What are the soundpaths one should calibrate to on the IIW Type 2 Block when doing shearwave? I am only familiar with the IIW Type 1 block. Also, are there any disadvantages to using the mini-IIW type 2 block?
The difference between a Type 1 and Type 2 Block is the Type 2 doesn't have the slot on the flat 12 inches length. To calibrate your time base, position your echos at 4 and 8 on your screen. The range of your instrument should be 10 inches.
Another similar IIW Block may have its thickness half in the radius. If this is the kind of block you are using, you should than position the echos at 2 and 4 on your screen.
As John mentionned earlier, if you take a ruler and measure the distance between the point where your transducer should be positionned and the radius of the block, you shouldn't go wrong.
Thanks for the replies. I should have been more thorough in my original post though. I have an IIW Type 1 block, but it has been bashed and nicked. I'm looking to get a new block. In a previous post, someone mentioned that accuracy may be improved by calibrating on an IIW Type 2 block (over the type 1). I was just wondering what the calibration radius was for both reflectors on the Type 2.
But if the calibration radiuses are 4 and 8, I don't see much improvement over the 4 & 9 of the type 1.
The types 1 and 2 both refer to the large A2 blocks (otherwise referred to as V1) with the 100mm radius. The A4 (V2) "kidney" block is portable and has 25mm and 50mm radii so with leg lengths of 25-50-25 its possible to calibrate for 100mm (25, 100) (1 and 4 in US parlance) and check your calibration by swivelling the probe to the 50mm radius to ensure A-scan shows a signal at 50mm.
I would like to had a comment in reference to blocks. Personally, I prefer the A2 Block that we talked about. Becausee of their size, I find them easier to calibrate on, but they are also heavier than the A4 Kidney Block and therefore a little harder to log around. Regardless, the condition os the block will reflect directly on the accuracy of your calibration. I think that if you buy a new block, maybe you should also invest in a carrying case and keep your block in it unless you are using it.
The IIW V1 A1 has echoes 4” (100mm) then repeating every 5” (125mm). Excellent for 10” 250mm test rang. If you were learning ultrasonic,s in the 1950,s. Other uses for this block, a door stop, or knock out the Plexiglas you can chain enough together and make a boat anchor.
IIW V1 A2 has repeating echo of 100mm that is a good all round test range for testing the majority of welds.
David ,when the beam hits the big radius of the IIW 2, a part of sound is received by the probe so on the screen you have the first echo of 50, while the rest of the sound reflects on the straight part , where jackets the probe, and goes towards the small radius , bringing on the screen at the same time the echo of 75, and so on, then the sequence might be 50,75,125,..... clearly if you'll start by the small radius, the sequence is 25,75,100,.....of course still we can use this block for the calibration, but it was more important once for the analogue instrument calibrations, concluding I think IIW2 is a little exceeded, but hasn't disadvantages.
from my II level. To calibrate paths with small IIW block type 2 start with 25 or 50 mm (small radius or large radius) and then add next paths by 75 mm each time (ie the sum of the two radii: 50 +25 = 75) .
Full scale 100 mm pointing radius 25: set first signal = 25 mm radius to 2.5 divisions; set second signal = 25 +75=100 mm to 10 divisions. Full scale 200 mm pointing radius 25: set first signal = radius 25 mm to 1.25 divisions , set second signal = 25 +75=100 mm to 5 divisions ; set third signal = 25 +75 +75 = 175 mm to 8.75 divisions.
Pointing radius 50, replace 25 with 50. Example 200 mm full scale pointing radius 50: 50 mm first signal ; 125 mm second signal (50 +75); 200 mm third signal (50 +75 +75). You can not do full scale 100 mm with a radius of 50 mm (first signal 50 mm, second 125 mm, that is more than 100 mm).
The block type 2 is very practical. A good policy may be big block IIW Type 1 in the laboratory with blocks DAC for check index, angles, etc., and small block type 2 in field (fits in your pocket !) for verification and changes the time base.
For longer path unfortunately you need the 100 mm radius of the block type 1, and for this there are no pockets……
Forgive the tedium of these numbers!