In this video I would like to talk about try squares and how to check if the
are really at right angles.
It may come as a surprise to most handicraft beginners that the most angles you can buy
can't have a right angle. so unlikely that sounds like it, but it is.
I've even had geotriangles that aren't were at right angles.
You wouldn't believe it.
This is a combination angle from which Starret Company.
That's the angle I took many years ago I bought it myself, and I'm not going to buy it from the
Company Starret nor anyone else for it to introduce this one.
That angle is, you could say that, very expensive.
However, from this model there are also cheap clones.
In this video I want to show you how to can check whether this angle or the replica,
if you have one, is also in the angle, or whether the 45° are correct or whether this spirit level
is actually really correct.
And I'd like to start by showing how you can check if an angle is really
90°.
Checking the 90° angle
All you need is a board with a straight edge. And then you put
the angle here and makes a dash and then you turn the angle to the
other side and the trick is now the, I won't try that line again.
but I will put a line right next to it.
These lines should be absolutely parallel and the amazing thing is that the human eye
detects even the smallest deviations.
But when you try to redraw the line, you don't see it so well because the thickness
of the pencil stroke, under certain circumstances the Error concealed.
Checking the 45° angle
To check if this is actually
45° are I'm gonna need a semicircle that goes right to
of this edge begins and because you can't stab here, with
I have here a board for the compass the same strength, that goes here
and I'm forcing myself to do it here, provisionally. So and now I can get here
put my compass right in this crack and make a semicircle here.
Now the clamp comes away again and the board too
So here's the semicircle and now
is created here at the corner and drawn a line
and then it creates the other corner and then the two lines should converge
here on the arc of the circle.
For all those who still remember their school days remind
this is the theorem of Thales
Checking the spirit level
And last but not least this angle here also has a spirit level
and that should of course also go exactly but because it's very small
I'm demonstrating this here at a large spirit level
But the principle is exactly the same and it works the same way on this little
spirit level The idea is the following
You put the spirit level on an edge here. Flush on one side and then
you look where the air bubble touched the line
or by how much it protrudes beyond it depending on whether the table is now horizontal
or not And as you can see
the air bubble on the right protrudes a small piece approx. one mm beyond the marking
Next up is I turn the level over
and put them in exactly the same place and then
the bubble exactly that one millimetre beyond it again.
I know just now and you can see
with this spirit level that is not the case
That means this level is not accurate.
In the same way you can also check this level
for the vertical To do this, you put them
to a vertical surface
in this case they are actually in the middle
and then you turn the level around. and puts them back in the same place
and then she should also be in the in the middle.
And here you can see a very small deviation
However, this dragonfly can be readjusted.
For a bricklayer this level would be sufficient.
This is the spirit level from the Starret brackets
and you can see in this case the ground is not quite even
the air bubble touches fairly accurate
at the right side the line and when I turn her over
it should behave exactly the same that is
and we see even in this case after I turned her over.
have it touches the air bubble on the right.
Page the line That means this spirit level is actually
exactly.
If you liked the video I'd cross my thumb up.
rejoice and if you have any questions
please write this in the comments below
Thanks for watching.
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