Let's see if I can do this without a book in front of me and keep it all straight:

TEA: Theoretical, Effective, Actual.  Fillet welds have different descriptions that define various aspects of the engineering involved.
Theoretical is the amount the engineer can calculate for strength and is the smallest of the three and extends from the root of the joint to the hypotenuse of the triangle.
The effective is from the weld root to the hypotenuse. 
The actual is from the weld root to the face of the convex fillet weld. 

Each progressively larger and obviously stronger provided you have no lack of penetration at the root so the weld goes beyond the joint. 

On a concave fillet weld the Effective and Actual are equal as the face's concave surface makes them equal from weld root to weld face. 

Now, for the rest of your first question, as inspectors we measure fillet weld leg size.  For regular T joints and skewed joints.  It is up to the engineer and/or detailer to calculate and give us the leg size compared to the throat size they want for strength required.  But, if you are looking at the throat then the theoretical is what the engineer has called for and is smaller than the effective or actual weld face because of convexity that protrudes beyond the hypotenuse, about an 1/8".  Then, since the other is also considering an estimate of weld root penetration, they will add another 1/16-1/8" for root penetration for a total anywhere from 1/8-1/4".  The gauge is designed to 'ESTIMATE' the dimension.  It will not be accurate. 

Second question, first, many people call it an AWS gauge.  Look at your own first description/name for the gauge and then give it initials.  'A'utomatic 'W'eld 'S'ize Gauge.  So don't make too much of the designation.  It doesn't have anything to do with the 'AWS' or any of it's codes.  It is a play on initials as identifying terms. 

Now, maximum convexity must be removed.  Maximum concavity must be added to.  There is NO comparison between the two.  Each weld has it's own criteria.  It is either concave with proper measurements or more.  Or convex with proper measurements or more.  Maximum Convexity is too much reinforcement which results in stress risers and other potential problems.  Maximum Concavity is to small of a weld that means the throat won't be adequate for the weld size required. 

Hope my descriptions clarified that for you.

He Is In Control, Have a Great Day,  Brent

Most likely those guages are sized to verify the theoritical throat and the max convixity per AWS D1.1. Compare them on an actual weld or sketch a full scale drawing of a fillet weld and apply the D1.1 criteria and you will see if that is the case. Most likely it is.

Ramon

Ok so there are a couple of areas of concern here:

1. Please don't think since I said I am a CWI that I am arrogant or think I know it all as I am very humble and always willing to learn, especially since there are very knowledgeable individuals on here.  I appreciate you taking the time to define the difference in TEA as you never know who you are talking to.  I wanted to try and convey some comedy and sarcasm instead of taking my response in a negative way.

2. After reading Al and your (brent) response I have a concern that I will never have a throat size requirement unless called out on a drawing or in a specification.  I'm concerned since this is an assumption, if you will, that a standard fillet weld size on a drawing will have to meet leg and throat sizes of a fillet gauge.  I have been taught this and this is a standard "assumption" of everywhere and by anyone who has measured standard fillet welds, not including skewed joints or any other fillet weld that is not a standard 90 deg/right angle geometry.  Are you saying I should never accept a weld unless the weld symbol, drawings, or specs call out specific throat sizes?  I am not disputing the fact in which there can be a throat dimension call out, I just have never heard of it unless it is a skewed joint, a T, K, Y connection or other situation that is typically determined by calculations of various angles and Z-loss and all that fancy stuff which we cannot measure anyways.

I used the extreme 1" leg size and 1/4" concave throat as an extreme to express the fact that if there are no requirements how can I accept or reject an underrun weld?  I have seen concave finish weld symbols as they are rare but still do not call out a dimension, is this where the AWS gauge comes into play?

If for example you have a 3/8" required fillet weld per D1.1 and there are no specific throat size requirements and a 5/16" leaf fillet gauge touches the throat for 5% of the total weld length and 100% of the weld has a leg size of 3/8", is this acceptable or rejectable as it meets the 10% requirement?

3. I guess it is unanimous that other than a typical "leaf" style fillet gauge is about the best bet for measuring fillet welds and shouldn't use any adjustable type including a bridge cam or AWS gauge.

4. There have been many situations where a leaf style gauge is not possible to use and a bridge cam or other style gauge is required.  I have seen many times where one of the larger gauges accuracy are affected due to warpage or some type of interference making them ineffective.

5. I still don't see someone explaining the differences on T and A on the bridge cam.  Why are they so different?  If I set a 1/2" throat on actual it is the same throat dimension as a leaf 1/2" fillet gauge but the theoretical is quite larger.  Please explain the difference.  This cannot measure the penetration of the weld to the root.

6. I personally don't like to use anything other than a V-WAC or a leaf fillet gauge, but a lot of times I cannot measure a weld since the unequal legs are so freaking large due to a retarded welder putting way too much time and effort into something due to lack of skill.

Maybe we need to back up and someone can give me very specific situations or videos or links to how to interpret the use of all the different gauges.  I have reviewed many videos, PDFs, manufacturers detailed descriptions and I am going to go back through some other references.  So far nothing describes what you both are saying or maybe I am missing something.  I wonder why after 8 years of various industries, CWI's, SCWI's, Level IIIs, engineers, prep courses no one has ever mentioned this.  I am not saying the information is incorrect as I have been lied to many times and never investigated myself and I have been burned because of it, I am reluctant to just agree but I challenge others to give me proof or references.

Al,

I checked out the link and I remember now reading that article.  I will be using that as a reference when training new inspectors if necessary. 

My concerns with this link in respect to the throat dilemma is it agrees with me which the throat is measured the same as leg size.  I understand that this is just to show how to size a weld and doesn't reference each weld has acceptance criteria but he still doesn't say inspectors are only required to size legs and not throat.  If you would like to check some of the figures and paragraphs I have some references you look at even though this is just something that shows how to measure fillet welds with leaf style gauges:

He sees to use a 1/2" fillet weld as a reference a few times which has a theoretical throat dimension of 0.354" as I'm sure you are aware.

He states this when describing leaf fillet weld gauges: "that saves the inspector time needed to calculate the required throat dimension for each leg dimension"

Figure 7 states "fillet weld gauge sizing a concave fillet weld that has insufficient throat to meet the size requirements of fillet weld with 1/2" legs"

Figure 4 "1/2" gauge used to verify throat is properly sized for 1/2" fillet weld"

Pg. 15 "As shown in fig. 4, the right end of the gauge is used to size the throat of fillet welds"

So you can see my concern as I am being fed information and I am reading information that seem to have some discrepancies.  I understand that you can have required fillet weld dimensions which may be unequal legs or throat but so far my assumption is correct and saying the leg size determines the actual throat is the "assumed" dimension  unless otherwise noted.  No one has provided me with reputable specific standard that says inspectors are not required to size throats of fillet welds.  Like I said before that I was trying to prove a point by what Al and Brent are saying is that you can easily have a 1" fillet weld with a sized 1/4" throat and be acceptable. 

I find it very hard to believe you have been hired to inspect some fillet welds on a job and told an engineer/detailer/PM or whomever that you were NOT able to do a proper weld inspection since the drawings or specifications didn't give throat dimensions or finish contour dimensions?  I would assume that you have accepted fillet welds without throat dimensions, am I wrong?

I'm not a ASME inspector and maybe that is a standard requirement.  Every job I have been on/at that has AWS specifications has never required specific throat dimensions.

I am still waiting on how the T and A sides are so different on a bridge cam.  GAL Gauge hasn't replied yet.

The concern with throat dimensions were not the original concern but the use of how to size them with various gauges.  Now a new concern with sizing weld throat has been brought to my attention.

I'm not familiar with ASME, so if there are calculations I'm not to concerned with that but I am concerned with the fact a welding symbol doesn't state a specific throat dimension so I will size it the same as the leg.

AWS 3.0 has some great figures and are very good to show examples of fillet welds, but AWS 3.0 doesn't show you how to size them with specific gauges and what is the proper way.  AWS 3.0 also doesn't state weld size includes the leg and throat but does clearly the differences on the definitions of each part of fillet welds.

You are correct in the fact that as long as you know what end to use it is quite obvious how to size with standard fillet gauges. 

You're asking me why I am using "the right tool for the job"?  Why would you use a "trimmed" gauge for a skewed T-Joint?  Why wouldn't you use a proper tool, such as a skewed filled gauge?  Why would someone use a modified gauge?  In the nuclear world I would be in a lot of trouble for altering a calibrated gauge when I could use a proper tool for the job.

AWS gauge doesn't mean it is used strictly on American Welding Society standards such as D1.1.  The instructions and this link also shows that it is recommended for sizing fillet welds:

http://www.galgage.com/AutomaticWeldSize.pdf

Like I said twice now, I would rather use a standard leaf type fillet gauge but there are man times I cannot use them.  I assume that since we are on a AWS forum that you have had experience with inspecting oversized welds and how 90% of the time there are no restrictions on making a weld that is oversized.  I would quote the requirement of oversized welds but I don't want to misrepresent the code.  When the weld symbol doesn't have a throat dimension, which is very common in structural welding applications, you will be assuming you are required to size the throat.  Example of when I can't use a standard leaf fillet gauge:

1. Weld symbol says 1/2"
2. An oversized weld was deposited and was considerably concave.
3. The actual weld legs are 1"
4. I cannot use a standard leaf 1/2" fillet gauge due to the fact that the legs are oversized to 1" and in order to perform a proper weld inspection I should use another option to size the throat now that I know the leg sizes are met.
5. I choose to use either a AWS or bridge cam to size the throat.
6. By choosing a bridge cam with what I can assume is the correct side to size with the "actual throat" I come up with 1/4" to 3/8" in various locations along a 24" weld. 
7. By this I find that the throat is under run and is rejectable due the fact here are no specific throat size requirements but do not meet the weld size of 1/2" according to the weld symbol.
8. By what some of you are saying that this is acceptable due the fact there are no specific throat size or contour requirements.

I'm throughly disappointed in what I'm reading, maybe because I'm held to higher standard in the nuclear industry, which has so much oversight and auditing including, the NRC, customer source inspectors, and our own internal people.  I've been stuck in the structural world for the majority of my inspection career since 2006 and I guess things are different in other industries.  I realize that other industries have different standards and practices and maybe those are the facts as I'm just trying to learn and be the best I can with proper references and standards to back me up instead of making guesses based on what people have told me in the past.

ANGELS  Al, unless you have figured out how to make my angle finder dance. 

Couldn't resist such an opportunity.

He Is In Control, Have a Great Day,  Brent