# Decimal dimension help

• posted on July 14, 2005, 5:26 pm

I just finished looking at the plans to build Jake's Chair. The dimensions were given in decimal form. There were several decimals though that I didn't recognize such as .9 and .6. How are these measurements figured?
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• posted on July 14, 2005, 5:42 pm

You can get strange things like that if the original was in metric units, with a 'clueless' conversion to ft/inches.
And, of course, there _are_ rulers marked in decimal fractions of an inch. Relatively uncommon, but they *do* exist.
If somebody uses 1 decimal place for things in "1/8ths", you typically get decimal parts of: .0 .1 .2 .4 .5 .6 .8 (sometimes .7) and .9
What you're actually dealing with is anybody's guess.
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• posted on July 14, 2005, 5:45 pm
I think they are rounded off. .9 is likely .875 or 7/8, .6 is likely .625, or 5/8.

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• posted on July 14, 2005, 8:19 pm

If they're not rounded then I do it when I made it - just figure .9 is 7/8" and .4 is close enough to 7/16" to not make much difference in building the chairs. It's not a matter of following the actual dimensions in the plans to the decimal point, but making components with the same specs the same dimensions.
--
Owen Lowe
The Fly-by-Night Copper Company
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• posted on July 14, 2005, 5:50 pm
snipped-for-privacy@yahoo.com wrote:

That sucks if in inches--if metric, makes sense....
To convert to nearest 8th, 16th or 32nd...
0.9*8 = 7.2
0.9*16 = 14.4
0.9*32 = 28.8
Depending on how anal you are you can choose...
For me, I'd look at the 0.8 and figure it was sorry CAD formatting and figure it was actually 0.875 rounded which would have been 7/8". 0.6 was probably 5/8".
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• posted on July 15, 2005, 2:10 am
99.999999% of the time .875 is .88 in 2 decimal places, and one place is most likely .9. Brian.
-- www.members.cox.net/bsnikitas
wrote:

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• posted on July 14, 2005, 5:51 pm
snipped-for-privacy@yahoo.com wrote:

If you want them in fractional inches, multiply by 64 to get 64ths, e.g. 0.9 * 64 = 57.6 so 58/64 or 29/32. Similarly, 0.6 * 64 = 38.4 so 38/64 or 19/32.
Double-checking: 29/32 = 0.906; 19/32 = 0.594. Within six-thousandths each time - probably close enough.
If not, multiply by 128 instead: 0.9 = 115/128, and 0.6 = 77/128 (both accurate within two thou).
--
Regards,
Doug Miller (alphageek at milmac dot com)
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• posted on July 14, 2005, 7:50 pm
snipped-for-privacy@yahoo.com wrote:

An "Engineers Scale" is calibrated in decimel form; however, It is only 12" long.
Not the answer to a maiden's prayer, but used in conjuction with a 12 ft tape, will get the job done.
Lew
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• posted on July 15, 2005, 1:24 am
I've got a 6 footer, marked in 1/100.

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• posted on July 14, 2005, 11:15 pm
On 14 Jul 2005 10:26:05 -0700, snipped-for-privacy@yahoo.com wrote:

Here's a site that might help. http://www.cjtkoolcarb.com/catalog/Technical/decimalconversion.htm
Mike O.