Locating Z height for diameter max

[[Ja...]]

Hello all. We have a setting master where we are trying to find the height of a max diameter on a split circle, so the OD has to be scanned separately on both sides. The drawing tells us to measure the OD ± 14° and find the "ball center" which I am assuming would be the furthest point away from center. I need to be able to report the height from the bottom (0) to the circle center. What would be the best way to get this measurement? We used the slot feature when brainstorming and it seems to get us close, but I am wanting to clarify that this is the method that should be used.

Master.jpg

[[Ky...]]

Hello Jason,

I'll be honest, I'm not following the "ball center" terminology either. Usually when I see wording like that, it's referencing gears, so unless they are interested in those cut outs on the side?

That being said, if you just need the point furthest away from center, I've had luck recalling that data into a line and then using max/min points, depending on the geometry of the theoretical line you make. Do make sure that in the max/min coordinate, you select "nominal geometry" though. Also make sure the Z of the 2D line is pointing in the either towards or away from the data. That's the direction it is using to calculate the man/min coordinate.


I hope this helps.

[[Ja...]]

The drawing says "Determining the center of the ball using a circle of two opposing tracks in a segment ±14°
below and across from the marking line (long, vertical line)". On the drawing it shows that height from the bottom as 11 ± 0.05, but then shows an OD of 56. I think what it is saying is that the ball center would be the "peak" of the diameter, or max value on both ends. I am not sure if this could be done in one pass, so I would assume you would scan the radius on one side, scan the radius directly across on the other, find the 2 max points (x+ and x-), maybe find the middle point between the two, and then measure the diameter at that height. Because of this, the scan of both radii needs to be done first to find the height, and then the CMM needs to measure the diameter of the OD at that height. Does this make sense?

[[Jo...]]

I would think that geometry is a torus(or sphere). Measured and vector constrained it should give you a "center" in Z. It doesn't work well for most constructions. Limit your measurement strategy to 14° above and below center.

[[Ro...]]

I might be misunderstanding the assignment, but this may be able to be done using Caliper Distance.
I just finished a program today that had an odd callout of 2 circles Edge to Edge distance.
I used Caliper distance and set both circles to Minimum, so the distance it took is the closest points between the circles.
You are looking for the opposite, you want the furthest points so you would set the circles to Maximum.

minimum feature1.PNGminimum feature2.PNGminimum feature 3.PNG

[[Ky...]]

Admittedly hard to tell from the print. It could be a torus, but I would think the print would show a tighter radius around. It does look more spherical to me.

Roberto's idea would be good if we are trying to get a diametral measurement between two circles on opposite sides. I was under the impression that we were looking for a Z height for the diameter.

I'm afraid at this point is where I would start asking for clarifications from the designer. Are we looking for a height? Are we looking for a diameter at a height? Are we just looking for a diameter of that sphere (or torus) with only that +/-14 degree range included? There are solutions to all of these, but without clarification I can't say.

[[Jo...]]

[[Ja...]]

We are looking for both. The machine on which the setting master is used scans both sides top to bottom and finds that max value (peak of the radius) and then uses that Z value to scan the OD of the master. So scanning the rounded areas bottom to top to find the peak of both sides, then at that height from the 0 plane where the peak is, those would intersect and determine the height value, which SHOULD land right around 11mm.

[[Ky...]]

If that is the case, then the process I outlined in my first reply (measure as circle path, recall feature points into 2D line, create max/min coordinate depending on the orientation of the line) should give you the Z-height of the "peak" of the diameter, as you described it. You can either use the resulting Z height in a formula to measure a circle around the full part, or use the caliper distance as Roberto mentioned (though you will have to make sure they are as close to 180 degrees from each other as possible).

I hope that helps.