View Full Version : Help picking motors

Keith Chester
03-29-2002, 07:01 PM
My dad has recently become as fascinated with FIRST as I, and we have decided as a father/son project to begin the building of a robot of our own, much smaller of course.
One of the questions I have no answer to yet is- what kind of motor shall I use, and where can I get these motors? Keep in mind, I don't have a budget the size of the FIRST teams.

Keith Chester
03-30-2002, 03:49 PM
Well since it seems no one can help me, how bout this- where oh where can I buy the motors on the first list? It's next to impossible to find them on the site, or I have to get the entire stupid set of some other assecory i dont want

Nate Smith
03-30-2002, 05:28 PM
Most of the motors FIRST gives out in the kit are donated from the respective companies. In many cases, these companies are not set up in such a way that they can handle orders from teams or individuals. Hence, the requirement of going though a local supplier(and sometimes buying extras you don't need) in order to get replacement motors. In some cases, FIRST will list the suppliers in the back of the manual. The listed suppliers have told FIRST that they are willing to take orders direct from FIRST teams. If a supplier is not listed, they are not prepared for individual orders.

However, many of the motors we use are automobile-related. Check out your local junkyard to see what they have(if they let you go into the yard yourself to pull off the parts you need/want, even better).

Matt Reiland
03-30-2002, 07:36 PM
A decent motor for a smaller bot are the Fisher Price motors which you can get at a PowerWheels service Center I think they cost us about $16 a piece. You could also buy some checp motors for RC type equipment at www.towerhobbies.com in the 540 size. The fisher price have a standard pinion which you can mate to fairly easily, most of the motors from tower you supply your own pinion normally with a set screw. The BOSCH motors are very powerful and you can buy them at a BOSCH repair center with or without the planetary gearbox. If you need to know more either post or send one of us an email someone should get back within a day or so.


Keith Chester
03-30-2002, 09:32 PM
Thanks. Now what about radio controllers? I know first provided the Isaac 32 (check spelling, sorry), which comes in around $1145. Now, has anybody tried building their own robot and has found a good radio controller for decent price. And yes, I know, Isaac is one of the best out there.

Nate Smith
03-30-2002, 10:41 PM
Originally posted by Replic
Thanks. Now what about radio controllers? I know first provided the Isaac 32...

The FIRST controller is very similar to the Issac in appearance, however, my discussions with FIRST and IFI/Innovation FIRST staff lead me to believe that the OI and RC hold custom firmware for FIRST as compared to the Issac system.

Matt Reiland
03-31-2002, 03:39 PM
Many, Many robots out there use off the shelf R/C equipment, only recently have you started seeing the Innovation controllers showing up at non-FIRST events. You can buy a 4-8 channel R/C package for 200-300 dollars then buy the speed controllers to go with it. For smaller motors you can probably go with the R/C types from a shop like tower. The Victor883's that we are using are quite capable of handling much more juice than we are giving them so they may be a bit overkill for a robot smaller than 130lbs but they are very robust. By using an off-the-shelf setup you will not have all of the trick features the innovation controller contains but you can get a driveable robot very cheap. You can get a 2 channel whell type radio for well under $100.

You may want to post to see if there are any teams out there that want to sell one of their older systems to you also. Since we get one each year teams that have about 5 years in probably have a stockpile of them they may want to get rid of an older one for a much reduced price.

12-10-2002, 11:44 PM
Originally posted by Replic
My dad has recently become as fascinated with FIRST as I, and we have decided as a father/son project to begin the building of a robot of our own, much smaller of course.
One of the questions I have no answer to yet is- what kind of motor shall I use, and where can I get these motors? Keep in mind, I don't have a budget the size of the FIRST teams. My first question is "do you have some electronics experience"? There are ways to build this CHEAPLY if you do.

If you wish to "work at this scale", you basically need four things:

1) A set of motors, on a platform
2) Power
3) Some kind of control system.
3a) Autonomous robots needs a CPU of some kind, and/or some sensors.
3B) Radio control needs both the radio link and some kind of decoder at the receiver side to talk to the high current motor drivers.
4) Some motor driver circuitry that can handle the motor's current needs.

IMHO, the cheapest way to get into this "scale" is the following:

1 - the motors and platform) Find a thrown out Fisher Price or other "kid's riding jeep". The batteries fail all of the time, and you can often get them for FREE. Make sure you get one that uses a PAIR of motors instead of just one. This gives you your platform and a pair of FP motors with gearboxes. If possible, find one that uses a standalone "tube frame" instead of the ones that rely on the plastic body to hold things together. If you can find one with a tube frame, throw away the body and add a simple rectangular board to hold stuff. If you can't, you'll have to cut an odd shaped piece of plywood to conform to the funny shape of the side supports.

Separate the wiring between the motors (they're normally tied together). This gives you two motors for "differential steering". Now replace the front tires with casters from a hardware store and your basic frame is complete.

BTW, I have found this works better if you consider the motor side as now the "front". The "tail" then swings around behind as you drive it, instead of it "brandishing a spear" in front of it as it moves.

2) For power, you can use a standard "maintenance free" car battery (to prevent acid spills). This is cheaper than a gel cell, but it doesn't like to be deep cycled. For a few more dollars you can get a Marine Battery that IS designed for Deep Cycling. You'll need a car styled battery charger for it. You can often find used car battery chargers in the "cheapie" for sale ads in the newspapers.

3a - Control System) Pick up one of several Basic Stamp style micros (such as from Parallax), or a LEGO RCX Mindstorms kit. This gives you a processor. "Nuts and Volts" magazine has a TON of ads for them. You can get into a processor system often for under $100 if you wire up your own board (under $200 if you don't or can't).

3b - Radio Control) If you are NOT going autonomous, there are various ways to create a cheap radio link, including surplus companies or ones like Jameco that have raw transmitter/receiver board pairs that are fairly inexpensive. Which system depends highly on how tightly you wish to control the robot. With straight RC control, you can use off the shelf RC car hardware. If you're commanding a CPU which then commands the power controls, there are inexpensive "remote control" raw transmitter and receiver pairs or TV remote "IR receiver" circuits that can be attached directly to a CPU. Either send "ritual commands" to the CPU to have the robot execute preprogrammed actions.

4 - Motor Power Control Circuits) To drive each motor you'll need either a full H-bridge control, or a single MOSFET circuit with an optional reversing relay. Once you have the first three items dealt with, I can show you how to build this.

BTW... A group I'm with is currently creating a set of VERY inexpensive control circuit PCBs to allow "kid's riding jeep motor hacking" from Stamps, or even an RCX brick! We're hoping to bridge the gap between Lego League and FIRST with them, as well as soon sponsor some offseason contests using them for teams with spare kit parts. If interested, email me after the 2003 build about it.

- Keith

Al Skierkiewicz
12-21-2002, 12:32 PM
Another store you can try is located here...
They have stores in Chicago and Milwaukee and have a variety of surplus motors of all kinds and sizes. They have the Fisher Price motor with transmission and Mabuchi and Johnson motors too. Also have all kinds of mechanical stuff.
There is also a busload of Internet sites dedicated to robot building. Good luck.

12-21-2002, 02:52 PM
The Atwood Motors can be found in camper jacks. We got spares last year when the company was out of stock by buying these power camper jacks. However, the jacks run pretty expensive and you probably wouldn't want to pay for them unless you wanted to keep really close to the FIRST kit of parts.

Adam Y.
12-21-2002, 04:44 PM
www.meci.com This place also has some nice motors also.:) www.acroname.com This place has nice sensors, microcontrollers, omniwheels, and lego kits cheap. www.lynxmotion.com This place has miniture robot kits.