When no tolerance on hole size is called out

[dodge78]

I have a hole callout of .097 dia. with a .002 tp at mmc. Since there is no specific tolerance on the hole size, is it standard practice to use the +/-.005 tolerance in the tolerance block for the drawing? My understanding was that on holes with no tolerance specified fell under some sort of spec where I believe the tolerance for a hole of this size is +.003/-.001 If any one can point me to a spec that shows this, it would be of great help

 

[ringman]

If the drawing is to be in compliance with Y14.5., the hole MUST have a tolerance on the size. I do not know of a case where the title block tolerances would be applicable.

 

[ctopher]

For all holes, the dim must have a tol applied. If a drill size is called out, the drill tol is used but not called out. If you assume the tol block on the dwg to be used, it is possible a machinists may use the drill tolerance (not called out on dwg) by default. Some companies have notes indicating basic drill tol in a block. If it is a hole that does not fall within a drill size, specify the tol.

Chris
Sr. Mechanical Designer, CAD
SolidWorks 2005 SP0.1

 

[ewh]

To quote ASME Y14.5M-1994, 1.4(a), "Each dimension shall have a tolerance, except for those dimensions specifically identified as reference, maximum, minimum, or stock (commercial stock size). The tolerance may be applied directly to the dimension (or indirectly in the case of basic dimensions), indicated by a general note, or located in a supplementary block of the drawing format."
So, unless the dimension is max, min, basic or stock, or there is a general note specifying the tolerance application, it MUST default to the title block tolerance.

 

[MadMango]

ewh, this is what I have come to know to be true (to include holes).

ringman, can you cite the ASME standard that says a hole must have a tolerance on size? Why would a hole be different than any of feature of form?

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[ringman]

It needs to be established as to what Standard is applied the drawing in question firstly. Scondly, assuming that the tolerancing of the hole is in doubt as dodge78 feels it to be,there is a clarification required. The Standard for the drawing should provide the method for such.