Improving the Neje Master 2S Max – Part 1

I have been wanting to get a laser cutter/engraver for a while now. Like, for a couple of decades. Just as with 3D printers, it’s only been within the past decade or so that laser cutters have first been affordable to build as a homebrew machine, and then affordable to purchase as a relatively inexpensive offering from China in the form of the explosively popular ‘K40’ lasers.

However, the ‘care and feeding’ of a CO2 tube laser is something that I did not want to have to deal with. Not only do they need water cooling, but the fragile glass laser tube doesn’t always endure international shipping and survive intact (leading to having to return the broken part, incur shipping costs for such, waiting weeks for a replacement, and so on). Plus, the K40 lasers have a very small working envelope around the size of a letter or A4 sheet of paper, whereas the project I had in mind needs around double that travel in each axis. Finding a CO2 laser with this sort of working envelope means an expenditure of above $3k. To be fair, this is an incredibly cheap price – my first job was working at a trophy and awards shop, and the first laser engraver we purchased in early-mid 90s was probably a $40k+ investment. However, I am also an incredibly cheap individual, and $3k is well more than what I’ve spent on any machine tool thus far (which is exactly how I view a laser cutter – just another machine tool).

Enter the laser diode. Originally finding widespread use in CD players, laser diodes were quite limited in power output, perhaps on the order of 5 milliwatts or so (but that was plenty for playing CDs). As technology improved and laser diodes found new applications (barcode scanners, laser pointers, etc.), output power steadily increased. By 2010, hobbyists were tearing apart Blu-Ray burners for laser diodes that could output perhaps 200mW, and began building machines that could cut paper (albeit quite slowly). The past few years have seen the release of ready-made hobbyist laser engravers that use laser diode modules with an output greater than 1W. Last year, ’40W’ laser engravers began appearing on various online shopping sites, though there’s a whole lot of number fudging going on – sellers have latched onto the idea of advertising the power as input electrical power, not output optical power.

The unit I purchased is the NEJE Master 2S Max, which while commonly advertised as a 40W unit, only has an output optical power of 15W according to the datasheet for the A40640 laser module. This module actually consists of two 7.5W laser diodes and a beam combiner. While many are rightly skeptical that the actual optical output power is a maximum of 15W, the laser does indeed have sufficient power to cut through 1/8″ hardboard, which is all I’m after for now. Just as importantly, it has an envelope just big enough to accommodate 18″x24″ pieces. In short, it is the largest, most powerful laser diode based cutter/engraver available on the market that I’m aware of (at the hobbyist level, that is).

That being said, it is without a doubt a no-frills machine. I would have much preferred something with the mechanics of the Ortur Laser Master 2 Pro (which has a stationary control box and drag chain for the wires), but Ortur doesn’t currently offer anything the size of the NEJE. Fortunately, the brutal simplicity of the NEJE means that it can be easily modified and adapted, and I already had modifications in mind before even clicking the buy button.

Naturally, once I had it out of the box and assembled (a remarkably quick process), I had to play a little bit before diving into hacking on it. I downloaded the most recent version of the NEJE software, fired it up, and found the interface to be… …rather spartan, to be polite. A good proof-of-concept.

I used the NEJE software to select a beetle from the included photo gallery, and successfully engraved the picture on a piece of scrap wood.

Well, the first attempt was poor due to me not setting a focus depth at all. The second attempt was much better and I was impressed that the laser was able to ablate the white paint away while leaving the wood intact. This hinted at the laser’s capabilities that I am still pondering.

I’m not sure that I was fully aware when purchasing the NEJE that there even was any supplied software available, as I had already figured on using LaserGRBL as software instead. What is interesting about the controller board on the NEJE is that it has two CPUs – one to interface with the (uh, ‘interesting’) NEJE software, and one that has the GRBL firmware. The controller board also has bluetooth capability, and even an accelerometer chip that can pause/halt a job if it determines that the unit has been bumped (though this is undoubtedly far more useful with the cantilever arm offerings – such units are much more likely to be jostled rather than a unit that encompasses a working envelope of more than four square feet).

Upgrade 1: LightBurn

Yes, I just wrote that using LaserGRBL for controlling software was my intent. And LaserGRBL is indeed superb software. I played with it for 30 minutes or so, and it looked like I could get it to do what I wanted, and much more easily than with the NEJE software. But for due diligence, I thought I’d try out a newcomer piece of paid software – though it was still in beta at my time of testing, it had a 30-day trial, so I figured I’d give it a a go.

LightBurn bills itself as “layout, editing, and control software for your laser cutter”. Unlike LaserGRBL, which would require you to build up your artwork in Inkscape or other program and then import the SVG into LaserGRBL, LightBurn is a fully-fledged content creation tool all on its own. 5 minutes into playing with the software, I exclaimed to myself “this is CorelDRAW for laser cutters!” Back at that first job at a trophy/engraving shop, I worked with Corel’s vector and raster editing programs, and absolutely loved them – their UI and commands were entirely intuitive. I spent countless hours on my own time just playing with editing photos and doing vector arrangements, so much so that I don’t understand why Adobe’s “learning curve like a brick wall” offerings became the industry standard. LightBurn’s interface and capabilities brings me right back to those halcyon days of discovery and delight.

The simple fact that I can create/edit/arrange stuff in LightBurn is phenomenal – I did this quick work entirely in LightBurn to make a stencil for spray painting the box on my sister’s Christmas present (uh, don’t tell her). After leaving beta, the cost for LightBurn jumped up a bit on August 16 to $60 from only $40 during beta. Still, this is a perpetual license [glares angrily at Autodesk, Adobe, et al.], so $60 gets you a year of free upgrades and you get to keep that version forever even if you don’t renew (and can install it onto 2 computers). No, this post has not been sponsored by LightBurn – they probably don’t know I even exist. I just absolutely love the product that they have developed, and think it is a perfect fit for hobbyist level laser engravers.

Upgrade 2: Height setting block

My very first attempt at engraving with the unit and having the module height (and thus focus depth) set incorrectly made me realize that I needed to 1) determine the optimal focus depth and 2) come up with a way to quickly set the module to that focus depth. It seemed to me that having the laser traverse across a vertically angled target would show a wide, smoky burn at one end, narrowing to a tight, narrow cut and then expanding back out to a wide, smoky burn.

As it turned out, the scrap paper I used to test with didn’t give a wide, smoky burn at each end. Instead it bleached or whitened at the ends, with a browned section between, indicating the zone of best focus. Measuring down from the transparent red plastic plate at the front of the laser module to the center of the burn length gave a distance of around 20mm. I whipped up a height setting block that allows for quick height setting from 14mm to 24mm in 2mm increments.

A copy of the STL file for the block is here. Usage is super simple: loosen the clamping screw for the laser module, slide up, insert height block on top of item to be cut/engraved, drop module, tighten screw, remove block. Easy peasy!

Upgrade 3: Mounting to a base board

Granted, it can be argued that #1 and #2 are not even proper ‘upgrades’, but this one certainly is, and was in fact the very first modification I wanted to do before even purchasing the unit. I admire the outside-of-the-box thinking for these small laser cutters as an approach of “bring the laser to the work” instead of vice versa (which opens up their capabilities greatly – you could engrave a maker’s name/logo on the corner of an entire table, for example). But for the working envelope of the Master 2S Max, it really is best suited to a traditional “bring the work to the laser” sort of tool setup. Improving the rigidity of the system was foremost in my mind, especially as the flex in the frame could certainly lead to out-of-square alignment. Since I was looking to do 18″x24″ workpieces, a tiny bit of misalignment of 0.15 degrees would result in over 1/16″ of error over 24 inches. Mounting the frame solidly to a base board was thus a no-brainer.

For the board itself, I figured on melamine shelving board from the local home improvement store as being the best option. Cheap, flat, and with a nice smooth surface. I cut the board to a size of 34-1/8″ x 22-13/16″ which was just perfect in Y to sit between the ‘feet’ endplates and small enough in X to provide just enough clearance for the mounting screws on the roller wheels to avoid scraping against the board. However, cutting the board to size was the easy part. Mounting the NEJE to the board wound up being somewhat more involved than I had initially anticipated.

My initial thought was to use T-slot nuts to secure the long bars that stretch from left to right across the top and bottom of the unit (when looking straight down at it). However, none of the T-nuts in the assortment I ordered would fit into the extrusion forming the frame of the NEJE. I quickly realized that NEJE had apparently made their own T-slot nuts for assembly out of short sections of thin metal strip. Even more concerning was that the extrusion was not at all square – 15mm on one side, 16mm on the other. This was looking jankier at every turn.

Armed with dial calipers, I made a pass at getting rough dimensions of the slot so that I could try to come up with my own T-slot nuts for this …unconventional… extrusion. There’s various designs out there for T-slot nuts that are based on standard hex nuts that are just small enough to slip into the slot, but since the ‘body’ of these are 3D printed, their strength, durability, and longevity are suspect in my mind – I’d like to have T-nuts that are strong enough to use structurally. Or whatever the ‘structural’ equivalent is when dealing with this weird 15×16 stuff…

I briefly considered trying to slip the head of a fastener into the T-slot rather than using a special nut (used on 80/20 with button head cap screws), but that’s a technique used only on blind joints, and I didn’t want to further weaken the already semi-floppy 15×16 extrusion. So, when faced with such a conundrum, I do what I always do… Flip through the pages of the McMaster-Carr catalog (pssst… McMaster… I could use a fresh hard copy, HMU). Within the great yellow tome I found 8895K363, a 3-foot length of 3/32″ x 5/16″ W1 tool steel. I certainly didn’t need tool steel for this application, but it was the only material available in that size. And even with those oddball dimensions, the material wouldn’t fit into the T-slot anyhow. I’d have to slightly bevel two edges on any homebrew T-nuts made from this metal stock. Still, it was the best option I had found thus far. I drilled holes at 1.5″ intervals along a good chunk of the steel, then tapped 10-32 threads (my go-to fastener size as a result of it being so commonly used on paintball guns) into each hole, and finally sawed the ‘nuts’ apart. A bit of deburring, and then I loaded them up in the mill with a 45 degree cutter to bevel two edges on each so that they would slide into the T-slot.

The resultant ‘nuts’ were perfect and slid easily into the 15×16 extrusion of the NEJE. All that remained was to drill holes in the melamine board for screws to secure the frame to the board. To semi-precisely locate these holes, I naturally 3D printed a guide block that I could use to easily drill the holes from the edge of the board.

Said guide block is on the left. Pictured on the right is a guide block that I attempted to use for drilling holes in the steel strip to make the T-nuts (only somewhat successful – the hardness of the W1 tool steel being drilled, the softness of the PLA guide block, and the use of a hand drill rather than a drill press led to a bit of inaccuracy). The board drilling block also allowed me to precisely drill holes into the side of the melamine board, which I then used to attach gate handles for more easily moving the whole assemblage around. I finished off the melamine board drilling with spots for some rubber feet.

This shows the culmination of these efforts – 10-32 button head machine screws securing the NEJE frame to the melamine board base with DIY T-nuts, pull handles for transport, and furniture feet for leveling and vibration absorption.

Fully assembled, it is a far more robust machine than without being attached to a base. I used a steel framing square to align the top bar with the left bar of the frame at 90 degrees, as the top left corner is what gets used during the homing process. The ‘clickiness’ of the Y-axis homing button may introduce an offset of perhaps 1/32″ between the left and right Y-axis steppers, but over that distance the angular offset is not even a concern for the sort of precision I need. Cutting out an 18×24 rectangle out of an even larger Dollar Tree piece of black posterboard results in a piece just as square as what a well-worn framing square can even indicate. More than good enough for my purposes.

Aviation pt. 2

It’s been close to 2 years since my previous post on the subject of aviation.  I’ve done a great deal since then – I obtained my sport pilot license, I’m now working towards my private pilot license, my main instructor moved away so she could become a test pilot for an aircraft manufacturer (which I […]

It’s been close to 2 years since my previous post on the subject of aviation.  I’ve done a great deal since then – I obtained my sport pilot license, I’m now working towards my private pilot license, my main instructor moved away so she could become a test pilot for an aircraft manufacturer (which I brag about at any given opportunity), and I stumbled into helping out with two different aircraft restorations via her father, who has since become a good friend and source of inspiration.  That summary glosses over a lot of details of little importance to anyone who is not, well, me.

Last night I drove to the field to drop off some drawings and get some dimensions for one of the restorations we’re working on.  I stopped by my flight school’s hangar to see if anything interesting was going on.  It was a perfect evening, with almost zero wind, endless visibility, and a beautiful setting sun in a sky dotted with only a handful of clouds – the sort of sky pilots dream of.  As it turned out, the school’s owner and chief instructor was doing a little flying with one of the kids who had been helping out at the hangar since I started my own training, and after they landed, he hopped out of the Cub and gave some instruction and encouragement to her.  Yes, this was to be her first solo.  She absolutely nailed her landings, leaving those of us on the ground wishing we could make our own approaches as cleanly.

One of my other instructors who was trained and then actually taught at the school (and is now a fresh new FO at a regional airline) even drove 2 hours to show up for the event.  After my own first solo, I’d still tell people that I was just a ‘student pilot’.  However, one pilot that I admire chastised me for prepending the ‘student’ moniker, admonishing that “there is no more binary distinction than those who have flown a plane by themselves, and those who have not”.

When she finally taxied back to the hangar, pictures were taken and scissors were deployed to remove her shirttails as per tradition – the rafters of the hangar are filled with the autographed fabric (mine included) of those who have made that leap across the divide.  There’s a lot more training and studying to be sure – but I hope she now calls herself  a ‘pilot’ instead of ‘student pilot’.  We’re all student pilots, after all – even my old instructor, the regional FO who now flies airline jets, will need to get checked out in the school’s Warrior before he can give an IFR refresher to one of the new instructors.

We all recounted our own first solo, how the plane becomes a rocketship without your instructor in front, and the fear and exhilaration that comes with flying an airplane all by yourself.  It’s a really special occasion, and I think it’s only properly appreciated by others who have gone through that same experience.  Flying is a very small brotherhood, but last night, we added one more to our ranks.


Perhaps I haven’t mentioned it a great deal on my blog, but I guess I should come out and say it if anyone is wondering: I love airplanes.  I suppose I always have.  Growing up on the shore of Lake Michigan, our house was under a frequently used training flight path for C-130s and A-10s, […]

Perhaps I haven’t mentioned it a great deal on my blog, but I guess I should come out and say it if anyone is wondering: I love airplanes.  I suppose I always have.  Growing up on the shore of Lake Michigan, our house was under a frequently used training flight path for C-130s and A-10s, and the sounds of Hercs or Hogs was enough to send me running outside to see what was passing overhead.  Some of my favorite early memories are of spending time at EAA Oshkosh with my uncles and grandfather on a foggy summer morning.  I distinctly recall seeing sometime in the very early 1980s an F-14 flying with wings swept in formation with a group of WWII warbirds (it may have even been a full Grumman ‘cats’ formation), then pulling out with an immense roar in the most memorable ‘missing man’ formation I will ever be witness to.

As a kid, I actually got kind of annoyed when going to the EAA airshow – I really wanted to see the jet fighters, but my uncles always dragged me first to see the WWII warbirds.  To be honest, I didn’t see their fascination with those old, propeller driven machines, when there were fast, exciting F-15s, F-16s and other such cutting edge combat planes as seen in An Illustrated Survey of the West’s Modern Fighters to look at (I swear, I absolutely devoured that book).  Many years later, I finally came to realize that it wasn’t a fascination at all – it was a deep respect and reverence for the planes and what they had accomplished so many years ago.  Now, when I go to that very same airshow, it’s not the modern jets that I go to look at first – it’s those old warbirds that so enraptured my uncles and grandfather.  The sound of a P-51 equipped with a Merlin V-12 is simply as magical as its engine name would imply.  Seeing the majority of airworthy P-38s in existence lined up together is the very best reunion imaginable.

I still love the jets, of course.  Oddly enough, many of the jets I knew and was fascinated by as a kid are now parked in that same warbird section – you might see an F-4, a MiG-21, or even a Sea Harrier in that area.  Sadly, with heavy restrictions now in place on what can be sold off into the civilian market, it seems quite likely that in another 10 or 20 years, there will still be more WWII vintage planes flying than the fighters I grew up with.  Apparently the government thinks shredding its heroes is for the best, and don’t even get me started on the USAF curtailing practically all airshow participation due to budget cuts (or so they claim – meanwhile, Canada was happy to send a few warplanes and even their phenomenal jet team to the Rockford air show).

Beyond my childlike desire for the sound of afterburning turbofans, I simply love airplanes in general.  I’m one of those weird people that simply have to look skyward when they hear something passing overhead, no matter how pedestrian.  I’m not even very good at being able to tell what type of plane it is.  It’s flying in the air, and that’s all that matters to me.  I’ve tried to scratch the itch – my bookshelves sag with books about airplanes, my hard drive is packed with flight simulators, and I have a pile of RC planes (and parts of RC planes, but I suppose that’s to be expected).  And yet it simply has never been enough.  I need to fly for myself.  I find it absurd that the concept of ‘aviation’ can be encoded into one’s DNA, yet the similar fascination of my uncles and grandfather appear to serve as at least anecdotal evidence that perhaps such desire is more rooted in one’s being than might normally be considered.  To be slightly more blunt, perhaps aviation is indeed in my blood.

I’ve been saving up for several years for flight training.  Flying isn’t cheap – despite the dreams and aspirations of optimistic 1950s post-war America, it’s not something you can pursue on a whim (and expect to succeed), unlike getting a motorcycle license (2 Saturday afternoons of training, a DMV test, bam – you can ride a bike).  I’ve heard that getting a private pilot certificate today actually requires more time/training than getting a commercial rating 50 years ago.  Despite the cost, I knew that this was something I simply had to pursue.  Stephen Force is an utter poet of piloting and has about the best summation that I can possibly imagine – “what do you owe to your 10-year-old self”.

No matter who who are or what are your own passions, I think this is a remarkably succinct distillation of what your true pursuits as an adult deserve to be.  If you had a time machine and visited yourself at 10 years old, what would disappoint them most about you?  Seriously consider that for a moment – looking at not a stranger, but yourself, 10, 20, 30, 40, 50, 60…  however many years younger than you now are.  What would you have to admit to your own self that you hadn’t even attempted, much less accomplished?  In my case, it would be “why didn’t you ever become a pilot?”  I would have to tell my 10 year old self that I had always wanted to, but you know, never quite got around to it, or some other bullshit answer.  And my 10 year old self would have looked at me with the most utter disdain imaginable.  They… you…  had dreams unrealized.  The opportunity was right in your face, yet you never grasped it.

I finally realized that in some way, I had made a promise to myself long ago.  I was going to either become a pilot or make the very best attempt at it that I could.  Your 10 year old self still lives inside of you, after all, subdued though they may be.  And I wasn’t going to let mine down.

Today I hope I did the 10 year old that lives inside of me proud.  I can’t verbalize the experience in any meaningful way, so I hope a simple log entry will suffice.

6 SEP 2014 – First solo – J-3 N42522

Capacitor replacement

Dad’s large screen TV has been having issues for quite a while, taking an increasingly long time to finally power up, culminating in a failure to power on at all.  He discovered that this is a fairly common issue with that model (Samsung LN-T4061F), and that the root cause is failing capacitors in the voltage […]

Dad’s large screen TV has been having issues for quite a while, taking an increasingly long time to finally power up, culminating in a failure to power on at all.  He discovered that this is a fairly common issue with that model (Samsung LN-T4061F), and that the root cause is failing capacitors in the voltage regulator section.  This reminded me that I still had to fix a friend’s Slingbox with the exact same issue, so it was off to the Makerspace to do some desoldering and order replacements.

The highlighted area shows the problematic caps on the board.  I have to say, this is one of the nicest PCBs that I’ve ever seen – all of the components are clearly labeled, test points are called out, saw cuts in the board provide additional voltage isolation, etc.  In an age where including circuit diagrams with a piece of electronics equipment is but a distant memory, could this board have actually been created with diagnosis and repair as design goals rather than the all-too-common approach of repair by replacement?

Left to right, top to bottom, the capacitors are:

CM880: Sam Young KMG 1000uF 25V 105°C (replaced with Digi-Key 493-4504-1-ND)

CM876: Sam Young KMG 1000uF 25V 105°C (replaced with Digi-Key 493-4504-1-ND)

CM852: Samsumg VMA 2200uF 10V 105°C (replaced with Digi-Key 493-4495-1-ND)

CM853: Samsumg VMA 2200uF 10V 105°C (replaced with Digi-Key 493-4495-1-ND)

CM881: Sam Young LXV 47uF 50V 105°C (replaced with Digi-Key 493-4512-1-ND)

CM854: Sam Young LXV 47uF 50V 105°C (replaced with Digi-Key 493-4512-1-ND)

CM851: Sam Young LXV 47uF 50V 105°C (replaced with Digi-Key 493-4512-1-ND)

CB850: Samsung VDE 1000uF 10V 105°C (replaced with Digi-Key 493-4494-1-ND)

The two components (LM852 and LM851) that look shrouded in heat shrink tubing are inductors and don’t need replacement (inductors are just coils and unlike electrolytic capacitors, don’t have electrolyte to evaporate away over time).  Obviously, the brown corrosion at the tops of CM852 and CM853 point to leakage on these caps, but it’s prudent to replace them all.

On the Slingbox I found:

CB18: 220uF 25v 105°C (replaced with Digi-Key 493-13386-ND)

CB45: 470uF 16v 105°C (replaced with Digi-Key 493-4499-1-ND)

CB43: 470uF 16v 105°C (replaced with Digi-Key 493-4499-1-ND)

If you look up the specific Digi-Key part numbers I listed, they’re all 125°C rated caps at the next highest voltage rating I could find.  I’ve heard that the rule of thumb is to just bump the voltage rating when replacing failed capacitors, but I figure upping the thermal rating in addition can’t hurt at all.  A bulb-type desoldering iron made quick work of removing them from the boards.

After waiting a few days for my Digi-Key order to arrive, I was ready to install the replacements.  I started with the Slingbox board, which had ample room for the larger replacement caps.  However, the solder pads were hesitant to actually take on any new solder.  By comparison, the Samsung board took solder on the pads with aplomb.

In comparison to the Slingbox board, the new caps on the Samsung board had to be shoehorned into place.  This was expected, though, as an increase in voltage rating or in thermal rating generally incurs an increase in package size as well.  I’ll happily take a board that may be less aesthetically populated in exchange for having it able to withstand a nuclear winter, zombie apocalypse, or Justin Beiber album.  While the initial failure of the Samsung board is a bit disheartening, I’ll still give Samsung praise for a superb, easily repairable PCB.  So to the unknown engineer(s) who toiled away on the design of IP-231135A to make it better than ‘good enough’, dad says ‘thanks’.

Rotary Phase Converter – Part 1

Once I had the big Keiyo Seiki settled in place in the garage, attention turned to the question of “how the heck do I power this monstrosity”?  For my Tree 2UVR vertical mill, I have a borrowed VFD (Variable Frequency Drive), which is able to transform the 240v single phase power (the same type of […]

Once I had the big Keiyo Seiki settled in place in the garage, attention turned to the question of “how the heck do I power this monstrosity”?  For my Tree 2UVR vertical mill, I have a borrowed VFD (Variable Frequency Drive), which is able to transform the 240v single phase power (the same type of circuit a house would have for an oven, for example) into the 240v three phase power that the mill needs.  It’s roughly analogous to the problem of powering a US intended appliance in the UK (120v versus 240v, respectively), only in this case additional power phases are needed.  Three phase power is how electricity is actually generated and distributed as part of the electrical grid – when you look up at a large electrical tower, you’ll almost always see 3 wires (or a multiple of 3). These aren’t for the ground, neutral and ‘hot’ wires of a standard electrical outlet, but are rather the 3 phases of power generated by the utility. One of those phases gets split off and lowered in voltage through a variety of transformers to supply the 240v and 120v single phase power that your house uses.

The problem with single phase power in the case of machine tools is that it’s rather inefficient for electric motors, especially as the size of the motor increases.  In addition, it adds to the cost and complexity of the motor.  3-phase motors on the other hand are simple, efficient, and (relatively) inexpensive, so they’re what industries use when a big-ass motor is called for.  Of course, the local electric utility isn’t going to be terribly interested in running 3-phase power out to my garage just so I can run some beefy machine tools.  As mentioned, I used a VFD on the mill, which is a completely solid state device that uses fancy electronics to create a 3-phase power output from a single phase power input (though using a 3-phase input is more common). Actually, the main use of a VFD is to be able to vary the motor’s speed (the ‘variable’ in VFD), hence why you’d want to have an input of 3-phase if you’re just going to turn it into a 3-phase output – you can run a standard 60Hz 3-phase motor at a crawling 20Hz or a blistering 200Hz (depending on how the motor is rated), but I had no use for this feature, as the mill has a variable speed head.

Getting a VFD large enough to power the lathe (a 7.5HP motor, versus only 1.5HP on the mill) would be terribly expensive, as I’d have to find a VFD of at least 10HP in capacity (most 3-phase VFDs can be run from single phase power, but they have to be derated).  And if I wanted to power brake (kicking a forward rotating 3-phase motor into reverse electrically to slow/stop the motor more quickly), I’d worry about smoking the unit.  The most cost effective way to power the lathe, I decided, would be to build a rotary phase converter (RPC).

The idea behind an RPC is simple and clever – you can actually run a 3-phase motor from single phase power, and when you do so, the unconnected leg of the motor will actually generate the third phase!  By connecting the lines from this helper motor (called an ‘idler’, since the motor shaft doesn’t connect to anything, as the motor is used purely for its electrical characteristics and not for rotary mechanical power) to the motor of the machine you wish to use, you can power on the machine just as though it were connected to ‘real’ 3-phase power.  To be nitpicky, the ‘fake’ 3-phase isn’t perfect (2 phases are 180 degrees apart rather than 120 degrees in a ‘real’ 3-phase system, and you have varying voltages on the 3 phases depending on load), but it’s ‘good enough’ for the majority of home shop applications.

I knew I needed a 10HP idler to power the 7.5HP lathe (I may have been able to get away with a 7.5HP idler, but it would probably have been marginal), so I started scouring various electrical suppliers, Surplus Center, etc. for a nice beefy TEFC (Totally Enclosed, Fan Cooled – a very rugged type of motor, with lots of thermal mass, making it good for RPCs). Not having much luck there, I turned to Ebay. Of course, I quickly realized I’d have to find something reasonably local, as the shipping charges for a 10HP motor are pretty hefty. I finally found one that looked to be perfect for my needs from a guy near Chicago. After chatting briefly over email with him about it, I decided to buy it. Turns out that the seller was Igor Chudov, whose RPC is actually the one shown on the Wikipedia page, and whose information on building RPCs I had stumbled across previously. I drove down to Chicago to pick up the motor in person, and Igor happily showed me his shop and the large dual idler RPC that he was currently using (he runs it with one idler motor spinning when he powers his mill or lathe, but kicks in the second idler if he needs to power his large air compressor).  [edit – Igor helpfully corrected me, see comments.  He does a staggered start on the idlers, but always runs both.]  We managed to heft the motor into the truck, and I also bought a few other odds and ends that would be needed in the project – a motor starter (“big 3-phase relay”), a disconnect panel (“dangerous looking gray box with a big lever on the side”), and what the heck, I took a 7.5HP motor that he had as well.

10HP on left, 7.5HP on right
10HP on left, 7.5HP on right

10HP rating plate
10HP rating plate

Rating plate for the 7.5HP motor
7.5HP rating plate

I’m not sure how I managed to actually get the 10HP motor out of the truck and into the garage by myself without requiring back surgery afterwards.  You know something’s heavy when it has an eye bolt for lifting it.  Before I could actually give it power, I needed to make sure that the garage wiring wouldn’t burst into flames.  When I had first gotten the mill, I ran a 30 amp 240v circuit from the breaker box in the garage (my first attempt ever at running conduit, and it came out quite nicely).  However, this wouldn’t suffice for running a max capacity of 17.5HP.  I bought a 50 amp breaker and replaced the 10 gauge wiring on the circuit with 6 gauge wires for the split phases (the two ‘hot’ 240v wires) and an 8 gauge wire for the ground wire (this suggestion made by one of our EEs at work, who pointed out to me that the ground never carries current unless something goes really wrong, hence you can undersize the ground wire by a notch.  This was needed because things were getting pretty tight in the conduit with 6 gauge wire.  Pulling the wire through the conduit actually went really smoothly – the outer sheathing on the wire I bought at Home Depot is super slick and I was able to push it all the way through the conduit with no fish tape required.  I topped it off with a beefy 3-pole outlet like we have at work for the welder outlet – looks nice and menacing and pretty much screams “don’t insert kitchen utensils here”.

If Chuck Norris was an electrical plug, he'd be this one.
If Chuck Norris was an electrical plug, he'd be this one.

With the facility wiring out of the way, I could finally try hooking up the 10HP monster and seeing if the blasted thing would spin.  I took the disconnect box I bought from Igor and slapped a pair of 100 amp fuses into it (one fuse for each of the incoming lines).  Really, I didn’t need fuses here at all – the breaker will pop way before the fuses go, but it was more expedient using ready-to-go fuses than trying to find some copper plate to use in their place.  I then ran wires from the bottom of the disconnect panel to the 10HP motor – 2 ‘hot’ wires and one ground, with the third phase on the motor left unattached to anything.  I used wire nuts for the actual wire attachment and electrical tape to cover up any scary looking bare conductors.  I then ran a cable off the top (input) of the disconnect panel and connected it to a 3-pole plug suitable for insertion into the 50 amp outlet.  The disconnect panel is basically just a switch.  A really big, mean, nasty, mad-scientist movie type of switch, reminiscent of the giant knife switches you’d see in Frankenstein’s lab.  The lever on the side actually takes a bit of force to move between ‘on’ and ‘off’, and it makes a satisfying ‘ka-chunk’ when toggled.  This ain’t no lightswitch, kids.

Disconnect panel exterior
Disconnect panel exterior

Inside the disconnect panel
Inside the disconnect panel - the three hook shaped contacts to the left of the fuses rotate downwards to complete the circuit as the lever is switched into the 'on' position

The scary part of testing the 10HP motor wasn’t just that I had to apply 50 amps of circuit juice to the beast, it was that I had to apply power with the motor spinning.  You see, once a 3-phase motor is spinning under proper 3-phase power, you can disconnect one of the phases and have it still run (known as ‘single-phasing’, which is generally not desirable, as voltages start getting wonky).  But you can’t apply single phase power to a stationary 3-phase motor and have it magically spin up – this requires special capacitors, which I did not have.  What’s needed is a ‘pony motor’ (usually just a small 120v single phase motor) that you can couple temporarily to the idler to get it spinning, then pull away the pony motor and apply single phase power to the idler.  Of course, then I’d have to wire up another blasted motor and figure out how to couple it to the idler and…  Well, there is of course a simpler solution, which starts getting into ‘horrible kludge’ territory – use a pull cord of some sort wrapped around the idler motor shaft.  I used the end of a tie-down strap, and wound it around the motor shaft about a dozen times (motor bearings were really nice and smooth, I noted – certainly a good sign).  I plugged the power cable from the disconnect box into the wall outlet and flipped on the breaker.  All that remained was to give the strap a smooth, forceful pull, then quickly flip the disconnect lever upward to apply power.  Everything I read said it should work, yet looking at those big copper wires still gives one pause – a healthy respect for electricity does tend to keep one alive, after all.  I grabbed onto the strap and…  had a second thought and rummaged around for my safety glasses.

Eye protection in place for any mishaps (note to self – buy fire extinguisher for the garage), I yanked the strap, tossed it behind me (loose straps and spinning shafts are not a good combo) and shoved the disconnect lever upwards to ‘on’.  The motor kept going, but it didn’t appear happy, making a disconcerting waohwaohwaohwaohwaoh noise, and it looked like the shaft wasn’t spinning nearly as fast as it should.  I stared at it in puzzlement for a few moments before hearing a ‘clack’ from the breaker panel.  Tripping the breaker meant it had certainly been drawing more current than it should have, and I wondered if perhaps I didn’t have it spinning fast enough.  After allowing a few minutes for the breaker to cool off, I wrapped the strap around the motor shaft once more and gave it a more forceful pull this time, getting it to a faster speed before applying power at the disconnect.  This time the motor happily revved up to its rated speed, emitting only a quiet, gentle hum that belied the massive power that it was capable of.

Next of course would be the real test – hooking the lathe up to the idler and seeing if I could get the lathe spinning.  This was pretty simple – just attaching a few more wires.  Once I had the idler spinning and powered again, I turned on the disconnect on the lathe, switched the power to ‘on’, made sure I didn’t have the carriage or cross-slide in feed mode, and moved the lathe’s control level to ‘forward’.  The contactors in the lathe’s power panel clattered and buzzed as the ammeter on the panel jumped around on the far end, attesting to the volume of electrons tearing through the system.  The giant chuck began turning, and the clatter died down, leaving only the whirr of properly meshing gears and the low growl of the machine’s motor.  Yes, it was alive.

R0xx0rz Ur B0xx0rz

Rockerbox was this weekend and Chuck convinced me to head there with him. I was a little hesitant, having just a simple 2001 GS500, which is about as pedestrian as bikes get. Okay, the carbs are jetted, it has a Vance & Hines exhaust, Buell turn signals, etc., but I wouldn’t say it has the […]

Rockerbox was this weekend and Chuck convinced me to head there with him. I was a little hesitant, having just a simple 2001 GS500, which is about as pedestrian as bikes get. Okay, the carbs are jetted, it has a Vance & Hines exhaust, Buell turn signals, etc., but I wouldn’t say it has the ‘street cred’ of Chuck’s XJ550, which he equipped with white racing stripes for the event (looks really nice). Still, the event is essentially “if it’s 2 wheels, it’s cool”, so all was well.

We were hoping to meet up with Frankie and see the bike that he was working on for the event, but he emailed Chuck to say that he wasn’t going to complete it in time and would just be there with his Moto Guzzi (which I wanted to see just as badly).  Apparently he made it, but we never collided with him. Still, we did find Steve, who we had met at the welding workshop, and he showed us the taillight unit that he had been working on in class for his BMW. Looked great on the bike, though it was mostly obscured by the tail fairing, so he also added LED flashers up top.

Walking around the contest area (where bikes are entered to win in categories from “Best European Modified” to “Worst Piece of Crap Award” is an amazing experience. Sure, I’ve seen episodes of American Chopper and the like where a custom bike is created, but the ones on display here were far more visceral and much more interesting.  You really have to walk around a bike a few times to take in all the details of its execution.

This was one of my favorites - love the wrought iron footpegs
This was one of my favorites - love the wrought iron footpegs

This bike is all attitude, and a deathtrap.  Note the lack of a left handlebar.
This bike is all attitude, and a deathtrap. Note the lack of a left handlebar.

Flickr photoset is here.

D600 CPU Upgrayedd

My primary machine is an ancient Dell Latitude D600 purchased in May 2004. I know when I purchased it because the warranty finally expired this past May, with no way to extend it further – 5 years is the max. I’ve bumped the RAM up to 1.5G (will take it all the way to 2G […]

My primary machine is an ancient Dell Latitude D600 purchased in May 2004. I know when I purchased it because the warranty finally expired this past May, with no way to extend it further – 5 years is the max. I’ve bumped the RAM up to 1.5G (will take it all the way to 2G one of these days, probably), upgraded the hard drive at least twice, etc. I expected that it would last me until I could afford to buy a new one (I’m holding out for an Arrandale based Latitude), and it’s still holding up despite daily use over the past 5 years (admittedly, it’s had quite a few service calls under its long warranty period).

One of my favorite pieces of software has a preview release available (I don’t think I can mention it by name without unleashing the demons of NDA), and I’m a sucker for “new and shiny” when it comes to software as much as anyone (I suppose it’s a good balance for running it on crufty old hardware). Unfortunately, though my machine meets the requirements of the approved hardware list, it’s an oversight – old 400MHz ‘Banian’ CPUs such as the one in my old D600 do not have the PAE feature that this shiny new beta requires. However, it appeared that dropping a newer ‘Dothan’ CPU into the D600 was entirely possible, so I took a chance on Ebay and nabbed a 1.86GHz Dothan (versus the 1.6GHz Banias I’ve been running with for over 5 years) for only 20 bucks shipped.

Left: New hotness Right: Old busted

There’s nothing like seeing the year stamped on a CPU to drive home how horribly out of date your system is.  That’s right, my existing CPU was state-of-the-art 2 years before I bought the blasted laptop.  Let me just fire up my brand new 33.6 modem on my AOL account to download some M3P files – I’ll show you whippersnappers some technology

Wonder of wonders, the thing actually worked.  Not only did it actually boot, but it runs the V*****e beta just fine.  It feels a smidge snappier, too – this is rather impressive, as I’m now running at only 1.4GHz due to the FSB being stuck at 400MHz – I’m guessing the doubled L2 cache isn’t hurting.  Still, I’d love to wrench out any remaining performance – it’s out of warranty after all, and the magic smoke can’t stay in those chips forever. This mod may be just what I need. Now where did I put my SMT resistors…

Yeah, like I need another hobby…

It seems that, as a boy growing up in the 80s, I was not alone in having an interest in R/C airplanes.  R/C anything, really (where R/C meant ‘radio control’, not the laughable ‘remote control’, which was toy company code for ‘has a 10 foot wire between the controller and vehicle, and anybody who buys […]


It seems that, as a boy growing up in the 80s, I was not alone in having an interest in R/C airplanes.  R/C anything, really (where R/C meant ‘radio control’, not the laughable ‘remote control’, which was toy company code for ‘has a 10 foot wire between the controller and vehicle, and anybody who buys it is a sucker’) – cars, boats, tanks, airplanes, helicopters, whatever, but particularly R/C airplanes.  I did get a control line P-51 as a present one year, but it never took to the sky, perhaps as part of my disdain for any sort of tether between plane and operator.  Looked good hanging from the ceiling, though, where it perennially engaged in a static dogfight of sheer will against a plastic model UH-1 Huey – first to fall due to weight of accumulated dust lost air superiority.

I had several issues of R/C Modeler, which was like crack cocaine for young imaginations.  Within the tattered and well thumbed pages were some articles (filled with technical jargon of unknown meaning) interspersed between glorious advertisements for incredible flying machines (and cars and boats, too – the ‘glass filled nylon’ bit in the Tamiya Hornet ad confused me for a while until I learned about fiberglass composites).  I recall ducted fan scale models of the fighter jets that graced posters plastered around my room, brightly colored aerobatic planes (which I didn’t pay much attention to – anything displaying a propeller rather than an afterburner didn’t merit much thought), and quite possibly the coolest thing ever, a scale R/C version of Airwolf, the baddest-ass helicopter EVER (although Blue Thunder runs a close second).

All of this airborne fantasy had one big drawback, however – price. I understood the hobby well enough to know that you had to have a lot of gear – an engine, radio, receiver, servos…   …oh, and the airplane itself.  I also understood the hobby well enough to know that crashes were a royal pain when repairs were needed.  Building a fuselage for a free-flight plane taught me that repairing cracked balsa gets old really fast, and the stuff will invariably warp on you.  Over the years, I’d thumb though other R/C magazines at the library, and I’d go to a few of the charity exhibitions held by the local R/C club to get a taste.  I even modified a ‘buddy box’ so I could play with an R/C Simulator on my computer. Eventually, it all sort of drifted out of consciousness.

Fast forward to this past Labor Day, where I went to a party hosted by my friends Chuck and Molly, with lots of kids in attendance. At one point, we all headed down to the local park to launch some model rockets, courtesy of Chuck’s sister. Chuck also brought along his son’s little 2-channel Air Hogs type of R/C airplane. Due to the slight wind, none of us could keep the plane in the air for more than a few seconds, but I was fascinated by its simplicity and manufacturability (i.e. low cost). I had a hunch that while I hadn’t been paying attention, R/C airplanes suddenly had become far more affordable than in my youth.

Sure enough, after a bit of web searching, it became apparent that advances in battery technology coupled with sturdy, lightweight foam and cheap outsourced manufacturing had yielded the ideal starter R/C aircraft, at a price that even a global economic meltdown couldn’t make unattractive. There were a number of such RTF trainers I found, but the least expensive (hey, ‘affordable’ is no reason to stop being a cheapskate) looked to be the Firebird Phantom. Several of us took the plunge, and we ordered 4 of them and a bunch of extra batteries. While waiting for them to arrive, I tried to consume as much information on them as I could, and I watched Dave Herbert’s Youtube videos on the plane (I figure if a guy who has been in the hobby for over 3 decades thinks it’s a good starter plane, I can feel confident about the purchase).

Upon receiving the package, I knew that the first thing to do was to strengthen the wing, so out came the strapping and packing tape. I even removed the stickers on the wing to reduce weight (a bit silly in retrospect, like being horribly out of shape, deciding you want to compete in the Ironman, and shaving your legs to give you a 0.6 second edge during the swimming phase of the event). I then charged up all 3 of my batteries, and eagerly awaited the next day.   After work, I excitedly rushed home, grabbed the plane and batteries, and headed over to the park we had been at on Labor Day.  I found an unused ball diamond in the park (crucial, as any witnesses to what was about to be attempted would undoubtedly result in exponential embarrassment) and quickly assembled my aircraft.  Despite the overwhelming possibility of failure, I hurled my charge into the air, then furiously worked the controls to adjust throttle, pitch and yaw.  Though my attempts were valiant, ‘soaring”, ‘majestic’, and ‘skyward’ were not adjectives applicable to the flight that followed.  After an ‘air time’ that generally requires the precision of an atomic clock to accurately relay the brevity of, the craft was reunited with terra quite firma.  Foam is nothing if not resilient, so second and third attempts were quickly mounted.  This third flight (I am of the opinion that any object, be it a tossed coin or a hummingbird, not touching a static, grounded item, may be considered ‘in flight’; issues of control, intent, and the ever-pesky ‘lift’ nothwithstanding) met with ‘arboreal interference’.  After throwing increasingly large sticks at the restraining limbs, I rooted around in the brush to find a 15 foot branch suitable for extracting the plane.  I was back in the air in no time (and nose-down in the ground in even less).  My final flight was perhaps the most dramatic, culminating in two full loops interrupted once more by tree branches.  This proved a disastrous end – though the plane miraculously managed to escape from the branches, the propeller was nowhere to be found.  Thus ended flying for the day, as well as the week.

After the disappointment wore off, I went back to the web to watch more videos and research what others had done with the plane.  I found that there were 3 things that had contributed to a less-than successful outing: Wind, space, and wing.  Though the wind was pretty low that day, it appeared that ‘dead still’ air was really what I wanted as a raw beginner without an experienced pilot to help me.  Additionally, more space (free of aircraft eating trees) was needed to allow for more altitude, larger turns, and simply much wider error margins.  Finally, a number of people commented that the stock wing was rather ‘fast’, and that a larger wing would slow down the plane and make it much more docile.

At the local hobby store, I looked at the selection of foam wings, and found a ‘Sky Fly’ wing for about $12 that had a generous surface area, more dihedral than the stock wing, and simply seemed a bit sturdier than the stock unit.  I then cut out the rear center of the wing to fit it to the Phantom.  Still without a prop, I did a number of hand tossed glides with the new wing to see how it ‘felt’ and whether it was too nose heavy.  I did some more launches with the stock wing and thought I could see a bit of difference – the stock wing felt ‘twitchier’ than the big one, and was more prone to rolling.  I also took the opportunity to tear out the ACT sensors, as the prevailing opinion seemed to be that ACT caused more problems than it solved.

At home, I started looking into better flying sites.  There are at least two local R/C clubs, but in order to use their fields you have to be an AMA member ($50/year) in addition to being a club member (another $50/year), and abide by 2 pages worth of rules and regulations.  I wasn’t interested in shelling out almost twice the cost of the airplane itself just for the privilege of flying it, so I spent time with Google maps to look for nearby wide open areas.  Local parks were the first place I looked, and I first checked the ball field where I had made my first attempts to see roughly how big the place was to serve as a baseline comparison.  Unfortunately, though parks are generally quite spacious, they tend to have a great many trees.  A local factory had a sizable vacant weedy lot nearby, and I wondered about the local soccer park as well.  I started a placemark map which I then shared with Chuck and Jared and we noted our discovery of possible sites with each other.  One mysterious location was what looked to be an enormous (32 acres, I’d later find) wide open field, just a few minutes from home.  Switching to Google street view, I ‘drove’ to a point where this field actually ran all the way up to the road, and I noticed what appeared to be an informational sign about the area.  Street view unfortunately doesn’t have a high enough resolution to read the signage, so I drove over for a look.  As I had guessed, the sign was indeed about the site, which turned out to be a floodwater retention basin operated by the city sewerage district.  I placed a call to the district office to find out if it was okay to fly an R/C plane there, and eagerly awaited a response.  A helpful gentleman gave me a call back a few hours later after checking with their legal department and said it was fine by them as long as I wasn’t a nuisance, and “hope you have fun!”

Not able to stand the wait for a replacement prop for much longer, I ‘borrowed’ the prop from Jared’s plane, as I had yet to deliver it to him.  I also opted to move the control rods down to the position closest to the control surfaces for maximum movement (this luckily turned out to work very well with the large wing).  Around 7pm, I drove to a side street bordering the field with the plane, Sky Fly wing, and freshly charged batteries.  I was amazed at the field seeing it from this vantage point – if I didn’t know any better, I’d swear that it had been designed for R/C flying.  A berm surrounded the basin itself, with a mowed path running around the perimeter.  The basin was covered in thigh-high grasses, making for soft landings all around.  And I had the entire place to myself.

With the wind at a standstill, I revved the motor, threw the plane into the air…   …and it was a completely different airplane from the one a few days before.  I could actually control it this time, making slow circles around the field.  Most importantly, it was enjoyable rather than aggravating.  By the time I was on the third battery, I was feeling very confident, making flyby passes and enjoying the realization of a long-desired experience.

I had a few more flights (and certainly more crashes) with the big wing, and then finally broke the boom, which seems to be an expected occurrence with this particular model.  But the other half of flying is ‘fixing’, and I have a feeling that the only R/C planes without battle damage are the ones that have hardly been flown.  The problem with the boom is that there is a slot cut into the top of it just forward of the tail where the control rods exit.  This is a very clean design, but the cut significantly weakens the (extremely thinwalled) carbon fiber tube.  Although there’s a plastic stiffener glued to the boom around the slot area, it is of little help.  I found that 5/32″ thinwall brass tubing slipped inside the boom perfectly, so I epoxied in a piece of about 3 inches to join the pieces back together.  I then glued another piece of carbon fiber tubing along the top (covering the slot).  I went a little crazy and also wrapped some kevlar line through epoxy around the front and rear of the added tube.  I don’t expect any further breakage.

The strapping tape is there just to hold the antenna wire - it has nothing to do with the boom repair.

Control rods now exit the fuselage just above the boom.

With the slot now covered, I had to route the control rods through a hole drilled through the back of the fuselage just above the boom and through the top carbon fiber tube.  This kept them as low as possible, which is needed now that I have added a larger prop (some forum posts had said that the Phantom has a 2.3mm motor shaft, but this was not the case on mine and I needed a 2mm adapter instead).

Antenna now runs out the front of the nose.

I tried to snake the antenna back through the boom, but just couldn’t get it (how the manufacturer managed to get it and the two control rods through the boom is beyond me).  However, since I had a handy hole in the bottom of the nose as a result of removing the ACT sensors, I just ran the antenna wire through it and used tape to keep the antenna running along the outside of the boom.

As a result of the added weight, I had to rebalance the plane a bit.  I started by adding some noseweight (a screwdriver tip taped inside the canopy), which worked well, but with the noseweight, repair weight, and weight of the large wing, it struggled for altitude.  I had better results by simply shifting around where the battery sits, moving it forward into the nose.  After a bit of flying in this manner, I was ready to move back to the stock wing.  The big wing had given me some much needed confidence and I was able to fly fairly happily with the stock wing, noting that the added maneuverability came at the cost of dropping out of the sky during very tight turns.

It’s not always a special feeling to fulfil a childhood desire. But in this case, it was.

“Why don’t you write about it in your blag?”

I’ve long eschewed any sort of ‘social networking’ technology (facebook, myspace, second life, twitter, etc.) because a) they’re useless, b) anything ‘social’ is severely at odds with my personality, and c) they’re often simply a haven for 12 year old girls and the 40 year old men that love them (see (a)). Still, it seemed […]

I’ve long eschewed any sort of ‘social networking’ technology (facebook, myspace, second life, twitter, etc.) because a) they’re useless, b) anything ‘social’ is severely at odds with my personality, and c) they’re often simply a haven for 12 year old girls and the 40 year old men that love them (see (a)).

Still, it seemed about time to finally create a blog for several reasons: a) I set up a blog for my friend Lee, and it would be kind of nice to be more familiar with WordPress if he has questions or problems getting it to work.  b) I needed a convenient place to write down nifty discoveries and problem solutions that I may have to refer back to later.  c) I already had a proto-blog of sorts back around 9 years ago when I was hacking Cuecats (will post a link to that as soon as I find the drive I have it archived on).

So after much wailing and gnashing of teeth (primarily due to figuring out how the heck to work with MySQL – I still view databases of any sort with much disdain, open source or not), this thing finally seems to be running.  We’ll see what sorts of grand, sweeping thoughts of truly visionary insight I’ll expound upon.  That, or maybe just a halfway funny fart joke now and again.