"Cutting Air"

[armo]

A few of our MC users are complaining that their tool paths tend to cut a lot of air... Is there anything that can help? A setting etc. I am not a MC user as such, but I will relay any info to them.

Thanks!

[cadcam]

Sorry sir but we do not have a button that says do not cut air.

 

You can take care this trouble by the style in wich you program.

if you have a file that you can share with us were it is cutting air that they would like to change. I would take time to look at and help.

 

J

 

[ 05-02-2002, 12:43 PM: Message edited by: cadcam ]

[armo]

Jay,

 

OK, I'll see if I can get the file!

 

Is there a central FTP site for emastercam?

[Bullines]

http://www.emastercam.com/ftp.html

[Zero]

I just did a job where a model that I had machined a couple of months ago came back for some revisions. I ended up macining the whole top half of the model off to the new parting line. I ended up cutting alot of air (minimized with tool center boundries) with the rough pocket toolpath which I've always just accepted. While watching the machine cut air I thought, wouldn't it be nice if I could tell mastercam what my "stock" actually looked like instead of just assuming that my stock was an extrusion of my tool center booundry, therefore eliminating alot of air cuts. Is there an option like this in the future for mastercam? Kind of like using an stl file in Verify for stock definition except maybe using surfaces or solids (stl files are just ridiculously large and take too long to read more complex "surfaces"). Sure would be nice!

 

[ 05-02-2002, 04:17 PM: Message edited by: Zero ]

[Charles Davis]

Have you tried using the Highfeed option? That keeps track of the stock as removed and will speed up the feedrate when cutting air.

[heeler]

If you are using surfaces, There is a Depthcut option that you can go in a specify what depths you want to cut at minimum depth, max depth and critical depths. I have elimated most air cuts with this manner and have been able to control where cuts would be when you come back to recut with a smaller finish mill. Also if you are using stock to leave make sure that you set the critical depths relative +Z the amount that you stay off the surface. Good luck

[Reece L Gibson]

We?

[jeff]

hey cadcam,

your version doesn't have that button?

lmao!

[Zero]

Yes I've tried the Highfeed option and use it most of the time nowadays(still experimenting a little with arcs and specific machine configurations for overtravel). I also use cut depths options ALL the time. What I'm saying is that I had an already finished prototype model that was an irregular shape nowhere near a simple 2D extrusion. It would just be nice if you could use surfaces or solids to define your stock. Or even be able to pick a tool center boundry that was say a 3D closed chain and have mastercam recognize that it was a 3D chain and not just see it as a 2D boundry. That way you aren't limited to constant z-depth rough pocketing. Am I making any sense?

 

Just a thought

[heeler]

I also do finish passes and stay of the surface what I need to then just increase parameters to make it more of a roughing style. Then I can copy the toolpath setup and tighten the parameters for the final finish.

[heeler]

I also do finish passes and stay off the surface what I need to then just increase parameters to make it more of a roughing style. Then I can copy the toolpath setup and tighten the parameters for the final finish.

 

Ops I mean off the surface.

[Camdude®]

if your surface routine is cutting air the problem may be the stock to leave parameter.

use the depth cuts button and using incremental tab adjust the top of the cut by placing an amount at least equal to the stock to leave. i usually add a value to the adjustment. i.e

if leaving .03 stock add .05 for first cut making total value in adjustment to .08

[Zero]

Since I can't explain things very well, I've uploaded a file to the ftp called CUTTING AIR.zip.

This is a rough estimation of what I'm talking about. The grey solid is my "stock" and the tan surface is the "parting line" that I'm machining down to. As you can see, there is a lot of material to be removed which in my mind calls for a rough pocket toolpath. You can also see that there is alot of wasted time cutting air(which is cut down considerably with HFM like Charles had mentioned). I'm just saying that it would be nice with one rough pocket program to eliminate all air cuts by telling mastercam that the grey solid is my stock and not to cut anywhere outside of the grey solid (besides lead ins and outs)therefore eliminating any unwanted air cuts.

Or again, use a true 3D boundry (like the combination of front view geo and top view geo used to create the solid) and have mastercam recognize that it is a 3D boundry (and not just convert the boundry to 2D) and get similar results. So in essence instead of constant z-depth cutting at a certain height(like z1.5,then z1.4, then z1.3 etc..), you could cut say a constant z-profile at specified step downs relative to the z-profile like cutting multiple stepovers of an xz arc with a radius of 5 and then stepping those same arcs down .1.

Or you could still use a constant z-depth method but have mastercam recognize that it is not cutting stock anymore and step down to the next depth cut. So in essence you have a constantly changing tool center boundry relative to your 3D stock at that z-depth. (I guess that you could create multiple boundries at multiple depths around the stock like every .1" and generate multiple rough pocket toolpaths only cutting between those .1 increments but that seems a little ridiculous not to mention time consuming, doesn't it?)

 

Does anybody understand what I'm talking about now? Sorry for hijacking your thread there armo.

I just thought that 3D stock recognition might be a nice feature to have in say V10?

 

[ 05-02-2002, 07:05 PM: Message edited by: Zero ]

[heeler]

I can't seem to get the FTP working right. But a thought. Have you roughed it out to the stock that you are talking about then turn off the posting of that path and do a remachine on the next path. I have been very successful with this on using different types of extrusion parts. Good Luck.

[armo]

Zero,

 

No problem! I am currently uploading my file into the FTP. It is called 1959-172.zip, and I put it into the MC9_files directory on the FTP site.

 

I am glad to hear this is not just a problem we have here!

 

Now lets fix it!!!

[armo]

Oh, I forgot to say...

 

The air time is really prevalent in the "Rest-Mill" operation of the file 1959-172.mc9...

 

Still uploading the file.... darn 33.6k connection!!! Give my file another hour (after my post time here ) before anyone tries to get it from FTP...

 

Thanks guys, keep these suggestions coming!

[armo]

Ok, the file is uploaded.

 

Cadcam - do your worst! I mean best!

 

Thanks!

[Zero]

sorry armo, I'm running V8.1.1 still here so I can't look at your file(unless someone would be nice enough to convert it for me ) and give you any suggestions, but I'm sure there's plenty of others here that could help you.

Good luck

[armo]

Camdude,

 

Your idea worked quite well! Another tip to keep in mind!

 

Thank-you.

 

Zero,

 

We tried saving it to a MC8 file, but it won't save the toolpaths. Kind of defeats the purpose. Thanks for your help!