I picked up a Fowler 52-646-400 bore gage to help check clearance on an engine I'm building. Specs .0005 Graduations .0009 Total Error .0004 Repeatability .00025 Self Centering Error I should probably have gotten the .0001 resolution since I'm trying to measure .0004 taper and out of round specs as well as bearing clearances at .0025. I am having alot of variability between reading on different days .0005 on a bearing clearance reading between yesterday and today. The block was approximately the same temp. I assume that is due to the error specs on the gage? Does anyone have a clear definition to the above specs or what I should look into for a replacement .0001 resolution gage For comparison I looked up a Shars gage for a possible replacement. 303-3117 Product description Measuring Range:0-1" Graduations: 0.0001" Accuracy (1st 2.5 Rev): +/- 0.0001" Accuracy (Overall): +/- 0.0004" Is Total Error the error over the complete range of the dial .0009 on the Fowler vs .0004 on the Shars for instance?