Positional tolerance using floating fastener formula
Positional tolerance using floating fastener formula
(OP)
Hi I have riveted assemblies which have rectangular coordinate system tolerance. Now I have to apply GD & T to locate holes. When I used floating fastener formula ending up with .001 or .002 Positional tolerance. Is this possible to inspect? Is there any way to increase positional tolerance?





RE: Positional tolerance using floating fastener formula
To increase your tolerances you either must enlarge your clearance holes, or drill (punch?) after assembly.
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JHG
RE: Positional tolerance using floating fastener formula
Carefully designed fixtures or punch tooling etc. can sometimes overcome this.
Alternatively you can separately machine with slightly undersized holes then just open them up by match drilling to size at assembly.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Positional tolerance using floating fastener formula
John Acosta, GDTP Senior Level
Manufacturing Engineering Tech
RE: Positional tolerance using floating fastener formula
I think many rivets rely not so much on the head and tail clamping the pieces together but by the shank swelling into the hole during installation.
I thought this is why the tolerances on rivet holes are often required to be fairly tight tolerance.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Positional tolerance using floating fastener formula
John Acosta, GDTP Senior Level
Manufacturing Engineering Tech
RE: Positional tolerance using floating fastener formula
RE: Positional tolerance using floating fastener formula
Before you go much further seems you need to determine for sure how the rivets you are using work - do they grip on the shaft or just the head & tail & I'm talking nonsense. I assume you got the current hole sizes from a standard or manufacturer data sheet or... so that may tell you.
If that same guide or handbook doesn't answer the question, and you can't find it with a web search then maybe take a look at forum725: Welding, Bonding & Fastener engineering and ask there.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?