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Is there a way to auto re-compute a Best Fit 3D (BF3D) Alignment?

Hi everyone,

I'm having a bit of an issue with regards to doing a Best Fit alignment to align a fixture, specifically the fixture datums (4-Way, 2-Way, A-Nets).

I like to start off my alignment with Iterative first off of the tooling bushings built into the fixture base,
Then I proceed to measure the datums in DCC, then I will proceed to create another Iterative alignment off of the datums if possible,
else I will do a Best Fit 3D using the datums and save my alignment to be recalled in another program.

I'm noticing that after I run the program the datums are sometimes out of spec. after BF3D,
taking a closer look I can see my Best Fit alignment needs to be re-computed! (it's even lost it's chosen directions).

Is there a way to set the Best Fit alignment to auto compute every time I run the program,
or is it rule of thumb that after performing an Iterative in DCC, that the best fit alignment always needs manual intervention?

My program is basically this:

1. Pick up 3 tooling bushings manually
2. Iterative pick up off of the same 3 tooling bushings using DCC
3. Measure datums in DCC (4-Way / 2-Way / A-Nets)
4. Create BF3D off of the datums
5. Re-measure datums to make sure they are in spec. within +/- 0.05 mm

Thanks for any help you guys can provide,
I don't want to have to re-compute manually every time I run my external alignment program.

- Pete

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  • You are correct sir.

    How would you align a fixture, just looking for new ideas.

    I usually always pick up off of the tooling bushings using iterative alignment but then I find that when I measure the datums (4-Way / 2-Way / A-Nets / and sometimes D-Nets on a different plane) they are out more than 0.05 mm , some show .100+ deviation. When this happens I will do a Best Fit 3D off of the datums to get everything tight and in spec.

    Ideally I want to use Iterative exclusively but I'm having trouble aligning when I have to use nets and positional locating pins that are not exactly built square to grid.
    Even if they are exactly square to grid sometimes the Iterative does not want to work, especially if the datums are on different planes (example D-Nets),

    Thank you for any tips you can provide.