dowel pin tolerance
dowel pin tolerance
(OP)
Hi,
I have a square plate with a bolt circle diameter on which lies a dowel pin hole.
If I wish to call out a positional tolerance for the pin hole, would I tolerance it with respect to the bolt circle or the plate faces?
Thanks!
I have a square plate with a bolt circle diameter on which lies a dowel pin hole.
If I wish to call out a positional tolerance for the pin hole, would I tolerance it with respect to the bolt circle or the plate faces?
Thanks!





RE: dowel pin tolerance
What are your datums?
I suspect datum A is one of the large faces but B & C could vary based on function/design intent.
For instance, if the dowel is used to give precision location to a mating component it may make sense for the dowel pin hole to be your secondary datum. With one of the edges as tertiary datum for orientation and have your bolt circle referenced to it.
KENAT, probably the least qualified checker you'll ever meet...
RE: dowel pin tolerance
Chris
SolidWorks/PDMWorks 08 2.0
AutoCAD 06/08
ctopher's home (updated 10-07-07)
RE: dowel pin tolerance
One job I had designing machine tools, dowel pin positions were within Ø.002"
RE: dowel pin tolerance
The pin will be a press fit onto the plate and it is indeed used for precise location.
I understand that the main face (front face of the plate) would be datum A, however how would the hole itself be the secondary datum B?
RE: dowel pin tolerance
A hole can be a datum, look at fig 3-4. Section 4 maybe better explains the implications of this, maybe look at 4-6 but imagine that the dia 25.5 is a hole instead of a shaft.
For your example the best illustration I can find is 4-24, someone else may be able to find a better one. On the top view your pin hole would be the equivalent of E, with the bolt pattern related to it like the 4 holes are. You'd use one of the plate edges for Datum C in the way B is used in the figure.
KENAT, probably the least qualified checker you'll ever meet...
RE: dowel pin tolerance
If I do not specify any modifier in the feature control frame, does that automatically mean it is RFS?
Would RFS be less advisable for a precise location dowel pin application as compared to MMC?
RE: dowel pin tolerance
A.If working to ASME Y14.5 then yes, I can't recall for ISO.
Not sure I'm qualified to definitively answer the second question. However, if this is an interference hole that the dowel pin is press fit into then the tolerance gained from MMC will typically be very small. If this is the hole mating to the dowel pin then depending what fit you have the implications of MMC may be more significant.
KENAT, probably the least qualified checker you'll ever meet...
RE: dowel pin tolerance
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RE: dowel pin tolerance
RE: dowel pin tolerance
RE: dowel pin tolerance
RE: dowel pin tolerance
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RE: dowel pin tolerance
RE: dowel pin tolerance
RE: dowel pin tolerance
I now need to delete a couple of MMC symbols from the print I'm redlining right now!
KENAT, probably the least qualified checker you'll ever meet...
RE: dowel pin tolerance
RE: dowel pin tolerance
The hole locations could have been RFS, MMC, or LMC prior to press.
The assembled pin locations can be RFS, MMC, or LMC post press.