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| soldering 101 |
| | The following guidelines will help you achieve good, reliable solder
joints, and will hopefully encourage you to be more adventurous with
your model’s on-board control systems. | | Rule One: Use a small soldering iron for small jobs and a large
iron for large jobs. Be sure to run the solder around the contact
region between the big tip and the coil of wire, to make a good thermal
contact.
Rule Two: A good solder joint is usually made
from the standard 60/40 blend of lead and tin. If this alloy is allowed
to oxidize by being overheated, or heated for too long, the binding
properties of the solder degrade seriously. Don’t use solder that has
been sitting molten on the iron tip for more than five seconds. Wipe it
all off. Discarded solder blobs are useless; don’t save them. Always
use fresh solder.
Rule Three: Keep a piece of dampened
sponge nearby to clean oxidized solder off the iron tip. This must be a
natural sponge. You’ll find the green Scotch-Brite kitchen pads ideal.
Clean off your soldering iron tip on this just before you make any
solder joint. The tip of your iron should look bright and shiny just
before you apply it. Oxidized solder looks dull and grainy. Get rid of
it! I find that I discard 70% of my solder by cleaning it off and
replenishing it with fresh, but its well worth it.
Rule Four:
Always use resin-cored solder. You should never need liquid or paste
acid-flux if you prepare your work correctly. The resin core melts when
you apply solder to the job and acts as a cleaning and flow agent so
the solder will bind properly.
Rule Five: Use only enough solder to bind the two objects together. Extra solder does nothing to increase strength, but only adds weight.
Rule Six:
Always tin both parts before joining together. Tinning means heating
the areas to be joined, applying solder to the junction of the hot tip
and the part, and ensuring that the part is evenly coated with a good,
shiny film of solder.
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| Joining Electrical Wires
1. Strip off 3/32- to 1/8-inch of insulation.
2. Tin the wire so it looks uniform and shiny.
3. If the solder “drags” and looks dull and grainy, apply the iron again, apply more solder, and clean off the excess.
4. Slide a piece of heat shrink tubing approximately double the wire diameter and about 3/8-inch long over one of the wires. (some day you will forget this step !!)
5. Lay the two tinned ends side by side.
6. Heat briefly with the iron so they flow together.
7.
Slide the heat shrink tubing over the joint and heat with your heat gun
or the barrel of your soldering iron. Once it cools, pull on the wires
to make sure the joint holds.
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| Joining Steel Wire
1. Prepare the joining surfaces by
thoroughly sanding them with sandpaper. This provides a good surface
for the solder to stick. Treating each piece separately, heat the
contact area with the iron and apply solder. Rub the tip all over the
contact area, while applying fresh solder and flicking off oxidized
solder, until the contact area is shiny and well tinned. While the
steel wire is still hot and the surface solder is still molten, quickly
wipe off the solder with a dry cloth. You’ll notice a different color
between the rest of the steel wire and the tinned surface indicating
that solder has penetrated the wire surface and has prepared the
contact area for binding.
2. Place the two tinned areas together
and wrap with fine copper wire. Strands taken from multi strand heavy
electrical cable is ideal, but have the strands ready for use before
you start. After wrapping tightly, twist the ends of the binding wire
together (so they don’t unwrap). Heat the whole joint with the iron and
apply fresh solder. Because you pretinned the steel wires, you’ll find
that solder will readily flow into the joint and adhere properly to the
surfaces. Any time you see convex blobs of solder you can bet the joint
has not soldered properly. Apply more heat, flick off the old solder,
and apply fresh. | |
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