Eliminate the Air Cut!

[CyborgCNC]

Hi All,

I was wondering if some of the experts here can shed some light on this...I am trying to eliminate having the tool do a lot of "air cutting" while creating roughing surfacing toolpaths..anywayz, here is what I mean:

I have a part, as you can see below. The STOCK model for this part, is going to be be very close to what the finished part is, but not as close as for me to just do a finishing path..I want to do a roughing path first....first on the surface you see...

As you can see, doing a flowline rough, assumes that there is a lot more material left, and hence, it creates a lot of air cutting, where basically material is NOT going to be....I wish that there was a way to SPECIFY the stock model, and then do the roughing pass, this way mastercam will know what the stock model looks like, and start from there, not do as much air cutting..I am already importing my stock model as an .stl, and this works great, but somehow for a roughing flowline, MC seems to ignore it...In other words, I want the toolpath to be calculated based on the .stl model...

So, what would be the best tool path to achieve this? Any ideas?

i have also attached the mastercam file is anyone want to take a look at it...

thanks all in advance for any advise!

[clay steinbach]

You probably already tried adjusting the feed plane to .1 or so above top of stock. Your acrually wanting to cut. And use depth of cuts. I would use surface rough parrell and select the surfaces you want to machine. But select the tall wall as a checked surface does that make any scence? Edit looking at part in cam I see what you mean now. I would still try the surface rough and select only the surfaces or high speed path rough with a raster pass.

[CyborgCNC]

Thanks for your reply.....

Still a bit confused....you say raster pass for surface high speed, but raster is not a roughing pass, it is a finishing pass...no real difference...if I could do a finish, I would simply do a flowline finish, and get the same result..see what I mean? Selecting a high speed rough, still air cuts, unless I am doing something wrong...but have tried most of the parameters with no change....

I do see that under a high speed rest rough, there is an option for a cad model...will give that a try to see if it makes a difference

So I need a ROUGHING pass, that will take into account the stock model....I guess that sums it up in what I am trying to do...

thanks again...

[clay steinbach]

You are right I missinformed that one. raster is a finish pass but you can leave stock with that pass. it is the path ive found that will allow me to do multiple surfaces flowline always gives me funny paths when I select more than one surface. I may be no help. But sometimes just talking it out can get you through it.

[KevinV_MEI]

Do a flowline finish and use the leave XY material offset to step it in like a rough pass. may take 2-3 "finish" passes. Not programatically elegant but machine efficient.

[CyborgCNC]

Yeah...I think that is the way to go if I do not want aircut...

Another thing which I think will work, and i am running the simulations now, is to do a rough High Speed and use the Rest toolpath...

I then tell it to use the stock model as a calculation of what to machine, and it seems to do a decent job....

What drives me crazy, is the fact that when I choose a check surface for any HSS rough path, it uses the check surface as drive geometry...

makes me scratch my head as to what the MC developers where thinking with some of this stuff....It would be a lot easier to simply have the stock model as part of the geometry calculation of what to cut, and what not to cut...I think it would simply give "more vision" to the machine as to what one is trying to do...

Anyway, we shall see....

Thank you for your comments however, really do appreciate the feedback here!

[Superman]

Another thing which I think will work, and i am running the simulations now, is to do a rough High Speed and use the Rest toolpath...

I then tell it to use the stock model as a calculation of what to machine, and it seems to do a decent job....!

Your thinking of using Rest Rough is correct,
what you need to do is create operations that would turn a rectangular block into your stock model --- and then ghost them ( not to actually post any code )
- it would then give out less air cuts, try putting an offset of 0.1" on your roughing pass and then ghost it, then do the operations to complete it.

BUT, your model has a large undercut area on the vertical leg, have you thought of doing it with the other leg in the air ??

[CyborgCNC]

Thanks!

That is actually quite cleaver!...to do the operation, not post it, and then do a remaining operation to cut the part with a rest machining pass...I learn something everyday here!

That I think will work the best...and certainly will go down that path. Yes, you are right about the undercut, and will flip the leg for that cut..

Thanks for the feedback....appreciate it!

[CyborgCNC]

Just some more on this...

It seems that CNC software is actually doing something about this!!

I was just browsing their website, and it seems that Mastercam X6 is now able to use a stock model as part of the machining tree, to create tool paths that take it into consideration...

I have not used it, and not sure when I will, as I am on X4, but looks like a good feature....

:-)

[rdpdo]

I think only topsolid can do this ?

[cadcam]

I think only topsolid can do this ?

What is Topsolid and why can it only do this?

[forrey45]

Topsolid 7 is a CadCam system and is aware of the stock conditions as you cut the part and makes tool paths to reflect these conditions.
We are evaluating this package at the moment and I am very impressed to say the least.
Forrey.