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Build a gear ratio program in excel with wheel sizes and all the motor rpm's including gears that the numbers are set to zero until you use them. Inserting the different sizes will make it easy to figure out what gears you will need very quickly.
| v v v v v v | GEAR1 SIZE | GEAR2 SIZE | GEAR3 SIZE | GEAR4 SIZE | GEAR5 SIZE | GEAR6 SIZE | GEAR7 SIZE | GEAR8 SIZE | ||
| ENTER SIZE | >>>>>>>> | 14 | 50 | 14 | 50 | 21 | 28 | 1 | 1 | <<<<<<<<<<< |
| MOTOR TYPE | MOTOR RPM | GEAR1 RMP | GEAR2 RPM | GEAR3 RPM | GEAR4 RPM | GEAR5 RPM | GEAR6 RPM | GEAR7 RPM | GEAR8 RPM | MOTOR TYPE |
| FISHER PRICE | 20326 | 20326 | 5691.28 | 5691.28 | 1593.5584 | 1593.5584 | 1195.1688 | 1195.1688 | 1195.1688 | FISHER PRICE |
| CHIPAWA | 5342 | 5342 | 1495.76 | 1495.76 | 418.8128 | 418.8128 | 314.1096 | 314.1096 | 314.1096 | CHIPAWA |
| VAN DOOR | 150 | 150 | 42 | 42 | 11.76 | 11.76 | 8.82 | 8.82 | 8.82 | VAN DOOR |
| GLOBE | 97 | 97 | 27.16 | 27.16 | 7.6048 | 7.6048 | 5.7036 | 5.7036 | 5.7036 | GLOBE |
| WINDOW | 91 | 91 | 25.48 | 25.48 | 7.1344 | 7.1344 | 5.3508 | 5.3508 | 5.3508 | WINDOW |
| LARGE CHIP | 2500 | 2500 | 700 | 700 | 196 | 196 | 147 | 147 | 147 | LARGE CHIP |
| MOTOR | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MOTOR |
| MOTOR | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MOTOR |
| MOTOR | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | MOTOR |
| ^ ^ ^ ^ ^ ^ | ||||||||||
| GEARS OF THE SAME COLOR ARE TIED TOGETHER | ||||||||||
Above is what we use in excel, simple to make and use. Contact us if you would like the file e-mailed to you.
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Above is a 8020 arm we used, it could lift the robot. We could lean it back to start on an angle which would allow for a longer reach when deployed. If stacked with three pieces it would go three times as high.
When running steel cable
1. The pulley that it will go around should not be too small, this will cause the cable to kink and wear out or become tangled.
2. Do not secure it solid, make a loop around a post or bolt and secure it to it self. This will allow it to move with the change in angle of the cable.
3. Allow for a way to keep tension on it, or an adjustment to tighten it. It will stretch as you use it.
4. You can run it through a cable housing (like bicycle brake cable) so you can make wide turns or allow for flexibility. Below you can see the curve cable (white) with the steel cable (purple) coming out to attach to the mechanism.
5. You can use pneumatics to drive it one way and spring tension to draw it back.
6. You can use a threaded pipe to drive it, as a motor turns the pipe the cable will feed in on one side and feed off the other side and because the pipe is threading as it turns the cable feed location stays stationary.
7. Use a bolt instead of a crimp. Take a bolt than install a washer on it and just below the washer drill a hole big enough to put you cable through than install another washer with a nut. With this assembly you can adjust it later or easily remove it.
8. If you lift a item that is 100 lbs. it will put more than a 100 lbs. on the pulley that it is going around. Angle and corners will stress a cable more than you would expect.
1. If you use a gear for a lifting arm you must watch out for coasting. The break on the motor control circuit will not be enough to hold it in place. You can make a break from a pneumatic that will release when power is applied to the motor.
2. Larger teeth for the gear are better than small teeth. They require less tolerance for gear centers.
3. Worm gears work better for arms, coasting is cut down.
4. Keep tract of your speed after gearing of items, you may under or over estimate the power need or lost in the process.
Large Gears
Need a large gear for a turn table that don't have to go all of the 360 degrees and have no way of making it or buying it. Take a Piece of 1/4 aluminum and cut it into the size you need. Lets say 12 in diameter, and tie a chain on the edge and wrap it around the circumference and bolt the other end. Now all you have to do is put a sprocket up against it on a drive motor.
1. Make sure you allow for chain tension adjustments in your design.
2. You can use blocks of HDPE to push against the chain to tension if needed.
3. Allow for room to get your fingers in to install the chain links.
4. You want enough chain to wrap around the gear to be sure there is not slippage of the chain.
1. You can use threaded rod to push or pull an arm, but the location of the pivot can cause problems. If it is close to the pivot you can make it move fast but there will be more heat on the threads from the weight. If it is farther away than you must increase the speed and that will cause more heat on the thread. You must balance weight and speed to keep the treads from over heating. When the thread heat up they will expand and make it hard to turn inside of the nut or rod coupler you are using.
2. A larger thread would help spread the heat out but that would cause more friction and make the motor work harder.
1. Caster are not a good choice to use unless most of the weight of the robot is over the drive wheels
2. Caster drag down the robot when you try to turn.
3. Omni wheels are a better choice over casters, especially if they are driven.
Make allowance for add-ons or repairs
1. The size of the robot should be less than requirements to allow for add-ons such as panels or bolts.
2. If you make an electrical board leave a space to add a relay or PWM.
3. Do not put a motor in a spot that it can not be easily replaced.
1. Use a different color tubing for the in and out for the cylinders. You can keep tract of which line is which.
2. Watch the size of your cylinders, large ones use a lot of air volume, you may have to weight until it pumps up to use it again.
3. If you need an extra storage tank you can use a cylinder, just make sure it is hooked up and can be used for some thing. This does not mean you have to use it in competition.
4. If you need to save air you can use a spring to retract it.
1. The pressure on the limit switch should not be more than the switch can handle. The speed or the weight of the mechanism can break the switch.
2. If you can build a mechanism that is separate from the limit. The item will push against the mechanism and the mechanism will push against the limit. This will protect the limit and also assure that it will work every time. With this you can design it not to break the limit at its extreme locations.
3. Roller type limit switches work better and last longer than sliding over the switch.
- You can load multiple balls but it is difficult to funnel them into one channel.
- If you load multiple balls you should store them in the same multiple direction of the pick up.
- Allow for spacing between balls when they are driven to exit. As they roll they will climb on top of each other and jamb.
- Do not use a basket or similar to catch balls unless they can separate as they go in. It only takes three balls to form a triangle to jamb the funnel.
- A single wheel at the apex of the ball will pick the ball up very well from the floor
