Do I have to run a DCC alignment

[djone368]

I am cerfyng a fixture

manual alignment is good
lacating pins manually using feature recognitin within tolerance
switch on dcc to measure auto surface point ( on a compound angle)
all four nets are out by 1.6mm
do I need to run alignment in dcc

thanks

Dave

[Matthew D. Hoedeman]

You should always get in the habit of doing DCC alignments, if for nothing else, they will eliminate the difference in probe comp that touches at different speeds will give you and they help a WHOLE LOT to get rid of human error. Even if it is just you doing it, everyone can a dn will make an error, the DCC alignment helps eliminate this.

That being said, it sounds to me like you might have a stock thickness issue. What side of stock is the cad data you are using? Also, you should ALWAYS use PART data, NOT fixture design data to check a fixture. It is, after all, the part that needs to sit on and be checked by the fixture. If some yahoo made a mistake in the design of the fixture and you use the fixture design data to check it, you will not find the error. However, if you use the part data, you WILL find the design errors.

[Rick Coleman]

DCC Alignment

I always, well 99.9% of the time, do a DCC. Just gives me a warm fuzzy feeling.....

[bw_bob]

Me personally...............I measure nothing without at least 2 alignments and both are DCC......OD or ID diameters are the exceptions

[simcityguy]

Me personally...............I measure nothing without at least 2 alignments and both are DCC......OD or ID diameters are the exceptions

I double up on alignments to. Better safe than sorry.

[Paul Barriage]

Matt, are those people still watching you??


Dave, here's an example,

Quality engineer thinks the capability is adversely affected by the machine operator. We have had this discussion before. 20th time running the SAME parts. I am tired of using words, he doesn't seem to hear them,.... Since I have a 6mm prehit in the DCC alignment, I push the part about 5mm off the stops. I tell the QE, if that deviation changes (same part) more than .003mm, we can do a GRR on the CMM for you, otherwise, go FIX THE PROBLEM!!! I leave, ..... come back 5 minutes later,....no QE,.... same deviation,..... guess he is fixing it??

As Matt said, the DCC pulls out the human error.

[Wes Cisco]

I am cerfyng a fixture

manual alignment is good
lacating pins manually using feature recognitin within tolerance
switch on dcc to measure auto surface point ( on a compound angle)
all four nets are out by 1.6mm
do I need to run alignment in dcc

thanks

Dave

When I attended B&S training the instructor said we should always follow the manual alignment with a DCC alignment. All of the most experienced and knowledgable people on this and other cmm forums I have seen address the subject say you should run a DCC alignment. Your machine will not blow up if you don't, but your results may be skewed. The machine can control the motion and touch off exactly the same way it touched when calibrating the tip on the artifact. No human can do this as well, and because vectors and touchspeed can be very important, this is considered essential by most. Think of it this way, if you bought a new 0-1" micrometer and you cleaned it and closed the jaws fully, would it matter to you if read 0.0002" instead of 0.0000"? The alignment establishes orientation of the axis/planes and the zero location for each axis. If your manual alignment differs from the DCC alignment by .0002" all of your measurements and results will be off by a factor of at least .0002". HTH

[Hilton Roberts]

I always try to do a dcc alignment after a manual alignment just to get the human variability out of the way. It is probably the best single thing you can do to make sure a part repeats. HTH

Hilton

[djone368]

I have done dcc align and am getting same error 1.6mm high
is there something basic I am over-looking here

[Matthew D. Hoedeman]

Did you check to see if you are using the wrong side of stock thickness?

[kevinb]

In programs I always follow a manual alignment with DCC or an iterative. Even if I'm just doing a quick little manual verification of something, I'll pick out the features manually, then run them DCC. The machine can get a much more precise reading than you can.

[Jeffrey Lovely]

I have been getting 1mm error doing manual measurements (points)
using a 2mm ball- dont know why
some one said it may be a work plane issue
its almost like probe comp was not working
always do auto dcc alignment whenever possible

you may be seeing the same thing
then running auto it shows up, and your cad may be wrong side of metal
honda part?

[djone368]

Mattthew

all our numbrers are inside of metal
I am not using cad to program
We find the nominals

[Gord Ashcroft]

I sometimes get CAD files that have no material thickness and this has to be compesated for with an offset. This may be the case here

[djone368]

I am only getting this problem in Z-Axis
x and y are comming in perfect
even if I change from 150mm tip to 100mm tip
could it be in the paramiters or set up
I am sure it is something fundimental that I am overlooking
B+s just certified machine last week