# Thread: Simple stepper speed control

1. ## Simple stepper speed control

So, I met a guy the other day that want's to make a musical string winding machine. A string winding machine basically spins a piece of music wire so that the operator can wind a thicker wire around it for the lower strings. The trick is that both ends of the wire must be spun at the same time for the thing to work right. Traditionally the ends are synchronized with a shaft. This gentleman had an idea to use steppers at both ends to maintain synchronization.

What I'm thinking is that something like that could be driven by a very simple controller, perhaps even just a pulse generator except for the acceleration at the beginning and end. This controller would also need the ability to control speed (perhaps with just a knob).

Anyone have any ideas on a simple way to handle something like this.

Idea one was to come up with something for an Arduino controller but, I haven't programmed an embedded device in about 17 years and it might be just absolute overkill but, it would be very easy to implement an acceleration phase for the stepper.

Second idea was to use something like a 555 chip to create the pulse signal and slap something on the input side to create a ramp up, perhaps even just an RC type of things to smooth things out. Perhaps one of these: 555 stepper pulse generator

I just haven't done anything like this for years and don't know if the 555 can go fast enough. I'm thinking this machine will have a speed of about 1000rpm or as much as we can get out of it.

2. I would think that you need 3 synchronized axis? Two to rotate both ends of the wire and the third to transition along the wire as it is wound, dependent on the wound wire thickness?
Also what about the rate of feed for the bobbin for the wire being wound on?.
For me that would be an ideal Job for a Galil controller with geared servos, one being the master.
MotionCode - Galil: We Move The World
You can have multiple slaves servo's at various ratios off of the master.
A simple Operator interface could be used to input different wire gauges etc, if needed.
There are legacy DMC-1000 or DMC-1500 (stand alone), that can be picked up on ebay.
But I am biased!.
Al.

3. He'd actually be feeding the wire by hand. Cost is also an issue on this as well. Using steppers to synchronize the strings at both ends isn't really a necessity either, he just thought it might be a good way to do it and I kind of agree if we can keep the driver simple and cheap enough. He's looking at \$400 to \$500 total on something like this.

Here's an interesting video of something similar but it looks to me that the motors this guy is using are way overkill for something like this. I was hoping that we could get enough torque out of a nema 17 or a small 23 or something like that.