How to fix things

[houseoftang]

A lot of people here probably aren't as handy as they'd like to be.  And knowing how to fix things is a very important skill, even now when new stuff is still being manufactured cheaply and in volume.

It's my observation that many people, more women than men, learn things by "rote" or "procedure". How do you repair a dryer?  Follow these steps. . .   This works fine if you're trying to do one thing at maximum efficiency; but in most of the real world where you're just doing it once, you run into a lot of things that the instructional can't cover, and you have to improvise and innovate.  Rather than a recipe, you have to be an Iron Chef, working from first principles and prior experience.

I've been taking things apart since I was old enough to lay hold of a screwdriver, and putting them back together almost as long.  I've become really good at doing it, in fact.  Nowadays my job is mostly putting things together, but I fix stuff plenty often.  Taking things apart and putting them back together are two sides of the same coin, the process in reverse (but not always exactly the mirror image), and knowing how something goes together and comes apart is the majority of knowing how to fix it.  Add in how it can potentially break, and you're 90% of the way there.  A very nice side effect of this kind of knowledge is that you can also build stuff on your own to do what you want rather than what someone else thought you might want.

There are almost too many principles, even generally speaking, to enumerate, but I'm going to try. You want to know how basic machines work; how to combine them; what the properties of various materials are; how to modify materials to do what you want; how various materials interact; how things tend to be put together; and probably a zillion other things.  I'll try to be as organized as I can, but no promises.  I figure this will be something like Megadoom's thread on treating gunshot wounds; part tutorial, part question and answer.  I hope others who know how to fix stuff will join in and help me out.

I'm not intending this to be a specific how-to guide for, say, your specific model of dryer or sewing machine or bicycle.  But I think examples are helpful, so if you have something broken, maybe we can help point you in the right direction (and in the process help you to learn how to learn to fix things).  At the very least we can maybe help you figure out what might be wrong.

As this develops, I'll modify this original post with an organized list of principles, hopefully.

Later tonight: simple machines, the building blocks for all the more complex machines we use.

[Six Gun Jim]

Good idea. The classes of fix it material would be pretty awesome to discuss too. Might help people stock up. -James

[freeyourmind]

Hmmm, simple machines are really an interesting topic. Are there 4? Are there 6? Should basic electrical devices count? Interested to see what direction you go!

[houseoftang]

It's not only the name of the forum engine, it's the name given to the basic devices that allow us to work more efficiently.  These are the building blocks of all the tools, gadgets, machines, and toys we use.

First, read the Wikipedia article:  http://en.wikipedia.org/wiki/Simple_machine

To summarize, a simple machine is a device that changes the direction or magnitude of an applied force.  There are 6 (or, arguably, fewer):, the Lever, Wedge, Inclined Plane, Wheel and Axle, Pulley, and Screw.  These actually cross over quite a bit--a screw is an inclined plane and a wheel put together.  Simple machines can be used to provide mechanical advantage, which basically means that rather than directly applying a force all at once, you spread it over a longer distance.  With a crowbar (lever), for instance, you apply a smaller force over a longer distance on one side, to get a much bigger force over a shorter distance on the other (like lifting a washing machine with the crowbar--you move the long end of the bar maybe 3 feet to get the washing machine to lift maybe 3 inches).  With a knife (wedge), you apply a smaller force over a broader area (the handle), and it converts that force into a much greater force over a smaller surface (the sharp end of the blade).  An inclined plane, like a wheelchair ramp, allows you to spread the lift over a greater distance--rather than just lifting the person in the wheelchair straight up, you lift it gradually over the length of the ramp (it'd still be easier if you were dragging the person in a chair up the ramp without the wheels).  With a wheel on an axle, you convert the greater force on the axle, which is applied over a short distance (the circumference of the axle), to a lesser force over a greater distance (the circumference of the wheel). A pulley is similar to a wheel in that it spins, but it directs the force differently.  A wheel is attached to the axle, but the pulley rotates on it, redirecting the force.  Pulleys are more useful in multiples; connect a few different size pulleys with a belt, and you can get mechanical advantage, having one turn faster or harder than the others.  Connect a few of them of the same size and you can get a block and tackle, splitting up the lifting between multiple ropes, so you pull a longer distance but gain greater force.  And as I mentioned above, a screw is an inclined plane and wheel put together; you can cinch things down tightly or lift heavy things slowly, because you have mechanical advantage by moving the "nut" as it were over a longer distance with a lesser force.

Yes, there are mathematics that go with this, but for our purposes, it's not really that important.  We're not trying to engineer things here, and most of the time when you fix stuff, you just kind of guesstimate.  This generally results in stuff being overengineered, if you do it right.  Or underengineered if you do it wrong.

There are, of course, things like hydraulics and electronics which also multiply force or redirect it.  These are also simple machines, in a way.  Hydraulics can allow you to move things gradually or in a different direction in a lot of different ways.  You can input force on one end of a hydraulic system over a big or small surface, and then have it come out over the opposite (think squirting liquid through a syringe).  You can put it through a tube of one sort or another, and make it come out somewhere else.  You can even store energy hydraulically, like in a water tower.  You can do similar things with electronic methods, what with solenoids and motors and such.

If anyone would like to add on, please do.  I'll give some examples of how complex machines are composed of simple ones a bit later.

Next up:  common parts (fasteners and others).

[shamaness]

This is an awesome idea for a thread, tang!  I'm more of a conceptual learner - I like to understand, so I CAN improvise and tinker my way through. 

Really looking forward to reading more here.  Thanks so much for taking the time to work on this discussion!   

[residualheat]

Brill! Look forward to more. Always been interested in achieving things with small amounts of technology.

[Annihilatrix]

Awesome idea--thanks and can't wait to read this!

[urbanfarmer]

Pictures too please! Words hurt my right brain. 
My friends have always said that if I could see it and handle it, I could figure it out. That is why electrical stuff is a problem for me.  I have put in several light fixtures, but I hate working with electricity. But the more I know, the better off I'll be.

[houseoftang]

Don't worry, there'll be pictures galore.  I've got a whole post (or probably two) on screws, but I have to find pictures to go with it.  Now that things are calming down in the thunderdome thread about me, I'll probably jump back on this thread.