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| Stepper motor mechanism for animated cab topper |
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| PL1:
This project thread was split from mrclean's inquiry here about using a small motor to generate linear motion. ------------------------- Without revealing the theme, the mechanics that Josh and I have been discussing have evolved into something more complicated (and cooler ;D) than previously discussed in this thread. - An arm raises/lowers about 2-3(?) inches. -- There is a 608 bearing (or similar) on the side of the arm. -- The item being raised/lowered at the end of the arm weighs less than one ounce. - A motor moves a platform 8-10(?) inches horizontally. -- The arm is mounted on this platform. The arm's fulcrum axis is perpendicular to the direction of travel. -- This platform is WAY too heavy for the 28BYJ-48. - The rise/fall of the arm is controlled by the bearing rolling through a track on a vertical piece of MDF (or layered acrylic?) mounted parallel to the moving platform. -- If the arm is moving left to right and the track is shaped like this ----\__/\_/\___ the arm will start high, then dip low, pop up/down twice and end low -- The bearing might pop out of the track if improperly aligned. Proper design should minimize this risk. - It's probably best to use a leadscrew, pillow bearings, and two limit switches (not shown) in the horizontal drive mech. -- It's far more durable than a scotch yoke . -- Used in the Z-axis of many 3d printers and CNC machines. - Will need to find/write Arduino code to make the motor run one direction until it hits a limit switch, then run the other direction until it hits the other limit switch. --------------------- NEMA series motors with A4988 driver boards have the power to do everything Josh wants to do, but they are much louder than the 28BYJ-48. The hard part is finding something between the $2 28BYJ-48 (380 g-cm) and a $10-15 NEMA 17 (60oz.in ==> 4320 g-cm?) commonly used in 3d printers/CNC machines. Any suggestions for an inexpensive, quiet stepper motor/driver combo mid-way between the 28BYJ-48 and NEMA 17? Scott |
| jennifer:
At slow speeds the noise would be less. Personally I like the bigger motor option, And would look for and upgrade to quality (brass or steel gears) for not only a good long life, but potential for less noise...But before I go I have to ask, does it really need to move something? or could the illusion of something being moved suffice? Peppers ghost is quite fun. |
| PL1:
--- Quote from: jennifer on August 15, 2019, 06:52:31 am ---Personally I like the bigger motor option --- End quote --- Didn't find any mid-range options and the 28BYJ-48 obviously doesn't have the torque, so I ordered two NEMA17 motors, some A4988 driver boards, a lead screw set similar to the one pictured above, and some 608 bearings. --- Quote from: jennifer on August 15, 2019, 06:52:31 am ---And would look for and upgrade to quality (brass or steel gears) for not only a good long life, but potential for less noise. --- End quote --- No gears in this design. - The lead screw coupler connects directly to the motor shaft to power the horizontal drive train. - The lifting arm will use 608 roller bearings, so that part will be very quiet. Depending on how noisy the prototype is, I may need to add a vibration isolation mount for the motor. --- Quote from: jennifer on August 15, 2019, 06:52:31 am ---But before I go I have to ask, does it really need to move something? or could the illusion of something being moved suffice? Peppers ghost is quite fun. --- End quote --- Yes, Peppers ghost is fun, but it wouldn't work for this theme. The physical movement of a 3d printed part travelling 8-10 inches horizontally and 2-3 inches vertically is essential to making Josh's theme work properly. Scott |
| Mike A:
What is this for? |
| PL1:
--- Quote from: Mike A on August 15, 2019, 10:33:36 am ---What is this for? --- End quote --- Read this post and the next 17 replies. :P :lol Scott |
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