Friday, May 30, 2014

Notes: Welcome to Taranis, Part 9: Basic Speech

These are notes to accompany the Welcome To Taranis series.  Follow the link to see the videos and other notes.

Part 9: Basic Speech

blogodex = {"toc":"Welcome to Taranis","index":"Taranis"};

Splicing Servo Wires

From RCG, a nice tip on splicing servo wires.  Stagger the joints, and you will only need one shrink tube to insulate everything.

blogodex = {"idx":["hints", "servos"]};

Thursday, May 29, 2014

Imperial Machine Screw Sizes.

I had a hard time finding this in such a convenient table, so I've copied this here.

Screw Size
Number of
Threads Per Inch
Minor Dia. Tap Drills Clearance Hole

Aluminum, Brass & Plastics
75% Thread 

Stainless Steel, Steels & Iron
50% Thread
All Materials
Close Fit Free Fit
No. or Dia. Major Dia. Drill Size Decimal Equiv. Drill Size Decimal Equiv. Drill Size Decimal Equiv. Drill Size Decimal Equiv.
0 .0600 80 .0447 3/64 .0469 55 .0520 52 .0635 50 .0700
1 .0730 64 .0538 53 .0595 1/16 .0625 48 .0760 46 .0810
72 .0560 53 .0595 52 .0635
2 .0860 56 .0641 50 .0700 49 .0730 43 .0890 41 .0960
64 .0668 50 .0700 48 .0760
3 .0990 48 .0734 47 .0785 44 .0860 37 .1040 35 .1100
56 .0771 45 .0820 43 .0890
4 .1120 40 .0813 43 .0890 41 .0960 32 .1160 30 .1285
48 .0864 42 .0935 40 .0980
5 .1250 40 .0943 38 .1015 7/64 .1094 30 .1285 29 .1360
44 .0971 37 .1040 35 .1100
6 .1380 32 .0997 36 .1065 32 .1160 27 .1440 25 .1495

Tuesday, May 27, 2014

Synchonizing Four ESCs At Once

 (note: this one has been sitting in the edit queue for quite a while.  Long time readers will notice with amazement the Arcticopter I.)

When setting up a new quad, it's important to set the endpoints on each of the ESCs.  Here's an easy way to do them all at once.

Grab a breadboard and five 3-way male pins.  Four of these will be for the ESCs, and one of them will be for the throttle channel of the receiver.

Put the pins in the breadboard like this.  This will allow all ESCs to be controlled at the same time by the receiver.
Hook up all the ESCs and the receiver.  Make sure all the connections have the same orientation.

Now follow the endpoint syncronization procedure for your ESCs. Almost all of them are similar to the procedure in section VII of this manual.

  • remove any props if the ESC are in an airframe
  • power up radio
  • move throttle to max
  • power up ESCs
  • the ESCs will make their initial sound, then go into a continuous beep mode
  • move the throttle to min
  • the ESCs will make the final beep
  • All ESC endpoints are now calibrated and consistent with each other.
blogodex = {"idx":"ESC"};

Monday, May 26, 2014

Configuring the Mobius Gimbal

Started tuning the Mobius Gimbal.  Pitch seems rock solid.  I greatly improved roll, but still doesn't seem to be quite as good as pitch.

Using BruGi v50 r207, which seems good.  GUI is nicely improved too.  Used this tuning guide.

Setting so far:
Reverse Z-Axis off
Pitch pwm,pid =  32.0, 10.4, 10.0, 19.7
Roll pwm,pid =  48.4, 8.8, 20.1, 25.2

Drivers (all platforms) are here.  Look for "VCP" (Virtual Comm Port).  Device identifies itself as "Future Devices FT232R USB UART".

Compile with Arduino as "Arduino Pro or Pro Mini (5V, 16 MHz) w/ ATMega 328".

blogodex = {"toc":"Mobius Gimbal"};

Nice Foamy Pushrods

 RCG Maven balsa or carbon has some nice shots of foamy pushrods. Here's how he does it.

Start off two two pieces of music wire, one with a Z bend and one with an L bend. Attach the Z bent wire to CF rod with CA and shrink tube .

Round the other end of the CF rod with sandpaper and attach it to the L bent wire with silicone fuel tube.  Don't glue it, this allows you to adjust the pushrod.

Stick the L bent wire through a piece of rubber band. Attach the L bend to the servo horn, and stretch the rubber band around the music wire as shown.  Tighten the fuel tube with a zip tie if it's loose.

Stabilize the pushrod with a zip tie glued through the airplane body if there's flex when moving the control surfaces.

If you don't have any silicone tube handy you can zip tie a rubber band to the rod.  Here it is holding the L bend wire to a bamboo skewer pushrod.  BoC reports that it's tight enouch that he has to use needle nose pliers to adjust.  Notice hi popsicle stick control horn!

blogodex = {"index":"push rod"};

Sunday, May 25, 2014

Notes: Welcome to Taranis, Part 8a: Basic Telemetry

These are notes to accompany the Welcome To Taranis series.  Follow the link to see the videos and other notes.

Part 8a: Basic Telemetry

blogodex = {"toc":"Welcome to Taranis","index":"Taranis"};

Wednesday, May 21, 2014

Easy Prop Balancing

 Here's the quick and easy way to balance cheap plastic props.  With larger props it makes sense to use a magnetic prop balancer, but this seems to work just as well.

 Start with a prop, and a screwdriver that's just about fills the shaft hole, but doesn't rub.  The prop should swing freely, but not wobble too much.
 Hold the prop level, and then push one side down, then the other.  If the prop is balanced, there will be no tendency for the prop to move.  If your prop is out of balance, one side will tend to sink lower because it is heavier.
Put a piece of scotch tape on the back of the heavy side.  You don't need much.  Check for balance again, and keep adding tape until the prop maintains a stable horizontal position.

Here's about how much tape I usually need.  Taping closer to the outside gives a stronger counterbalance.

blogodex = {"toc":"Prop Balancing","index":"props"};

Tuesday, May 20, 2014

CME Meeting Minutes, Tuesday, May 13, 2014


Tuesday, May 13, 2014

CALL TO ORDER:  7:30 pm


    Monthly meeting, Second Tuesday, 7:30 at Concord Airport Terminal.

    Friday Fun Fly, Third Friday, 7:00 - 9:00 pm.
    Gym at the Church of the Nazarene, 1650 Ashby Dr., Concord


Mobius Brushless Gimbal

 Here's some notes on making muellerr_ch's brushless gimbal (BLG) for the Mobius.  He has a parts list of motors and other required parts on his page.
 The parts printed out nicely on our Makerbot 2.  There's a version 2 of arm 2 that has a deeper recess for the sensor. Use that one, it holds the standard Martinez-style sensor perfectly.

From front to back, the three pieces are Arm 2 (holds camera), Arm 1 (holds Arm 2), and Arm 3 (attaches gimbal to airframe).
 I made all  the motor attachments using only two bolts per motor.  It seems to make a nice sturdy connection.  I used M3 x 10 bolts.

Start by attaching a motor to Arm 3.  Note that Arm 3 is extending away from the gimbal.  This was for convenience in experimentation, and I'll flip it around so that Arm 3 extends under the gimbal when I've got everything figured out.
 Atach Arm 1 to the motor attached to Arm 3.  This motor controls the roll by rotating Arm 3.
 Put the ball bearing into the 8mm hole in Arm 2.  I screwed up ordering my ball bearings from ebay.  I ordered 3x8x4, when I should have ordered (I think!) 4x8x3.  Note how it stands proud by 1mm.  That's not a problem.  I had to replace the M4x10 machine screw lower down with an M3x10.
 Attach the other motor to arm 2.  Make sure the wire points towards the rear.  If you get it wrong, just remove the motor and flip 180 degrees.
 Oops, before you attach the motor attach the M4x10 machine screw.  It's easier to screw in if you do it before you attach the motor.
 Here's what Arm 2 looks like when it's completed.
 Be sure your ball bearing is in Arm 1, and wiggle Arm 2 into Arm 1.  Attach the motor.  Arm 2 should rotate smoothly in Arm 1.
 I had to replace the M4x10 machine screw with an M3X10 machine screw in order to fit in the ball bearing.  The extra mm of ball bearing width did not affect the fit.  I had to be extra careful tightening the M3 machine screw to make sure it was centered, since the hole was sized for an M4 machine screw.  So far it doesn't seem to have had a bad effect, but I'll get the proper sized ball bearing and swap things out if need be.
 Here's the entire unit assembled and hooked up.

(photo question: all these pictures were taken by the same iphone.  Is there a way I can force the white balance to be consistent?)
  I'm not sure why, but the roll is super-unbalanced.  I drilled a hole and screwed on some random pieces from the junk box to make it balance.  It would be great to figure out how to eliminate these weights.
 The sensor board fits nicely in the new revision of Arm 2.  I attached it with two M2x8 machine screws and locknuts.  I was concerned that there wasn't enough vibration protection because of the direct attachment, but I haven't noticed a problem yet.  If I do notice excess vibration, I'll try using some gyro tape instead of the screws.

I drilled a hole on Arm 3 to attach a zip tie for strain relief.  Move arms 1 and to into their farthest positions to see how much wire slack is necessary.

I downloaded and installed the latest BLG software for the Martinez board.  Be sure and unclick the "reverse Z axis" option, since the sensor is sitting component-side-up.  I'll follow up later with some notes on the latest BLG software.

Here's two videos showing the progress so far.  I've done a bit of tuning.  I think the tilt axis is good, but still need some work on the roll axis.  I'll get the RC tilt/roll control going as well.  More to come!

blogodex = {"toc": "Mobius BLG","idx":["mobius", "blg"]};

Signature Edition OPQ!

Well I finally got all my stuff together and put together my OPQ.  I'm not wanting to boast (hmm actually I do!), but it is a genuine Crash Hancock Signature Edition!
The new OPQ models have nice mounting slots.  This early model didn't, so I had to drill my own mounting holes.
It was easy enough, just clamp a motor mount onto the arm and use it as a drill guide.
I make a bit more clearance for the bottom of the motor.
Looks good!  I understand why people enjoy working with delrin.
Here's the final mount.  That motor's not going anywhere!  Not shown: two of the arms were a bit off, so I just used two bolts.  They still look rock solid.
It was handy to have some metric sized drill bits to get the exact size holes.  I wish Amazon had better deals, or that HobbyKing or somebody would carry metric drill bit sets.  I bought this set from a tiny shop in the Akihabara district of Tokyo that specialized in all kinds of electronics and small machine tools.
I screwed the power distribution board onto the top.  It was nice and flat, so no problem to mount the flight control board on top.
Black on black with black trim looks cool, but might be a bit hard to see in the evening! Here's some lights.
The lights look good outside, but are a bit bright.  I'm going to wire them to a brushless motor controller so I can adjust the light while flying.
Ethernet wire seems to be great for wiring LEDs.
I'm trying this 3M Dual Lock for attaching the battery.  It's super-strong and has a nice clean "snap" when it connects.  (update: way to strong, you have to give a King Kong yank to pull the battery off.  But it's great otherwise... I'm going to try trimming the piece down so there's a smaller surface area and see if that's better.  If so, I'll try it on some other air units.)
As soon as I get around to it, I'll shorten all wires to eliminate the clutter.
Flying with a Flip 1.5.  Forcing myself to be a better pilot who doesn't rely on a bunch of sissy autopilot stuff!
Hot glue seems to work well for insulating the LED strips.
I tried this voltage converter for the dimmer, but the adjustment was pretty rough.

Part 2 coming up, it's a sweet flyer!

blogodex = {"toc":"The One Piece Quadicle","index":["opq","builds","Crash Hancock", "CrashCast","The Fleet"]};