small chamfer measurement

[[Ün...]]

Hello,

I need to create a reference from a 1mm wide cone and look at the other diameter runout with that reference. We process the Ø22.4 dimension and the 1 mm chamfer at the entrance at the same time and with the same tool, but our customer especially wants us to take the chamfer reference instead of Ø22.4 diameter.

I'm thinking of creating a cone with the Ø0.3 probe I have and creating intersections by making vertical scans with the Curve.

I would like to know your valuable ideas.

[[SH...]]

I would say that this design violating the datum condition requirment of any kind of gdt standard....

[[Ma...]]

I would say - I donť want to be machinist who will make this - and I don't want to be measuring man who will be explaining why is this nonsense.

To fulfill the purpose, I would measure only one circle on the cone to get datum B - the same goes for datum A ( I think the same shape is on the other side )

[[No...]]

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A picture is worth a thousand words, so let me illustrate what may happen here. The following is an example I had on my table recently. They wanted me to measure the perpendicularity (!) of the outer diameter. The red arrow marks the cone of diameter 90 mm and 1 mm height. I admit it's a plastic part (sorry I can't show more of it), so my deviations may be much bigger, but the principle is the same.

The upper purple part is the CAD with the cone marked by the arrow and a slight blue color. The lower is the actual part, scanned with GOM. The actual cone is marked in green. By the way, the cone consists of more than 29,000 points, but still....How many can you scan on a CMM?

[[Ma...]]

If I understand this image so you have just slice of cone ( not full 360° ) of diam. 90 - I think it is unmeasurable accurately.
For CMM i would just use line profile for such small areas.

Because of author's part is turned part, then i would avoid measuring angle - just use position - unless it is made from adamantium 🤣

[[No...]]

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No, this was a full 360 degree diameter. No gaps or anything. The arrow is only there to show the position of the cone and that the ribs above don't belong to it.
Being a plastic part it may be slightly warped etc., but the point is: If the ratio between diameter and length is as bad as in this example, fitting algorithms reach their limits, as every tiny inaccuracy can cause large deviations. It's the same effect as if you use a very short feature for the alignment of a much larger part. It's just not stable enough to use it as any kind of reference.

[[Ma...]]

This looks like a center rather than a chamfer. Depending on the rest of the datum structure and the features that require measurement, perhaps you could measure it with a set of bench centers instead of the CMM or with a CMM with a tailstock.

[[Ma...]]

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Sorry, but I don't see there anything - zoomed in to chrome max, but still nothing.

[[Er...]]

Based on seeing the machining method...
For the concectricity datum I would measure a Circle on Cone in an alignment using the 22.4 diameter for each end. Just make sure the point vectors are normal to the chamfer.

[[Ch...]]

I think everyone has covered the major issues here. I've checked many parts like this,
with an internal diameter runout/concentricity relative to centers datums. If you put this between centers, its clear we cannot get an indicator inside the part.

I typically measure the part parallel to the granite (in V block, etc), with a 0.6/0.8mm probe in this case. Probe about .005" (0.125mm) off each end of the centers. I would probably do 2 paths, single points (8 points each).

After measuring both centers/chamfers, you can construct a 3D line from the cones/centers (tip : I would make sure both paths are equal, for example if Datum B is 2 paths .005" (0.125mm) off each end, makes sure it is same for other side center).

You can then probe the ID and report concentricity to centers axis A-B.

Another tip : I would have a rough/pre-alignment before just going in to find this short center/chamfer. Maybe start with the end face or the bore as rough alignment reference, so that is finds the parts orientation approximately.

If they are interested in concentricity to -B- center only, I would do as mentioned above, except I would probably measure 8 line paths on the cone (probably 3 single points each line = 24 points) after roughly finding the part. Check angle/skewness of cone after measuring (A1/A2). If angle is good but concentricity is high, you may need to constrain this cone/chamfer to end face or ID.

Good luck.

[[Ün...]]

A is the reference cylinder. There is runout measurement on other surfaces of the part according to the common reference A and B. 0.015 / 0.05 (can't share any more data)

No parts have been produced yet, the program is in preparation

I will proceed with 3 different scenarios.
a circular measurement in a cone.
circular measurement and 6 vertical scans
Scanning from the Ø22,4 end (because the chamfer and Ø22,4 are machined with the same tool)

The problem here was shared with the engineering unit. Since the part is in the project stage, we will share the problem with the customer. Since it has an annual production of 600k, the bosses are unfortunately pressuring to take the order 🙂

[[Ün...]]

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Shabu, There are many technical drawings that do not conform to the Standards. Design teams don't look at much standards. Especially the new generation

I'm trying to get in touch with the customer's quality team to find out how they measure. Since the piece is new, there is no information on them yet.

[[Ri...]]

I would just ask how the bore and chamfer are machined.
If its bored in one tool path, its good.
If its made from a Port tool, check the port tool certificate....and its good.

If either of the above methods produce an out to tolerance condition, stop, throw away the machine and get a new one.