Random Points added

[CNCMATT]

So I am fairly new to the CMM world. I have been with this company for almost 1.5 years and have been getting my hands on the CMM, programming and setting the machine up. I have been thru the PC-DMIS introduction class and can do some basic programming and editing. Please bear with me while i try and explain this. Also on a side note, the initial operator who programmed this part, is no longer working here, so I cannot ask him. So here is my description of the issue at hand.

The program we are using and have been using for many runs has been adding in random vector points whenever it is making an "AIR HIT" most common when we are changing the probe out to use a 5-tip star probe. If we have the Probe enable button turned off on the control pendant, we do not have this issue. (i know - problem solved - just leave this turned off.If we leave this turned off then we cannot calibrate the probe to the master sphere. Plus operators forget to disable probe while changing out probes.) This is the only program we have this issue on. So after a little investigation, from what i can see we are using a READPOINT command to initially hover over our starting point and then it goes into DCC and aligns the part and works just fine. I tried to eliminate this and just use the manual hits of the planes and circle but we are still having it create random points if we bump the head or if we have air hits.

I am thinking that we either have some kind of parameter set or the READPOINT command that i initially thought was the issue is not the cause. I am almost to the point of creating a completely new program the way we do all of our other parts, but there is a lot going on with this part that I don't feel comfortable trying to program. Thought it would be best to just modify original program first.

Has anyone else had this issue?

I understand that I may not be using the correct terminology, so I assume I will have many more questions than answers from anyone who can help.

Thanks in advance for any and all help.

[DAN_M]

HI Matt. Welcome to the CMM world.

I am having a hard time understanding exactly what your problem is.

Can you please post your code? That is the easiest way to troubleshoot.

Copy the code directly from PC DMIS and paste it into the forum. Put (code) before and (/code) after what you paste. (replace the parenthesis with brackets..I put parenthesis just to show you).

[louisd]

The program we are using and have been using for many runs has been adding in random vector points whenever it is making an "AIR HIT"

The creation of random vector points during a false-trigger (air-hit) shouldn't be happening when you are in DCC. It should only occur when you are manually orienting machine with the jogbox.
Disabling probe active button mitigates this as you've discovered.

If you are getting false triggers in DCC, it should just stall the routine and an error should appear, saying "unexpected collision/hit detected".

There's an FDC setting in most controllers that will disable the probe during DCC moves, and make the probe inactive during moves (active ONLY when it's conducting a prehit/retract). This is not a good idea to change if you are a beginner, and/or have a high variation of product on your machine.

whenever it is making an "AIR HIT" most common when we are changing the probe out to use a 5-tip star probe.

Are you manually changing probes? do you have a rack? not following how you are getting an air hit while changing the probe. Please clarify? Are you only getting false triggers when the star probe is on the machine? If so, either your star probe module is too heavy/long/big, the module is too sensitive for your probe build (LF), or the module is broken/worn out.

If we leave this turned off then we cannot calibrate the probe to the master sphere.

You should be calibrating everything in MAN/DCC or DCC/DCC. If you are calibrating in MAN/DCC, and you cannot successfully take the first hit on the top of the sphere without an error, either your probe module is too heavy/long/big, the module is too sensitive for your probe build (LF), or the module is broken/worn out.

but we are still having it create random points if we bump the head or if we have air hits.

If your machine is stationary, and you bump the head, it should be detecting a hit. it did its job. Same with an air-hit. if your probe circuit is opening and detecting a hit, machine should stop and store that data point. (--The air hit itself is not normal, see above RE: broken, too heavy, too long, or too sensitive of a module).
Now for those hits to automatically become a point, there must be something toggled in an FDC setting for this be occurring. Are you sure its actually producing a feature point, or is it just storing the hit?

One last thing to look at is your F10 Probe options. We would need to know what probe system you have to help you if these values are set too prudently.

[louisd]

DCC = Direct Computer Control, when the machine is moving and taking hits on its own.
FDC = Firmware Distributed Controller (PCDMIS Settings Editor) this controls the 'back end' of the CMM to computer interface, behind the scenes of PCDMIS programming.

[neil.challinor]

As louisd says - it should not record hits whilst running in DCC mode & any false triggers ("air hits") should result in the CMM stopping and an error message being displayed. What I suspect is happening is that when you are "manually changing" probes, the probe is getting triggered and this will result in a point or hit being added to the routine. You can avoid this by either turning off the probe enable button whilst manually interacting with the probe (as you have previously mentioned) or by running your programs in protected mode.

Protected mode is available for PC-Dmis 2011 onwards and essentially prevents anybody from being able to edit the programs. You enable it by going to EDIT>PROTECTED MODE on the first screen you see when starting PC-Dmis. It will prompt you to enter a password and will then lock all editing functionality - even if PC-Dmis is shut down and re-started. To disable, go to EDIT>PROTECTED MODE and enter the password.

[Matthew D. Hoedeman]

I haven't tried it, BUT, after all your moves, and BEFORE your tip change, insert the IGNORE MOTION ERRORS command, then AFTER the tip change and BEFORE any moves, turn it back off.

MAYBE it will work.

            IGNOREMOTIONERRORS/ON
            COMMENT/OPER,NO,tip change command
            IGNOREMOTIONERRORS/OFF

no way would I ever leave 'ignore' on, if you get a bogus move point, or something isn't right about the part causing a crash, the machine WILL.... NOT.... STOP and will keep going until massive and expensive damage has been done.

[CNCMATT]

louisd

Thanks for the response. Let me see if i can try and answer some of your questions. Maybe my wording of "AIR HITS" is incorrect

The machine does not create the hits when we are in DCC mode and running the program. This is only occurring when we are changing the probe tips.

We do not have any type of automated changer like we have on our Ziess. This is a Brown and Sharpe that we must manually unscrew and screw in either single or 4-5 tip star probes based on the part we are running. We have 4 different operators on 2 shifts that fight over this machine daily and are constantly changing the probes for their job demands. When we are unscrewing and screwing in the probes while the machine is sitting idle, the machine will beep and then adds this for every time it beeps:

PNT1 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<0.522,7.3705,4.9636>,<-0.6905053,-0.0026973,0.7233223>
ACTL/<0.522,7.3705,4.9636>,<-0.6905053,-0.0026973,0.7233223>
TARG/<0.522,7.3705,4.9636>,<-0.6905053,-0.0026973,0.7233223>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO
PNT2 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<0.4375,7.3707,4.9857>,<0.9993887,-0.0142854,-0.0319092>
ACTL/<0.4375,7.3707,4.9857>,<0.9993887,-0.0142854,-0.0319092>
TARG/<0.4375,7.3707,4.9857>,<0.9993887,-0.0142854,-0.0319092>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO
It places these points where ever we have the cursor in the program. So when we get done changing the probes and calibrating them and run the program, it will try and move to the random points it is creating and will either crash into the part or go to space and alarm with "missed hit"

Hope this clears up some things for you.

[neil.challinor]

Definitely look at running in protected mode. That way you will only be able edit the program and add points when you have entered the password.

[VinniUSMC]

Still, it shouldn't be adding hits just because you touched the probe. It shouldn't add the hits unless you hit "ENTER" after those hits. If you have PC-DMIS open while changing probes, just change the probe while the probe utility window is open (F9 on the LOADPROBE line, or Ctrl+Alt+P).

If you do have hits added, you can see in the bottom right corner of the PC-DMIS window. It will show to the right of the current probe coordinates how many hits you've taken. It should show "0". If it doesn't, then you can use "Alt+-" (Alt then hit the "-" (minus) key) to erase hits.

[Matthew D. Hoedeman]

Still, it shouldn't be adding hits just because you touched the probe. It shouldn't add the hits unless you hit "ENTER" after those hits. If you have PC-DMIS open while changing probes, just change the probe while the probe utility window is open (F9 on the LOADPROBE line, or Ctrl+Alt+P).

If you do have hits added, you can see in the bottom right corner of the PC-DMIS window. It will show to the right of the current probe coordinates how many hits you've taken. It should show "0". If it doesn't, then you can use "Alt+-" (Alt then hit the "-" (minus) key) to erase hits.

it MIGHT be making points because he has the F5 "point only mode" turned on.

[CNCMATT]

Matthew D. Hoedeman

Thank you thank you thank you.

1st rounds on me for the weekend.

I checked the program in question and sure enough "point only mode" was checked on. Unchecked the box and no more random points.

Cant thank you enough.

[neil.challinor]

You will still need to be careful as hits will still get recorded in the hit buffer (bottom RH corner of screen - you'll notice it count up each time the probe is triggered). If there are hits in the buffer they could get randomly added to a feature (or create a new feature) at some point. The safest solution would be protected mode.

[louisd]

Also, you should really look into convincing the boss to at least cough up some dough to buy extra probe modules, that way you aren't stuck unscrewing probes all day, just pull probe+module1 off and place probe+module2 in place... this will also increase throughput, as you won't have to calibrate the probes each time you swap them.