Adventures in ADS-B

I find myself using websites like Flight Aware and Flight Radar 24 quite a bit. Whether I’m tracking a flight with friends/family on board, just checking to see what big quad-jet is flying overhead, or keeping tabs on the occasional ‘unicorn’ squawking ADS-B I usually find myself wishing I had a subscription.

Snap from FlightRadar24.com based off ADS-B data.
Snap from FlightRadar24.com based off ADS-B data.

Both sites offer free subscriptions if you’re willing to contribute ADS-B data to their databases. To do this, you need an antenna, and some way to get the ADS-B data from the antenna to the internet. The most common being a RTL-2832 USB dongle, and a Raspberry Pi. You can request they send you a kit (I doubt I’d qualify as I live in an area that already has decent ADS-B coverage), you can purchase a prepackaged kit, or you can piece everything together and save a couple of bucks. Guess which option I chose…

I see this as a win-win as it’s a combination of three of my hobbies (ham radio, electronics, and aviation). Not to mention that I’ve always wanted to tinker with a Pi.

I placed an order for the Pi, SD card, power adapter, and a second RTL-2832 dongle today. Current plans are to build an antenna and mount everything remotely as close to the antenna as possible.

I’ll run 5v power outside for the Pi and hopefully still have a strong enough WiFi signal to avoid running a patch cable outside as well. Eventually I’d love to track power consumption of the Pi and piece together a solar setup (small panel and battery) so that the unit is entirely sealed and stand-alone….but we’ll save that project for the future.

This project will also be forcing me to re-mount my 2m HAM antenna since the same mount will most likely be used to attach the 1090mhz antenna for the Pi. The antenna has been down since we re-roofed the house.

More to come soon!

KISSed out Alien: ARGHHHHHH!

Finally building out my KISSed out Impulse RC alien.

Trying ESCs on for size.
Trying ESCs on for size.

ESCs soldered to motors, PDB, and to KSS FC. Powered up and smoke checked without issue.

Motors reversed as necessary.

All soldered up and ready for a flight controller.
All soldered up and ready for a flight controller.

Micro MinimOSD configured and flashed with KISS OSD firmware, tested, attached in line and mounted piggyback on my HS1177.

Running my Micro MinimOsd piggyback on my HS1177. Needs a dab of hot glue to lock down the wires.
Running my Micro MinimOsd piggyback on my HS1177. Needs a dab of hot glue to lock down the wires.

Finally soldering up the power leads to the FC and…F*CK! While soldering the negative lead, I ended up with a gob of solder on the backside of my solder tip. The solder took a small SMT capacitor off the board, and I lost both the gob of solder and capacitor when I cleaned off my tip (before I realized the cap was even gone).

FAAAAAAAAACK!
The tiny capacitor just disappeared…couldn’t even tell it was gone at first until I pulled up a picture of a new FC…

Emailed Flyduino support to ask if the capacitor was necessary and if I could power the board without it…hoping it was only there for an obscure feature like running a Spektrum satellite receiver or something. I even asked if they could provide me the component value and size so I could order a couple from mouser and try to repair it myself. They said they would investigate and get back to me. Unfortunately its now been a couple days, I’m still waiting and given how busy they probably are, doubt I’ll ever get an answer.

In the meantime, I ordered a new board from Rotor Riot…just waiting for it to arrive so I can de-solder everything and try and get her in the air.

Ugh…

Update:

The new board I purchased from Rotor Riot showed up and I had it installed in an hour. Quad flies great, and is a HUGE improvement over my previous hunk of junk. A day or so after the new board arrived, the folks at Flyduino provided me with the value and type of part that I accidentally knocked off along with a link to DigiKey (making ordering a replacement a snap).

I placed an order (ordered 10 since they were only $0.16 a piece). When they came in I was able to get the board repaired with a little cursing and a little care. So, thankfully I have a backup board (or a board for my next quad) rather than a keychain or mirror hanger.

 

Shapeoko 3 Dust Shoe

Since receiving an updated board from the lovely folks at Carbide 3D I’ve been running my Shapeoko 3 a great deal more than I was previously. This has lead to my small shop being covered in a progressively thickening layer of fine wood dust and aluminum shavings. If I had a dedicated wood shop this wouldn’t be an issue, but my small shop pulls duty as my R/C build area, my electronics shop, my wood shop, my metal shop, and a Ham radio shack…

I needed something to contain all the dust.

There’s a handful of dust shoe  designs available (in both plan form and assembled), but in my opinion nobody has nailed it. The flaw I’ve seen is attaching the dust shoe to the router using the two fasteners that attach the spindle lock.

DW611 Bottom Screws

Sure, it will probably get the job done, but I wanted a mounting solution that would be slightly more robust; especially since I wasn’t going to be using uber thick acrylic or aluminum.

So as I always do, before starting into the design I laid out a list of requirements to meet.

  • Mounts to either spindle mount, or Z-carriage…not spindle
  • Works with 1-1/4″ vacuum attachments (since I’m using HD Bucket Head as suction)
  • See-through (I like to be able to see the business end)
    • This means acrylic or polycarbonate.
  • Use ‘brush strip’ as a skirt (looks cool, works well)
  • Brushes can be easily changed for different heights
    • Probably attach with magnets (not a big deal since I don’t run any ferrous materials on the shapeoko)
  • Relatively inexpensive
  • Easy to machine (no crazy 2 hour 3D tool paths).
  • Must work with stiffened Z Axis Carriage plate.

Then I went into my shop, sat down, and stared at my machine for 30 minutes, took some measurements, made some sketches, and at the end had everything designed in my head with critical dimensions on paper.

This is how my mind works...
This is how my mind works…

Moved to my desk and about an hour had everything modeled and CAMd up.

Completed Models for Assembly Check
Completed Models for Assembly Check

Models done, I put in an order to McMaster for some brush strip and ran off to Home Depot for some .200″ thick acrylic, 1/8″ aluminum angle, and magnets (does anyone know how they work yet?).

Once the brush strip arrived, I did some test cuts int he acrylic to work out what kind of a fit I needed for the brush and the magnets and to try out some speeds and feeds in the acrylic. I ended up increasing the pockets for the magnets .005 over their actual diameter to get a slip fit. The brush strip was hard rubber and gave a nice snug fit at net sizes.

Then ripped the sheet of acrylic down to manageable sizes on the table saw and buzzed out the parts on the shapeoko. The aluminum angle was a little trickier, but I was able to get the radius cut out in acceptable fashion. I transferred the 8 holes from the machined acrylic to ensure alignment (I haven’t really done much drilling on the shapeoko…that’s something to experiment with later).

This project left me with a love-hate relationship machining acrylic. Your job can be chugging along with a beautiful surface finish and next thing you know you’re melting the acrylic to the tool and your surface finish goes to hell. I’m still running a 2-flute end mill…so I need to give it another go with a single flute plastic endmill, or maybe it’s as easy as tweaking speeds and feeds (probably up my feed rate).

Once everything was assembled I jumped on the opportunity to run some test cuts…and…NO DUST! I was also a little surprised because I feel (no hard evidence) like it quieted the machine down a bit.

After some test cuts I found that the brush strip was a little long for what I needed (I had ordered the 3″ tall stuff) so I decided to trim it down; but that was the only adjustment I had to make.

I plan to make at least two more shoes for varying length bits with 1″ strip, 2″ strip, and then the 2.5″ (trimmed) strip I have will round it all out. The next parts I make will also use proper Acrylic welding adhesives.

Finished up, running the router to make sure no cooling air is blocked and that theres clearance to the spindle.
Finished up, running the router to make sure no cooling air is blocked and that theres clearance to the spindle.
All finished, I thought I would need another support for the vacuum hose, but turns out the dust shoe was plenty.
All finished, I thought I would need another support for the vacuum hose, but turns out the dust shoe was plenty.

Shapeoko3 Z-Axis Carriage Stiffeners

Once I got comfortable with the basics of running a CNC (CAM, manual g-code, homing, zeroing, etc) I wanted to start to push the Shapeoko3 to reach the limits of material removal and surface finish. I started off with a block of aluminum, a 0.25″ 2 flute end-mill and just started entering g-code to jog the machine back and forth at set depths, widths of cut, router speeds, and feed rates. This quickly confirmed the difference in stiffness between the X and Y axis.

Despite being made from heavy stamped steel the Z-Axis carriage was flexing during cuts in both the X and Y directions resulting in loads of chatter at high material removal rates, and poor surface finish during finishing passes. To fix this I decided to build a pair of stiffening gussets that would tie the carriage plate directly into the spindle (while trying to keep things somewhat clean looking).

Initial sketches and dimensions taken from Shapeoko.
Initial sketches and dimensions taken from Shapeoko.

The stiffeners would run from the top of the carriage to just below the spindle mount. They’ll be notched to wrap around the spindle mount so that the attach fasteners will see lower loading. They’ll tie into the carriage plate at 3 locations with countersunk hardware.

Whipped up a model in Inventor and  got everything CAM’d and made a trip to my local material supplier of choice: Shapiro Supply. I cut out the right hand support first, tweaked the CAM, and cut out the left hand a day later. The first RH part required a some filing to fit it to the spindle mount the LH part with slightly revised G-Code (to repeat finishing passes and make up for machine flex) came out quite nicely.

STEP Files for anyone interested: Shapeoko3_ZCarriageStiffeners

Model for LH Stiffener after tweaks.
Model for LH Stiffener after tweaks.

Then I stripped the Z-Carriage off of the machine.

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Centered the spindle mount and test fit the stiffeners.

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Measured the offset of the stiffeners from the side and added half the thickness to the measurement (to give me the center line of the stiffener that I could transfer over to the carriage plate). Applied some layout fluid to the backside of the  and scribe a center line. Center punch holes and drill pilots.

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Dykem the mating surface of the stiffeners and transfer holes. Drill pilots in the stiffeners and open with tap drill. Tap for the screws I’m using (#8-32).

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Another sanity check after I finished tapping the holes in the stiffeners to make sure everything fit together before countersinking the holes in the carriage plate and laying out the holes that would tie it into the spindle.

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Layout the fasteners that will attach the stiffeners to the spindle mount.

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Drill, Tap, Countersink all fasteners.

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IMG_20160123_151347

IMG_20160123_154846

Re-install the Z-Axis carriage. Done…almost.

IMG_20160124_145108

After I installed the carriage I was still a little dismayed at how much movement  was present in the Y direction. Upon further examination I realized the movement was no longer the carriage plate flexing, but in the V-wheels…I thought I was stuck with it and the slop was just inherent to the design of the machine. Then while applying pressure to the spindle I noticed a slight popping coming from one of the wheels (that was associated with ~0.010″ of movement). I assumed something was loose, and tore back into the Z axis.

I tried to trace down where it was coming from: did I have a loose fastener somewhere…? I completely disassembled the Z Axis again and re-assembled, re-tension all of the v-wheels on their rails etc. The play was still there, the ‘popping’ was still there. It appeared to be isolated to my lower LH V-wheel…so I concentrated on that.

IMG_20160124_161957

When I disassembled the suspect V-wheel,  I took some measurements and the shim between the two bearings mic’d at 0.042. Measuring the delrin V-wheel itself, it checked with a 0.030 wide internal ridge. The 0.042 shim was to thick and was allowing ~0.012 of float between the bearings.

vwheelspacingjpg

I changed out the oversize spacers with thinner washers (which should result in a nominal fit to a  slight pre-load on the bearings) and the remaining slop was gone.

Chatter was greatly reduced allowing me to increase material removal rates, and finishing passes could easily take full depth cuts on 0.25″ thick stock while still maintaining great (for a desktop machine) surface finishes.

Video shows me machining a pocket in 6061-T6 at 20ipm, 0.10″ width of cut, 0.050″ depth of cut.

This was one of the first tests I did after the mod and have since settled in on 30ipm, 0.10″ depth, and 0.050″ width cutting 6061.

Now if only I could control the spindle speed through the software…

Shapeoko 3 Dropped Connection

I received my Shapeoko 3 in June of 2015 and couldn’t wait to get it up and running in my shop. The design is solid, much stiffer to the X-Carve and Shapeoko 2. The machine gave me the ability to quickly and accurately cut wood, aluminum, brass, circuit boards, and plastics.

Starting out running simple jobs that didn’t require any tool changes I began to notice that the connection would drop upon turning off the DWP611 router that I was using as a spindle. This would result in a lost zero, and would occasionally drop the spindle a couple inches letting the cutting tool gouge the work. It made running complex jobs requiring tool changes nearly impossible.

I contacted carbide 3d and they recommended adding ferrite beads to all the cables. I ordered a USB cable with ferrite chokes build in from amazon and a bag of 7mm clip on ferrite chokes for the router and any other cables that needed them.

I installed everything, and the problems persisted. I continued by trying just about everything short of buying a big universal power supply.

  • Plugging the router into a separate circuit in my house.
  • Adding chokes to the stepper motor wires.
  • Adding multiple chokes to all wires.
  • Removing the controller board from the machine and moving it behind a piece of sheet metal as a shield.

After these solutions failed, I sent several emails to Carbide3d that all went unanswered.

Finally, I landed on a post in the Shapeoko forums where a user said he had added a shielded three conductor extension cord to his spindle. Unfortunately he didn’t provide any instructions (so hopefully this will help those who are hesitant).

THIS INVOLVES WORKING WITH 120V AC POWER. INCORRECT WIRING CAN KILL YOU! IF YOU’RE NOT SURE EXACTLY WHAT YOU’RE DOING GET SOMEONE WHO DOES TO HELP.

I dug an old PC power cord out of a cabinet and went to work. Before I made anything permanent I mocked everything up. The router uses crimp on spade connectors, and luckily I had a couple from a previous project. I did have to bend the power wire connector on the switch 90 degrees to fit it into the location of the original. Once finished I power cycled the router and…NOTHING. No connection drops!

Mocked Up and Ready to Test
Mocked Up and Ready to Test
Crimp on Connectors tying in Power, Neutral, and Ground.
Crimp on Connectors tying in Power, Neutral, and Ground.

After everything was working, I tidied up the wiring I bit. I had to slit the router casing using a Dremel to allow the ground spade connector to sandwich between the router cap and metal body. Once lined up I used a dab of hot glue on the back of the connector to hold it in place.

Slot in router cap to allow terminal to clamp up on router body.
Slot in router cap to allow terminal to clamp up on router body.

I located the switch back in its original location, routed the wires in a manner that they wouldn’t be pinched, and reinstalled the top cover. Once the cover was installed, I metered continuity between the ground prong and router body to ensure the terminal hadn’t shifted out of place.

Done, ready to re-install the top cover.
Done, ready to re-install the top cover.

I’m still using a ferrite bead on the power cable, and the USB cable with built in chokes. Since the mod (~4 months) I’ve only had one or two dropouts, and at least one was caused by static from my shop-vac hose when vacuuming up Kydex (plastic) chips during a job. Compared to the drops every-other power cycle I consider this a success.

Robotics Season is Officially Open

wabbitseason

As of Saturday 1/9 FIRST Robotics season has officially begun. Over the next six weeks the team of high school age kids I mentor will attempt to build a 120lb robot capable of traversing medieval castle defenses, throw boulders at castle ramparts, and lift itself roughly three feet off the ground. This years game is FIRST STRONGHOLD:

I’m going to try and post weekly updates as the build season progresses and my sanity diminishes.

HobbyKing Mini Composite DLG Build

Well, HobbyKing managed to suck me in with their Black Friday sale this year. I’ve been teasing myself with the possibility of a Discus Launch Glider (DLG) for the past year, but kept shelving the idea because of the initial cost (even the budget-minded Libelle will be ~$200.00 to get in the air), so when I saw the 2 channel HK Composite DLG ARF on sale for $39.00 I had to jump at the opportunity.

All Dressed Up
All Dressed Up

Parts List for this Build:
-HK Mini Composite DLG: $39.25 (on sale)
-2S 300MaH nano-tech: $5.95
-Orange R615X Receiver (Overkill, but I had one on hand): ~$10.00
-Assorted JST connectors: $1.11
-Home-Brew BEC: ~$1.00 in parts

Orange R615X, LM7805 BEC, Turnigh Nano Tech 2s300MaH Batt.
Orange R615X, LM7805 BEC, Turnigy Nano Tech 2s300MaH Batt.

The glider showed up a week later and overall the construction impressed me. Covering was tight, wooden joints appeared to have sufficient glue, and all the aerodynamic surfaces were straight and square. The tail boom appears to be unidirectional wrapped carbon, and the connections to the fuselage pod up front felt sturdy (only time will tell). The wings are one piece with a healthy dose of dihedral (you know, no ailerons and all) and had a finger peg pre-installed for a right handed pilot (they include a second carbon peg for lefties too). The vertical stab is glued into the tailboom out of the box, and the horizontal stab and wing attach with a couple of screws.

After mounting the horizontal stab and connecting the pushrod to the elevator I quickly discovered the biggest flaw with this model: lack of pushrod support. The pushrods for the rudder and elevator are thin (0.020″) wire and are only supported along the tail boom every three inches. With any resistance on the rudder or elevator the pushrods buckle resulting in mushy control throws for up elevator and left hand turns which put the pushrods in compression. This should be an easy fix in the future, however I decided to build the model as-received to see how much of an issue it would be given the low weight of the glider.

One thing HK did right was provide plenty of room up front for the 300MaH battery,  de-cased RX, and BEC. RX was attached using some double sided foam tape, and battery was held down using a strip of electrical tape for easy removal during charging.

Plenty of room up front of electronics.
Plenty of room up front of electronics.

The 6ch Rx and 3s 300MaH battery (both total overkill for this model) resulted in a slightly nose-heavy model so some paperclips were added to the end of the tail boom to bring the model into the recommended CG range. The paperclips can be easily removed down the road when I add additional weight to the tail to stiffen the pushrods, or swap out the Rx and battery for something more sane (HK Orange R410 Rx).

High Tech Balancing System
High tech tail weights

After everything was stuffed, I powered her up and set the recommended control throws in the radio. I had to set servo throws biased in one direction in order to compensate for the pushrod flex, but it all worked out to get me into a flyable range.

Maiden consisted of a couple of gentle overhand style tosses to make sure the CG was in a flyable location (you never really know what to expect with the recommended CG and control throws from HK) and then some very light discus tosses. The glider felt slightly  tail-heavy, which was remedied by pulling one of the paper clip weights from the tail boom. Properly balanced, I attempted a few (more powerful) launches and easily achieved altitudes of ~50-60 feet and glide times of 20-30 seconds.  The glider tracks straight during launch, and down elevator and left hand turns did result in the expected mushiness due to the control rods buckling under compression. The quick maiden turned into an hour out in the park experimenting with different launches until my hands went numb from the cold. The model flies great (even in a light breeze) and almost doesn’t want to land; a slight breeze blowing over the trees was enough to create some lift an extend some of my flights by more than a few seconds.

TOW of 5.6oz (158.7grams)
Flying weight of 5.6oz (158.7grams)

I can’t recommend this DLG enough as an intro into unpowered flight. I’ve had the model out a couple times this winter as weather has permitted and enjoyed each time.  In the end, the only downside I see with this model is that people who find out they do enjoy flying DLGs will quickly outgrow this tiny, 2ch, balsa-winged model (I’m already looking into full-blown glass/carbon models). Those who aren’t quickly hooked will be left with a fun model that they can take along anytime and fly anywhere.

Future Improvements to Look For:
-Smaller 3-4Ch Receiver
-Supports for pushrods to prevent buckling.

Hello World

This started as a sort of engineering journal with the intention of better documenting my projects and general tinkering. After some further thought I decided to move to the web to better allow sharing and to solicit feedback/help.

I have many hobbies (RC Flight, Photography, Machining, Ham Radio, Woodworking, Robotics) so things might initially seem scattered, but I foresee a general theme emerging.

Welcome aboard,

-Tim