Bin-Dex App Prototype using Adobe Xd!

Adobe Xd is a free tool for visualizing work flow for an online app. We used it to show how a user might browse our Bin-Dex library for a template.

The Bin-Dex system takes the thinking time out of organizing your stuff. Have a bunch of screws to organize? What are the common sizes? Lengths? Driver Types? Metric or Standard? How many fit in an organizing cabinet? An elegant organization scheme takes tons of time to develop! Bin-Dex takes on that organizing so you don't have to! Just browse, download, print, and get organized!

Buying a new TIG welder

TIG Welder Purchasing Checklist

·         Power into your location (Single Phase, 3-phase)

·         Dual vs Single Voltage & Portability

·         Maximum and Minimum Material Thickness

·         Working Materials: Steel, Aluminum, Other

·         Aluminum Welding Features

·         Parts and Service Concerns

·         Price

I started TIG welding steel with a little Miller MaxStar portable unit. This unit was given to me as compensation for engineering work I did on a job. It wasn’t that flexible of a unit nor could it weld very thick material, but it did get me started in TIG welding. My second encounter with TIG welding was at the Kinglsand Design and Engineering Lab in Brooklyn. Here I used my first AC/DC inverter type TIG welder. This type of welder can weld both steel and aluminum and is the modern way of TIG welding. The traditional transformer machines (Miller Dynasty, Lincoln Precision TIG) are rock-solid dependable, but are large in size, heavy, draw a lot of amps, and lack features that the newer inverter type welders have. The Chinese inverter we used in the Brooklyn shop was a Chinese no-name unit bought off of Ebay. It had a name like Green-Bird or something like that. But, it was the size of a large toolbox and could put out 200-amps of DC or AC welding current. And, even though it was an off brand, an entire shop used this unit when TIG welding was needed and it never missed a beat. We welded brass, stainless, mild steel and aluminum with no issues. I think this Chinese box was around $600. Not bad at all.

So, when I moved from Brooklyn back to Minneapolis, I was in the market for a new welding machine. Since I didn’t have any immediate need, I was able to browse all the options and educate myself on what welders were on the market and what features they had. I honed my decision making down to seven different issues that needed to be considered.

Power into your Location

The first deciding factor in my TIG machine purchase was the location that I would be doing most of my welding. I moved into a small garage-sized shop with a colleague of mine. Our main breaker into the space was 100-amps. Since we are a design/build shop, not all that current can be devoted to machinery. We have heaters, computers, lights, and printers that all need to run while someone welds. One major difference between the traditional transformer welders and the newer inverter welders is current draw. I was originally looking into a Miller Synchrowave 250. These can be found used on Ebay or Craigslist for around $1800 in great condition. They are very dependable, so picking up a machine with a number of years on it would not be a problem. The issue for my shop was the amp draw. If I were to have to weld aluminum of significant thickness, I’d need 100-amps of current, which is far more than we have available. A 250-amp inverter welder uses transistor technology in such a way that it can produce those welding amps and only draw 35-amps out of the wall.

The power phase coming into your space is important. Typical AC voltages are 120v single phase, 240v single phase, 480v single phase, 240v three-phase. Most electrical boxes allow 240v single phase to be produced by simply installing a two-pole breaker. This is what many larger household appliances (washer/dryer) hook up to. Most larger welders work off of 240v single or three-phase power. However, many smaller inverter welders and larger “dual-voltage” welders can also run off of everyday 120V outlets. Sometimes, it is very handy to be able to run your welder off of 120v power, which I’ll get to in the next section.

Single vs Dual Voltage & Portability

One major decision that I made while looking for a TIG welder was it’s ability to operate on both 120v and 240v power. This ability makes the welder much more flexible and portable. Running on 240v allows you to weld up to 3/8” aluminum on a single pass using a 200+ amp inverter welder. Larger inverters get into the 350-amp or even 700-amp range, but these units are larger and are not easily moved. Some 200-amp units are offered in only 240v versions, but are still small enough o be carried to another location. If the location you are traveling to doesn’t have a 240v outlet, you are out of luck. I could see myself using TIG for a metal sculpture on-site, or going to a buddies place to weld up a trailer, so the ability to run on 120v was a must-have for me. Inverter machines also work great as stick welders. So, no need to drag your tanks out for the job. Just buy an electrode holder and an extension cord.

Maximum and Minimum Material Thickness

Depending on what type of work you are doing the most, you may only require a certain size welder. Say, if you were welding thinner aluminum radiators and that was your primary use, a smaller 180-200 amp TIG machine would be all you need. If you are welding aluminum trailers or castings that are ½” or thicker, you’ll need to go up to a higher amp-welder to get the current you need. The larger welders also have a higher minimum arc current, so if you are doing very thin & delicate work, the larger welders won’t be able to come down enough for the fine work. Personally, I find myself needing to do more work on the thin end of the spectrum rather than really thick sections.

Steel vs Aluminum

If you are only doing steel or stainless, a DC-only machine needed. If you want to be able to weld aluminum, you’ll need the TIG to perform in AC mode. All AC/DC welders can weld aluminum and steel, but DC-only welders cannot weld aluminum. Aluminum also take much more power to weld than steel due to its heat conducting properties. So, you would need a higher-amp machine to weld ¼” aluminum than you would need to weld ¼” steel. If you are getting into brass and copper, you will also want AC.

Aluminum Welding Features

If you are going to weld aluminum, inverter-type welders have a number of features that set them apart from their older transformer brothers. Inverter welders are kind of like high-power computers. They are able to take the AC wave coming in a split it up and manipulate it to achieve many different waveforms. The older transformer welders used a sine-wave form. Then, the transformers were able to do square-wave for better aluminum welding. Some inverter machines can switch from sine to square to triangular wave forms at the push of a button. Most TIG welding is done with square waves and many new inverter machines also have AC wave balancing and Advanced AC Pulsing controls. AC balancing allows the user to adjust the AC+ and AC- parameters. This giver control over the amount of cleaning the arc does vs the amount of penetration into the aluminum. So, if you are welding thicker aluminum, you can minimize the cleaning and get maximum penetration into the joint…just be sure to clean the area well beforehand. Advanced AC pulsing is a feature found an Everlast machines that switches between AC and DC current many times/second. Whereas Transformer machines are stuck at an AC frequency of 60 Hertz (because that is the frequency coming out of the wall), inverter machines can alter frequencies from 20Hz to 200Hz. This adjustable frequency allows the user to narrow or expand the welding arc.

Parts and Service

In this age of Amazon and McMaster-Carr, people are very used to purchasing products online. But, when something breaks, its really nice to be able to bring the unit in and get parts or service to repair it. Miller and Lincoln welders have this down pat. Any major city in the US is likely to have a few welding supply stores that service Miller and Lincoln products. Some other brands like ThermalArc and ESAB and Thermal Dynamics are also popular.

The flip-side to these brands are the online-only imported brands like Everlast, HTP, Longevity and a slew of others. The better import brands offer longer warranties and 30-day no-questions returns in order to make up for the lack of physical presence. These units are also significantly less than the USA-made brands. In my opinion, if your welder is down and you need to finish a job, you are going to have to rent a welder anyway. Perhaps if you buy a Miller or Lincoln and it fails under warranty, they will provide you an immediate replacement free of charge...but I'm not sure on this point.


There is a wide variance of pricing over the range of transformer and inverter welders. The “Made In USA” (or at least assembled in USA) welders from Miller and Lincoln are the most expensive, but are rock-solid service-backed industrial-grade welders. If you want that, it will cost you.

Miller Synchrowave Series

Miller Dynasty Series

Lincoln PrecisionTig Series

Lincoln InverTec


Less expensive domestic welders are also available:

Thermal Arc

Hobart (Owned by Miller)

Imported TIG welding machines from Europe and China are the most economical and some brands offer great warranties. The down side is that if you need to service it, you are either replacing circuit boards yourself, or you have to send in the unit to be serviced which cost a lot of money. However, it may balance out when weighed against the expensive Miller and Lincoln parts.

Everlast Welders

HTP Welders



My Decision: HTP Invertig 221DV

I decided that I wanted an AC/DC dual-voltage machine with 200+ amps. An inverter-based design in this range would give me a wide range of materials and thicknesses and not blow the main breaker in our shop. I couldn't justify the high price for the industrial Miller or Lincoln machines. After exhaustive research I had it narrowed down to the Everlast 255EXT, Everlast 210EXT, and the HTP 221DV. The Everlast machines have a lot of online video reviews and lots of people seem to be happy with them. There is also quite a bit of questionable feedback on these machines. It sounds like Everlast had issues when they started up with the quality of their Chinese-made machines. Some welders were missing screws or would be Dead-on-Arrival. It also seems like Everlast repaired or replaced many of these problem machines and it sounds like the quality is getting better. However, this is the “you get what you pay for” part of the deal. A Miller or Lincoln having these problems out of the box would be unheard of. One reason that I went with the HTP is that it has had great reviews and it is sold by USAweld, which is a popular online reseller of all sorts of welding equipment. So while they only sell one version of an AC/DC TIG, they also sell parts and consumables for a variety of other brands. This HTP welder also comes with top-of-the-line accessories like a CK torch and SST foot pedal. The Everlast accessories are no-name Chinese parts which while okay, seem to be replaced frequently with better versions. The HTP is a rebadged version of an Italian-made welder known as STEL in Europe. One review that really sold me is a YouTube tear-down of the HTP machine. From the review, it seems like a lot of thought has been put in to the HTP design with lots of structural support and high-grade beefy components. So while it may be missing a few of the neat features that the Everlast machine has, it seems like a lot of thought has been put into the guts of the machine.

I've been using the HTP 221DV for a few months now and I'm perfectly happy with it. I typically run it off of 240-volts, but I've also ran stick on 120v. I made a little pig-tail converter for running at 120v so to switch over, I just plug into the converter. I've had questions on the initial setup and welding features and USAweld has been excellent for customer service. Tech-Support is even open on Saturdays. I'm happy enough that I'd look into HTP for their 240-V MIG machines when I'm in the market. 

A typical Inverter-Type TIG Welder

A typical Inverter-Type TIG Welder

AXN-RXN Engineering has relocated to Minneapolis

I started AXN-RXN Engineering seven years ago in Saint Paul, MN. I told myself that if I passed my Professional Engineering exams that I would try to go it alone as a freelance/self-employed engineer. Just at that time some very interesting sculptural work came up in NYC, so I left my job at WhiteBoard product development to pursue expanding my sculptural engineering portfolio. The Saint Paul Cooperative worked well as a studio between NYC and the Twin Cities for a couple years, but I eventually moved out to Brooklyn full-time.

While in Brooklyn i helped co-found the Kingsland Design and Engineering Lab. This was a cooperative Design/Build shop that offered the tools and help to other self-employed engineers and designers in the NY area. After about five great years at the Kingsland D&E in Brooklyn, I've decided to move my live and work back to the Twin Cities and set up shop once again.

I'm currently running AXN-RXN engineering from a temporary office in my home in south Minneapolis. I am actively looking for a suitable studio in the area where I can offer the same services as I did for my clients when I was working at Kingsland D&E. But, I am also excited to work with past colleagues in the Twin Cities area to build something greater.

Stay Tuned! There should be exciting projects and announcements coming along shortly!

---> Karl

Torsen Differential Animation

It is difficult to wrap your head around how a common differential in a car works. It's not difficult to understand because there are a lot of parts, it is because every part in the assembly is moving relative to something else. For instance, to understand how a differential is working when you go around a tight corner or when you spin a wheel on ice, you have to mentally "sit" on one of the gears and imagine what the other gears, axles and case are doing from your specific vantage point.

This is a great animation of how a Torque-Sensing differential works. A Torsen differential. It uses worm gears and worm wheels so that the power from your engine always goes to the wheel with the most gripe. So, you wouldn't spin just one wheel on ice, the power would go to the wheel not on ice, or you would spin both. I like this gear train because it's not much more complicated than a traditional differential. It doesn't use shims, wedges, clutch plates or hydraulics to pull off what it is supposed to do. 

So, to my earlier point, I find it interesting to try to "sit" on one part of the gear train and try to think of what is happening to all the other parts around me. Why when one wheel is slipping does the power get transferred? What if one wheel is completely off of the ground? Does it still work? What if you applied this mechanism to something else like a ratchet system? Could you change two linear inputs of different strokes into a rotational output? Am I a geek?

Engineering in Design

During my study of mechanical engineering at the University of Minnesota, I always was jealous of the Architecture students. It seemed like they always had creative projects that involved cool models, layouts and graphics that were interesting. My education seemed to be mostly numbers, equations and Excel spreadsheets. The only graphics I made were line charts. I remember thinking that there must be a discipline like architecture, but for "stuff" rather than just buildings. There was. It was called Industrial Design. But, they didn't offer that at the U of M, or any other place in Minnesota as far as I know.

After getting into industry a bit more, I found myself getting into Product Design. First at a medical startup and later for full-fledged product design consultancies. I was constantly wondering if I should go to grad school for Industrial Design so that I could get more into what I considered the "fun" stuff. Now, what is it?, twelve years later, I'm pretty happy with my decision on Mechanical Engineering. I find that I still get to do lots of aesthetically creative work (i.e. brainstorming sketches, surface modeling, product aesthetics) but I also get more into the mechanically creative than perhaps a typical Industrial Designer does. By mechanically creative, I mean gear trains, mechanisms that move a lid or door a certain way, electronics/programming/motion control, as well as prototyping skills like CAM, welding and machining.

I think the only skill that I wanted to pluck from an Industrial Design background was the ability to sketch quickly and clearly so that I could get ideas across to colleagues and clients without looking like a 3rd grader with a crayon. We used this book in engineering school and I thought it was decent:

Although, I just don't practice enough and my sketches still look like a 3rd grader with a crayon. I'm much faster and clearer with ideas by starting in SolidWorks. But, you can't do that if you're tossing around ideas at a bar. If anyone has a good book or method, let me know!