drilling issues with Retract plane

[razmosis]

I often use a selected planes (start and end) in drilling cycles and most of the time things go well.  However, when I need it to go well the most, such as when I need to put out a quick hole pattern for an operator things don't go as expected.  A lot of parts I work on are round, sort of like a big wheel hub.  Operation Z Zero is the center portion of the hub.  Clearance plane for the operation and all of the sequences is set to a plane above the center hub.  The hole pattern lies below the center hub on the flange.  About a quarter of the time (maybe less), the resulting post will put the drill pattern out with the R plane at .025" above the flange and will put the tool right through the center hub without retracting to the clearance plane of the operation or sequence.  In order to fix this, I have to select the top of the center hub as the start surface, which causes the drill to run at feed rate the entire distance - but at least it isn't broken.  My predecessors have taught me that this is a problem for years, and that I should be starting all drill cycles from the highest plane on the part and calculating the depth that I want the drill to go to and entering it as a blind depth.  I see that as an illogical fix to what should be a simple sequence in NC programming.  I could set the clear distance to be as high as the operation and sequence retract planes, but that isn't right either.

Any ideas on what is wrong, is this a problem for others?  Most of the time I can see it in the values of the play path, so I know it is not a post processor issue.

Thank you for any help!

Matt

[RaphMORIN]

Hi,

In this case if you select the part as a control surface and set a value just below you can define the start surface below the retract plane. It will avoid gouging into the part.

[SteveLucas · Accepted solution]

Matt,

If you specify a check surface with clearance it should avoid running into your part.

I specified the center hub as a check surface with .125 clearanceresulting tool path avoids the hub.

[razmosis]

Steve,

Thank you, that does solve it.  I don't necessarily think that it is something that should have to be done for something as simple as a drill sequence, but that's just my opinion.  If I go about drilling this pattern, I guess I have to go through the extra steps of selecting those check surfaces that can't be plowed through with a drill.  Ironically, the next sequence can be threadmilling the holes I just drilled (there is no check surface tab available for threadmilling) and that sequence seems to work just fine.  Two very similar paths referencing the same axes, but more steps involved in the drilling that in the threadmilling.  That doesn't seem quite right to me.

Thanks again,

Matt

[SteveLucas]

Matt,

I agree it should not be that difficult to just drill holes. It's almost as if the hole sequnces were completed thinking everyone drills on a single flat plane then part avoidance was an after thought. Maybe you should turn that in as an idea to make it an automatic function to avoid the part model by the offset or clearance distance automatically. I would vote for it. 

[razmosis]

Steve,

I posted it as an idea this morning.

Thanks,

Matt

[StephenW]

Put a link to the Idea to get the best exposure.

[razmosis]

https://community.ptc.com/t5/Creo-Ideas/Clearance-in-Drilling-Cycle-Add-clearance-to-part-model-by/idi-p/492074/jump-to/first-unread-message