Why NeoBlade's Blade Tip Is Round

You reach for the NeoBlade you have been using for the past two weeks. The edge has dulled, and it is time for a new blade.
You take the magnetic cover and slide it down over the tip until it seats. When you draw it back off, the old blade comes away with it, held there by the magnet rather than by your fingers.
You bring the magnetic cover down over the tip, and it takes hold of the blade. When you draw it back off, the old blade comes away with it, held there by the magnet rather than by your fingers.
You set the cover down with the blade still in it and pick up a fresh one, bringing it up to the clamp until it seats and locks.
The whole exchange takes about 3 seconds. At no point in it do your fingers come into contact with a cutting edge.
That sequence is the part of NeoBlade we spent the longest on, and it is the part least likely to be noticed. It is also worth explaining in the order it actually happened, because the rounded blade tip that makes it possible was not introduced for safety reasons at all.

Handling the Blade

Most ultrasonic cutter blades end in a rectangular tip, which leaves two sharp corners at the far end of a 4 mm strip of steel. During cutting, those corners contribute nothing. The handling risk they create belongs to the moments around cutting instead: reaching into a drawer, setting the tool down and picking it up again, brushing the tip while attention is on the workpiece rather than on the hand holding the tool.
NeoBlade's tip is rounded instead. The corners have been removed through a controlled curve, which eliminates the point most likely to catch skin without affecting cutting performance, since cutting takes place along the edge under 40,000 vibrations per second rather than at the corner. The material removed was not doing useful work to begin with.

Blade replacement is where that risk is most concentrated. The used blade has to be drawn out of a clamp, which requires gripping it, and on most tools the blade itself is the only available grip. We designed the magnetic cover so that the blade could be held by magnetism rather than by friction against fingertips.
In practice, you bring the cover up to the blade and the blade attaches itself to the cover, so the blade is drawn out of the clamp by the cover rather than by your fingers. A new blade arrives held on the cover in the same way: you carry it to the clamp, seat it, and lift the cover away. Your hand is on the cover throughout, never on the blade.
In a working studio, where blades may be changed several times a day, the number of times fingers touch a blade accumulates. The magnetic cover reduces the risk of a cut at its source.

After the Blade Is Discarded

The risk we spent the most time on is the one that no longer belongs to the user. A discarded blade in a bin has no owner, and the next person to encounter it has neither chosen the exposure nor any reason to expect it: a roommate compressing a bag of trash, a sanitation worker sorting waste by hand, a pet investigating a bin because something in it smelled interesting.
Our position is that a blade's safety record should not end at the point where its owner is finished with it, and the one-way recycling case follows from that. The opening is narrow and the interior deep, so a used blade drops in with almost no effort while retrieval is close to impossible. The interior volume is large enough that a blade which has fallen in almost never comes to rest at an angle or position from which it could be shaken loose or drawn back out.
A tool that protects the person holding it and then releases a bare edge into the waste stream has addressed only half of the problem. The recycling case is our answer to the other half. It is the case the blades themselves come in, and it does both jobs across the life of a blade: it holds the new ones before use and takes them back one-way once they are spent. It was never something to sell separately, because it is how the blades arrive in the first place.

Where the Rounded Tip Originated

Interestingly, the rounded tip came out of a constraint on weight rather than out of any of this.
At the core of an ultrasonic cutter is the transducer, in which a piezoelectric ceramic converts electrical energy into high-frequency reciprocating vibration, 20,000 times a second. The blade is part of that vibrating system, so its weight bears directly on how well the tool maintains its intended vibration. The heavier the blade, the more inertia the system has to overcome, and past a certain point cutting efficiency falls and heat can rise. The target we worked to was 0.3 grams per blade, with a tolerance of ±0.001 grams.

The rectangular tip made that target difficult to hold consistently across models. Each blade model has a different profile and therefore a different quantity of material, even with the exposed length and the clamped section standardized, so weight varied from one model to the next. The tip compounded the problem, since a rectangular profile uses the maximum possible material at precisely the point where the least adjustment was available. 
We tried two ways of reducing weight, and neither was usable. Drilling holes was the obvious approach, but at 4 mm wide the blade retains too little material on either side of a hole, and vibration could open cracks around it. Shortening the blade also reduced weight, but the blade case and the clamp have fixed dimensions, so any change in length compromised the fit and made installation unreliable.

With both routes closed, we returned to the outline of the blade and reconsidered which material was doing useful work. Removing the corners through a controlled curve brought the weight down while avoiding both the structural weakness introduced by drilled holes and the fit problems introduced by a shorter blade, which gave us a more controllable way to bring each blade within the 0.3-gram window without compromising its strength. From the first rectangular design to the finalized curve, tooling, prototyping, and testing took about a month.

Beyond the Original Problem

What started as a solution to a weight constraint ended up shaping much more of the product. The rounded tip didn't just change how the blade was made. It changed how the blade could be handled, covered, and discarded.
Sometimes a constraint doesn't stay a limitation. Solved well, it can resolve more than one problem at once, quietly enough that the person using it never has to notice.