Servo attachments???
MarkCrCo
Posts: 89
It seems to me like there should be an accessories kit for the servos. I have a wheel and an X and that's all. I would like to do more. I bought a radio shack servo that came with a star type attachment. I'd like to have a small wheel maybe like the one in the tank tread kit for the boe-bot. I really want to experiment more with what I can do with the servos but seem to be limited by only having two options for attachments.
How do other people get around this. I don't know how I could build my own and make it work with the gear teeth. Do you just attach to the X?
How do other people get around this. I don't know how I could build my own and make it work with the gear teeth. Do you just attach to the X?
Comments
BTW, general off-the-shelf servos have about 180 degrees of rotation.
For wheels, a continuous rotation (CR) servo is required. CR servos bypass the feedback circuit which provides angular positioning.
How do servos work?
A CR servo tuns CW and CCW and that's about it. You can hold position with a little tweaking/experimentation.
A lever and cable sounds like a job for a standard servo.
As long as you have the one horn, you can attach other things to it.
Here's one with a Lego gear added,
If you purchase extra horns, make sure you get the right kind. They are not interchangeable. The Parallax servo uses a Futaba horn. The center screws are also different with different servos. Many metal gear servos use a M3 screw which makes it easier to attach other items to the servo.
After one had been in a hobby which uses servos, they generally end up with a surplus of servo horns. If you have any friends who fly RC airplanes, they'll probably have some extra servo horns they would probably be willing to give you.
I think if you only were to have one servo horn the nice X horn that comes with the Parallax servo is the one to have.
If you want to experiment with multiple servos, you might want to find some inexpensive sources. I like HobbyKing myself. Their little blue servos cost less than $3.
I have collected some links to servo related threads and to some of my favorite servos in post #10 of my index.
http://www.ebay.com/itm/281295998759
Agreed, best 9g servo I have used. Same servo on Ebay: http://www.ebay.com/itm/NEW-HexTronik-HXT900-Micro-Servo-9g-1-6kg-/370648951905?pt=Radio_Control_Parts_Accessories&hash=item564c662c61
That's a glitch, but curiously, there are no deals on HXT900 servos on Ebay. People actually scalp them there for some reason. Maybe because orders from Hobby King take so long to ship. Maybe I'll order a thousand servos and scalp them on Ebay to pay for the twins' college fund. I got time.
Edit: I just ordered ten to give them away to my forum friends: totally free but $10 each shipping & handling. Won't last!
A lot depends on how much force you want to exert.
ePVC is really cool stuff to custom make servo attachments out of.
That little servo sure looks dwarfed by the long crank shaft. I still have yet to make a CR version of a little blue servo. I'll add that to my list of 2014 robotic todo's.
It doesn't look like anyone has mentioned Polymorph (aka ShapeLock).
I first learned about Polymorph from Crabfu.
I have a servo/Polymorph creation I made yesterday and I'll post a video of it in action later today (I still need to program it). Stay tuned to this (The Epoxy Curing) channel.
I sort of wonder if the shine is off Polymorph with the rising interest and use in 3D printers. You don't need a machine to make anything with Polymorph, but the results aren't exactly commercial-grade. I once had someone ask me if it was hardened Play Doh (or is it Play, D'oh! ?)
It's an attempt to experiment with 3D motion control. I'm starting off trying to use a HMC5883L 3-axis magnetometer.
The current version of the code is pretty underwhelming so I'm waiting to make a video of it in action until have the servo ramping working the way I want.
An no, those aren't injection molded parts nor are they 3D printed. Believe it not, those are hand formed Polymorph servo brackets.
The two bottom servo share a signal line and act as a poor inventive man's 360 degree servo (a trick I saw on the forum). The 360 degree servo parts works better than I expected. Both servos connect to the same I/O pin and the angular motion is double of a single servo. A neat trick IMO.
The pitch and roll servos are limited to 180 degree motion.
The HMC5883L code is available here.
The compass works pretty well until the servos start to move. The magnetic fields from the servos cause all sorts of noise to the sensor. For something like this to work well, the gimbals would need to be made with the motors farther away from the sensor. Even though there's noise, the contraption works reasonably well.
I hope to post a video of it in action tomorrow.
The idea is to keep the little HMC5883L board's orientation stationary even if the base is rotated or tilted.
Yes. I'm really pleased with how well this part works. I'm pretty sure I got the idea from a link you posted.
My other servo projects had the servo positions computed in a nice orderly fashion. With this contraption, the target angle can be constantly changing so the acceleration and velocity equations aren't as easy to compute.
My initial attempts to get keep the sensor board stationary have resulted in a lot of oscillation as the end point is continual overshot. I'm presently adding the code to decelerate the servo prior to it reaching its destination.
Um, there's always gravity! Hang it by a string or use this.
$80 What?
Haven't you ever heard of ebay? $4.99 shipped (and I've sure there are better deals)
It's also weather proof and would look great on your yacht.
The contraption never really worked as I had hoped it would. This hasn't stopped me from starting a thread in the Projects forum for it.
I posted a couple of videos of the contraption in the other thread (in one video the servos don't move) For your viewing pleasure, I'm also embedding the main video here (in this one the servos move).
I've found Polymorph merges with the blue plasitic of these servos. In an attempt to keep the plastics separate, I used some copper tape as a barrier between the two types of plastic.
Which post are you replying to?
He was finally answering a question in the original post. I (and apparently many others) had missed the simple question.
Nope. Now that I reread the OP, it looks like he wasn't asking how to attach the wheel but was showing the two attachments he knew of which could be used with a servo. He was wondering how he could attach other things to the servo. Hence the many suggestions including the Polymorph.