Start as you mean to go on -- The Coptermatic Chronicle Part 1

Minor background before I start.

I've been playing with wheeled robots for a while, using the Basic Stamp as a controller. Just tinkering, and more interested in the software side of things (as well as having something that annoys the cat). My enthusiasm died out about 7 years ago, then my son gave me a Lego Mindstorms NXT kit for Christmas, and I was off and running again.

At about the same time, a co-worker got me started on radio controlled helicopters (Blade CP/2 to start with, moving up to Blade 400 and TREX-450 over the last few years). You can't have too many expensive hobbies :)

Managed to do quite well at this helicopter hovering in the back yard, and was doing quite well until about a year ago when I flew my pride and joy into a tree and broke just about everything except the tree.

"I wonder," I wondered, "if it would be possible to combine my robotic hobby with my RC flying hobby?"

Poked around teh intarwebs a bit, and ended up here looking at the APM and the Arducopter code.

Thus started work on what I am now calling Coptermatic, the Automatic Helicopter. (with apologies to Wallace & Gromit)

So off we go:

Got my workbench set up, got me new Weller soldering station set up, played with some Arduino programming for a practice, and decided that tonight was the night.

I solder all the pins on the APM. I solder all 48 pins on the right angle servo connector (the three pin monstrosity on the end of the board). I've got all the pins on the APM,

But the servo connectors seem a bit fragile, and my attempts to test-connect a couple of servos and Rx connectors seems wonky. Imagine my amusement when I discover that I've soldered the damned servo connector on backwards. For that connector ONLY, the black plastic bit doesn't go flush with the top of the board. What's worse, I compared what I was doing with the pretty picture in the instructions four or five times and didn't notice my error.

OK, so now I am sort of stuck. I'm an amateur with the soldering iron (more of a software engineer with a predilection for tinkering). I'm not at all sure how to unsolder 48 connections; I think I need something more than desoldering braid and bad language.

The current plan (as blessed by my long-suffering and patient wife) is to use this APM as the brains for a small wheeled robot which I shall call the Pipbot (in honour of the Fallout series of games) and to buy another APM from DIY Drones for the 'copter.

So a bit of a (not-so) cheap lesson in following instructions. This hardware stuff is a lot less forgiving than software.

I don't like solder braid! You over heat the board and destroy the whole thing.

This is is even more true if you have a lot of pins to un-solder. It also leave a lot of solder in the through holes.

Use a can of compressed air. (Blow off stuff).

Start as Chris said. Cut off all the pins on the top side (not the solder side) flush to the board. This will take a good pair of cutters. Cut the pins down to the plastic, then pull of the black plastic stopper off the pins, then cut the pins flush. If your pins are really blobbed with solder you might clean them up quickly with some solder wick.

With the air ready! heat each pin. As soon as the solder melts blow the pin through the board. This will both remove the solder, clear the hole and cool the board.

CAUTION: Protect other components with masking tape so solder splash will not sort things out.

When your done your board will look like a new one.

Here is an example pic.

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Comments

Nigel Conliffe May 5, 2011 at 2:04pm

Sorry, it's been a busy week at the paying job :(

I ordered and already received a second APM and more headers. Much soldering in my future for the quad-copter.

When I have a spare minute this weekend, I'm going to unsolder the connector on the original (thanks to all for various good suggestions on how to do it) and add a bunch of pig-tails (servo sockets -- male or female depending) to the original board, which I will then use for a second robot project (land-based wheeled vehicle with delusions of autonomy).

More this weekend.
ARHEXA May 5, 2011 at 10:44am

HAHAHA Dany...

i hope you mean 1-row for the signal row,

because soldering extensions for the 3 rows..... i'd like to see that !! :D
Distributor

Dany Thivierge May 5, 2011 at 10:40am

any updates on what you did? I think it's way simpler to just solder new male pins to the existing (wrong side ones) to extend them... what did you do?
Mark Grennan May 1, 2011 at 3:23pm

I don't like solder braid! You over heat the board and destroy the whole thing.

This is is even more true if you have a lot of pins to un-solder. It also leave a lot of solder in the through holes.

Use a can of compressed air. (Blow off stuff).

Start as Chris said. Cut off all the pins on the top side (not the solder side) flush to the board. This will take a good pair of cutters. Cut the pins down to the plastic, then pull of the black plastic stopper off the pins, then cut the pins flush. If your pins are really blobbed with solder you might clean them up quickly with some solder wick.

With the air ready! heat each pin. As soon as the solder melts blow the pin through the board. This will both remove the solder, clear the hole and cool the board.

CAUTION: Protect other components with masking tape so solder splash will not sort things out.

When your done your board will look like a new one.

Here is an example pic.
Developer

Jason Short April 30, 2011 at 1:50pm

To finish my post: odds are you will ruin one of the through holes. Just solder on the wires from the radio directly. You only need to attach the white leads. These are the signal leads. Then you only need to attach one set of power and ground to the radio. Use shrink tube to protect your joints.
On the servo out side do the same, or use breakaway headers soldered to extend the length.

And watch a demo online to learn how to solder. Worth 10 minutes of your time.
Developer

Jason Short April 30, 2011 at 12:05pm

Don't unsolder the pins. You'll mess it up and ruin the board.
3D Robotics

Chris Anderson April 30, 2011 at 7:07am

I've taken the liberty of modifying your photo and adding it to the top of the original post, to conform with our posting guidelines (image/video should lead every post)
ARHEXA April 30, 2011 at 12:56am

when i think of it - you can use nippers to pull each pin out while you heat the solder on the other side.

it might be some work now, but will allow you a much cleaner and not messy environment in the future..

splitting servo extension wires to power and signal wouldn't take 5 seconds neither...

these 3 row headers are a common type and you should find it locally on pro's electronics stores...
Nigel Conliffe April 30, 2011 at 12:51am

Thanks, Jack.

That's an interesting idea -- running a separate power bus for the servos and just using the signal connections on the pre-stuffed socket strip. That, or cutting off the 3-deep socket strip and wiring up a set of pig-tails for the servos. I shall not blame you if it leads me astray :)

And @AR.. the IMU clears the pins on the 3-pin socket-strip, so we could be on to something here. I'll play some in the morning (it's about 1:00am here in Seattle)
ARHEXA April 30, 2011 at 12:44am

@Jack,

i like the idea of using the signal pins only.

the question is - does the IMU board sits correctly on there ? or the headers are too high pushing it ?

unsoldering the pins sould be doable.

just use the soldering iron to heat the pins on the solder side, once the solder point is melting, push it down, it should slip out, melting the plastic connector a bit to allow it loosing out.

don't forget to start from the highest (inner) row, and try to work on a pin on each side of the PCB altering, to allow the pcb environment to cool down a bit...

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