Soldering
- Do not blow on what you just soldered, this can harden the joint.
- Clean both the components and the solder with isopropyl alcohol immediately before soldering.
- Clean the iron for every joint, wet the tip solder to conduct the heat, then heat the components, then add solder to the joint, pull the solder away then pull the iron away.
- Do not solder leads before you crimp them. They were not engineered for you to do so.
- Cut the component leads and bend or "cinch" them in the direction of the trace BEFORE you solder.
- Through-hole length proud is one wire diameter.
- Bend through-hole component leads only up to 30 degrees.
- Use Orange wood "orange sticks" to manipulate components and bend leads after you have cleaned the parts.
- When tinning wires, you should still see the strands.
- It only takes a little bit of solder.
- When stripping, just cut and pull a little off, then twist the insulation the rest of the way off.
- Do a figure eight in the solder pot to tin wires.
- Flux your solder-wick.
- Do not touch your work, after cleaning or after soldering (after cleaning off your access flux and dross).
- Cut the solder, don't burn off a piece.
- clean the solder as well.
- you want concave joints of shinny solder.
- Remember, clean and re-tin the soldering tip every time you put it back in it's cradle, this slows corrosion.
- 63/37 is eutectic, "mil-spec", 37 percent lead, solder. Out of the box 60/40 is not truly eutectic.
- Silver alloy solders typically do not grow wiskers.
- Unleaded solder on Silver solder can de-alloy the Silver from solder that is already in place.
- Do not pre-tin wires, or apply solder to crimp connectors. They are designed to be crimped, and work-hardend solder can make the crimp fail.
- Use a thermal stripper for leads that are going in high-performace crimp connectors so that the strands are not disturbed.
- Use 90%+ isopropyl alcohol as a lubricant when pushing contacts into hermetically sealed connectors.
Quality as Money Allows
- Engineering - Materials - Tolerances is the triangle of part quality. Design for the lowest fully functioning tolerances, but build to the highest. Make every part you can serve more than one purpose.
- NEVER engineer or design in behavior modifiers for the end user. The user is the master, the product is the slave. For example, you can alert the driver that his seat belt is off (if you have to) but do not make it so loud he can do nothing else until it is buckled! Don't build in a thousand "are you sures?" into you code. It's ok to design in internal safeties like preventing a battery from being inserted if there is a power cord, etc. But let the user pervert the intended use as much as possible without killing your machine. This is because the user knows better than you what he or she needs.
- Make your products as open-source as possible. History has shown it is more lucrative in the end, for both you, and the customer.
- Whenever possible, engineers should be made to use the products they are creating.
- Use "Hunting Tooth" gear designs. Whenever possible, use gears with a prime number of teeth, or a ratio that allows every tooth on the master to eventually make contact with every tooth on the slave, for even wear.
Assembly and Disassembly
- Safety wire gets 6 to 8 turns per inch, and 1/4 to 1/2 inch pigtails, or 3 to 6 turns for the ends.
- The more you work with safety wire, the harder it is to work with (it work hardens) so always take more than you need, but not too much!
- Staking bolts and pins that heat cycle is just fine.
- When setting any timing, turn in the direction of operation to align. This will take the lash out of the gears/belts/etc. I know it is obvious but easy to forget.
- Loctite will work OK to remove something later with heat, but if it gets too hard to remove, you should have used grease. (use grease)
- Super glue is great loctite, if the component will let you use heat to remove it. (great for steel cased watches)
- If no other information is given, go for the center (middle) torque value of the torque spec.
- Hand start screws and bolts, starting in reverse direction to find threads, especially when the bolt and substrate are of different materials/hardness-es.
- cold contracts all dimensions and heat expands all dimensions in metal. you can engineer a hold to break even, but never to reverse this rule.
- Dry-ice on the inner and heat on the outer, can help you remove pins, bolts, and barrels. Otherwise heat to loosen, freeze to install. For Steel, it is .001" of change, for every 1" of diameter, for every 100F.
- Set new threads by backing off and re-tightening.
- Don't use graphite on aluminum.
- When using a Crow's Foot, do you know if you have to recalculate the torque value for the added length? .. or is it built into the spec?
- Use Valve Lapping Compound on the tip of your hex, or screwdriver so the driver doesn't slip out of stuck screws.
- When fitting a new AR gas-tube, always run a copper coat-hanger down the tube to push out the "coin" of steel sometimes left by the drilling process. Otherwise it will end up in your bolt carrier.
American Household AC Tests
- Hot to Neutral must be within +3% to -6% of voltage specified.
- Low voltage could be an overload or incorrect wire size.
- High voltage could mean the utility company strapped the transformer wrong.
- Hot to Ground voltage should be higher than reading in Hot to Neutral test.
- A lower voltage means that either Neutral and Ground are reversed, or there is a poor ground connection.
- Neutral to Ground voltage should be the delta between test 1 and 2 above. the reading should not exceed .3 volts.
DC
The Voltage Divider
Coding
- NASA Says: Simple Flow Control. No goto, setjump, longjump, and NO RECURSION. NASA will sacrifice speed of the code and size, for readablilty and reliability. Personally Recursion is my favorite thing in C.
- NASA Says: All loops must be bound by a hard upper limit. So even if you don't know how long a loop will run, a known itteration limit must be put in place.
- NASA Says: No Heap, Malloc, or Free, and all variables must be of a known size. It's too hard to know if you might have a memory leak and too hard to test.
- NASA Says: Functions must only do "one thing," and be 60 lines max. It has to be readable and another person must be able to quickly figure it out.
- NASA Says: All non-void function return values must be checked in code.
- NASA Says: No Function Pointers.
The above is what NASA says helps make critical code. This is the slow, big, ineffecient way, and probably not the way you want to code everyday. However, if you're having trouble with the code, maybe start here to get it working, and optimise from there.
Thermal Expansion in Various Materials
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