Posted by DanO on November 12, 2002 at 10:04:35:
In Reply to: Re: DIN 5480 posted by James on October 12, 2002 at 13:12:20:
Try this for a lay explaination for the problem.
With your basic fits, 'H' internal mates with 'h' external with no additional clearance, but with a tolerance bandwidth appropriate for the nominal diameter which allows for effective variations beyond the actual sizes. The normal internal spline fit is H, which has it's lower tolerance limits on the nominal tooth thickness point (with no clearance or interference. The normal male spline governs the 'fit' by specifying the clearance or interference with lower case letters for the tolerance allowance h,g,f,d,c allowing more clearance with the lower letters after the effective errors are considered in addition to the actual sizes [I didn't claim my explaination will be easy to follow]. The allowance for effective variation is given by the numeral, eg h7, d9, where the number stands for a tolerance for effective errors (index, lead, involute)that affect the fit. The tolerance is defined by this numeral and the nominal diameter of the hole, and so a larger nominal diameter will have a larger allowance for a given 'fit'. For your example, the H11 tells me you are talking about a hole (capital letter) and the tolerance is given by the 11. H11 tolerances are .060mm on 1mm basic size, .090mm for 10mm basic size, .130mm for 20mm basic size, .160mm for 40mm basic size, and .190mm for 80mm basic size, and so forth. So it goes for all fits and all basic hole sizes.
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