Exploring Ring Scanning Options

• TM

  Tom Meeks

  11/24/25, 4:53 AM

  In educating any students; but, in particular, at-risk students, projects that promote critical thinking skills are highly desired.  From personal experience, teaching hundreds of at-risk cadets from 4 different localities, there are few disciplines that offer as amny critical thinking possibilities than 3D printing and 3D scanning.

  To be successful, ALL 3D scanning projects involve some form of strategy to achive the scanning goals.  This is particulary true if the project's goals are set high.

  As I was experimenting with scan staging, it quickly became obvious that finding ways to capture every feature of a ring, seemed deceptively simple.  But, it's not.  Some rings have full patterns that make alignment more difficult than others, etc.  So, a high goal, when it comes to scanning rings is this:

  Capture ALL features of a complex ring with perfect alignment in every respect.

  Pursuit of this quest should result in multiple scan 3D staging designs.  Most require some significan hardware, like screws and nuts.  But, one of the goals I wanted to achieve was to design something that was almost completely 3D printed.  The result was this design that still requires two 3mm bolts with nuts.

  This Ring Ring relies on very thin >.25mm clear monofilament sewing thread to position the target ring near the center of the rotating ring.  I will upload the files if it is successful in reaching our goal.  (I ran out of time this weekend to try it.)

  The monofilament is streteched between adjustable outrigger hangers by being wound around hubs and held in place with a locking cover.  The question will be just how to run the monofilament to hold the target ring in place tightly with the least interference with scanning the featueres.  Considering the possible combinations tests critical thinking skills to the max.

  Here is The Ring RING:

  

  Note:  The crossbeams can be secured in place with 3mm screws or the small 3D printed sliding locks in the lower right of the image.

  Wish me luck.

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• TM

  Tom Meeks

  12/3/25, 4:35 AM

  Sorry for the slow progress.  I am designing the tool with education in mind, providing for different students to see 3D scanning as a process and providing multiple oppotuninties for individuals to do a step in the process so that multiple students have a stake in the outcome.  So, the ring staging tool is now designed to be used in the sprying process as well as the scanning process.  In most classrooms, there is only budget for a single scanner, so providing opportunity for a group of students is important.  Otherwise, there is the potential that one student has the experience and all others are passive watchers.  Extending the process includes more individuals.  And, spraying is not as simple as one might think with rings of complex features or holes in the design.  

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• TM

  Tom Meeks

  12/8/25, 1:06 AM

  I have finally gotten around to the point where I could confidently run a realistic test of a concept for a rig that would hold a ring for both spraying and scanning where the entire ring is able to be captured with reference objects for optimal alignment.

  

  The basic system is a series of mounting posts.  There are four in front and four in back.  Monofilament is strung from one post, through the ring and to another post.  In my first test, three strings were used. Two in front and one in back.

  

  Note that there are two screws (or capstans in a screwless version) at each mounting point.

  The reason for this is that spraying corrupts the string, making it visible in the scan. 

  

  The second screw allows us to string new monofilament in exactly the same configuration BEFORE removing the corrupted string.  We replace all the sprayed string and replace it with new, clean string.

  

  The new string is less likely to be captured by the THREE.  Notice that the ring remains in just about the exact same place and orientation.  The ring does not move since the strings are pulled tightly.

  

  The previous image gives us a hint as to just how small the ring is relative to the THREE Scanner.  Here is the actual scan with the THREE measurement tool.

  

  Having to spray the ring results in a rougher than hoped-for surface. But, that is only because the THREE is capable of incredible resolution!  Here is the final scanned result with two 13-scan passes.  Note the precise alignment between the scan groups due to the included purposefully designed reference points.

  

  EVALUATION: The concept works exactly as I had hoped.  But, it can be improved.  The connectors on the tested rig were vertical (up and down), they will probably be easier to use if horizontal (side to side).  While the reference objects worked exactly as hoped, they can be improved by better placement and layout.  As it is now, they block the view of the scanner more than they should.  Because the system is modular, both of these improvements will be trivial to design and replace.

  All-in-all, I am VERY pleased with the first results and look forward to making the improvements and running a second test.

   

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