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Thread: stepper motor use.
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26th January 2018, 02:45 PM #31
I said in an earlier post that you can't expect this to operate in a real load situation. I could give many technical reasons why this is a silly idea. There is a reason why the step pulse for each winding is a square wave and not a sine wave.
Stepper motor torque varies with speed and how you drive the windings, some designs also have less torque at low speeds that others. Steppers are usually geared for most applications, especially in higher torque / load applications, on the other hand you can get them with 80 volt windings rated at hundreds of Watts and more.
A standard smallish geared DC motor (not a stepper) can easily lift 100's of pounds at reasonably low cost - the choice depends on what application you are using a motor for.
No you won't get the torque that the motor was designed for because stepper DC motors are not designed to run on SINE WAVE. BTW you can get a stepper driver board for $9, that needs a variable frequency square wave generator to drive it. A simple pulse generator could likely be had for around $10. You don't need a microcontroller for simple tasks that require no automation.(1) Our small workshop layout __ (2) Bandsaw circle cutting jig __ (3) Spindle sander modifications __ (4) Dust Sensor
(5) Router table redesigned ____ (6) DC and where it all began __ (7) Bandsaw dust extraction build
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26th January 2018, 03:07 PM #32Woodworking mechanic
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Thanks for the post. I looked at a variable square wave generator (probably using 555 and a MOSFET - lots of home built kits using this little gem) and a driver board but I couldn’t work out how to reverse stepper direction. The driver boards I looked at had 2 +ve output pins and 2 GND output pins for the stepper and I assume to reverse you would need to reverse current flow? It certainly is the cheaper and simplest solution. As I said before, my experience is Automotive and we just use Scan tools tell the PCM to drive them
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26th January 2018, 03:17 PM #33
Hi, most good driver boards have a direction pin, the pin is taken either hi or low for reverse. Just check the current rating of the motor and board when selecting a board.
https://www.littlebirdelectronics.co...-potentiometer(1) Our small workshop layout __ (2) Bandsaw circle cutting jig __ (3) Spindle sander modifications __ (4) Dust Sensor
(5) Router table redesigned ____ (6) DC and where it all began __ (7) Bandsaw dust extraction build
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26th January 2018, 03:26 PM #34
BTW Another board I've used is this, a lot dearer but someone wanted to use one in a project, I coded a tiny micro for him to drive it for auto up /down and current sense stop for a window winder.
https://core-electronics.com.au/big-...ver-11779.html(1) Our small workshop layout __ (2) Bandsaw circle cutting jig __ (3) Spindle sander modifications __ (4) Dust Sensor
(5) Router table redesigned ____ (6) DC and where it all began __ (7) Bandsaw dust extraction build
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26th January 2018, 03:55 PM #35Woodworking mechanic
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The LittleBirdElectronics store is less than 2km from home.
If I read the data sheet correctly, if I connect a switch to the “DIR pin and leave it open, the internal resistor will hold it low so it will move in one direction. If I connect the “DIR” pin to eg. 5v via the switch, the stepper will turn in the other direction.?
I connect the Square wave generator to the “STEP” pin?
Nice solution
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26th January 2018, 04:30 PM #36
Dam, lucky you - postage is as much as the price of some low cost items. Also that's correct with the DIR pin and STEP input. These motors are really simple to get going with the low cost and availability of these driver boards. I think LittleBird also have a heatsink for a few dollars if ever needed. Add a few dollars for the simple 555 generator you mentioned and it's driven properly allowing you to really explore the capabilities of the stepper motor.
You may already know this but I'll add it anyway, to play with single stepping the motor you could just use a push button, but even better you can get a $5.00 (mechanical) rotary encoder and connect one side to the STEP pin, every step you turn the encoder steps the motor in the preset DIR direction, now that's where a micro comes in, or a bit of logic, you also change the direction pin state depending on the direction you rotate the encoder. A small micro with some encoder code is the preferred option, which would then be used to also supply the STEP signal.
NOTE: With some boards you have to be careful with simple single stepping, depending on the driver, it could keep the motor winding energised with too much current when the encoder stops. It always pays to check the current in both windings during the testing phase.(1) Our small workshop layout __ (2) Bandsaw circle cutting jig __ (3) Spindle sander modifications __ (4) Dust Sensor
(5) Router table redesigned ____ (6) DC and where it all began __ (7) Bandsaw dust extraction build
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26th January 2018, 04:43 PM #37
One thing I forgot to add, if you use a 555 to play around with, you really don't need a FET to drive the STEP input, this is usually a very low current input and really only wants logic HI / LO, some are 3.3 volt only but most are 5 volt tolerant so just keep the input below 5 volts unless the spec says otherwise.
(1) Our small workshop layout __ (2) Bandsaw circle cutting jig __ (3) Spindle sander modifications __ (4) Dust Sensor
(5) Router table redesigned ____ (6) DC and where it all began __ (7) Bandsaw dust extraction build
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26th January 2018, 04:53 PM #38Woodworking mechanic
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I like this unit even though it’s a bit dear. Lots of potential for future projects.
https://www.littlebirdelectronics.co...-motor-control
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26th January 2018, 05:21 PM #39
Yes a nice unit to use once you decide you really want to get into using them, when you consider the options and control software available it's really good value.
(1) Our small workshop layout __ (2) Bandsaw circle cutting jig __ (3) Spindle sander modifications __ (4) Dust Sensor
(5) Router table redesigned ____ (6) DC and where it all began __ (7) Bandsaw dust extraction build
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26th January 2018, 06:05 PM #40Woodworking mechanic
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Post for sacc51.
This thread has inspired me to build a stepper motor driver to drive the automotive stepper drivers I come across. I believe these items would suit your build.
- MP6500 Stepper motor driver board - can comfortably control 1.8A and over 2A with heat sink. $8.22 pickup
- NE555 Duty Cycle Frequency Adjustable Module Square Wave generator - 1HZ to 200kHZ - $4.80 delivered - eBay
- Toggle switch - $4.95 - pickup
i also bought a Stepper motor for bench testing circuit - $11.27 - pickup
I will Power mine from the vehicle battery.
Should have it up and running next week
Cheers
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9th February 2018, 06:36 PM #41SENIOR MEMBER
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I know I can get it to move one step at a time by flicking a switch, but as I explained in my original post I just want it to spin continuously. This is starting to look like the blind leading the blind.
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9th February 2018, 06:42 PM #42Woodworking mechanic
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It needs a pulse/square wave. The Step ports needs to see Logic High then Logic Low then repeated continuously. By flicking a switch you are providing a single pulse.
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9th February 2018, 08:54 PM #43Member
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Sacc51, you are on the right track, to have the motor to move continually you just keep taping the + or - battery post depending on the direction you want it to turn BUT you must tap it about 30 or 40 thousand time at a very fast rate!
Nick
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9th February 2018, 10:07 PM #44SENIOR MEMBER
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Better things to do than that, I want something that will do it for me, are you volunteering. Good job but no pay!
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9th February 2018, 10:26 PM #45Woodworking mechanic
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Here you go. Just built a steeper circuit using a MP6500 driver board and also using a NE555 pulse generator ($2) to provide the Pulse/Step signal is. A low/off and a high/on. The driver board required a 5v signal for its Logic circuits.
First video is a slow pulse (approx 1hz) so you can see it Step
https://youtu.be/aGnz7wCiLPY
Second video is a very fast pulse so you can see it continuously rotate.
https://youtu.be/a1JNG7c3x-wLast edited by Lappa; 9th February 2018 at 10:55 PM. Reason: Overpriced the NE555
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