datum xy left side of part

[mike561h]

These guys her keep the datums on the top left always no matter what op.

total BS .. flip it on y x goes to op side. keeps the y plane in th esame spot.. whats your take.

[GoetzInd]

Depends on where the part is dim'd from.

 

Mike

[djstedman]

Well seems like you mean they always set there work offset to the top left of the part, regardless where the datum's are.

 

Datums will be based off the Blueprint regardless where your work offsets are set.

 

That being said, I agree its generally a good practice to work from the same side of the part rather than working from both sides since any dimensional error in width will increase your amount of error.

 

I suppose if you had wide open tolerances on dimensions that were being held pretty close then it wouldn't matter much and might be worth doing to simplify setups. ie one stop for multiple setups.

 

To me the main thing is does the setup continually make good parts without the setup guys / operators pulling thier hair out, the only right answer is consistantly good parts in a timely manner.

[mike561h]

WHY PUT THE ORIGINAL Y DATUM OUTSIDE WHEN U FILP 180 ON x AXIS. DOES NOT MAKE SENSE. ANY ERROR WILL BE MAGNIGFIED. FLIP ON Y AXIS AND KEP YPUR Y DATUM THE SAME THEN YOIU KNOW ALL FEATURES ARE CORRECT.

mAKING ANOTHER Y DATUM MAKES NOP SENSE AT ALL/

[Newbeeee™]

Do they use the top left because of vice work - ie the fixed jaw???

[djstedman]

Well if you have .03 tolerance and your job is repeating within .003 it makes no difference .. thats all i was saying.. I do agree its better to work from the same side of the part, however was just saying theres plenty of times where it doesnt make any difference depending on the tolerances. Is it best practice? No.. Is it the end of the world if done once in a while where it makes no difference? I think not..

 

BTW.. sorry I disagree.. but you did ask what people's take was.. sometimes that means you might not get the answer back you expected..

[Joe6Pack]

My take,

first op X/Y Z comes from the vise/keyed jaws with a G10 to edge of mtl

2nd op comes off the vise/keyed jaws with G10 to edge of machined part

3rd op same as above

 

In your example they should have machined the far end so when the part was flipped it located against the original left side stop. Bouncing offsets around makes guys pull out an edge finder.