possible motor question
Ok, about to reveal my utter cluelessness here, “runs in either direction by reversing power supply polarity”—can that be done with a switch?? Or would that require re-wiring something? Cause that sounds like I’d need to switch which wire (from the power supply) goes where.
Motor direction
Assuming that you are going to use a processor to set the speed then motor direction is built into the electronics. Between the processor and the motor sits a high power electronic switch commonalty called an h-bridge. It accepts CPU logic levels as inputs and generates high power outputs capable of driving a motor. What you will do is at a relatively high frequency turn the motor on/off to adjust the speed. Should you chose to use an Arduino much of this is already done for you and there are 1000’s of examples.
You will need some sort of rotational speed feedback. Some motors come with them builtin. You might get external encoders and mount them on the drive shaft. Perhaps you might use a second encoder on the bobbin to monitor its speed.
I suspect you would have a switch or two indicating direction and on/off plus a rotary dial indicating desired speed. All of which comes under the category entry level Arduino programming.
Should you chose to use a different CPU such as ARM or Microchip the level of support will vary.
You might want to joint the LMR Shoutbox. It is on the right hand side of the LMR page. Click on the blue “On” label. This is a online chat. Asking for Help is discourged. It is good for asking simple questions The chat logs disappear after a few days so any project specific details should be in the forum. General rule is if it of interest to everyone it dosn’t belong in the Shoutbox.
No Microcontroller
I believe the load will be relatively constant, and looking at the other eSpinners (but not super closely) I don’t think any of them are using microcontrollers. These are all geared motors and I think the gearing (and other losses) itself will present a load which in this case is helpfull.
I’m thinking one of these or a varient:
I believe that has some kind of provision for a small reversing switch, otherwise a DPDT (double pole double throw) directly at the motor. They also are about $6 including shipping
This is not ideal, but it keeps from throwing in a new layer of complexity. My thinking is to get this up and going and leave the encoders for later, if they are needed.
motor direction
Cool, and yup, thats part of why I was looking at Arduino.
And I just heard back from the maker of my wheel and that bolt should come off, he had some ideas as to the problem, so I’ll try again today to see if I can get it off, so that would simplify it anyway.
Arduino
UNOs are a good choice and widely available. Easy to program with the Arduino IDE as are they all.
This is not complex but does require some work. In addition to this forum, Arduino has a huge support community:
It seems to me that you have this in hand, so I will not be checking in very often. Good spinning to you…
Arduino
Thank you for your help!
DPDT Switch
DC motors consume the most power a low speeds, max if stalled, so make sure the switch can handle 10A.
Where to get
Ok, other than ebay can either of you suggest a website or websites that are decent to shop from for things like the switches etc? Yes, I can hit google, but if you’ve had good service with this or that company I’d like to know.
Battery
Ok, so if its a 12v motor with a Rated Current of 650mA, that means its using 7.8 Watts? Or for the other linked motor 13v (why 13?? Will it work with 12v stuff??) with 750mA so 9.75 Watts? So I can start looking at battery needs too…
Back to the original plan
Got the bolt out of the center of the fly wheel!
13V motors
A 13V motor will work at 12V with a slight degradation in performance.
LiPo batteries come in multiples of 3.7V. Closest are 11.1V and 14.4V. These are nominal values. They will be slightly higher when freshly charged and degrade with use. To add to the confusion they come with discharge ratings. The higher the Q, the more the battery can instantaneously deliver. You do not want a super high Q as a short circuit would be disastrous (plus the cost is way more). You will need the max current on startup (another reason for CPU).
Sealed Lead Acid (SLA) are another option. 12V is used on lawn tractors. Heavier that LiPo.
Nickel Metal Hydride (NiMh) are in between in weight and are the least powerful.
The adjustable speed control has a 10A fuse. You may want to stock up on 5A fuses for testing. I would not be concerned about a 3V overvoltage as there is some loss in the motor controller and the controller is using PWM.
Have you given any thought to how fast the device will be spinning. Just turn the knob till to looks right and the house walls aren’t shaking. Missing the desired speed by a factor of 10X would probably destroy the device.
Speed
Yah, I figure there’ll be some trial and error involved in figuring out where to turn the speed controll too…
What are the chances of being able to wire in a foot pedal for speed control? Or is that getting beyond complicated?
foot pedal
or a speed controller where I could wire in something like this: http://www.robotmarketplace.com/products/4QD-BNL-103.html to make a foot pedal?
Options
How about:
All possible. I would do 4, 6, 7 & 9.
I’d rather have a foot pedal speed control. And I hate fricking touch screens…
Once a thread breaks it doesn’t matter if the motor shuts down instantly or when my reactions can shut it off, I’m going to have to go digging for the end of it anyway…
Going forward
I think it is time for you to write a few pages describing how your beast is going to operate. Try to stay on the ideal side and avoid too many details. One area that I am uncertain about is the motor mount. I’m assuming you do not want to mar the existing wood.
motor mount
The base of the wheel is pre-drilled to mount a left foot pedal base (so it can be made a double treadle), my plan is to mount a board on the left side using those pre-drilled holes to hold the motor and everything. THAT at least is simple enough.
