I am wondering, if it's possible, to scan a part without a CAD File and extrapolate data and measurements from the scan and export that data into a CAD File. If this is possible, how do you do that?
I have used single points all over a model an exported them as an IGES, then imported that into solid works and went from there. Im sure you could do the same with a pointcloud from scans. I would assume that you would need the add-on cad translators for your specific cad program ( if its even possible ) to be able to output as a CAD to your specific cad platform. A solidworks CAD is not the same as a PRO-E cad . That's why the outputs for step and iges are both available
I am wondering, if it's possible, to scan a part without a CAD File and extrapolate data and measurements from the scan and export that data into a CAD File. If this is possible, how do you do that?
Thank you!
It certainly is, though depending on exactly what you are going to, it could be difficult.
Measuring off of the scan is easy enough. You should have an alignment prior to scanning that allows you to know where they are in space from your origin, which is all you really need to be able to measure. Anything you can do with data probed/scanned with a model, can be done with data probed/scanned without a model.
PC-DMIS can output STP/IGS files, but as the number of points goes up, the ability of another software to handle it goes down. If you are working with, on the order of, 100-1000 points, you should have no issues. As you approach 1,000,000+ points, other software (CATIA/Unix in my experience) will take so long to import, that you'll be lucky if it ever completes.
In my experience, the easiest to work with is to work in faux-2D. If you are scanning something orthogonal (ie, machined rectangular objects) like trim steels, scan it in Z+ in a top-down view and export it as a DXF. The 2D DXF points are much easier to work with in a sketch (and lots of softwares can work with it) and then can be easily thickened/extruded from there.
Without cad to generate the scan paths, you should probably turn OFF the probe comp. With a TTP, you will only EVER get 2D probe comp, unless you use surface points for the 'feature' and use 3 sample hits for each and every touch in the scan. I am not sure about scanning probes, but I doubt you would get 3D even then as it would require the path to make an "X" for every point gathered. COMP=OFF isn't a problem, as long as the cad people know how much to comp for your ball.
Point clouds, you probably don't have them for a CMM as they are a laser type item (as far as I know).
Without cad to generate the scan paths, you should probably turn OFF the probe comp. With a TTP, you will only EVER get 2D probe comp, unless you use surface points for the 'feature' and use 3 sample hits for each and every touch in the scan. I am not sure about scanning probes, but I doubt you would get 3D even then as it would require the path to make an "X" for every point gathered. COMP=OFF isn't a problem, as long as the cad people know how much to comp for your ball.
Point clouds, you probably don't have them for a CMM as they are a laser type item (as far as I know).
Even if you are doing a line variable scan in a defined alignment set to master?
Even if you are doing a line variable scan in a defined alignment set to master?
Yep. There is no way to get a 3D TTP scan unless it is generated from CAD or you use surface points w/ 3 sample hit.
The start point and end point make a "line", all hit will be perp, IN ONE DIRECTION, if ya follow me. But yes, a TTP scan w/out cad will only ever be a 2D scan. I'm not saying that it will be square to X or Y or Z, but it will only be 2D in some planar slice. That plane may be 15* off your axis, but it will still only be "2D". take a plane, ANY plane, and that is the CUT PLANE and that is the 2D 'slice' you will get from the data, the probe will ONLY be comped "IN" that plane. If the shape 'rocks' (twists, whatever) in and out of perp to the CUT PLANE, you will NOT get correct probe come.
Yep. There is no way to get a 3D TTP scan unless it is generated from CAD or you use surface points w/ 3 sample hit.
The start point and end point make a "line", all hit will be perp, IN ONE DIRECTION, if ya follow me. But yes, a TTP scan w/out cad will only ever be a 2D scan. I'm not saying that it will be square to X or Y or Z, but it will only be 2D in some planar slice. That plane may be 15* off your axis, but it will still only be "2D". take a plane, ANY plane, and that is the CUT PLANE and that is the 2D 'slice' you will get from the data, the probe will ONLY be comped "IN" that plane. If the shape 'rocks' (twists, whatever) in and out of perp to the CUT PLANE, you will NOT get correct probe come.
Ah, I get what you're saying. That's generally what I am expecting from a scan, a 2D slice.
Even if you are doing a line variable scan in a defined alignment set to master?
Master takes the raw data it finds upon initial execution and sets it as Nominal for all other parts. It pretty much makes a best-guess on probe comp. Great for pre-CAD legacy parts that are based on a quality master part.
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Agreed about turning off probe comp for rev eng, but make sure you tell the CAD jockey to offset by your actual probe radius (as reported during probe qual).
Master takes the raw data it finds upon initial execution and sets it as Nominal for all other parts. It pretty much makes a best-guess on probe comp. Great for pre-CAD legacy parts that are based on a quality master part.
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Agreed about turning off probe comp for rev eng, but make sure you tell the CAD jockey to offset by your actual probe radius (as reported during probe qual).
Would you also turn it off for a scanning probe? I've never used one, so I am not 100% sure how they work, but I would guess it should be off for them as well.
Would you also turn it off for a scanning probe? I've never used one, so I am not 100% sure how they work, but I would guess it should be off for them as well.
Yep. Probe comp works the same, except for the little detail where after the scan is completed PC-DMIS processes the ball-center-data it gathered and applies the comp to each datapoint.
Without using CAD the comp can be fine for simple, smooth, low-rate-of-change surfaces or wildly wrong for compound complex surfaces. Even with CAD you can still have comp error if the part is too far from nominal.
Scanning is fun and profitable, you should try it. So much data! Make beautiful full-color plots that perfectly illustrate just how bad the parts are - a picture is worth well over a million numbers in today's market.
Also, it has this little time savings over TTP when Reverse Engineering - jobs that took me 40 or 50 hours using TTP take about 3 or 4 with scanning.
