Our brass blanks stick out different amounts

RebeccaAllen0343 · 26 Apr 2025, 23:37 UTC

Closed
RE
RebeccaAllen0343
I'm helping gather samples for a UR5e lathe-loading proposal. Hand-loaded brass blanks stick out by different amounts, and that's all the old sheet measures. How can we tell length variation from poor seating? Automatic loading isn't approved.

18 replies

TH
TheoArcher0410
Replying to RebeccaAllen0343

I'd identify and measure the loose blanks first. We confused part variation with fixture variation on a bench job because every sample got called the same thing. I'm not a lathe setup person, so the seating checks need someone who is.

21 points
RE
RebeccaAllen0343
Replying to TheoArcher0410

Loose lengths do vary. I've numbered the samples so we can link each length to its protrusion reading rather than compare two anonymous lists.

14 points
TH
TheoArcher0410
Replying to RebeccaAllen0343

That should help. Are the protrusion readings taken from the same reference each time? I'd want that clear before doing sums on them. It's very easy to manufacture a seating problem with two different measurement habits.

9 points
OS
OscarCarter0967
Replying to TheoArcher0410

Have the machinist define the intended seating surface and the protrusion reference. Length minus protrusion may help only if those dimensions relate to the same seating geometry. Otherwise the arithmetic can look tidy and still mean the wrong thing.

21 points
TH
TheoArcher0410
Replying to OscarCarter0967

Thanks, that is the part I wasn't comfortable assuming. My suggestion was to link the measurements, not to use a formula without checking what the dimensions represent.

6 points
HE
HenryAdams0090
Replying to OscarCarter0967

Photograph the measurement setup for the sheet. It helps the next person repeat it, though the machinist still needs to define the actual check.

9 points
TH
TheoArcher0410
Replying to HenryAdams0090

And leave a place for the sample identifier in that photo record. A lovely picture of an unidentified blank won't tie back to the two measurements you just collected.

16 points
RE
RebeccaAllen0343
Replying to OscarCarter0967

Machinist has defined the references and is checking the seating surfaces under the shop procedure. The old protrusion measurements used two different reference edges. We're starting that comparison again.

20 points
AN
AnikaBell0682
Replying to RebeccaAllen0343

Who decides when the seating evidence is sufficient for the proposed automatic-loading review?

23 points
RE
RebeccaAllen0343
Replying to AnikaBell0682

Our machining lead owns that review with the integrator. I'm gathering the identified measurements, not approving the loading setup. No automatic trial scheduled yet.

19 points
AN
AnikaBell0682
Replying to RebeccaAllen0343

Good. Keep that decision separate from finishing the measurement sheet; one does not automatically authorise the other.

14 points
TH
TheoArcher0410
Replying to RebeccaAllen0343

Did the repeat measurements explain most of the spread, or are individual blanks still inconsistent when checked again? I'd be interested now you've removed the two-reference muddle.

23 points
RE
RebeccaAllen0343
Replying to TheoArcher0410

Some spread follows blank length, but one sample still gives different seating readings. The machinist found debris at a contact area during inspection and is checking it properly before we blame that alone.

16 points
OS
OscarCarter0967
Replying to RebeccaAllen0343

Record which contact and which sample. Then repeat the defined comparison after the authorised maintenance work. Finding debris is a useful observation, but you still need the before-and-after result to connect it to seating.

12 points
TH
TheoArcher0410
Replying to OscarCarter0967

That sounds like two threads to follow: dimensional variation in the blanks and repeatability of seating. At least they no longer have to fight over one unexplained protrusion number.

21 points
HE
HenryAdams0090
Replying to RebeccaAllen0343

Keep the inconsistent sample aside until the review is done. It is more useful than another good-looking example for the supplier.

17 points
TH
TheoArcher0410
Replying to HenryAdams0090

Yes, and mark why it's retained. Our interesting samples used to vanish into the normal parts pile whenever somebody cleared a bench.

10 points
RE
RebeccaAllen0343
Replying to OscarCarter0967

The post-maintenance readings are more consistent on that sample. We've kept it and the full record for the machining lead. Still waiting on the loading review, but the sheet now distinguishes blank length from the seating check.

20 points

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