skewed fillet guage use

Date 10-22-2008 15:04

Gal can do one better than that. they have a CD they can send you with physical demonstrations. At risk of sounding like an advertisement for GAL They've been exceptionally helpful for me in the past and the present. That CD in question also covers gap olets.

As for how to, remember to keep the arm fully extended, trying to move it back on the pivot point will screw up the scale.
As for taking the measurements, remember the right triangle rule for fillet welds doesn't apply as you do not have the standard 45 degrees.
You can calc these out manually, but I suggest you get the slide rule from GAL, it's a lot easier than calcing it out each time.

By eekpod

Date 10-22-2008 19:38

I have one, but havent had the need or energy to figure it out. I should practise with it now, so when I ned to rely on it, I am confortable using it. It just that it looks intimidating.

By CWI555

Date 10-22-2008 20:18

It's fairly easy to use. The key is to read what information it's asking for, and remember the definitions of W dimension, L dimension etc. After that it's about a 2 to 5 second process.

By ctacker (****)

Date 10-23-2008 00:11

get the slide rule from GAL. it makes it so much easier to use.

By supermoto (***)

Date 10-24-2008 17:00

I have the slide rule. Now I am clear on where to read the W dimension on the actual guage, but how does the theoretical throat, leg size of fillet, and inspection dimension on the slide rule all work together?

In other words how do I read the slide rule/skew-t fillet weld calculator? I see the instructions on the left side:

Set Theoretical Throat at arrow.

Read Leg Size of Fillet and Inspection Dimension at Dihedral angle.

If I did what it is asking me then I should know the Theorectical throat but say I don't know that but I do know the what the leg size should be, how do I set the arrows on the Theortical throat if I only know the leg size?

By Mwccwi

Date 10-24-2008 17:57

how do I set the arrows on the Theortical throat if I only know the leg size?
Multiply the leg size by .707--- now you heave the throat.

By supermoto (***)

Date 10-25-2008 17:25

Ok, so .707 is a constant to figuring out the theoretical throat once you have the leg size.

Didn't know this, and very great calculation.

By CWI555

Date 10-25-2008 19:25 Edited 10-25-2008 19:31

Theoretical throat is the designated weld size per drawings. the .707 comes from a right triangle on a standard fillet weld. For the standard fillet you'll have a 90 degree perpendicular member/face. for skewed T by definition you do not have that. .707 is short for .7071 which is the sin of 45 degrees.

Draw out a lines for an equal leg fillet weld and you will find that the angle created in the cross section is 45 degrees. If you had a 1" equal leg fillet, the face to root would be .7071 " at the center of the face.

you do not have that in a skewed T therefore the sin of 45 (.7071) does not apply.
For instance:
45 sin = .7071
45 cos = .7071
45 tan = 1

as compared to say a 50
50 sin = .766
50 cos = .643
50 tan = 1.19

What do you think that is going to do to your measurements. .7071 is derived for calcing out your throat when you have a concave fillet weld as the size is the largest right iscolese triangle that will fit when you measure the throat.

a)A right triangle has one 90° internal angle (a right angle). The side opposite to the right angle is the hypotenuse; it is the longest side in the right triangle. The other two sides are the legs or catheti (singular: cathetus) of the triangle.
b)An oblique triangle has no internal angle equal to 90°.
c)An obtuse triangle is an oblique triangle with one internal angle larger than 90° (an obtuse angle).
d)An acute triangle is an oblique triangle with internal angles all smaller than 90° (three acute angles). An equilateral triangle is an acute triangle, but not all acute triangles are equilateral triangles.

That is where the obtuse and acute terminology comes from.

You can break out the right forumulas and calculate by hand, but this is why I advised using the slide rule calculator. For the inspector, he or she should be working to a set of drawings, those drawings should give the required weld size, be it acute or obtuse in this case, and that value is what you plug in for Te.