Jump to content

Welcome to eMastercam

Register now to participate in the forums, access the download area, buy Mastercam training materials, post processors and more. This message will be removed once you have signed in.

Use your display name or email address to sign in:

Machine Simulation false collisions


sharles
 Share

Recommended Posts

We've recently started using machine simulation, but I'm regularly getting false 'tool and workpiece' collisions. Is there some setting that I can change to get rid of them? It typically seems to happen when I select ALL the operations for a part. If I leave the simulator and only select a few of the ops at a time to simulate, then the false collisions go away.

Any suggestion? Thanks,

Scott

 

Link to comment
Share on other sites

What kind of machine?

Are you seeing rotation collisions that won't really be there?

If your simulation isn't tied to your post, simulation is "sketchy" at best, it misses things....one thing I have is my post gives me clearance moves automatically at rotation and offset changes for my HMC's...becasue I do this in the post, I get crashes that I know are not going to happen....what I am really using the simualtion for is checking clearances between holder, fixtures and parts.....I set my retract value to a large number and run simulation...once I know the clearances I am checking for are good, I set my clearance back to 1" and post.

Not sure if you're seeing something similar.

Review the collisions to see what's actually being reported.

  • Thanks 1
Link to comment
Share on other sites
On ‎6‎/‎15‎/‎2019 at 9:53 AM, Old_Bear said:

What kind of machine?

Are you seeing rotation collisions that won't really be there?

If your simulation isn't tied to your post, simulation is "sketchy" at best, it misses things....one thing I have is my post gives me clearance moves automatically at rotation and offset changes for my HMC's...becasue I do this in the post, I get crashes that I know are not going to happen....what I am really using the simualtion for is checking clearances between holder, fixtures and parts.....I set my retract value to a large number and run simulation...once I know the clearances I am checking for are good, I set my clearance back to 1" and post.

Not sure if you're seeing something similar.

Review the collisions to see what's actually being reported.

It's a Johnford 3axis milling machine. No rotations. And when I click on the 'errors' and look at the graphics, I can tell there isn't any problem...and like I said, if I select a smaller amount of operations to simulate at one time, then the errors go completely away...but it's annoying. I'd like to select all the ops and let it run and see a clean error log. Sometimes that happens. Sometimes it's full of false positives. Just wish I knew why so many false positives so I could deal with them and it would increase my level of confidence.

Thanks for taking the time to respond.

Scott

Link to comment
Share on other sites

It may be the setting of verify. By default MasterCAM uses non-interpolated rapids (X and Y axis move at max.feed rate independently). This may give false crashes in tight spots. You have to change settings in the control definitions, (see image below) so that X and Y arrive at destination simultaneously. This may help.

image.thumb.png.818f035c73b619083f1ff838154ff4b6.png

  • Thanks 1
  • Like 2
Link to comment
Share on other sites

You're likely seeing crashes during the rapid moves that link operations, and what Radical1 mentions is the way to remove these 'false positives'. Be aware though, that now you may have a clean Machine Sim that actually does crash or clip a corner at the machine. The control definition setting "Each axis moves at maximum feed rate independently" is basically showing the dogleg motion that will occur in real life during a G0 move. This will depend on the machine and the acceleration of each axis of the machine. Usually, G0 moves between operations are at a clearance height that is above all part and fixturing features, but if you're down in between things, you have the chance of collision because of this dogleg.

Note the Linking Parameters page of a Dynamic Optirough path. When you set the retract strategy to Minimum Vertical Retract, you have the opportunity to convert all rapid G0 motion to G1 motion with a designated feed speed. This is to avoid dogleg crashes that now become much more of a possibility while keeping the tool so close to the part- now all our motion will be linear interpolated at the feedrate specified.

Link to comment
Share on other sites

Dylan, I'm not getting these in rapid moves. I'm getting them when the tool is right down on the part.

 

Grievous, are you saying I should tighten the tolerance. It comes up at .007 tolerance. I've never messed with it. Maybe that's the problem, but will it significantly lengthen the simulation time on a part that's a gigabyte big? I guess I can try.

Scott

Link to comment
Share on other sites
8 minutes ago, Grievous said:

My question stands..Why do you need to check the tool against the workpiece?

I guess I don't 'need' to do it, since I also verify my parts. Normally, I just tell the simulator to ignore all similar errors for the op...but that doesn't address the fact that the simulator isn't working correctly unless I have some setting wrong...I was just trying to figure out if my relative ignorance about machine simulate was the reason for the errors and I simply didn't have some parameter correctly set...

Link to comment
Share on other sites
On ‎6‎/‎20‎/‎2019 at 12:25 AM, samairakh said:

SPAM LINK DELETED BY GCODE

odd place to ask the question, but yes some mechanical engineers use 3d printers, cnc machine, etc. in their line of work. Emastercam is more of a CNC machining and mastercam software forum rather than a 3d printing forum although many of us may have experience with both.

Link to comment
Share on other sites
On 6/17/2019 at 12:03 PM, sharles said:

I guess I don't 'need' to do it, since I also verify my parts. Normally, I just tell the simulator to ignore all similar errors for the op...but that doesn't address the fact that the simulator isn't working correctly unless I have some setting wrong...I was just trying to figure out if my relative ignorance about machine simulate was the reason for the errors and I simply didn't have some parameter correctly set...

I use both simulation and verify to check for collisions. Simulation is mostly for fixtures, and tool movement, and machine dynamics. Verify for gouges or compare to model etc. This might be obvious to some, but it took me a little while to figure it out, make sure your stock and all fixturing levels are not visible on Mastercam before you start verify. And/or turn off collision checking to workpiece.  Also, make sure that all axis arrive simultaneously as shown in the screenshot above. Otherwise, it will pull the tool holder through the part on 180deg rotations. 

  • Like 2
Link to comment
Share on other sites

ok. Well, I think I've figured it out. Mastercam defaults my machine simulation to .0072 tolerance. But if I use a tool like a scribe with a .006 tip, it will automatically narrow that tolerance down to .001 (gives me a warning that it's doing that). And if I machine simulate that scribe tool along with all my other programs, then I get the false positives on all my finish ballmills. Essentially, I think the false positives are just where the ballmill is contacting the part surfaces with 0 stock. So if  leave out the scribe program and the tolerance stays at .0072, I don't get any false positives.

The other place I get false positives regularly is in my drilling and tapping programs. I haven't messed enough with them to figure out if there's a way to get rid of them, but if I do, I'll try to give an update.

Thanks for all the input.

Scott

Link to comment
Share on other sites

Just some updated information after looking at the part file in question here- The Collision Tolerance in Machine Simulation (under Info on the menu when a Machine Simulation window is open) is a calculation based on, in part, the Simulation Tolerance in the Machine Simulation settings page. Because the very small scribe tool radius on the etching ops of this part forces that Machine Simulation tolerance to a very small value, and that applies to all operations being actively simulated, we now see all these false collisions for the previous ops. There is no current way to maintain two different tolerance sets for operations being simulated in a single instance of Machine Simulation, and thus the workaround would be to simulate your etching ops separately from the rest of the ops on this part.

Also,

On 6/25/2019 at 9:38 AM, jerms said:

I use both simulation and verify to check for collisions. Simulation is mostly for fixtures, and tool movement, and machine dynamics. Verify for gouges or compare to model etc. This might be obvious to some, but it took me a little while to figure it out, make sure your stock and all fixturing levels are not visible on Mastercam before you start verify. And/or turn off collision checking to workpiece.  Also, make sure that all axis arrive simultaneously as shown in the screenshot above. Otherwise, it will pull the tool holder through the part on 180deg rotations. 


The Linear interpolate choice will also remove this tool holder orientation swap from the operation transition move in Simulation. In the future, all three options will keep the tool from starting the first point of a subsequent op in the wrong orientation in Simulation.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.

Join us!

eMastercam - your online source for all things Mastercam.

Together, we are the strongest Mastercam community on the web with over 56,000 members, and our online store offers a wide selection of training materials for all applications and skill levels.

Follow us

×
×
  • Create New...