Made programming error this week, looking for feedback

[Dead Money]

I programmed a fairly complex part this week and QA found some features out of tolerance at 1st pc inspection. It turns out the customer supplied solid cad file does not match their print. The print has 350ish dimensions. How many of you verify cad matches print before applying cutter paths?

[neurosis]

It depends on which takes precedence. Which we usually know ahead of time.

 

Depending on the customer, the model usually takes precedence over the print. We only have a few occasions that are the other way around.

 

When the print takes precedence, I usually go through everything on the model ahead of time.

[gcode]

It depends on the PO

If it's a model based part, I use the model.

If it's a print based job, the model is supplied as a courtesy and you trust it at your peril.

I have customers that will supply a Rev N/C model for a new part and never up rev it.

3 years later you're building a Rev T or something and the model is completely useless.

[gcode]

and QA found some features out of tolerance at 1st pc inspection

 

kudos to your QC department.

It would have been really bad had they used the model for inspection and signed off on a bad part

[SledGeek]

It depends on the PO

If it's a model based part, I use the model.

If it's a print based job, the model is supplied as a courtesy and you trust it at your peril.

I have customers that will supply a Rev N/C model for a new part and never up rev it.

3 years later you're building a Rev T or something and the model is completely useless.

 

^^^^^^ cuz in the end, all that really matters is what's on the p.o. Regardless of intentions.....

[gcode]

I have customers that absolutely refuse to supply models for just this reason.

The real reason is their models are so hosed they're embarrassed to let any one see them

I also have customers that supply models and state "Reference Only" as a line item in the PO.

[Guest MTB Technical Services]

I programmed a fairly complex part this week and QA found some features out of tolerance at 1st pc inspection. It turns out the customer supplied solid cad file does not match their print. The print has 350ish dimensions. How many of you verify cad matches print before applying cutter paths?

 

FWIW, I have this problem all the time.

 

I recently did several custom firearm parts where the print didn't match the model and was detailed incorrectly.

The customer still said the print takes priority.

 

I make it a part of every quote that the customer must specify which takes priority.

If the print takes priority over the model then you know right away that their design engineering

department doesn't have the first clue about data integrity and PDM.

 

In cases like this, the models are nothing more than pretty pictures when rendered and a self-imposed cost on themselves and their vendors.

[neurosis]

It depends on the PO

If it's a model based part, I use the model.

If it's a print based job, the model is supplied as a courtesy and you trust it at your peril.

I have customers that will supply a Rev N/C model for a new part and never up rev it.

3 years later you're building a Rev T or something and the model is completely useless.

 

We have had the opposite experience. Models have been updated and prints have not been updated to reflect the changes.

[Dead Money]

We have had the opposite experience. Models have been updated and prints have not been updated to reflect the changes.

 

This is the case as it turns out. The solid file was updated and the print was not. The customer would like the parts made to cad and will be supplying new prints. The PO does not specify either way.

[Brando]

your definetly not the only person to be burned on a model vs print diff,

my level of trust depends on the customer, some of ours are horrible at modeling and some are very good

ive made mention to the quoting people on the time savings of a good model , on feature rich parts we offer a lower part cost on small batches where a good solid model is provided along with prints

[Brian B 74]

All of the work I do is model based and the model is the "master" for all dimensions. Since prints are derived from the models most jobs I work on I never see the prints.

[Machineguy]

I'm with gcode. All the military crap we did the print takes prededance over any model. I could never figure out how the prints are so correct and the model is so off. Makes the job 10 times harder, and the boss is complaining about the time it take to do the job.

THey should have asked if the any model we got was up to date. If not, CHARGE the cost it takes to make a new model based on 8 pages of prints so the program comes out correct.

The whole idea from the vendor is get the lowest cost. The contractor is responsible for a perfect part, on time and we eat the cost if a major problem happens. And then the print changes midstream by 2 rev's.

 

Machineguy

[SledGeek]

......and don't forgot to charge engineering time to draw it right when a good model is needed. It only took me a few " why do you have so much time" questions before I insisted the " accurate working models need to be supplied or design charges will be added" to the p.o. " Funny how quickly customers start getting you better and better models

 

ahhh.....ya beat me to it machineguy !!

Edited August 22, 2013 by SledGeek

[Joe788]

One time we had a rush job on a part that had two compound angle holes through it that were dimensioned in an odd fashion. We made the part to the model, and inspected everything to the print, except those two holes. I just clicked them in PC-DMIS and used the model the generate the vectors and spit out a true position, and the part was within a few tenths of the model. We just documented the true position, but not the actual dimensions.

 

It turned into a big clusterxxxx because my customer inspected it with a manual CMM, and couldn't just generate the vectors from the model. They inspected to the print - which was completely wrong. Their customer (we were second tier) who was using NX in India, had accidentally snapped the centerlines to some random points instead of creating a hole axis, and then used those randomly snapped centerlines to create the dimensions.

 

Our screw up ended up being a stroke of good luck for everybody, because this was a large part, that gets gold plated, and goes into a huge multi million dollar assembly - and those two holes would have been out of position by an eighth of an inch on an assembly designed for .005TP. No telling what the repercussions could have been, but for sure nobody would have noticed a problem until they were assembling that component.

 

Now we always clarify ahead of time.

[gcode]

had accidentally snapped the centerlines to some random points instead of creating a hole axis

 

I see this all the time. Dimensions right out of left field because the draftsman's Autosnap is out of control

[htm01]

we have a customer that draws models in SW and then does prints in autocad

[TK-32™]

I get cardboard mock ups

 

[Machineguy]

Man, If i had a penney for every change, phone call ......

 

Machineguy

[rocheey1]

we have a customer that draws models in SW and then does prints in autocad

 

He might just find the extra effort necessary. If I'm plotting which could essentially be a Legal Document to a customer, I'd want total control over the process.

And Acad can give you that total control. And, it unfortunately hasn't been replaced in that regard.

 

And I'd be willing to bet, that 51% of the lurkers that read this, will agree .... I calculated this, on my SLIDE RULE

[FROZEN]

I always try and check every dimension on the print before programming. I have found many differences and the print is your bible. Unless you get the customer to ok the build of solids which does not happen very often.

[htm01]

He might just find the extra effort necessary. If I'm plotting which could essentially be a Legal Document to a customer, I'd want total control over the process.

And Acad can give you that total control. And, it unfortunately hasn't been replaced in that regard.

 

 

not in this case, they just change things on the print instead of changing the model.

[Guest]

As I process ALL the work heading out onto the Machine Shop floor, I see and touch everything.

 

When I find a discrepancy between the print and the model, that leads to an immediate documented question as to which is correct.

 

To me if someone has both and isn't looking things over, that is a breakdown in the process. Also, going in, it should be stated on the PO especially if both print and electronic data is provided as to which one is correct.

 

I have seen cases where companies say the model is god and others that the print is god, that needs to be stated going in.....

[Newbeeee™]

we have a customer that draws models in SW and then does prints in autocad

Yup - same here

[Guest]

That is just friggin' insane

 

SW's IS a full detail CAD system.....stupidity reigns

 

Yup - same here

[Newbeeee™]

If companies understood it a little more, they would realise they could cut a ton of time out of the whole process.

Model up a part and use this as the master (obviously with all features on nominal - are you jockey boys listening ).

The drawing then just needs to say part no and description, general tolerance, manufacture and inspect to model file number ###, mtl, threads, finish, and obviously any key dims that fall outside of the general tolerance limit.

This saves buckets of time on the detailing/drawing side of things and also more time on the checking (but does anyone actually do this now or do they just sign that they've checked it...)

Anyway, quicker to market parts as less time in engineering.

Quicker programming as everything is driven from the model = cheaper NRC/parts

Quicker re-engineering when parts raise in issue.

Quicker Inspection checking direct to the model.

Some of our customers do this - some of them this frightens them to death.

 

Lastly, the most important note on a drawing is 'If in doubt Ask'.

Back a while one of our customers revised their drawing templates removing this all important note.

I asked the chief drafty why did he do this.

The reply was 'to try and stop bloody subby's phoning up and questioning things all the time'.

He was crap, drawings were awful, he has now gone, and things have got better since he's gone