VERICUT Users' Forum

DavidB

Member

From: Australia

Registered: 2005-02-09

Posts: 27

Tool Holdser collision

Hi all,

I can't get Vericut to detect a collision with the Tool Holder.
I have Collision detection ticket. My Holders are imported .STL modals
What am I missing.  :?

Thx in advance

DavidB

Member

From: Australia

Registered: 2005-02-09

Posts: 27

Re: Tool Holdser collision

OK If I use an STL file to define a Holder it does not detect a collision.
But if I draw the same thing in Vericut it detects the collision.
Why is the STL holder not detecting a collision?

Thanks

NCDALE

Member

From: St. Louis, MO.

Registered: 2004-12-16

Posts: 7

Re: Tool Holdser collision

G'day mate.  Sorry about the timing and hope this can be of help to you still.  But we found that some of our holder rubs were going undetected and documented the following for our nc programmers. I have some nice graphics for illustration, but cannot get them posted in this reply.

Software: VERICUT
Version: 5.3 and 5.4
PROBLEM
Vericut is not detecting when the tool holder is colliding or rubbing the stock in all cases.
With error checking set to stop at every error,  the toolholder rubs can go undetected and not stop as you would think. It usually shows them as a red mark.  They may go unrecorded in the log file also.  These may be hard to catch with visual check when the cutting is complete since subsequent cuts can remove the red mark from the cut model as it progresses to the end of the file.

Work-around/solutionChange the tolerance value for Minimum Error Volume in VERICUT properties.

The default value is 0.000.  This needs to be some number greater than zero.  With VERICUT running, go to File-Properties-Tolerance-Minimum Error Volume set the Minimum Error Volume to .00005, it will catch the errors.

I like to eat at Outback Steakhouse here in the U.S. if it's any consolation.
Dale

BryanJ

VERICUT Specialist

From: Irvine, CA

Registered: 2004-10-05

Posts: 84

Website

Re: Tool Holdser collision

I have some nice graphics for illustration, but cannot get them posted in this reply.

Dale,

You can use our public FTP space to upload images to use in the forum.

ftp://ftp.cgtech.com

On the FTP site you will find the folder “pub”. Please feel free to upload your images to this directory. You won’t be able to see the images in the directory because only anonymous access is allowed. Please try to keep the images under 40kb.

When posting an image in the forum you use ftp://ftp.cgtech.com/pub/imagenamehere.jpg (E.g. ftp://ftp.cgtech.com/pub/TakeOff.jpg) but surround the url with the  tags.

Let me know if you have any questions. I look forward to viewing your images.

Thanks,
Bryan

BillH

VERICUT Specialist

From: Irvine, CA

Registered: 2004-10-08

Posts: 146

Website

Re: Tool Holdser collision

Hi David,
Are we talking milling holders or turning holders? "Turns"-out there is a difference (sorry for the bad pun). The answer is a bit complicated, but here goes.

Tool Holders
Milling holders are generally rotationally symmetric about the spindle CL. You can create milling holders in VERICUT's tool manger, using a profile, cylinder, cone, etc. By definition, these holders are rotationally symmertric.

If you use an STL file (or a simple block for that matter) for a milling holder, it likely is not rotationally symmetric about spindle CL. VERICUT has no way of knowing.

Turning holders are, by definition, not symmetric and there is no "spindle" CL.

There are 2 kinds of holder collision detection in VERICUT 5.4: workpiece and machine. And each uses different logic for milling vs. turning holders.

Milling Holder Collisions
For milling holder collisions with the workpiece, a rotationally symmetric holder is swept the same as a milling cutter, and the holder removes material, the same as a cutter. Any material removed is flagged as an error.

The volume removed is tested against the "minimum error volume" value, as Dale describes. If the "minimum error volume" setting is zero a small internal value is used (been this way in VERICUT since forever). If the volume is less than the min value, no error is reported. But VERICUT has to remove material to do the calculation, hence the holder "cut" is painted red but the error is not reported, if less than the min error volume.

If a milling holder is not symmetric, such as an STL file, then VERICUT issues a warning that workpiece collisions will not be detected. This is because no logic exists to create milling holder swept volumes from non-symmetric objects.

Congratulations if you managed to wade through the description so far. There's more...

Machine Simulation Collisions
If you use machine simulation, and turn-on collision detection, then VERICUT can detect collisions between any moving objects, symmetric or not, milling or turning or whatever. This is similar (but different) logic compared to what I described above. The result of this collision check is not a "volume" that can be displayed as a "cut", but rather an error message telling you that component "A" collided with component "B". In this case, the min error volume does not apply, since there is no volume.

This collision check is only available if you enable Machine Simulation and Collisions Detection, and specify what components to check between. You can enable this check between the tool holder and the cut stock, for example.

And finally,
Turning Holder Collisions
Turning holders are, by definition, non-symmetric. If you are simulating turning, and you are NOT using machine simulation, AND the turning holder is visible in the workpiece view...

...then, VERICUT checks for collisions between the cut stock and the holder. It does this using a variation of the machine simulation collision logic described above. You do not have to be using Machine Simulation for this check to occur. No volume is created (or displayed). An error message tells you "Holder collided with Cut Stock at record nnnn".

Ok, so that's a "brief" summary of the current state of things in VERICUT. It has grown-up this way over the past 20 years.

VERICUT 6.0
We are planning to change this significantly in VERICUT 6.0 (and probably into 6.1). Our goal is to reconcile the collision checks into one unified method.

One of the major changes (from an old VERICUT user point-of-view) is that milling holders will no longer remove material from the cut stock. Last time I checked this did not happen out in the shop either (On my desk I have some holders that I "welded" onto workpieces to prove it).

Instead, a "positive" volume of the holder collision is superimposed over the cut stock. You can measure and query this red blob of material to see what caused the collision. You can blank it, or display it. The Cut Stock is not modified by holder collisions.

This eliminates the problem of not detecting a holder passing thru the same collision-area twice. Under the current 5.4 method, the second collision is not detected because the material is removed by the first motion.

I hope this long-winded description helps with your VERICUT usage.

Bill

NCDALE

Member

From: St. Louis, MO.

Registered: 2004-12-16

Posts: 7

Re: Tool Holdser collision

Thanks Bryan.  I'll keep that in mind next time.

Thanks for the in-depth explanation.    :? 
<just kidding>

But it sounds like V:6+ will do the trick.

Thanks!
Dale