Tips for measuring this tool

[[Ma...]]

Hello,

i have to measure position of sphere made of cutting edges on this tool.
Any advices? I tried 3 circles with unknown contour 1mm speed and 0,05mm step.
Points recalled to sphere with outliers 2,0 20reps and clear to element ( lost in translation ).

It gives me 36,18 diameter - it should be 36mm tool.

We are looking for tool setup on machine where length of tool will be flat on top.

[[No...]]

Isn't there a clearance angle on each cutting edge? That would mean the edges are razor-sharp (in theory). I doubt that it is possible to filter your points in a way that only points which lie exactly on the edge remain.

[[Da...]]

In my experience, tool measurements are best done using sample parts. Trying to hit the cutting edge doesn't tend to work very well.

Get the shop to cut a test part, similar to the final application, and measure that.

[[Ma...]]

I tried to scan it counter clockwise to avoid edge jumps.
Still i don't know how to properly filter it. Can not use outer tangential on sphere and with three circles i don't trust to results made with cuts.

Yes, testing this on sample would be best option, but we have similar problem with other tool, where due renewing by grinding we get R2 length mismatch ( aka it's upper or lower than it is programmed ). This should solve optical devices which should be at machines ( we are talking about it for min. 6 years )

[[Mi...]]

Like Norbert said, if there's a clearance angle it'll be impossible to measure exactly on the cutting edge.

The only thing I can think of is to create each cutting edge as an intersection, but that only works if the clearance surface and the flute are "standard" shapes, like planes and spheres, which they likely aren't. If they're freeform surfaces, I don't think you can create intersections.

[[Lo...]]

I would avoid using the CMM for this, cutting edges are too tough to measure for they are razor sharp and impossible to scan. For form tools ,like this, I have used a vision system, optical comparator or toolmakers microscope.

[[Da...]]

Zoller makes a great machine that measures length and diameter. It is expensive but it can be used for all the tools in the mills.

[[Ma...]]

OK thanks to all. I'll try some magic. I would presume that this tool should have almost exact diameter ( since measured deviation is in tenths of mm )

[[Er...]]

Nowadays CAD should be available from the supplier. Calling the maker and asking how it is made may give insight to measuring. A short video would be great.

As mentioned, measuring a sharp edge is near impossible. An alignment for each flute would be needed due to how this is probably made. Pick a depth. Then create a scanning line perpendicular to the cutting face and clearance of the flute where the cutting edge and clearance intersect. Pull the Maximum Point from the line. Repeat for each flute. Then repeat for different depths. Recall the maximum points into a sphere, hopefully Calypso will allow that, I would make a rough program with 5 maximum points to test before making more points.

But as mentioned, the real result will be when the part is cut. So many factors in machining can alter the end results.

[[Ma...]]

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Thanks for your reply.
This is custom made tool - unfortunately we can not find drawing for this, so I was told to measure it as close as we can get something to set up at mill.

Now I can play with it since I am not needed too much.

[[Ma...]]

To measure cutting edges you can qualify the carbide stem of a stylus and use this to measure the edge. To accomplish this, qualify the same stylus tip twice, say once as tip #1 and once as tip #2, then manually edit the stylus coordinates and diameter until a circle measured with the shaft on the calibration sphere yields the same location and diameter as the stylus sphere.
For measurement, the part should be aligned physically as close as possible to the CMM -a rotary table makes it much easier to get very close.

[[Jo...]]

I would make an alignment using cylinder as primary and 2 translations. Then the plane at flute to stop rotation. You should be able to calculate the truncated portion of radius and set that as your Z tertiary with offset amount. That will allow you to create a circle in each alignment ,with a controlled immersion depth on cutting edge. You should be able to calculate where the circle center is, then measure roughly a quadrant. Repeat this on all flutes, and recall into sphere with correct nominals. If you want to bypass that, try creating the sphere first with rings of single point measurements from (30°-90 °) ? coverage. You could measure 3 strategies clocked in small increments and use O.T.E as this is what the cutter will make.