Hole angularity mismatch
Hole angularity mismatch
(OP)
I am doing an angularity mismatch study on determinant assembly holes between two composite parts. Both parts have two determinant assembly holes of .1285 dia. drilled. What is the allowable angularity mismatch (in terms of degree) between the hole center line on two parts if they are pinned together by cleco/pin ?





RE: Hole angularity mismatch
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Hole angularity mismatch
RE: Hole angularity mismatch
if the mating faces "mate", then drill both parts from the same face.
what's going in the hole ? a rivet ? a bolt ? clearance fit or interference ?
RE: Hole angularity mismatch
Right-size [1/8-D, this case] "Clecos" have intrinsic ability to shrink small-enough to snake into significantly [0.016-inch or greater] mismatched/off-angle holes... and partially spring-back to hold/clamp alignment "good-enough" for match drilling/reaming surrounding holes up to final diameter where larger clecos can be installed [IE: 1/8, 5/32 or 3/16 D, etc]; then these pilot-hole clecos are removed and their bunged-up holes are drilled to final precision diameter (while the larger surrounding "right size" clecos maintain tightness and alignment).
NOTE. I have seen mechanics use next smaller diameter clecos [ie: 3/32-D this case] to punch-thru and sorta-align/hold/clamp significantly (1/32 or greater) misaligned holes, so that the surrounding holes can be step-drilled into common alignment/size for larger Dia clecos [5/32 or 3/16 1/4 D, etc].
Note.
clecos are a brand-name that identifies the family of temporary hole fasteners.
NOTE.
I real terms, modern tooling should be able to hold within +/-1-deg hole perpendicularity at any surface location. This should occur by a combination of digital definition [3D precision] and/or drill-head sensors that find/touch the surface location and instantly define the precise contour at that exact surface to "set" the best-fit drill-head angle.
Regards, Wil Taylor
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RE: Hole angularity mismatch
The two determinant assembly holes of .1285" dia on each composite part are used to index in order to drill the other holes from drill plate. They plan to install 1/4" bolts into those holes. The angularity mismatch is from .15 deg to .42 deg between the center line of the determinant assembly holes of the two parts. On each of the composite part, the positional tolerance for those determinant assembly hole is .028".
Thanks for all of your informative inputs.
RE: Hole angularity mismatch
is the misalignment real (measured) or theoretical (dim'n'd from CAD) ?
will the misalignment be "resolved" when the fasteners clamp the details together (causing bending of the details) ? do the faying surfaces align ?
these holes sound like tooling holes, it's not common practise (in my experience) to join tooling holes together.
RE: Hole angularity mismatch
This is the case when the design install the same angle in multiple locations on the base part (contoured doubler) to reduce tooling cost.
RE: Hole angularity mismatch
if the fasteners are not normal to the skin then their load state is more involved (tension and shear).
RE: Hole angularity mismatch
RE: Hole angularity mismatch