Compostie Positional Tolerance on Different Size Holes
Compostie Positional Tolerance on Different Size Holes
(OP)
Hi All,
I have a situation where I have 5 holes of different sizes on a plate. I am currently holding their position using independent positional tolerance callouts on each hole (e.g. hole #1 is specified as diam. 5 +/- 0.5 with a GDT feature control frame specifing a true pos. of 0.1 back to datums A, B & C; hole #2 is specified as diam. 6 +/- 0.2 with a its own GDT feature control frame specifing a true pos. of 0.1 back to datums A, B & C... etc, through all the 5 holes on the plate). This works OK, but I really want to treat all of these 5 differently sized holes as a pattern, and then tighten their tolerances to each other (i.e. have a single feature control frame that applies to all of the holes with a true pos. of 0.1 back to datums A, B & C in the PLTZF and a true position of 0.05 in the FRTZF). If the holes are of the same size it is easy to do this just indicating that all of the holes are in a common pattern by pointing to only one of the holes and then indicating the pattern with a "5X" in front of the specification for the hole. My question is this:
Is their a way of indicating that all these different size holes are in the same pattern so that I can tighten the tolerance on the holes within the pattern?
I have a situation where I have 5 holes of different sizes on a plate. I am currently holding their position using independent positional tolerance callouts on each hole (e.g. hole #1 is specified as diam. 5 +/- 0.5 with a GDT feature control frame specifing a true pos. of 0.1 back to datums A, B & C; hole #2 is specified as diam. 6 +/- 0.2 with a its own GDT feature control frame specifing a true pos. of 0.1 back to datums A, B & C... etc, through all the 5 holes on the plate). This works OK, but I really want to treat all of these 5 differently sized holes as a pattern, and then tighten their tolerances to each other (i.e. have a single feature control frame that applies to all of the holes with a true pos. of 0.1 back to datums A, B & C in the PLTZF and a true position of 0.05 in the FRTZF). If the holes are of the same size it is easy to do this just indicating that all of the holes are in a common pattern by pointing to only one of the holes and then indicating the pattern with a "5X" in front of the specification for the hole. My question is this:
Is their a way of indicating that all these different size holes are in the same pattern so that I can tighten the tolerance on the holes within the pattern?





RE: Compostie Positional Tolerance on Different Size Holes
Fig. 5-53 in AMSE 14.5M-94 on page 149 of the standard is exactly what your situation.
Yes, you can have a composite positional feature control frame for the 5 holes that are of different sizes by placing FIVE COAXIAL HOLES below the feature control frame. Each hole size and tolerance must be shown though.
Dave D.
www.qmsi.ca
RE: Compostie Positional Tolerance on Different Size Holes
I dont believe these holes are coaxial, they are on a plate.
RE: Compostie Positional Tolerance on Different Size Holes
Thanks - sometimes I should read the question a bit more carefully.
This is a bit different and there is no example that I can find in the standard but here is what I would do. I would mark each of the 5 holes with a letter - maybe A. Below the composite feature control frame, I would state "FIVE HOLE PATTERN HOLES MARKED A. That would cover it.
Dave D.
www.qmsi.ca
RE: Compostie Positional Tolerance on Different Size Holes
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com
RE: Compostie Positional Tolerance on Different Size Holes
RE: Compostie Positional Tolerance on Different Size Holes
In automotive transmission valve bodies there are bores with mutiple land sizes... some repeated multiple times and there are often many of these type of bores. To describe one of them with three different sizes in the bore and three lands for each size we typically specify 3X size1, 3X size2, and 3X size3 then point to those size callouts from a common composite position control 9X PLTZF [pos|dia0.X|A|B|C] FRTZF [pos|dia0.X(M)].
By using composite controls for these valve bores our coaxiality refinements for functional fit (FRTZF) are free of simultaneous requirements relative to other valve bore sections... while the general locating controls (PRTZF) that are subject to simultaneous requirements insure good relative location for automated assembly and good stacked location relative to the casting.
Paul
Paul
RE: Compostie Positional Tolerance on Different Size Holes
KENAT,
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