actually 0.8 millimeters.

##### Share on other sites

The Round ( number ; 0 ) will shorten the error to 0.2 millimeters ( in your example )

##### Share on other sites

[round] seems to be the function I want.

Integer drops everything to the right of the decimal and my goal is to get the value as close to accurate as possible but still show up on a CAD document as an integer.

Thanks.

##### Share on other sites

You know, I once new a senior engineer who applied exactly this philosophy - it's okay when your dealing with only a few inches but watch out on longer lengths - say, 1 metre.

##### Share on other sites

If the unit of measurement is always millimeters, even on that case the error will be always ≤ 0.5 millimeters.

##### Share on other sites

Measurements in cabinetmaking have an interesting phenomena.

We try to be as accurate as we can, but more importantly we try to be unambiguous. A CAD drawing is often a pretty small document anyway and we want to have a value that easy to recognize and set up on a machine.

Millimeters are much more easier to work with.

Part of this is because it is easier to add or subtract 400 + 7+ 19 than it is to add 15 13/16 + 1/4 + 23/32.

Part of this is because 426 fits better on a CAD drawing than a fraction does.

Then you have to find the number on a vernier.

If you have ever tried to run tablesaw you will know what I mean.

Then there's the part where wood expands & contracts with changes in humidity. The same conditions that make your lips get chapped or the backdoor get sticky happen to our cabinet doors.

For all of these reasons, and several more, rounding millimeters at the halfway mark is just good practice.

If we were making rockets or automobiles our unit of measurement would be more precise. It's kind of like database making. There's a variety of routes to climb the mountain.

## Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

×   Pasted as rich text.   Paste as plain text instead

Only 75 emoji are allowed.

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×

×
×
• Create New...