OFFSET feature in creo parametric.

[ssms]

hello everyone in ptc community.

I need a small help. What is the meaning of OFFSET feature.

because, when I offset a surface before some extrude done on that surface, it wont ove that extrude accordigly, it leaves the extrude there itself and move the remaining surface.. i need a

clear explaination of this error. i guess its a bug from the creo parametric software.

Can anyone give me the answer?????

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[Mahesh_Sharma]

Sandesh,

Could you explain this in detail?

Offset in model is to offset a curve or surface.

[ssms]

actually wat I was asking was,

wen I offset a surface, the extrude done from that surface should also move na.. but in real case that's not happening.

like wen i go bfore the extude and offset that surface, the extrude remains same.

it's happening that the extrude remains there itself and the surface only moves.

similar to offsetting the surface after the extrude.

[ajoshi-2]

Offset is to project a certain curve/line at a specified distance which u can mention.

[ssms]

actually i hope u alll didnt get wat i'm asking here..

as u see in the above pics,

the cyllinder is extruded from the surface in first fig., after that i take insert mode before that cyllinder extrude and select the surface and give offset 500mm.

so wat i'm asking is wen i go bfore that cylinder extrude and offset the surface to 500mm then wen i resume the extrude it shld be still from that surface only rite ( means the length of cylinder should be 1000mm only )

if NO, then it is equivalent to keepting insert mode after the cylinder extrude and selecting the surface and offseting.

wi both cases are same is my question.

[TomU]

Just hold down "CTRL" and pick both the square surface and the round surface on top of the extrude.  Then they will both offset together.

[TomU]

Here's a video:

Video Link : 6187

[dgschaefer]

When the surface is offset, it gets a new surface ID. Creo "remembers" the old surface ID and its location and that your extrude was created on the old surface, so it continues to create it there.  If it didn't, the extrude would fail because the old surface is gone.  You could argue that it should fail if the surface is gone, but that's not how it works.  (in fact, years ago, it would fail in this situation and our models would fail constantly as a result.  Trust me, this is better.)

You'll need to redefine or reroute ("edit references") your extrude to refer to the new surface.

[ssms]

Tom Uminn‌

the video was good. but the thing is if u have more than one extrude on the surface and u have to move the surface so that all the features shld move along it wat will u do???

AND

Doug Schaefer

wat u said is correct. i agrree.

but wat i'm asking is, then wat is the difference of offseting the surface before and after that cyllinder extrude ????

both giving same results.

my arguement is wen u select the surface after that extrude, only the surface other that the extruded part will get offsetted.

but if u go bfore the extrude and select the surface, then u'll be selecting the complete surface rite. so the extrude shld also be offsetted.

simple example is like,

u have a wall i ur room and u have a wall clock and a AC fitted to wall's surface.

now

if u remove the clock and AC, move the wall and then fit clock and AC.

or

u keep clock and AC and add some wall material,then only it will submerg the clock and AC..

hope u got my point.

[dgschaefer]

I would agree that this "feels" like it shouldn't work this way, but it does. it seems like you are moving the surface, not replacing it. I'd say this is a good spot for an enhancement request, either changing the current functionality or creating the option to maintain the surface ID during the offset.

Nonetheless, understanding why can help you work around it in the future.

[TomU]

Creo is Parametric software.  This means if you edit the original "wall" feature, the clock and AC mounted to it will move with it.  Using the Offset feature is fundamentally different and creates entirely new surfaces.  It does not change the original placement reference for the clock and AC.  Take a look at the video below.  The first two edits directly change the original wall feature.  The third edit uses the offset feature to extend both the wall and all the three extrudes together, creating new surfaces on the top of each of them.

Video Link : 6194

[ssms]

nice video. thanku. i understud that it creates new surface id and all those things..

but wat will u do if u dont have a straight wall feature.

something like wat i'm working with.

washing machine outer body.(plastic)

its surface with shell and has some rib features and some snapps and some curved features and all.

in that case i dont want to increase shell thinkness, i just want to move it. dont tell about nonuniform wall thickness option. i cant even use that.

i'm sorry i culdnt upload videos, as this is my office pc.

hope u guys understud wat i'm telling..

[ssms]

and in ur video, i'll tell u to try  two cases.

case 1 :

after u've build that wall and done those three extrudes, select the wall's surface and give expand feature.

case 2 :

after u have build that wall and those extrudes from that surface, go bfore those three extrudes and use offset expand feature..

tell me the difference..

wat i'm telling is that two cases also give same output. then wat is the use of giving offset bfore and after thosde extrudes..

i consider it as a fault or bug or some design aspect of creo software.

[dgschaefer]

I appreciate your perspective, but it's not a bug.  It's working as designed, you just wish it were designed differently.

[ssms]

then wat is the difference in two cases which i said above????

[TomU]

Nothing.  If you only select the wall surface, then only the wall surface will move.  It will not have any impact on the extrudes since these are referencing the wall feature itself, not the offset.  Zipping up the model tree and adding a new feature doesn't automatically make later features change their references.  In some cases they may adapt to the new geometry (rounds, chamfers, etc.), but they still continue to reference the original geometry.

Wall

Extrudes (referencing the wall)

Offset (only moves selected faces)

(or)

Wall

Offset

Extrudes (still referencing the wall still since they were created prior to the offset)

If is possible to "edit references" of the extrudes and change their placement reference to the new offset face if you want, but this has to be done separately after the offset has been created.