hexagon logo
Register Sign in
  • Replies 20 replies
  • Subscribers 224 subscribers
  • Views 314 views
  • Users 0 members are here
Options
Related

Composite position, threaded hole pattern

d.evans
I have a cylindrical part with a set of holes drilled 90 deg apart (3 o'clock, 6 o'clock, 9 o'clock and noon) around the circumference. Total of 8 holes- 4 at one level, 4 at another. The callout is very common to this type part, a PLTZF callout of .038" RFS to A|B, then a FRTZF callout of .018" RFS to A.

My question, if I have done this properly in my PC-DMIS program, is there any way that all 8 holes could pass for the upper PLTZF callout, and simultaneously all 8 holes fail the FRTZF callout? I can't see how they could, but when I executed a program recently that I've used on many of these same parts, this is exactly what the results show.

On a side-note, the drawing doesn't restrain all 6 degrees of freedom, so I chose a feature on the part that made sense to me to use to close that gap.

Thanks in advance Confused
Parents
  • Datum A must remain "leveled" when evaluating lower tier. 3D best fit allows datum A to become "un-leveled".

    OK, I get that. So, knowing that the holes appear to fit into the basic 90 deg X3 callout, and simultaneously into the basic 3.707" distance between levels, why would these fail when evaluated within a 2D best fit alignment, using the holes themselves (equally weighted)? It just seems to be falsely telling me that they are out of spec, hole-to-hole wise.

    Is there some other type of 2D BF I should use? I chose Z-plus (looking down onto the top of the cylinder that is Dat A) and rotate&translate. Is there something else that makes more sense? I attached a section of the drawing for clarity.
Reply
  • Datum A must remain "leveled" when evaluating lower tier. 3D best fit allows datum A to become "un-leveled".

    OK, I get that. So, knowing that the holes appear to fit into the basic 90 deg X3 callout, and simultaneously into the basic 3.707" distance between levels, why would these fail when evaluated within a 2D best fit alignment, using the holes themselves (equally weighted)? It just seems to be falsely telling me that they are out of spec, hole-to-hole wise.

    Is there some other type of 2D BF I should use? I chose Z-plus (looking down onto the top of the cylinder that is Dat A) and rotate&translate. Is there something else that makes more sense? I attached a section of the drawing for clarity.
Children
No Data
© 2025 Hexagon AB and/or its subsidiaries. Privacy Policy | Cloud Services Agreement