I love automatia/automation. Pinball machines, coin op, coo-coo clocks, etc.
I need to purchase some magnet wire so I can start making my own devices.
14awg is too large for the scale of my interests, so I'm thinking 28 gauge to
42 gauge? What gauge do automotive door locks use? I ancipate holding and
momentary action.

 

I love automatia/automation. Pinball machines, coin op, coo-coo clocks, etc.
I need to purchase some magnet wire so I can start making my own devices.
14awg is too large for the scale of my interests, so I'm thinking 28 gauge to
42 gauge? What gauge do automotive door locks use? I ancipate holding and
momentary action.

That's an interesting question.

Calculate the magnetic flux you need to create and then look up a formula that includes the number of turns and the current required.
If you know the average diameter of your coil and the number of turns, you can calculate the length of the wire.
If you know the voltage applied to the coil, you can calculate the resistance of the wire for a given current.
When you know the resistance of the coil and the length of the wire, you can then select the gauge of the wire.

Or you can do everything is reverse order.
That is, select a wire gauge, diameter of coil, number of turns, supply voltage, and work out the magnetic flux.

There must be an app for this.

 

http://markgibson.zenfolio.com/fun-with-pinball/learn/flippers-coils-and-power

 

thanks folks, I'll look into that pinball link.

 

One bit of advice. Don't plan on making your own coil with 42 gauge wire. It is too small to work with. I have had 44 gauge wire literally dissolve into the solder on the soldering iron tip.

 

Usually the first step in designing almost anything is deciding what you want it to do. In the case of a solenoid the first steps are to decide on the force required and the distance that force has to travel. The inherent challenge with solenoids is that the force is the least at the greatest distance, and then it increases as the distance to fully engaged with zero air gap decreases. There are several books on designing solenoids but I have not looked at that for over 30 years. One thing that I recall is that many light duty 24 volt solenoids used what looked like either #24 wire or #26 wire, and a few hundred turns.

 

Lots of automotive door locks are motors that run a rack.

 

Lots of automotive door locks are motors that run a rack.

I think that applies to all of them since the 1980's.

 

I've been out of the loop a few days, thanks for all the great replies! ebp and panic mode were very
helpful, and I liked the advise from richardo. Small wire dissolving in fine copper wire, argh!
I think I'll buy a roll of 28awg and make some coils with the help of a cordless screwdriver.
Maybe I can get some experience.

 

My transformer guy told me the smallest wire that doesn't break all the time (during winding) is 30 gauge.

 

Hello,

I've used 32 gauge a LOT over the years, that's the lowest i like to go though. It is strong enough to use for interconnections on PC boards if you need light current flow like in logic circuits.

As far as making coils, it all depends on what kind of voltage you have available. You cant use a million turns of #32 wire if you only have a 5v power supply because the current will not be high enough.
There is an optimum wire size for a given voltage but that's another story and sometimes it cant be used anyway.

As to the door locks, someone said already that the usual door locks use a small motor and a rack and pinion. As the motor turns one way, the rack moves outward, and as the motor turns the other way, the rack moves back inward. It works much better than a solenoid although not as fast action. A drawback is that you have to have a way to reverse the motor current, which means either a half bridge or a full H transistor bridge or a driver like a stepper motor driver chip. You can use a DPDT switch with center off if you dont mind doing it by hand, flipping the switch. I happen to have one set up for experiments with a momentary DPDT switch with center off, so i press one way and it goes OUT, then press another way and it comes back IN.

 

pinball machines use high current to create strong magnetic pulses. in general wire is quite thick (AWG 22-24)
flippers may be held on (energized) by players for long time this is why they have aux winding (much thinner wire, something like AWG26-28).
aux winding is bypassed until flipper actuates - then NC contact opens and both winding are in series which limits current and prevents meltdown.
but that was old strategy, today one could also solve this electronically with PWM....