Nirvana Posted October 27, 2013 Share #1 Posted October 27, 2013 Hmm, I was cleaning my work table and placing items in their proper areas. I have four metallic rulers, both showing the metric and imperial units. By pure curiosity I placed the shortest one, 15.24cm - 6" next to my 30.48cm - 12" and my two 45.72cm -18" and found differences. None measured as the other. The difference is so slight, but could probably cause error when mixed. Now I marked the 15.24cm and 45.72cm that are almost identical. The other two to be donated to friends 3rd grader school kids. A high quality digital caliper needs to be purchased. sonicmcdude and trippwj 2 Quote Link to comment Share on other sites More sharing options...
realworkingsailor Posted October 27, 2013 Share #2 Posted October 27, 2013 As long as you continue to use the same ruler every time, the error should be constant... rather than random.... Still.... something for everyone to be aware of. Andy WackoWolf 1 Quote Link to comment Share on other sites More sharing options...
JeffT Posted October 28, 2013 Share #3 Posted October 28, 2013 Good catch. You'll definitely want to use the same one consistently. WackoWolf 1 Quote Link to comment Share on other sites More sharing options...
sonicmcdude Posted October 28, 2013 Share #4 Posted October 28, 2013 Compare a metal ruler with a caliper and then use ONLY them. I compared a plastic triangle and is off almost by a mm. Quote Link to comment Share on other sites More sharing options...
cdogg Posted October 28, 2013 Share #5 Posted October 28, 2013 Good to know. I also know what I am doing when I get home from work tonight! I have about 6 different rulers, thanks! Quote Link to comment Share on other sites More sharing options...
BANYAN Posted October 28, 2013 Share #6 Posted October 28, 2013 Sinan, but first check the caliper is accurate first Mine were out and I have just invested in a "Certifed" digital readout Caliper. Per, the other trick is to check them for straightness. I believe the check is done by using one edge to draw a line then flip the ule vertically (same edge but running the other way) and draw another line over that and see if they are coincident - repeat for the other edge. I use a square or solid base to rest the ruler on but you need to be sure the bases (short edges) of the ruler are square also. There used to be a good write-up on MSW 1 ... another lost .... cheers Pat sonicmcdude 1 Quote Link to comment Share on other sites More sharing options...
Patrick Matthews Posted November 5, 2013 Share #7 Posted November 5, 2013 there's an old story somewhere about the buyer of a ship slipping into the shipyard one night and replacing the shipbuilders measuring stick with one that was stretched by 10 percent. Of course he ended up getting a ship 10 percent bigger! WackoWolf 1 Quote Link to comment Share on other sites More sharing options...
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