Cannot release the nest drawing with five unexplained contacts

BrunoChen1148 · 23 Jun 2025, 03:34 UTC

Closed
BR
BrunoChen1148
I have a proposed FR5 inspection nest with five bottom contacts under a milled bracket. A sample sits on three, another sits on a different three, and the designer's answer is a stronger clamp. I am holding the drawing. I'd like the contact scheme explained before we spend money making the part obey it.

9 replies

SA
SarahBaker0502
Replying to BrunoChen1148

Ask which contacts establish the datum. Five equal-looking pads don't answer that.

20 points
BR
BrunoChen1148
Replying to SarahBaker0502

Designer calls all five supports. The part drawing uses one base face as the datum. They haven't said how those five pads are meant to cope with variation in that face.

6 points
SA
SarahBaker0502
Replying to BrunoChen1148

That's the missing answer. Have them show the intended location before discussing clamp force.

23 points
DA
DavidBennett0780
Replying to BrunoChen1148

I would also check that the samples are identified and clean. Not because your objection is wrong, but because a burr on one sample can send a fixture review down a very long side road. Cheap thing to rule out.

5 points
SA
SarahBaker0502
Replying to DavidBennett0780

Clean samples still won't explain five pads. I'd pursue both questions.

14 points
DA
DavidBennett0780
Replying to SarahBaker0502

Both is what I meant. I have watched a team redesign around dirt under one part, so I tend to mention it early. I wouldn't let the designer use cleaning as the whole answer either.

7 points
PA
PavelCarter0962
Replying to BrunoChen1148

Bruno, is the inspection intended to report the bracket in its free condition or under a specified restraint? That needs to be clear before anyone decides how much clamping is acceptable in this particular nest.

22 points
SA
SarahBaker0502
Replying to PavelCarter0962

Yes. A firm clamp can make a lovely measurement of the shape you've forced into it.

12 points
RA
RaviArcher0389
Replying to DavidBennett0780

I would put the sample numbers on the photos as well, because after our tray comparison I no longer trust a folder of near-identical metal bits to explain itself.

8 points

Discussion closed

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