hexagon logo
Register Sign in
  • Replies 8 replies
  • Subscribers 221 subscribers
  • Views 92 views
  • Users 0 members are here
Options
Related

How could least square be larger than minimum circumscribed

lovethepirk
I'm running a part on Sunday, main datum is a half external sphere. It measures 5.5mm diam using least squares BF, in tolerance, all is good. All vector pts, lots of them prob 40-50, constructed sphere. I mic it for fun in varying angles and get 5.51mm. Totally acceptable diff being lst sq vs Mic and all the other errors floating around.

So I decide to run it at minimum circumscribed....should be larger than lst sq, no? Welp....i get 5.48mm. How could min cir be less than a lst sq? I'm baffled.
Parents
  • Neil,

    I fixed all those grammer errors...im aware of what all the fits are...ran 5 separate runs both with lst sq and min circ, all slightly twisting the part 1 deg for variance. i know they arent stable but its hard to believe the results were all near identical and there are plenty of pts to use...and its a full 180 deg...at the boarderline of too little but i figured enough.
  • in reply to lovethepirk
    OK, just checking. A few more questions...

    Were you using BF or BFRE to construct the various fits?
    Did you include any outlier filtering?
    How much of the sphere were you measuring - how many degrees of arc?
    What was the total form error?
    Do you still have the data and if so, can you share it?
Reply Children
No Data
© 2024 Hexagon AB and/or its subsidiaries. Privacy Policy | Cloud Services Agreement