>The best I can find on the web is 1/64" but this is the tolerance that the gage is held to prior to being shipped.
This makes good sense to me, since the gage is incremented in 64ths. But really you can write the tolerance into your quality manual that you are comfortable with. I'm not aware of any national standard, so use what makes sense to you at your facility, and still ensures a sound product.
I would tend to go with tolerances listed in Table 6.1 of D1.1 for undercut, since we use that table for acceptance criteria that will be checked with teh V-Wac gage.
For the most part I agree with John. Your QC manual should have tolerances for all your company's QC tools written into it. I will have to look at who makes it, but I have a 'calibrated' V-wac gauge for doing checks of my everyday user. Also have calibrated fillet gauges to compare wear on them. My personal QC calls for 1/64th I believe, I will have to look it up again now that you have asked.
As far as industry standard, I don't know where you will find it, I have always been instructed that the equipment is only accurate to plus or minus whatever the smallest measurement mark is. Rather that is on a micrometer, V-wac, tape measure, etc. Now, most machinists I know, as well as the rest of us, will often guess at a half measurement in between. Such as, the micrometer is laid out to .001 increments (thousands of an inch) and when measuring the part comes out to between .043 and .044 so they call it .0435. We often to the same with a tape measure marked in 1/16ths. If it comes out in between we call it out in whatever 32nds.
Having said that, when measuring for code compliance, it is either to the code and gauge specified allowable measurement or it is not. No need to guess at in between increments. It is either within the allowable, or it is outside the allowable. When it is greater than it is rejectable. No need to get that precise, just say, it was greater than the code allows.
Most tooling, micrometers, V-wacs, etc have adjustability to zero them for a while. Once they pass being adjustable it is time for replacement.
Have a Great Day, Brent
I don't believe the V-Wac gage has any adjustment other than to bend the pointer.
I do not believe you can calibrate a measuring instrument that has no adjustment feature. You can check it using a gage block to verify it is reading within accepted limits, but there are no adjustments that the user can make to cause it to read more precisely.
If the pointy ends get worn, I suppose one could "sharpen" it. The lever arm could be tapped with a ball peen hammer "adjust" the pointer. However, should the fit of the pointer on the pivot develop excessive play, there is little that can be done to correct the situation.
Al
Always check to gauge on a flat surface before use, to see if you need to adjust the pointer.
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