Creating qualification for 2 reference spheres on same stand?

[[Lu...]]

Hello, for reference i have never created a new probe or a new qualification program or anything. I have done research but I am having a hard time finding info on a couple different things.

Currently we use a 30mm reference sphere at a 45 degree angle for every probe we have, even our small probes. this has caused some major inaccuracy in some of our smaller probes and I am getting it set up to where I would like to have the 30mm sphere standing straight up, and a 8mm ball at the 45 degree angle (unless there is a better setup that you all recommend). 

I believe I know how to edit our current reference sphere to stand straight up, and i believe i can figure out how to add another reference sphere at a 45 degree angle. what i want to know is do i need to put in somewhere that they are both there at the same time, to where when it does the qualification of some probes it doesn't crash into the other sphere? I'm going to be creating a new qualification program that would hopefully qualify all the probes at the same time, though if necessary i will have 2 separate qualification programs for out smaller and bigger probes. 

Is there anything else to consider when modifying the qualification spheres? I have never had any official training on CMMs and though I have found work instructions that help I havent yet seen something about this. Thanks!

[[Ma...]]

I think there is no problem with having two ref. spheres on same stand. Calypso is asking only for it's center.

If you are removing that stand with spheres, then you have to first tell it's new position of both spheres before running a program.

If i remember correctly, then in program you have finding center of ref. sphere ( i am not sure if you can select which ref. sphere is selected ), but in program you have two spheres with correct diameter, which will later be used for calibration.

[[Lu...]]

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So Calypso wouldn't crash into the other sphere during qualification even without telling it to path around another sphere?

[[Ma...]]

That's not what i said - you would describe closely how they would be used, positions and so on.

We are using star probe systems, so we have one ref. sphere at 45 angle and rotate it by 180° to cover all 5 probe tips.

Calypso won't alter movements just because there can be next sphere, but if you correctly set calibration, then you can avoid collisions.

[[Je...]]

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Hi

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.  Thanks for posting about this.  Very interesting.

We use a measurement plan to qualify all stylii, and this utilizes both 30mm and 8mm spheres.  These two spheres, however, are mounted on different posts.

Important:  Calypso does not automatically adjust the navigation paths of a stylus qualified on one reference sphere based on the location of another sphere.  Collisions are possible without proper planning.

If it's necessary to fixture both your reference spheres on the same post, you'll need to plan for clearance.  I'm sure this can be plotted and mathed, but you can also just observe a qualification in CNC on slow speed to get an understanding of required clearance.

Edited July 15

[[Ri...]]

I have worked on systems with 4 master spheres.

Two were at the far -X and two were at the far +X.

At the far -X:

One sphere was 45 +X+Y and 45 +Z

The other sphere was 45 +X-Y and 45 -Z, just the opposite for the far +X.

You would have to qualify each master sphere giving each sphere a number.

Then when qualifying individual styli, you program what stylus used which master sphere by the master sphere number.

This was on a system using VAST XT Gold from single -Z styli to multi star and custom probes with up to 6 tips. I see no reason why this wouldn't work with VAST XTR Gold and RDS XXT.

With the RDS XXT, you would have to use Lists, I do not believe the CAA would be able to work on the configuration I described.

 

Edited Thursday at 11:42 AM

[[Lu...]]

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Yes that is probably what I will end up doing, i believe i have it figured out to where all my probes "should" qualify without crashing into the other sphere but i can only wait and get it done whenever out 8mm sphere comes in (which i absolutely will be running slowly and monitor). Thank you very much

 

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This is something I haven't really considered yet, could i write my qualification program to check the location of both spheres at the beginning of the program automatically? Or would that need to be done before by using the "reference sphere position" in the probe management menu first. I saw on a work instruction I found that you can put a "qualification" characteristic for the master probe and it will check the reference sphere position, but to only do this if you can put the reference sphere stand in the same spot/rotation which I can do. If not its no big deal its just something I'm curious about, thank you all for your help!

[[Lu...]]

I have another question, I believe i don't understand the "Sphere coverage" and "Taper angle" for the probes when qualifying against the reference sphere. Based on my understanding, a "180" sphere coverage would mean the probe covers half of the reference sphere right? Yet i have a probe that physically could not reach below my current reference sphere (its a probe facing to the left, pretty small ruby and the shaft is facing upward really close to the ruby.) yet the sphere coverage for that probe is also set to 180. Am i not understanding "Sphere coverage" and "Taper angle" correctly? I can take photos if it would help you all to understand

[[Ma...]]

Sphere coverage would be for scanning ref. sphere - but tensor is ignoring that number and is doing 180° anyways.

I am not sure about taper angle - once i am doing aquisition of ref. sphere, then i am setting up some angles.

[[Ri...]]

Short video of my Master Sphere setup.

1 thru 5 are all 30mm Master Spheres, 6 is an 8mm Master Sphere.

Each one you create can be assigned an orientation (Inclination Angle, Rotation Angle), as seen in the short video.

From this, if I have Master Spheres 1 thru 4 setup on the CMM and a Star probe with 4 tips (-X, +X, -Y, +Y) I can assign each stylus tip to a specific Master Probe by its Number assignment. 

When you run an Automatic Qualification, the built-in routine will run each stylus tip to its respectively assigned Master Sphere when you manually qualified each tip.

Clearance Distance is established for each individual Master Sphere in the "Clearance Distance dialog". In my case, the Clearance Distance is the same for all Master Spheres.

Edited Thursday at 02:50 PM

[[Je...]]

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, make more videos about Calypso programming.  Youtube or other platform perhaps?

[[Ri...]]

I haven't thought about posting any. I have deleted more than I can recall from other forums.

[[Lu...]]

So after doing more research, I learned about how there is a "manual" or "single points" way of qualifying probes instead of "tensor" or "six points". The probe i was questioning is set to manual which is likely why the "180" degrees i mentioned earlier doesn't actually apply. Is there a way to see exactly where these manual points are on the reference sphere besides just running the qualification?

 

The whole reason i am doing this is because we have a custom probe that has been used (rarely, but still used) for years now, and i have just discovered it is wildly inaccurate (I picked up a point in the same spot with the 2 different probes, and it was .002 inches different than a trusted probe) and I am just trying to find out as much info as to what went wrong and how it has been qualified in the past to make sure I wont be making those same mistakes. Thanks!

[[Lu...]]

Sorry I keep flooding this one topic with a lot of questions, i just don't want to flood the Calypso general forum. 

I did some basic trig and i think the max degrees i will be able to get with my new sphere will be about 100 degrees, will that be enough? I think technically i could do 110 but that's with 0 clearance so i think 100 would be pretty good, though i have seen before it is recommended to get 180 degrees for the qualification but will i see a dramatic loss in accuracy with only having 100 degrees?

[[Ma...]]

If you would rely on directional touch point in direction of probe, then it would be sufficient. If you plan to touch sideways of probe tip, then it may be not precise enough ( but tolerance is boss here - with tight tolerances is coverage needed )

But you can always do comparison with known fully calibrated probe and how much it differs.

[[Je...]]

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, no apologies necessary.  Your participation increases engagement across the forum, and that's a win for all of us.

Please keep posting about anything, anytime.

[[Ri...]]

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I have delved into this far in the past.

Typically, the stylus industry uses a Grade for ranking the sphericity of styli tips, in this case I will speak on ruby styli.

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I have run test in the past on Master Sphere's and Master Ring Gages.

Qualification Methods Evaluated

1. Full standard qualification (180° coverage)
2. 160° coverage
3. 140° coverage
4. 120° coverage
5. 110° coverage
6. 100° coverage
7. 90° coverage

Results

Testing showed no measurable degradation in diametral accuracy when qualification coverage was reduced from 180° to 120°. (Based on my data, this was not peer reviewed).

When qualification coverage was further reduced to between 90° and 110°, a measurable decrease in diametral accuracy was observed, resulting in diametral measurement errors of up to -0.00008 in.

Measuring on a Master Sphere allowed me to report location spherically.

This was completed with a spherical true position and a tolerance of .0003 in, all location data in the tests passed, I have been searching my USBs for this old data with no luck, but I do recall no deviation from 0.0,0.0,0.0 was greater than .00021 at 90° coverage.

All of this is well and good when based on artifacts themselves with 0.76um cylindricity (Basic Class XX ring gage) or sphericity 0.13um (Basic Master Sphere).

Note: Ring Gage cylindricity changes by size.

I have not yet evaluated these parameters on machined products; however, they provided a useful baseline for projects where qualification with less than 180° of scan coverage during qualification is acceptable. This led to what I refer to as the Three Keys of scanning:

Capability – Can the feature be effectively measured using the scanning method?

Accuracy – How closely do the measured results represent the true value? This is typically demonstrated through a Measurement System Analysis (MSA).

Repeatability – Can the system consistently produce the same results under the same conditions? This is also typically evaluated through an MSA.