How square?

[andrewm]

How square is square? I have just had a Japanese carpenter?s square delivered from Axminster. I normally use a standard carpenters square but got this for the construction of large carcasses. It is described as ?they have to be very accurate, because if the carpenter's square is 'out' then the whole building is going to be 'out'.? A quick test by laying it along a straight edge shows that the 500mm arm is about 1mm out when it is turned over. That makes the angle about 0.05 degrees out which doesn?t sound very much but just how accurate should a square be?

 

[Dewy]

A square should be perfectly square.
Return it for a replacement.
I had one carpenters square that was out.
I only realised when I put it against my engineers square.
It was only worth hanging up for show.

 

[chiba]

Andrew - you can return it, but they wander out of square in use anyway. They can be adjusted though... with a hammer. :twisted: First, figure out whether you're going to make the angle more acute or obtuse (the usual draw a line, flipover and redraw). If acute, lay the corner of the square flat on an anvil and tap the metal toward the outside of the corner. You don't need to whack it, you're just trying to distort the metal fractionally and bring the arms together slightly. Remember, whatever you do will be magnified - keep redrawing to check how close you're getting. You naturally do the opposite to make the angle more obtuse, i.e. tap the inside of the corner. Good luck. 8)

 

[Mdotflorida]

They can be adjusted though... with a hammer.

Won't this make the whole thing loose. Could you ever trust it again ?

 

[Anonymous]

Andrew

Is it the square that is out or the thing you tested it against? When you flipped it over, was it resting against the same piece of the material as for first line? if not, then it might be your datum that is out rather than the square. Or, in other words, how stratight is the straight edge you used? A cut piece of wood is likely to have the sort of error you mention.

All engineers squares come stamped to BS???? for squareness and so I would check the new square against one of these rather than the method you previously used.

Cheers

Tony

 

[Gary H]

Won't this make the whole thing loose. Could you ever trust it again ?

I think you really need to fix the blade in some way, and not hold the body, otherwise it could become loose. Depends on how 'delicate' you are with a hammer, I guess.
I'd be no use. It'd end up looking like scrollwork by the time I'd had a go at it! (Thats why I bought a brad gun )

Ta muchly

Gary

 

[Alf]

For slightly more precision in adjustment, you could use a centre punch between the square and the hammer... :roll: I think, on the whole, if further tests confirm it is out, I'd consider returning it. An out-of-square square you've paid good money for might just end up being a sore point. :? BTW, can't good old Pythagoras help on square testing? 3-4-5 and all that? (I'm floundering here; no one told me at the time that maths of that sort might turn out to be actually useful )

Cheers, Alf

 

[Anonymous]

Are you sure the straight edge is straight ?

I've got a 1m metal rule that I use for drawing long lines between pencil marked measurements, and noticed on Sunday that it had developed a concave curve along one edge and convex on the other :shock:

When not in use it hangs by a nail on the wall, hasn't been dropped, or missued in any way.

So, I have to assume that the heat buildup in the workshop (sounds grand for the garage!) has affected it in some way as it can get to over 90º in there.

 

[Dewy]

Andrew, If you do decide to return it don't hit it 1st to try to correct it.
They will say you caused it going out of square so are unlikely to exchange it.

 

[Anonymous]

Generally speaking, if you want square, get an engineer's square - as stated before, should be marked with a BS kitemark (don't recall the number), which guarantees a very small 'non-squareness' in a quite large distance!

Squares with wooden stocks are the most likely to be out, BTW.

 

[gidon]

I would ring up and ask for a replacement. I had to so the same recently with a slightly bent large square - and had a replacement next day from Axminster. And got to keep the old one .

Cheers

Gidon

 

[andrewm]

Just to clarify what may be some confusion here this is a single piece of metal type square (as described here http://www.axminster.co.uk/default.asp?part=384026) not one with a handle, i.e. one arm of 250mm and one of 500mm so correcting it with a hammer might work and won't leave a loose blade since it is all one piece.

Goo point about the straight edge I was using a piece an Axminster straight guide rail but I've never tested it so I will take a look tonight.

For smaller work I use and engineers square but for large carcasses I was looking for something that would show up errors over a larger distance.

Alf,
3-4-5 does indeed make a perfect right angle but that just rather shifts the problem to making sure that your 3, 4 and 5 are accurate. Ho hum.

Andrew

 

[Alf]

3-4-5 does indeed make a perfect right angle but that just rather shifts the problem to making sure that your 3, 4 and 5 are accurate. Ho hum.

Yes, well, I didn't claim it'd be easy... :wink:

 

[Anonymous]

Goo point about the straight edge I was using a piece an Axminster straight guide rail but I've never tested it so I will take a look tonight.


Andrew

This is exactly what I was talking about in my post earlier in the day. The error may be in the reference edge rather than the square.

I have an Axminster 'straight edge' and it isn't!!!

Cheers

Tony

 

[johnjin]

Hi Andrew

Send it back
You paid your money for a square.
If you try to adjust it and screw it up they won't have anything to do with it.

John

 

[Anonymous]

To claim any sort of descent squareness it needs to conform to BS939 probably Grade B (workshops).
I'm not too sure of the figures as you only seem to be able to find them by looking at what is printed in catalogues. Interpreting what is printed, this seems to be +/- 0.016mm for squares up to 300mm.
For squares over 300mm up to 600mm this would be a tad bigger but I would say that being out by 1mm is unacceptable.
Trouble is to get a big square with that accuracy, you are going to pay a small fortune.
Looking at the item on the Axminster site, I doubt if you would ever get a real level of accuracy just from the use of words such as flexible.
I would bet that due its construction that there is little you can do to make it accurate or to even keep it accurate.
Try checking the width of the arms as well to see if they are parallel along the length and of constant dimensions as well. I bet they're out a bit as well which will add to the inaccuracies.

 

[mudman]

Blast thought I was still logged in.

Cheers,
Barry

 

[Dewy]

Just been reading the axminster site.

The exact equivalent of the western carpenter's framing square and used for exactly the same purpose. In fact they have to be very accurate, because if the carpenter's square is 'out' then the whole building is going to be 'out'. However, unlike western framing squares these are light and flexible. The cross section of the arms shows a bevel on each edge allowing the square to be tilted when marking out, bringing the graduations closer to the workpiece,minimising errors caused by parallax. This bevel also helped prevent ink from smudging when the Japanese carpenter drew a line or, more importantly, it kept the marking knife's edge from damaging the square. The arms are graduated in centimetres and millimetres. Interestingly the reverse of the long arm has a scale for determining the maximum size of a square beam obtainable from a round log, simply by placing the scale across the diameter and taking the measurement. Small square 300mm x 150mm, large square 500mm x 250mm.

The square delivered does not appear to conform to it's desription.

 

[The Wizard]

Question: When is a square not a square?
Answer: When it is not a square!

If you are looking for high levels of accuracy, then an engineers square is the way to go. I would however agree with other posts that accuracy over greater distances is difficult to achieve.
I liked the earlier comment that "If the square is out, the whole building will be out", have you seen the way they build houses these days. :roll:
I bet that donkey gets sick of its hind leg been used to line things up. :lol:

On the 3-4-5 thing, if you are wanting to square a cabinet or other carcass type construction, use a measuring stick. You don't need a measure or Pythagathingy to ensure the job is square.

Wiz

 

[devonwoody]

I purchased a combination square whilst on holiday earlier in the year from one of those cheap type warehouses , paid the equivalent of around £2 At the time I thought I might be wasteing my money but I regularly check by turning the piece over and its still accurate over the 12" blade.
So I wont be buying any more expensive square setting tools. (also got a roofing square and thats OK as well).