Simple CNC Engraving Head

My very first summer job was working at the local trophy shop, where we had several computerized engravers.  As it turns out, they were extremely similar to the Taig CNC mill that I would many years later acquire – driven by steppers in the X and Y axes and controlled via a desktop PC, it’s […]

My very first summer job was working at the local trophy shop, where we had several computerized engravers.  As it turns out, they were extremely similar to the Taig CNC mill that I would many years later acquire – driven by steppers in the X and Y axes and controlled via a desktop PC, it’s really not a stretch to consider them specialized CNC tools.  Our most commonly used engraver was a ‘diamond drag’ type, which essentially used a diamond tipped tool to scratch through the lacquer covering a sheet of brass or aluminum (our other engraver used a rotary cutter for engraving on plastics).

Once I had my Taig, I realized I could certainly do a little engraving myself, I just needed the right tool.  On the engraver at the trophy shop, the ‘head’ was actually pneumatic – rather than a Z axis, there was simply a 3-way solenoid valve that would apply air to a spring retracted engraver.  More air pressure meant deeper engraving.  There had been plans in Home Shop Machinist (might have been the sister publication, Machinist’s Workshop) for a spring-loaded engraver for use on CNC mills a while back, but I wasn’t thrilled with the design – not only did it reduce the working travel in Z, but had to go in the spindle.  I wanted an engraver that could be attached to the side of the headstock (Taig headstocks have T-slots for such purposes) which would not only be a bit more rigid, but would allow me to machine a shallow flat on a part and immediately engrave in that area without any tool changes.

Construction is simple – the only purchased parts were the diamond drag engraver (I used a DG-250 from Antares), a pair of clamp collars, and a spring. The body was a hunk of scrap extrusion from work – it had a 5/16″ hole already down the length of it. I machined a pair of bushings from some Oilite bronze rod stock and pressed them into each end of the body (I had bored each end out a little bit). Though I had reamed the bushings to have a 1/4″ hole through them, there was enough axial misalignment between the two to cause the engraver to bind when I tried to run it through. So I tried something a little crazy – I chucked a long piece of 1/4″ drill rod in the lathe, lightly scuffed the last two inches or so of the rod with a diamond hone, slathered it in oil, and ran it through the bushings. This trued things up just enough to allow the engraver to slide through the bushings freely, but with zero side play. A bit of strip steel, some threaded rod and wingnuts, and it’s ready to attach.

Assembled engraving head
Assembled engraving head
Engraving head parts
Engraving head parts

The Zen of Metalworking

Last month Chuck forwarded me an innocuous sounding email from the local vintage motorcycle mailing list.  There were a few metalworking classes being held at the art school at UWM, and he was thinking of signing up for a few. They did sound intriguing, and I figured I’d tag along with him for the soldering […]

Last month Chuck forwarded me an innocuous sounding email from the local vintage motorcycle mailing list.  There were a few metalworking classes being held at the art school at UWM, and he was thinking of signing up for a few. They did sound intriguing, and I figured I’d tag along with him for the soldering and welding classes (I had taken TIG and stick welding classes before, but welding/forming sheet metal was new to me, and I really wanted to learn soldering techniques for when I eventually try tinkering around with brass paintguns). The emphasis on hand work both intimidated and excited me – I’m used to the sharp, prismatic capabilities of mills and lathes, and the ability to create free-flowing shapes without use of CNC is a skill that I covet and admire.

Being that the classes were run through the art school, I was a little apprehensive – I’ve never really ‘gotten’ fine art, though I have certainly tried. I did take an art history class as an elective long ago, and though I did come away with an appreciation for the intent of the Dadaists and marveled at the technical skill of the Trompe-l’œil painters, I just can’t get past the attitude that seems part and parcel of ‘art’ – the feeling that ‘art’ is more and more meant only to be consumed by others in the field, removing it from the reach of the common person. I checked out a DVD of Chihuly Over Venice at the library a while back, as glassblowing certainly takes a great deal of skill and I wanted to learn more about the craft. However, the video was disappointing – Dale Chihuly struts around the whole time, commanding other glass blowers in what to do, and the end result is a bunch of twisted orange glass hanging from some steel pipes that he had no hand in the actual making of. I wanted to see more of what the craftsmen were doing, as they should be given the credit for creation. It basically reinforced my appraisal that to be an artist requires only two things: a beret and an attitude.  (Addendum – I’ve since found that Chihuly had suffered a shoulder injury some time back that left him unable to continue doing his own glasswork, thus he relies on other craftsmen. I have to give him a pass on that account, but I still don’t get his art.)

Still, the fact that our instructor, Frankie Flood, had an interest in motorcycles and had made motorcycle themed pizza cutters (which I actually remember seeing on a number of blogs last year, and could actually appreciate as artistic objects), I had hope that I could learn some new skills rather than simply be baffled by ‘art’. I was not disappointed. Class ran from 6pm to 9pm, though Chuck and I invariably stayed long after to chat extensively with Frankie over the widest range of topics imaginable, from machining techniques, to educational systems, to the philosophy of craftsmanship (we’ve all bought copies of Shop Class as Soulcraft). Refreshingly, even though Frankie was art department faculty, he had the same difficulty of wrestling with ‘art’ that I have had. When he elected to build a chopper for his thesis, his professors were abhorred, decreeing such work as lowbrow and worthless (wonder if they said the same of Roy Lichtenstein). He still struggles with this, noting that ‘art’ has become more about the ‘idea’ rather than the craft. It all leads me to wonder – maybe I won’t be able to ever understand ‘art’, but with artists and teachers like Frankie out there, maybe someday ‘art’ will understand us.

Photos and details to follow.

The mother of all CNC programs

I’ve been working on cocker threaded Phantom bodies for quite some time, and the latest incarnation is a ‘full round’ version.  I had a job shop do the internal machine work on them as I didn’t yet have the big lathe running (which I’m now having some regrets on – the cost was substantial, it […]

I’ve been working on cocker threaded Phantom bodies for quite some time, and the latest incarnation is a ‘full round’ version.  I had a job shop do the internal machine work on them as I didn’t yet have the big lathe running (which I’m now having some regrets on – the cost was substantial, it took over 5 months, and despite what I was told at first, they want the invoice paid in full NOW).  I wanted to do the final machining in a single setup, as they’re round and alignment would be a concern were I to try multiple setups.  Furtheremore, a single setup would require 4th axis operation, as there are features on the top and bottom of the part.  In short, there were a lot of ‘firsts’ for me in this project, and it’s the most ambitious CNC program I’ve yet done (experienced CNC machinists would laugh at its simplicity, but hey, I’m learning).

Roundhead body on the mill
Detent slot milling operation in progress

I broke the program down into pieces, some of which I had already done.  There are 5 subroutines in use:

  • sear slot
  • threaded insert counterbore
  • feed port
  • threadmilling for insert counterbore
  • detent slotting

The sear slot is first, then the underside counterbore, rotate 180 degrees, then the topside counterbore and feed port.  Tool is changed to the threadmill, top counterbore is threaded, rotate 180 degrees and thread the bottom counterbore.  Finally switch to the ball end mill and run the detent slots.  Total run time is still over a half hour, which I hope to cut down a bit by removing some unneeded ‘air’ cuts, increasing feeds, etc.  Still, the satisfaction is immense – I’ve had a lot of tools (the 4th axis, tooling plate, tailstock, bullnose live center, etc.) sitting idle for a very long time (they were all purchased with this project in mind), and it’s a great feeling to finally have them put to use.

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Mach3 while running the CNC program
The three tools used in the program, held in A2Z endmill holders
The three tools used in the program, held in A2Z endmill holders

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 […]

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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.

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

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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.

Clie UX-50 and Palm Desktop 6.x

I’ve been using a PDA for ages.  I started out with YONPY on my beloved old HP48GX (no self-respecting engineering student would dare use anything else). Wasn’t bad (was downright fantastic for cribbing notes, actually), but something a bit more task-suitable was needed, and I wound up getting a PalmPilot Pro. I’ve been on the […]

I’ve been using a PDA for ages.  I started out with YONPY on my beloved old HP48GX (no self-respecting engineering student would dare use anything else). Wasn’t bad (was downright fantastic for cribbing notes, actually), but something a bit more task-suitable was needed, and I wound up getting a PalmPilot Pro. I’ve been on the Palm platform ever since, upgrding the old Pro with a card from a Palm III, moving up to a IIIxe, destroying the IIIxe in a fit of lockup-induced rage, and finally getting a Clie UX-50.

The UX-50 is still a great device, and it just keeps on running (though the battery just doesn’t have the runtime it once did).  Being that it is long out of support (and Sony’s software was never anything to write home about), I always wonder how long I’ll be able to keep it syncing with my laptop.  Fortunately, quite a while it appears.  After doing a fresh install of XP on my laptop (had gone a good 16 months without a reinstall – I think that’s a new record for me), I grabbed Palm Desktop 6.2 (I had been using 4.1.4e, but I’m a sucker for newer versions as much as anyone).  The sync process completed successfully, but when I launched Palm Desktop, I had zilch.  I noticed during the sync that there were actually double entries for Address Book, Memo Pad, etc., so I assumed that it must have been grabbing the data, but Palm Desktop wouldn’t show it to me as it was data from an ‘old’ device and not one that 6.2 expected to communicate with.

All was not lost, and a bit of searching found this very simple fix. I fired up regedit, dug down to HKEY_LOCAL_MACHINE\SOFTWARE\PalmSource\Desktop\UiModule[0-3] and modified the file extensions from .mdb to .db for each of the four File0 registry keys.

Palm Desktop 6.2 registry fix

I synced once more for good measure (not sure if it was needed), fired up Palm Desktop, and sure enough, all my data was there.  I guess the UX-50 will remain a mainstay in my pocket for a good while longer, assuming 6.2 works well under Windows Seven.

“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.