Randy Meijer
05-15-2006, 4:52 AM
There are two active threads on tape measures right now and after reading through them I thought I would ask a questiion that hasn't really been addressed in either.
How do you go about checking the accuracy of a tape measure?? I imagine there are many ways to check; but some, presumably, are simpler than others.
Just for fun, I gathered up all of the tapes I could find and checked them by measuring a single premarked distance. I have everything from a 30 year old Craftsman 20' tape to 16' Wal-Mart Special. There were a total of 5 tapes checked and they ranged from 10 footers to 20 footers. I don't like big bulky tapes and don't have a need for them so the stable does not include a 30 footer. The distance was marked off from the edge of a desk to a line scribed on a piece of paper taped to the surface of the desk at the other edge. The distance was 54 and 5/16" and that is exactly what each tape measured ± the thickness of the marks which are about 1/100 ". Pretty darn good, think!! But I probably need to check them at 1' and 3' and 10' and 15' and 20' to be sure that those distances are accurate and how do I know that each 1 foot interval is divided into 12 equal 1" increments??
And how do I know that all of those tapes that say 54 and 5/16" are correct and are not really measuring 54 and 3/4"? I understand that if yoyu have 5 tapes that are all reading the same, you are probably OK; but what do you do if you only have 2 tapes and they don't agree.
Please correct my thinking if it is wrong. Seems to me that a tape measure is sort of like a roll-up story stick and it doesn't really matter much if the marked distances are correct or not provided you only use one tape on a project and that you don't do any math; but rather measure all distances, i.e. two measured distances of 5' may not equal a measured distance of 10'?
Thanks.
How do you go about checking the accuracy of a tape measure?? I imagine there are many ways to check; but some, presumably, are simpler than others.
Just for fun, I gathered up all of the tapes I could find and checked them by measuring a single premarked distance. I have everything from a 30 year old Craftsman 20' tape to 16' Wal-Mart Special. There were a total of 5 tapes checked and they ranged from 10 footers to 20 footers. I don't like big bulky tapes and don't have a need for them so the stable does not include a 30 footer. The distance was marked off from the edge of a desk to a line scribed on a piece of paper taped to the surface of the desk at the other edge. The distance was 54 and 5/16" and that is exactly what each tape measured ± the thickness of the marks which are about 1/100 ". Pretty darn good, think!! But I probably need to check them at 1' and 3' and 10' and 15' and 20' to be sure that those distances are accurate and how do I know that each 1 foot interval is divided into 12 equal 1" increments??
And how do I know that all of those tapes that say 54 and 5/16" are correct and are not really measuring 54 and 3/4"? I understand that if yoyu have 5 tapes that are all reading the same, you are probably OK; but what do you do if you only have 2 tapes and they don't agree.
Please correct my thinking if it is wrong. Seems to me that a tape measure is sort of like a roll-up story stick and it doesn't really matter much if the marked distances are correct or not provided you only use one tape on a project and that you don't do any math; but rather measure all distances, i.e. two measured distances of 5' may not equal a measured distance of 10'?
Thanks.