Wednesday, 13 February 2019

Can a Handheld Rechargeable "Ultrasonic" Scaler Be Turned Into a Cutter? (Spoiler: Nope)

I made a compact DIY ultrasonic knife by modifying an ultrasonic dental scaler I purchased from China for a little over $100. It worked great for fine detail work.

Well, someone showed me that there are also small, handheld, rechargeable "ultrasonic scalers" available for around $20. Could they also be made to work? I decided to purchase one to find out. It arrived today. The answer is no.
A roughly $20 "ultrasonic scaler" that -- spoiler alert -- is not ultrasonic.
So why not? Because the tool is not ultrasonic, meaning it does not vibrate at ultrasonic speeds (over 20,000 Hz) To do that, one requires an ultrasonic transducer. The transducer will vibrate the tip a tiny amount at super high frequencies. As a result of this motion, the tip gains some mild superpowers when it comes to breaking up different stuff, such as -- in the case of dental scalers -- breaking up hard calculus (tartar) on teeth without damaging the teeth themselves.

These tools may be advertised by sellers as "ultrasonic scalers" but they do not contain a transducer. In fact, the product packaging and manual themselves make no claims of being ultrasonic. It's just a vibe motor -- much like the one that vibrates your phone, or a cheap electric toothbrush. And that's all it is. A handheld vibe motor with a dental scaling tip on it.

I burned the $20 so you don't have to! eBay uses the magic word "ultrasonic" in the name and description of these tools but they are not. Maybe I can make a micro sanding tool out of it or something, but I won't be making an ultrasonic cutter out of it, that's for sure.

Friday, 8 February 2019

Early Hardware Test of Robotic Envelope Addressing

One of my big ideas involves a robotic system to address mail and stuff envelopes. Today I successfully had a robotic system pick up a blank envelope, have another robot write on it (with placeholder data), then move it when it was done.

At this stage, it's mostly playing around with the hardware and tools and getting familiar with the capabilities and limitations, and creating the "glue" parts that let everything work together. Integration work is the embodiment of the phrase "the devil is in the details."

I'm currently using a uArm Swift Pro from UFACTORY, and an AxiDraw from EMSL (which I happily purchased from a Canadian distributor, Solarbotics.) The support hardware and systems are all my own work so far, but it's nice not to re-invent the wheel with the rest of the robotics.

There is still a long ways to go (and I still need a name) but it's very gratifying to have something come together and do useful work, even just as a test.

UPDATE: I make and sell clever little clay target hangers and as of Feb 18th, I shipped by first robot-written order!  An important milestone! Buy one and get a robotically-addressed envelope!




Monday, 7 January 2019

How To Make a Small DIY Ultrasonic Knife

Some time ago I made a DIY ultrasonic knife. It's a small tool for fine detail work, and I use it for removing tricky supports from SLA 3D prints. I wrote an article about it that you can review for details.



The tool was made from a cheap ultrasonic dental scaling tool I bought from China. I sharpened one of the tips into a sharp chisel point. This knife edge vibrates a tiny amount at a high frequency, which gives the knife edge some mild superpowers. It's able to cut through hard plastic (like the supports of 3D prints from my Formlabs Form 2 SLA printer) with ease, without putting stress on the part being cut.

In the animation below, you can see my tool slice through the supports on a tiny piece that would not normally survive being cut by a utility knife or side cutters. The supports on Boba Fett's helmet-mounted rangefinger (I printed it at 25% size so it's much smaller than usual) are larger than the piece itself and would normally be too delicate to reliably remove supports, let alone leave a good surface finish.

One potential application that I have been made aware of for a tool like this is to post-process prints that are intended for casting jewelry. They often have fine details that must be preserved.

DIY Ultrasonic cutter removing supports from SLA 3D print. Note the puff of particles and water vapor when cutting.
The liquid droplets are water; I used a small spray bottle to help control the dust.
Note: the rangefinder is a separate piece in the original 3D model. I attached it for the express purpose of printing it as one piece and seeing if my ultrasonic cutter could handle removing the supports from such a small and delicate part, and it worked great!

If you'd like to know more, there's a video and additional details on Hackaday.com. The device turned out to be a handy addition to my toolbox, and wasn't particularly expensive. About $125 in parts and a bit of work to modify one of the steel tips, and I had what I needed.

If you'd like to try making your own, search eBay for "dental scaler" and "EMS Woodpecker" in the description. Buy one that has the correct plug for your country and you should be set for trying your own experiments.
UPDATE: Perhaps you have seen even cheaper handheld "ultrasonic dental scalers" for sale and have wondered whether they could be made to work. I bought one to find out. The answer is no.

Thursday, 30 August 2018

Get MUSICAL for the Final Round of The 2018 Hackaday Prize

The Hackaday Prize is in its fifth year, and the final round of entries is currently underway: the Musical Instrument Challenge. It runs until October 8th. Twenty finalists will receive $1000 each and go on to the final round where a $50,000 cash prize (and more!) are waiting.

What's the money for? It's cash, for you to use to develop your open-sourced idea or concept. Make something, and make the design and details open and available to others; that's it. 

The 2018 Hackaday Prize consists of multiple challenges (of which an entry can enter more than one) which run in sequence one after the other. Twenty finalists from each will receive $1000 cash, and will go on to the final round where the following prizes are up for grabs:

  • Grand Prize:​ $50,000
  • Second Prize:​ $20,000
  • Third Prize:​ $15,000
  • Fourth Prize:​ $10,000
  • Fifth Prize:​ $5,000

All you really need to get started and entered is an idea and some documentation. So if you have an idea rattling that has been on the back burner waiting for an opportunity, this is it. 

Monday, 30 July 2018

3D Printing Used to Manufacture Rifle Compensators

Who says 3D printing isn't a viable manufacturing process? The Salen Compensator (named for Kenneth Salen, competitive Norwegian IPSC shooter) shows it can be done. Tonrud Engineering manufactures the Salen Compensator and a write up about the compensators themselves is on The Firearm Blog.
A build platform of Salen Compensators (Image source: The Firearm Blog)
Note the flat support structure visible through the side holes on each compensator. These are required as part of the manufacturing process, but will be removed with post-processing.

When printing in plastic, support structures are normally only for supporting the geometry of the part. But with printing in metal, support is often used to provide stability across the parts of the entire model; otherwise some warping can occur as smaller and thinner parts cool faster than larger areas, leading to deformation.

3D printing can be used not only for manufacturing, but for cheaper and faster prototyping and to open new doors. For example, 3D printing in metal can be used to create suppressors in strange, nontraditional shapes like those shown below. These are shapes that would be impractical or impossible to create using any other method. In the image shown, the barrel of the gun goes into the hole on the left. The bullet exits from a hole inside the "wedge" on the right.
Unusual design firearms suppressors 3D Printed in metal. The top is a centerfire suppressor, the bottom for rimfire. (Image: The Firearm Blog)


Tuesday, 17 July 2018

Adding Color to FormLabs SLA 3D Prints

I use a FormLabs Form 2 printer whenever I need detailed, high-quality, smooth prints. The results are fantastic, but recently I needed to change the color of some small parts. The parts were so small and finely-detailed that I wanted to avoid paint if possible. FormLabs sells a color kit where you can make a batch of resin into any color you want, but I didn't need or want to buy a whole separate batch of resin; I just needed to do a few small pieces. I decided to try dyeing the parts, and the results were fantastic.

I purchased some liquid Rit Dye ("Chocolate" color for synthetics in my case) from Amazon; it's intended to change the color of synthetic fabrics. Since synthetic fabrics are basically plastic, I figured it might work out okay to dye my 3D prints, which are also plastic. This kind of simpleminded reasoning was all I needed to give things a shot.

Testing consisted of simply filling a plastic cup part way with very hot (but not boiling) water. Then I poured in a small amount of the liquid dye; I didn't measure anything, but it was probably a couple of teaspoons.

Then I dropped in a test piece, which was a scrap base and support structure. I stirred it a few times over five minutes, then removed and rinsed it. The result is shown below on the right.

Plain Grey FormLabs resin on the left. On the right is also Grey resin, but after five minutes of dyeing.
The results were impressive! I was expecting only to get a rough idea of whether this might work, and what direction to go in next. Instead, it worked beautifully on the first try! The color was even and smooth.

I decided to do a production piece. Five minutes seemed plenty so I did four minutes. The results are below. On the left are regular prints, on the right are the dyed pieces.

Left: undyed Grey FormLabs resin results. Right: results from four minutes in dye solution.
I honestly hadn't expected the results to be so good and so easily done. There is more to be learned, but if you're looking to dye a small 3D print out of a FormLabs printer, it's awfully easy and fast to do so with the liquid Rit-Dye and some hot water. Probably this is feasible for other 3D prints and other resins; I haven't tested any, but the results here were so readily done that it certainly looks to be worth trying out.

Thursday, 24 May 2018

Free Machine Learning Crash Course by Google

I was really impressed by this introductory course for machine learning by Google. Not only is it well designed and put together, but as someone who is extremely hard of hearing, I took special interest in the subtitles for the video section.

The closed captioning is incredibly well done. It's more than just subtitles, it shows a time-stamped list of the spoken part that scrolls automatically. This is much better than subtitles for learning material, since the viewer can see not only what is currently being spoken, but quickly review what was just said as well as what's coming next.

They're even clickable so that one can skip ahead to salient parts of the video. Oh my god -- a way to skim and basically page-flip in a video. I'm on cloud nine.

I'd be happy just with subtitles, but this interface knocks it out of the park. Videos in place of documentation is more and more common, but even simple subtitles are a luxury for most learning material. Autodesk's Fusion 360 training materials, for example, are almost entirely video based and have no subtitles whatsoever.

Millions of people in North America suffer from some level of hearing loss, and half of them are still in the workforce. If your documentation is all on video where the subject matter is unfamiliar to the viewer and the speaker (and their mouth) is not visible, it makes learning far, far harder than it needs to be.

Anyway, not only is the video and captioning done extremely well in the course I linked, the course itself is really well done. If you have any interest in this area at all, give it a look.