Hi all,
I have a plotting machine where the up-down motion for the pen is controlled by a micro servo.
The drawings I’m making sometimes consist of thousands of distinct, very short vector paths, so the servo can be running almost continuously for 3 - 4 hours at a time.
I have 3 Tower Pros (MG90S - seem to be original ones) in front of me now which have stopped working and I’m looking for something more reliable.
There are a lot of servos to choose from in the RobotShop store - can anyone recommend anything? Micro size is easiest but I can adapt the build to accommodate a slightly bigger motor.
I’m wondering if there is a big difference between the £5 servos and the £20 ones. Am I doomed to continually replace the servos? If so I will stick with the cheaper metal gear micro servers.
running almost continuously for 3 - 4 hours at a time.
Torture for most small inexpensive servos. Certainly possible, but the chance of the servo heating up is fairly high. Consider a servo with a coreless or brushless motor. Alternatively if you can move to a stepper motor, they normally operate at high temp.
I’m wondering if there is a big difference between the £5 servos and the £20 ones.
The vast majority of Chinese-made small servos are in the $5 to $20 price range and offer very similar quality. Some are produced in very high volume in order to make the cost as low as possible to try to get a share of the market. Companies like Hitec offer small servos at considerably higher cost, and yes, you would find the quality of parts (like the potentiometer, gears, motor, electronics), fit and finish, and overall support is quite a bit better.
Thanks @cbenson - i will have a think about a stepper motor. I have the Z axis controller free on my controller board, so that is a possibility if I can find a compact one. Failing that I will take a look at the Hitec options.
@Lemmy
make sure the servo/pen mechanic doesn’t block. A servo dies much faster, when it can’t reach it’s target. Maybe add a spring to control forces.
Would it be possible to use an electric magnet or an linear actuator instead? (think tattoo-needle)
It seems to be an digital action anyways (on/off or up/down)
I don’t think it was blocking - I was using a spring mechanism. Good thing to be aware of though. A binary system is possible but I would like to keep open the option for variations in pressure. So I will try with a small stepper first.
