I am making an all terrain robot and I need I strong motor for the caterpillar tracks.
I was thinking of using power drill motors but I can't find a controller for drill motors ANYWERE.
Please help! thanks!
I have been meaning to weigh in on this one for a while. I had the same delema a while ago when I started my all terrain bot, and I found the solution to be automotive 5 pin relays. they are cheap ($12 for 5 on ebay) and have LOTS of current handeling capibility (80 A) you can even get speed control if you reuse the MOSFETS in the drill motors. The only downside is you are going to have to do a bit of work with some driver electronics to get it to play well with an arduino or something like that (in my mind, WELL worth the savings you get) If you are interested, have a look at my build where I give a little more detail on the whole construction process. http://letsmakerobots.com/node/34827
Drill motors work great for a robot so long as you don't give it to much voltage/current. If you want your robot to do 80mph give it the full 18v and see what happens you will not be able to catch it. Harbor Freight has a 18v cordless drill for aroun $20 that has a good motor in it and you get a battery pack that can be taken apart an re-used as well as a charger. If you apply about 3.6 volts to the drill motor it will work at a low speed and will last forever. The other motor to consider it the brushless and a controller they are more foregiving and because they are brushless you have fewer items to wear out. Most of your hobby shops carry the brushless motors and have various types of gears you can get to attach to them. If you use two cordless drill motors you will need a controller to count the revolutions to make sure the tracking stays the same. Don't try to do it without a controller with two motors as they will never track the same and you will be frustrated. You can have to identical DC motors built by the same company the same day and at the same time and they will never track the same. The next thing you can do depending on the weight of the robot is to use two servo motors and hack them for continous drive motors, while you will still need to track them you will get the torque to drive the unti so long as it doesnt weigh too much.
Taking a cordless drill apart is easy and only requires a few simple tools.
There are some great videos out on youtube that will help you if you decide to go this way.
Here ae the basics of taking one apart.
1) Open the chuck up all the way.
2) Down inside the chuck you will see a screw most likely a phillips or straight.
3) Remove screw, it is left handed so turn it clockwise to remove it.
4) Take a allen wrench of good size that will fit in the chuck and put it in the chuck and close it.
5) The chuck removes in the normal fashion.
6) Strike the allen wrench with a hammer and the chuck will spin loose.
7) Next is the clutch, remove the screws that attach the rotation part of the clutch and the spring.
8) to lock the clutch in continious movement put 8mm set screws into the holes where the bearings came out of.
There you have it and drive motor for a robot.
Windshield wiper motors come to mind as a possible alternative. Most likely they will be 12v, and, I doubt they will pull 80A at any time in their useful life. :)
ok thanks every1!
You might want to have some fun one afternoon and imagine all of the things your robot needs to be able to accomplish. For example, it sounds like you know you need some good mechanical power to drive all terrain, and drill motors are attractive because they provide lots of that torque. They also seem pretty electrically imprecise and inefficient at times because they aren't made to do all of the things a robot wants to do in order to beat that terrain. I would wonder where I can pick up a better motor that might cost a bit more, but not require me to have a gigantic driver circuit for my motors. Heck, if you get the right stuff, it'll end up being more inexpensive because through your research, you'll find the right parts, instead of spending money and time on more trial and error than necessary.
WOW 80 amps that is TO much power erm is there any over strong dc motors that are just a few volts! 9-18v?
Great, you are familiar with this stuff.
Well, just like folks said above, it simply comes down to figuring out what you will need in terms of what your drill motors draw and then getting a driver that will handle that amount of current.
It should be noted that your motors are going to draw INCREDIBLE amounts of power when stalled (up to 80 amps) and your driver needs to be able to deal with this so it does not fry itself (over-current protection and/or fuses).
In general, when drill motors are running, you can count on 10-20 amps per motor, but this will vary greatly depending on brand and quality of the drill.
Finally, drills run forward a LOT more efficiently than they run in reverse. Encoders will probably be needed to keep your two motors going straight.
Do you know what's the reason for some drillmotors going better forward? All the drillmotors+gears have been planetary gears, and i have seen no significant difference of speeds.
I have know a bot that has two motors from 14.4v drills. I source them from single 11.1 lipo. As my Oddbot H-bridge is under construction i use two basic L298N Motor controllers, one per motor, channels coupled. They get very hot but the bot performs surpsisingly well :) I haven't done very extreme testing yet. I plan forced air cooling with those cheap 12v brushless PC fans.
I know these motors aren't ideal but they have some pros. They are cheap or free (if somebodys drillbattery is dead he gives whole thing to you) They have much torque, actually they are too powerfull. I find the long axle, exposed after chuck is removed, quite nice to mount the wheels.
It is not the gears that causes the difference in forward/ reverse performance, it the motor itself.
To be honest, you would have to talk to an EE to get specifics, but I have read and been told that it has to do with the direction of the windings, the "timing" of the comutator and brushes, etc. Again, I don't know specific-specifics...
That said, in practice, I can tell you there is a big difference (100 RPM at least and an amp or two difference in current draw). I have noticed this difference and can repeat it by simply swapping the motors from one side to the other, or driving in reverse. Put simply, drills are designed to drill (clockwise) and they do this best when they are indeed going clockwise.