SpikeyJp_68 Posted December 5, 2016 Share Posted December 5, 2016 Hi guys, Gotten round to measuring my crankshaft and I got the following numbers:No.1 = 40.045mmNo.2 = 40.048mmNo.3 = 40.048mmNo.4 = 40.043mmThe limits are 39.985mm - 40.000mm so how is this so ? Had my micrometer calibrated the day before in a machine shop and double checked my measurements which came in at +/- 0.0002" of the originals. Any help appreciated Quote Link to post Share on other sites
5e colin Posted December 5, 2016 Share Posted December 5, 2016 is your micro in mm or " Quote Link to post Share on other sites
SpikeyJp_68 Posted December 5, 2016 Author Share Posted December 5, 2016 (edited) It's imperial. 0.0001"Converted via google Edited December 5, 2016 by SpikeyJp_68 Quote Link to post Share on other sites
5e colin Posted December 5, 2016 Share Posted December 5, 2016 hove you got your calibration rod with your micrometer it might be off i know you said you got it done but !!! Quote Link to post Share on other sites
SpikeyJp_68 Posted December 5, 2016 Author Share Posted December 5, 2016 hove you got your calibration rod with your micrometer it might be off i know you said you got it done but !!! It never came with a standard so that's why I sent it to the machine shop. It's a 1-2" micro calibrated at 1". It looks like I'll be sending the crank off to them anyways Quote Link to post Share on other sites
AdamB Posted December 6, 2016 Share Posted December 6, 2016 Even if it is calibrated, it will be calibrated with a tolerance. It might be that tolerance you're measuring. Quote Link to post Share on other sites
SpikeyJp_68 Posted December 6, 2016 Author Share Posted December 6, 2016 (edited) Even if it is calibrated, it will be calibrated with a tolerance. It might be that tolerance you're measuring.Ah I see so for example the standard they used might be 1" +/- .04mm ?I've ordered plastigauge anyway so that will confirm if I'm within spec or not Edited December 6, 2016 by SpikeyJp_68 Quote Link to post Share on other sites
5e colin Posted December 6, 2016 Share Posted December 6, 2016 o.4mm is a lot !!!! should be WAAAY smaller for the micrometers ok for varnier calipers maybie Quote Link to post Share on other sites
SpikeyJp_68 Posted December 6, 2016 Author Share Posted December 6, 2016 o.4mm is a lot !!!! should be WAAAY smaller for the micrometers ok for varnier calipers maybie I was thinking that. I'll plastigauge it and if it's in spec happy days Quote Link to post Share on other sites
5e colin Posted December 6, 2016 Share Posted December 6, 2016 ya i dunno where adam got that from think he is swapping them around wit varniers or so easy mistake tolerance should be no more then 0.0000# gose even lower in the uk size inch tingy 0.000000 i think it is if my tools ever go of from ware ant te3ar i replace them with new after al there " precision tools" ave a look true this link http://www.mitutoyo.com/wp-content/uploads/2013/04/E11003_2_QuickGuide.pdf Quote Link to post Share on other sites
SpikeyJp_68 Posted December 6, 2016 Author Share Posted December 6, 2016 I was looking at getting a brand new digital one but they're quite expensive to use once/ twice. It's only 0.04mm over which is a lot in oil clearance terms I know but physically it's a tiny tiny measurement so it could be their standard that's out. Quote Link to post Share on other sites
5e colin Posted December 6, 2016 Share Posted December 6, 2016 (edited) I was looking at getting a brand new digital one but they're quite expensive to use once/ twice.It's only 0.04mm over which is a lot in oil clearance terms I know but physically it's a tiny tiny measurement so it could be their standard that's out. HHHHHMMMMMM NO thats like fitting sandpaper between the bearings and crank tbh a new 1 will last you till you are dead ( diy use ) amd no not that expencive ( 100£ 150 ) gets good 1v for life if thats to much get it build 0.4 is not o.ooo4 !!!!!v Edited December 6, 2016 by 5e colin Quote Link to post Share on other sites
patman Posted December 6, 2016 Share Posted December 6, 2016 I still have the micrometer aswell Colin from my engine rebuilt always did think was it ever worth selling 👍🏻 Quote Link to post Share on other sites
SpikeyJp_68 Posted December 6, 2016 Author Share Posted December 6, 2016 HHHHHMMMMMM NO thats like fitting sandpaper between the bearings and crank tbh a new 1 will last you till you are dead ( diy use ) amd no not that expencive ( 100£ 150 ) gets good 1v for life if thats to much get it build 0.4 is not o.ooo4 !!!!!v I know it's very large in oil clearance terms either too much or too little clearance but if you were to put 2 lines on a piece of paper measuring 0.04mm it would be tiny. Plastigauge will give me a good idea of the oil clearances. If I'm still unsure, I'll send it to the machine shop and ask them to get me bearings suited for my crankshaft with or without a regrind Quote Link to post Share on other sites
AdamB Posted December 7, 2016 Share Posted December 7, 2016 Try an keep the units and decimal points correct lads. It's either inches or mm. Don't mix them as even conversions aren't 100% correct. Personally try measure in inches because this is usually tighter than the mm specified tolerance from my experience 0.04mm is not a lot, bearing in mind that 3 decimal places is about the best you can measure to, anymore than 3 decimal places is rarely significant unless you're in Aviation, Medical or Medical industries. Quote Link to post Share on other sites
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