How to Build a Motor Controller Assembly

So you want to build a motor controller assembly that can swim to about 50 feet deep? OK, here are the parts you will need:

available from Radio Shack

1 project box 6"x4"x3" Model: 270-1806 Catalog #: 270-1806

3 double pole double throw switches (momentary contact)
Model: 275-709 Catalog #: 275-709

1 fuse holder Model: 270-1217 Catalog #: 270-1217

1 fuse, 20 amp Model: 270-1074 Catalog #: 270-1074

1 set bananna plugs PN# 274-721

available from Home Depot

160 feet speaker wire ( 16 gauge,2 conductor) I like the kind that has two different colors of wire but eiether will work.

wire nuts (2)

hose clamps

pvc cutter

sheet metal screws

3 10/24 screws in brass or stainless steel

Thruster Components

3 Mayfair bilge pump cartridges 500gph,(you want the replacement cartridges) available at Cabela's

3 prop adapters from Master Airscrew available at Tower Hobbies

3 Octura propellers from:

Octura Models Inc 7351 Hamlin Ave Skokie, IL 60076 (847) 674-7351

The part numbers you need are listed below:

1250 PL (left-hand)

1250 RPL (right-hand) Use 2 of one and 1 of the other

If you call Octura you can order the parts. The lady I spoke with was very nice, and very helpful! You must send them a check and then they will ship out the parts. It sounds cumbersome but I got my parts in under a week.

Other items you will need include:

5 minute epoxy


solder


electrical tape


heat shrink tubing


wire nuts


Locktite (red)


You will also need some tools,and a healthy dose of patience if this is the first time you've tried to do something like this! The next installment will cover tools, tool safety, and if time and space allow, we will start to build.


For those who want a camera assembly to take underwater video for under $50.00, stay tuned. That will be the next big project! Have fun! The best part of building anything is that you get to work with tools and materials. The most important thing to consider when working with a tool that you are not familiar with is to read the owners manual! Tools are wonderful things but if you are careless with them or uninformed about how to operate them correctly, they will bite you in the butt. If you start a project with ten fingers and two eyes try to finish with the same number. It is considered unprofessional to have any fewer body parts when you complete the project than you did when you started it!. (It is also considered unprofessional to leave the project unfinished.)


Tool safety is paramount. Get a good pair of safety glasses and use them to protect your eyes. Don't get in the habit of moving them onto your forehead when you take a break, as it is too easy to not put them back over your eyes when you start back up. Don't use a tool that is broken or that has a power cord that is frayed. If you are uncertain how to use a tool, Ask! No one was really born knowing how to use tools I don't care what the old timers tell you. As for materials, certain types of woods, glues, solvents and epoxies are toxic under certain conditions or are highly flamable. Take the time to read the user information on the packages. If the instructions say to use a mask, use a mask even if it makes you look like a large bug. You will be glad you did. Don't eat while your'e working. That sounds kind of nit-pickey but if you are working with solvents or toxic materials and get some on your hands or in your food or beverage it can ruin a perfectly good day.


The tools I use to build a bot are:


A soldering iron ( I use a Weller butane iron but corded ones are nice too!)


a PVC cutter (You don't really need a slide compound miter saw to cut PVC but if you have access to one, go for it. I personally have never met a power tool I didn't like!)


a hacksaw


a drill/driver (Again, you don't really need a drill press, but if you need an excuse to buy one...)


a set of phillips and flathead screwdrivers


a set of electronics screwdrivers


a heat gun


a set of drillbits


Wire cutters also known as side cutters or dykes


wire strippers


a flush cutter


A vise and/or clamps


a tapemeasure


a ruler


a combination square


a centerfinding ruler (OK you don't really need one of these, but I use mine a lot!)

Did I mention SAFETY GLASSES?


Go shopping! Have fun! While you're at the store I'll try to figure out what exactly I want you to do next.

We are going to get parts ready to work with today. Cut your speaker wire using your side cutters into:


3- 50 foot lengths


1- 8 foot length


Cut the remaining 2 feet into 4 inch lengths, and seperate the wires into seperate conductors.


You will use the short pieces to wire the switches.

Take the switches out of their plastic bags and take a close look at them. You will observe that they have 6 metal pins on the bottom and a toggle on top. The base of the toggle is threaded and there is a washer a nut, and a knurled ring that thread off.

If you are looking straight down at the bottom of the switch, you can look at the following wiring diagram and see where the wires will go. A, B, and C are on the left side of the diagram going top to bottom, and D, E, and F go from top to bottom on the right.


A,B,C,D,E,and F are the pins. Vs and Vo are battery positive and battery negative.


Don't worry too much about that part now. When we start wiring and soldering, I will be building right along with you and will post photos as we go along. Lets move on to wiring the switch.

Solder 4 in. wires at B, C, E, and F. I will try to find a better diagram but in the meantime, A, B, and C are on the left side of the diagram going top to bottom, and D, E, and F go from top to bottom on the right. B and E will be the power and ground wires. If you got the speaker wire with different colored conductors then at pins B and E, use one color for all the B's, and the other for all the E's. This will make your life easier down the road.


Thread the three 50 foot motor wires that you cut from your speaker wire through the hole in the end of your project box.
What! There is no hole??? Take a drill with a spade bit of the appropriate size and make one! Do be careful to clamp your work so you drill the box, not the table, yourself or the friend who is helping you. And pleeeeeze wear safety glasses!
Put the hole in your project box on one end as shown below in red.


Seperate the ends of the conductors and strip the ends of them back about 1/4 inch. Twist one motor wire and the wire coming from C together and insert them in the hole in pin D.
Solder the wires in place.
Twist the 4 in. wire coming from F with the other motor wire an insert them into the hole in pin A. Solder these wires in place too. You will connect the power and ground wires after the switches have been installed in the project box. Do all three of your switches like this.
I like to solder everything on the switches before I install them in the top of the project box as I hate trying to solder in close quarters.


If you are new at soldering, a text soldering tutorial is available at: http://www.apogeekits.com/electronic_tutorials.htm

and below is a great little soldering tutorial video compliments of the MAKE blog.

Click To Play

In this Make: Video Podcast, Joe Grand shows us how to solder and de-solder electrical parts.

Next drill holes in your project box. Size your drill bit to match the size of the threaded shaft on the switch. The switch shown here is slightly different than the one you'll be using but the threaded part shows up better.



Place the holes in your project box as shown below in red.
Remove the knurled ring and the nut from the threaded shaft of the switches and install them into the project box.




Whew! You're almost done! At this point feed your power and ground wire into the hole in the box you made for your motor wires. Seperate the conductors about 5 inches and strip the ends of each. The copper colored conductor (wire) will be battery positive, and the silver conductor (wire) will be ground.

Look at the bottom of the project box cover where you have installed your switches. There should be two wires coming from each switch that haven't been connected to anything yet. Take the wire on the right from each switch and gather them together with the copper power wire. Twist all four wires together and install a wire nut. Now do the same thing with the wires on the left hand side of each switch and the silver ground wire.
Take your Mayfair bilge pump cartridges and remove the impellers.
The impeller is the flat white disc with fins on it at the bottom of the pump. Gently pry the impeller off of the motor shaft. Be careful when you do this so that you don't bend the motor shaft. If you can't get the job done with your fingers, use a flathead screwdriver and gently work all around the disc until it lifts off.

Once the impeller is off take a close look at the motor shaft. It has a little flat spot on it. When you put the prop adaptor on, the set screw will line up with the flat on the motor shaft and keep the propeller from "freewheeling".

Take the prop adaptor out of its bag and put it in a bowl or shallow dish. It has a small set screw and an allen wrench that have been known to mysteriously dissapear if they aren't watched carefully. Keeping then contained in a bowl or something is a good idea.
This is the prop adaptor: