What is square?

[paul cottingham]

I am building my first tool cabinet, and have a rather embarrassing question. If my diagonals are out less than a sixteenth, (over 43 inches) is that square enough? I know that is probably a matter of personal taste, but does anyone think it will be a huge problem?

thanks!

Paul

[johnny means]

Sounds square to me.:)

[Brian Kent]

If I looked at a nice tool cabinet that was 1/16" out of square over 43" I would say, "Wow, nice tool cabinet!"

[Tom Veatch]

+ 1 for Brian's comment.

1/16" over 43" is 1 part in 688, about 0.0015, or 0.15%.

As my wife says when I grunch about the screwups in my work, "Nobody but you will ever see it". (Seems to me like she says that way too often. :D)

[Tom Hintz]

If you measure diagonals with a tape measure and do not hook the tape in exactly the same position and read the tape from the same side for each of them you can have way more than 1/16" variation anyway. If I get down to the little numbers like that on something that large, I call it square. I want diagonals to be identical but then I also want women to think I look alot like Brad Pitt. Compromises at various levels are a part of life.

[John Keeton]

I don't think anyone could ever see that difference, but it may cause a little bit of work if your door is out of square the other direction. But, that is why you should own a nice little block plane!!

[Caspar Hauser]

'What is square?'

It's a mathematical fiction, that's what that is, along with its cousins plumb and level.

[Angie Orfanedes]

1/16 in 43 inches is less than a tenth of one degree, assuming my math teacher in high school was right. Yep, that's square enough.

[Rich Neighbarger]

[QUOTE= As my wife says when I grunch about the screwups in my work, "Nobody but you will ever see it". (Seems to me like she says that way too often. :D)[/QUOTE]


Too funny.

[Chris Damm]

Being that it is made from wood it will probably move that much as the seasons change.

[Rod Sheridan]

Paul, that's perfectly acceptable on a cabinet of that size.

I always had trouble measuring diagonals accurately, was the tape tip in the same place etc.?

I made a pair of sliding sticks with the end double bevelled so that it fits inside corners.

The stick method is so quick and accurate it's amazing. I wish I had thought of it first and patented it.:D

Regards, Rod.

[Prashun Patel]

As long as your doors fit and close flush, then nobody will ever see.

[Ted Calver]

+1 on Rod's sliding stick method.

[glenn bradley]

You're good.

[paul cottingham]

Thanks for all the replies. I strongly suspected that my margin of error, especially with a tape, canceled it out, but have no idea about which tolerances are acceptable. The fellow I am learning from is very precise, so its a mixed blessing. I am sure he would say it is OK tho'. :-)

[Tom Veatch]

...I made a pair of sliding sticks with the end double bevelled so that it fits inside corners.

The stick method is so quick and accurate it's amazing. I wish I had thought of it first and patented it.:D



I'm glad you didn't patent it, else I might be paying royalties. That's exactly the same method I use. And I certainly agree, much quicker and more accurate.

In fact, you really don't need an elaborately constructed sliding stick (adjustable story stick), a couple of pieces of scrap and a couple of spring clamps work almost as well.

[Mac McQuinn]

Being that it is made from wood it will probably move that much as the seasons change.


+1,
Finish it, learn from it and apply the knowledge to your next project. ;)

Mac

[Paul Atkins]

Ever have a furnituremaker frame a building? The guy that helped me wouldn't quit fussing till my 24x40 shop building was within 1/8" diagonal. I'm sure as soon as it was set the wet doug fir started moving all over the place, but he was happy for a little while. Also the real error is half of what you measure.

[paul cottingham]

I gotta say, I really appreciate all the feedback, without all the attitude and sarcasm I have received on other websites.

So to all who took the time to respond, thanks!

Paul

[Andrew Auletta]

I am building my first tool cabinet, and have a rather embarrassing question. If my diagonals are out less than a sixteenth, (over 43 inches) is that square enough? I know that is probably a matter of personal taste, but does anyone think it will be a huge problem?

thanks!

Paul
A really cool tool for holding the tape in place when checking diagonals: http://www.rockler.com/product.cfm?page=18032&filter=square%20check

[Darius Ferlas]

I don't mean to get into nitty gritty but since the topic is precision, it needs to be mentioned that diagonals do not necessarily prove that the geometric figure is square.

Example (where diagonals are identical):

[sean m. titmas]

I also use the pointed sticks and a spring clamp method to check diagonals but even when the box is a bit out of square i will match the inset doors to the panels so that the reveal is consistent on all edges.

even though i aim for true PLS with my cabinets and furniture most times i try to keep some sort of realistic minimum standards for accuracy. 1/16" in 40" is, by most any woodworker, an acceptable deviation from true PLS.

[Rich Aldrich]

I work at a paper mill for my day job. When I was a college boy and worked at the mill as summer help, the people had a saying " good enough for who it's for." I use this jokingly all the time. My wife laughs at me when I say this because I am more picky than she is and she knows I dont give up until I am satisfied. What would you expect from an engineer.

I agree with the others, less than 1/16" on 43" is very good. Until I did a good tuning on my tools, everything I made was 1/16" out - regardless of size. That got to me - hence the tool tune up.

[Jeff Bratt]

I don't mean to get into nitty gritty but since the topic is precision, it needs to be mentioned that diagonals do not necessarily prove that the geometric figure is square.

If opposite sides are the same length - then the diagonals do indicate whether or not a rectangle is square. And if the pieces are not sized correctly, then nothing you assemble will ever be square. So the diagonal measure can be though of as the sum of any errors in both squareness and size.

[Harold Shay]

this will be square until you try to hang it on a sheet rock wall that has mud out of square and you will have to use a scribe mld to make the crack look good.
close enough for me
Harold

[Tom Veatch]

I don't mean to get into nitty gritty but since the topic is precision, it needs to be mentioned that diagonals do not necessarily prove that the geometric figure is square.

Example (where diagonals are identical):

True, you also have to verify that opposite sides are equal in length. Only then does equal diagonals = square

[Tom Clark FL]

Square = a 90 degree angle. (Unattainable.)

How close you need to perfect is simply whatever tolerances the project requires.

Us old tool-and-die makers know that there is no perfect. However, for us woodworkers, whatever works is good enough! To try to obtain perfection is a waste of time better spent on other projects.

I have a couple of dozen shop cabinets. None are perfectly square but all work perfectly.

( I just use a contractor's square for assembling my projects.)

[Mitchell Andrus]

Being that it is made from wood it will probably move that much as the seasons change.

Plus, It'll deflect more than that as you load stuff into it.
.

[Thomas Bank]

Ever have a furnituremaker frame a building?

Trying working with a machinist on any similar task... :D

When I'm lopping things off to weld them up and my father is talking thou's I do my best to just tune him out.