Why, and how, you should buy a 3D scanner
We’ve already looked at resolution and accuracy, the two most important technical considerations when buying a 3D scanner. In this post, we’ll consider the final piece of the puzzle: why should I buy a scanner and what sort?
The answer to the first part is clear: cost and time savings.
Let’s be honest here. If you want to model something simple, made up of geometric and primitive shapes, the chances are that it will be faster and easier to start from scratch in CAD. The potential cost-saving you’d make by introducing a scanner is small.
The biggest returns will come from scanning more complex objects with freeform shapes. Reproducing a guitar, for example, with a curve to the top and sweeping lines around the outside, a complex geometry on the neck, and so on, is tricky.
Measuring the dimensions of such complex objects with a ruler or micrometre, then rebuilding it in CAD, would be time-consuming, and require the services of expensive, skilled CAD specialists. It could take days, if not weeks to complete the work – or, you could scan it in a few minutes to get the information your CAD engineers need.
Scanners make most sense when you have an object for which there are no 3D electronic (CAD) drawings. For example, if you want to make spare parts for old cars by copying original parts, make copies of sculpted original works of art, or when you need to capture existing machinery so that new attachments and components can be designed to fit.
You can also use scanners where change over time needs to be monitored, such as press tool wear. This can allow tool downtime to be planned ahead of time.
3D scanner varieties
There are two primary types of 3D scanner: handheld and tripod mounted.
Handheld scanners are the most visually striking because they are very intuitive. You use them like a paint brush, sweeping them over the object. They are typically mounted on the end of articulated arms, or can be completely free standing. However, there are a number of issues with this type of system.
Firstly, the scanning head has to be tracked in space, usually by movement of an arm or by tracking markers, which carries its own errors (add these to the scanning errors discussed in our piece on accuracy).
Secondly, results can be very operator dependent, so different users can end up with different results, or the same user can get different results from scanning the same object. The result you get therefore depends as much on the operator’s skill as it will on the quality of the device itself.
These are the main reasons why most engineering grade scanners are tripod mounted. They take away the influence of the operator, so reproducibility and repeatability are much better.
Tripod mounted scanners are either moved around the object to capture each view, or left in place as the object itself is rotated. With a fixed point of reference, and fewer variables to accommodate, they usually produce a more accurate result that will require less work in post-production.
There is no industry standard for measuring accuracy for scanners, but look for a scanner that offers calibration to VDI/VDE recommendations, with which any premium manufacturer will comply.
The point of a scanner is to save you time and money. Choosing the right one is crucial to achieve this and, if you are considering getting a scanner, a chat with our scanning specialists is highly recommended to get you on the right track.