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1  Using Arduino / Microcontrollers / Re: Stepping up to a closed loop system with a positional feedback. on: June 20, 2014, 09:19:12 pm
Closed loop stepper drives do exist but they are really an entirely different animal from a standard drive. My understanding of how they work is that the stepper motor is driven as a high pole-count BLDC motor through some magic known as "phase vector control"  (don't ask me to explain, it's way above my pay grade!) so the lowly stepper motor actually becomes a true servo motor.
Only recently have they become affordable. Here are a couple of examples:
 http://www.automationtechnologiesinc.com/products-page/hybrid-servo-system/hybrid-servo-drive-kl-5080h
http://www.evarobotics.com/
From all I've read they really are quite good, allowing the motor to run much cooler and smoother with greater resolution.
Having said that, there is nothing at all wrong with standard steppers if they are properly matched to the machine they are driving.
My CNC machine, which I built about 5 years ago, has been running happily and productively with no problems, sometimes for 8 hours at a stretch.
If you really want to improve the performance of your machine I would move away from the GRBL controller (which really is quite amazing since it runs on an Arduino) and step up to LinuxCNC which will give you all the capability you would ever need. It's free and open-source software which has traditionally required a computer but is now ported to the Beaglebone as well as other small single board computers making it an affordable alternative to GRBL.
2  Community / Exhibition / Gallery / Re: Motorless stir plate on: July 29, 2013, 06:17:59 pm
Very nice work! But it really isn't "motorless" , you just created a motor in the apparatus. 
Does the propeller have a shaft or is it held in place by the magnetic field?
3  Using Arduino / Motors, Mechanics, and Power / Re: Synchronize Stepper Motor To DC Motor on: June 26, 2013, 09:56:47 pm
What you are doing sounds needlessly complex. Stepper motors can be quite powerful, large enough to drive a heavy milling machine table, so why not use a stepper instead of the DC motor?
It sounds like you are trying to read the DC motor current which is not going to have a linear relationship to position. To get position information you need to use a potentiometer (as a hobby servo does) or an encoder, either optical or magnetic. If you used a stepper instead, the position would be known and the same number of pulses could be issued to the second motor.
A little more information about your project would be useful:
How much load is the DC motor moving and at what speed?
What is the purpose of the stepper motor?
4  Using Arduino / Project Guidance / Re: How to write RPM Counter Code on: June 15, 2013, 12:46:50 pm
Here is a very good tutorial that should help you: http://www.pyroelectro.com/tutorials/tachometer_rpm_arduino/hardware.html
5  Using Arduino / General Electronics / Re: EDE1144 - Encoder Chip on: June 03, 2013, 09:29:34 pm
Why use 4 pins if you can use only 2?
This is probably what you're looking for: http://playground.arduino.cc/Main/I2CPortExpanderAndKeypads
6  Development / Other Hardware Development / Re: BLDC shield development suitable for Arduino due on: May 24, 2013, 12:23:15 am
If you could develop position control for BLDC I'm sure you would find some interest in the CNC and 3d printer communities.
7  Using Arduino / Project Guidance / Re: how to use a digital tachometer with an arduino on: April 30, 2013, 07:26:05 pm
I agree, doing it all with an Arduino would probably be easiest. Although I haven't built it yet my next project will be based on this: http://www.pyroelectro.com/tutorials/tachometer_rpm_arduino/hardware.html
8  Using Arduino / Motors, Mechanics, and Power / Re: Open source driver for stepper motor above 3A on: April 23, 2013, 05:43:45 pm
That driver board uses step and direction signals which is the standard for stepper drivers. The AccelStepper library can provide these: http://www.airspayce.com/mikem/arduino/AccelStepper/.
Building high power stepper drivers is not an easy subject. I would reccomend using a commercially available driver and saving yourself a lot of grief. A good selection of affordable drivers can be found here: http://www.automationtechnologiesinc.com/products-page/kl-stepper-drivers.
But I have to wonder why you would want to use an Arduino to control a CNC machine when you can have a full featured control program for free. I use LinuxCNC for my machine: http://linuxcnc.org/. I run it on a hand-me-down P4 computer and it's great. But if you're intent on a minituarized solution there are a number of people working on a version for the Beagle board and Raspberry Pi. I've been told a ready to run distribution will be ready in a matter of weeks.
9  Using Arduino / Motors, Mechanics, and Power / Re: Stepper Motors and control for lathe on: April 21, 2013, 10:54:59 pm
  It sounds like what you are trying to do is build a lathe with "live" tooling whereby the workpiece revolves slowly and is cut with a milling cutter. A stepper motor can indeed accomplish this though you will likely need to gear it down via timing belts to get sufficient resolution. I would go to http://cnczone.com/forums/forum.php. It's a very large site and can be intimidating at first but you will find all you need to know there.
10  Using Arduino / Motors, Mechanics, and Power / Re: Quadrature encoder on: November 19, 2012, 11:37:44 pm
You could gear your encoder with a timing belt and pulleys to achieve a higher resolution.
11  Community / Bar Sport / Re: Your opinion on piracy? on: August 28, 2012, 10:45:17 am
Quote
Most current companies are trying to sell virtually limitless goods, in a system which is designed to deal with scarce goods. Forcing law suits on a bunch of individuals will never solve that problem - the only way to solve the problem is by changing the market strategy. Slowly people are catching on to that.)

Amen, brother!
12  Community / Bar Sport / Re: Your opinion on piracy? on: August 25, 2012, 05:17:30 pm
He's not from the US, he's from Texas!  smiley
13  Using Arduino / General Electronics / Re: Tips on double sided PCBs... on: August 21, 2012, 06:34:46 am
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I know what resin is!   smiley-eek (Amsterdam is just over the water smiley-evil)
Lucky you! LOL
Rosin is the flux inside of the the solder. It helps the solder flow and stick to the intended surface but it also can cause corrosion if it is not removed.
14  Using Arduino / General Electronics / Re: Tips on double sided PCBs... on: August 21, 2012, 02:03:01 am
Quote
Does anyone want to confirm for me that the black marks are because of no heat control on my iron then I will rest easy!
It looks to me like the black marks are just rosin. It can be easily removed with some rubbing alcohol and an old toothbrush. A temperature controlled iron is nice to have but a simple iron can give good results with proper technique.
15  Community / Bar Sport / Re: Your opinion on piracy? on: August 17, 2012, 05:58:05 pm
Glad to hear Australia has such consumer protection laws. Corporations in the US handily hide behind license "agreements" that can't be read until the package is opened and not returnable and even if one does read them cannot be deciphered without the help of an attorney. Unfortunately this tactic is not limited to games but is also a feature of credit agreements, insurance policies and many other products of more vital importance than games. Caveat emptor is a useful principle but only when transparency exists. But the "free market" proselytizers seem to always resist such transparency.
Perhaps if we spent less time playing games and more time examining the realities of the current system we would choose lawmakers that work to create a more fair playing field. Intellectual property laws have become entirely perverted and need to be changed. The concept of "corporate personhood" ensures they won't.
I embrace the opensource movement because it exists as an alternative to corporate control and I see it as one of the few bright spots in our future.
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