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I've never seen limits done this way so I can't tell you if this is go practice. But under the properties dialog for the dimension select plus-minus and then place a minus symbol in front of the tolerance value in the tolerance box. Placing one in the upper tolerance box will make the value negative and placing one in the lower tolerance box will make the value positive.
I agree with kdem. You will never get limits like that ( there's no +/-) just upper and lower. And if you go to your config.pro it will not be that way.
You need to turn on your tolerance settings in the drawing using your .dtl file or options. Then in your environment menu. You do this in the drawing by left clicking in the drawing careful not to select a view and right hold down. All this right click stuff does not work to well in WF5.0 I noticed.
Then left click on the dimension right hold down to access properties. Choose there the option. Minus an Minus is weird tho... Edited by: design-engine
Here is a simple way. Double click on the dimension u wanna edit. Dimension properties dialog box opens, in tolarane combo box click on plus-minus. Now type tol in upper tolerance and in lower tolerance boxes. click ok.u will find upper tol with +sign and lower with - sign. if u wanna have both tolerances with - sign, type - with UPPER LIMIT press enter.If u want both tols with + sign then type - with LOWER LIMIT. Try ..
u have to decide your tolerances first.I u are working on fit standards like G6 or f7 h11 etc. then u will have to go to setup in model environment---tol setup--tol std. set to iso/din then retrieve all tol-tables. the other method is that u describe ur tols during modeling and then in drg mode set tol display as plus-minus in tools---options. and in drg options.
Excuse me for asking... But what message are you trying to get across withthis tolerance display? A drawing is a communication between design and production, and becomes part of the contract. What is the builder supposed to do when they see this?
Tolerance are given to specify what is the allowable deviation that is acceptible for the part to perform its intended job. it is not possible to produce parts to exact dimensions that are given on the drawing.
say for example on a piston cylinder pair, if the clearance betweenthese twois too large(bigger cylinder smaller piston)the fuel mixture at higher pressure escapes into crankcase. if the clearance between these two too small there will be higher friction/jamming. to avoid these two cases. the designer specifies what is the optimal clearance required between the two. to achieve this piston and bore dimension shall not vary beyond some limits. the buyer accepts the parts whose dimensions are within the allowed tolerance limits, others are rejected.
fits play major role wherethere is an interface betweentwo are more parts. wecan achievedifferent fits depending on the tolerance band of the hole and shaft features.
it is a convention to use nominal diameter as say 50mm though it will never be 50. the actual min and max allowable sizes are controled by tolerances. like kdem described 49.940/49.894. In a clearance fit bore diameter is alway bigger and shaft size is always smaller than nominal size in general pracice. so normally in shafts both tols will be negative and in bore both dimensions will be positive.
Thanks for the explanations. I had thought it was something like that. I learned to draw with mechanical drafting and always learned that the nominal dimension was a mid, upper or lower desired target; not a nominal "stock" dimension. It seems counter-intuitive to put a dimension on a shaft/bore that you don't want to attain.
You have the option of showing the BASIC (nominal or target) dimension and the tolerances or applying the tolerances and showing the limits of the feature. If you have a drafting book or access to tolerance tables for fits take a look at them. Depending on the fit you select you will notice that you may end up applying two plus tolerances, twominus tolerances, a plus and a minus tolerances, or the table my give the limits for the feature based on a BASIC size. Edited by: kdem
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