Unexpected Probe Hit Question

[gsepan]

I have been struggling with a repeated machine error “unexpected probe hit” on some of my tip rotations. I have to hit the continue button every time this happens. I am reluctant to tighten the tp2 as it is set to factory specs. Is there a way to override this error so I can run my program without interruption?

[Underspec]

You can use ON ERROR commands with LABELS to do what you gotta do. Why are you getting these errors? Wouldn't it make sense to fix the programmed features? Or rewrite that part of the code?

[gsepan]

My tp2 is firing hits when I rotate certain angles due to the tip configuration I am using. The program runs flawless otherwise.

Being fairly new to the "demon" could you please elaborate what you mean by ON ERROR commands with LABELS? I'm one of those guys who uses strictly DCC functions with cad when I program so be gentle with me when explaining.


Thanks,


Greg

[bw_bob]

What size probe & extension are you using. It might be too heavy.

[craiger_ny]

Like Bob said you might be swinging too much shaft around if that is possible (I get a lot of e-mails soliciting the possibility). You can adjust the TP2 but you'll have to readjust it for other styli perhaps there is a "sweet spot" you could adjust it too that will accomodate the majority of your styli.

Craig

[Underspec]

Sounds like you have a TP issue and not a program issue. I'm not sure about TP2's but I use TP20's and I have difference force modules I can use depending on the probe size. I haven't heard of any speed adjustments you can do on the rotation of the head either.

You can try this:

Insert ON ERROR at the beginning of the program from the pull down menus. Then inserting a LABEL at the end of the program. Edit the ON ERROR for "Unexpected Hit" and call this LABEL for the error. Under this LABEL you can add what you need to do if the error occurs.

Doing this can get complicated though. After your LABEL code, you'll probably want to continue on to more features? So I would LABEL after each spot of error so you can continue on.

[Wes Cisco]

I would suspect weight and/or tip inertia due to length. I run some outragous tips on the tp2, (2x110mm), but I do tighten it up and I run really really slow.
If you do decide to tighten, calibrate, then adjust, calibrate, compare std dev. adjust, calibrate, compare, etc. by doing this you can "walk" it into the best adjustment. I adjust about 1/8 - 1/4 turn each time.

The other thing you might look into, if you haven't already, is different tip materials. Ceramic is lighter than steel and very rigid, although also brittle. Carbon fiber is even lighter. Renishaw makes a wide variety of tips with a ruby directly on ceramic or carbon fiber as well as extensions that may reduce your number of false hits. HTH

[gsepan]

my build up is as follows...

PH9
EXTEN50MM
EXTEN10MM
10BY6.5STAR
TIP#1: TIP2BY10MM
TIP#2: TIP2BY10MM
TIP#3: TIP2BY10MM

This is not my typical setup, I usually use a EXTEN10MM with a TIP2BY20MM with no problems. Me's thinks that the added weight of the STAR is causing it to fire prematurely.

[craiger_ny]

Definately is the added weight.

[bw_bob]

If your extensions are steel thats your problem. Use Wes's suggestion about ceramic or carbon. They are fairly in-expensive. Thats what i use when needing something long & stiff....

[Don Ruggieri]

Another option

The other choice is to enable the option called "Ignore Motion Errors".

From the help file -

IgnoreMotionError
IgnoreMotionError tog:=(Integer)

tog: TRUE or FALSE. TRUE indicates that we wish to begin ignoring CMM motion errors. FALSE means we wish to stop ignoring CMM motion errors.


ps, this is only advised once the program is completely debugged for path obstructions!!!!!

[gsepan]

Thanks so much guys!!! I'm going to go with Wes and tighten my tp2 up a bit. I'll give her a try with a 1/8 of a turn first, calibrate and give her a go... rinse and repeat if nessessary. My boss won't go with ceramic as our company is tight and spending is at a standstill. Working in automotive here in Michigan has been tough of late, nobody want to spend a dime.

Best Regards,


Greg (gsepan)

[craiger_ny]

From the Renishaw catalog:

M3 3X50 ceramic $70
M3 3X50 tungsten $53

From Carbide Probes Inc catalog:

M3 3X50 ceramic $36
M3 3X50 tungsten $38

If you find adjusting to be too finicky give Don's method a shot. But like he said you should be completely debugged and make sure no one puts anything on the CMM that you could crash into that your program is not taking into account of being there. Good luck getting a raise, not being able to spen $36 is not a good sign that you will.

Craig

[kpayne]

I have the TP2 probe system and you can adjust the measurement forces. I ordered a force gage from Renishaw and usually set TP2 with 20 to 30 mm probe length at 5 to 7 grams and a probe length of 80 to 100 mm at 10 to 12 grams

http://www.renishaw.com/client/produ.../PRD-576.shtml

Kevin

[Wes Cisco]

A force gage makes it faster and easier to adjust tension, but my method acheives the same end result without spending $.

BTW, I could not agree with Craig more. $36 or even $70 for a needed piece of equipment should not be a problem even in tight times.