03-29-2018, 02:26 AM
Greg, I don't know about your set but Starrett says they express their deviation in microinches (0.000001") or micrometres (0.001mm)
They measure a reference point (3 times) and average them. Then that number is compared to measurements taken at 4 other 'auxiliary points' (1 time each) to get the deviation. So the way I am reading it a deviation of '4' would be equal to 0.000004"(?) which is certainly way beyond my capabilities for measurement. I'm thinking once I get mine cleaned up I will run them under a 10ths indicator on my surface plate and if I can see any needle movement at all the block is probably junk. Of course that only applies to the 2 lapped measuring surfaces. Starrett also has instructions on how to check a gage block's wringability using an optical flat. It just so happens I bought a couple of optical flats some time ago during a Surplus Shed sale. So I'll be checking them for that as well.
Randy, I also read the Starrett use and care pages and there it says the average life expectancy of a gage block is about 3 years.
One thing I remember from watching one of Tom's videos was that he recommends using plain old Vasoline petroleum jelly for lightly coating your gage blocks for storage. I have been using his idea ever since for the pin gage sets I have and found it works a treat. So I'll definitely be doing the same with the gage blocks as well.
They measure a reference point (3 times) and average them. Then that number is compared to measurements taken at 4 other 'auxiliary points' (1 time each) to get the deviation. So the way I am reading it a deviation of '4' would be equal to 0.000004"(?) which is certainly way beyond my capabilities for measurement. I'm thinking once I get mine cleaned up I will run them under a 10ths indicator on my surface plate and if I can see any needle movement at all the block is probably junk. Of course that only applies to the 2 lapped measuring surfaces. Starrett also has instructions on how to check a gage block's wringability using an optical flat. It just so happens I bought a couple of optical flats some time ago during a Surplus Shed sale. So I'll be checking them for that as well.
Randy, I also read the Starrett use and care pages and there it says the average life expectancy of a gage block is about 3 years.
One thing I remember from watching one of Tom's videos was that he recommends using plain old Vasoline petroleum jelly for lightly coating your gage blocks for storage. I have been using his idea ever since for the pin gage sets I have and found it works a treat. So I'll definitely be doing the same with the gage blocks as well.
Willie