Hi all,
have a question about motors. Almost everyone use nema - 17, is it possible to use with arduino - ramps stronger alternative a which one is the strongest ?

Bigger steppers, like NEMA23, have more torque at the cost of top speed. They work with Pololu-like stepper drivers just fine.

Torque is also roughly proportional to the current flowing through the motor's coils. If you need more current, you need bigger stepper drivers. Arduinos and RepRap electronics can drive them all as long as they work with Step and Dir signals. Take care of 5V vs. 3.3V.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Thanks for tip, I will look at it.

I'm using NEMA 23's in my current build project, I've had no issues in my testing thus far related to motors.

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"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

Like Traumflug said, your other option is using the Pololu stepper drivers to send signals to larger stepper drivers that are able to push more power to the motors without burning out the boards. In addition to those larger stepper drivers you will also need to have a power supply with more amperage in order to drive the motors as well.

For example, if you have 3 stepper motors that use 3 amps a piece, you will need a 10 amp power supply in order to drive the motors and have a bit of extra power for the board and the stepper drivers.

Alternatively, you can also get geared stepper motors so that you are using a lower amount of power but still getting a high amount of torque. The downside to these is that because of the gear box these kinds of motors are much slower. Robotshop.com sells 666 oz NEMA 17 motors that have a 99:1 planetary gear box on them. Which means for every 99 rotations of the motor shaft you get 1 rotation of the geared shaft. You get an incredible amount of torque from a tiny package at the sacrifice of speed.

The voltage of your power supply has a big effect on stepper performance, if you are using 12V you may want to step up to 24V.

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Hi guys, thank you for comments and Iceman086 for closer explanation.

I use external stepper drivers which can easily be interfaced to the RAMPs step and direction lines. I bought these geckodrives for cheap on eBay. They can handle steppers up to 7amps. High performance drives that can easily spin nema23 motors well over 2000rpm. Overkill but I've been using similar drives on my big cnc and they never miss a beat. Parker compumotor and certain ones from leadshine are also very good drives. Keep on eye on eBay if you are interested in using external drivers with your 3d printer.

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Jim Fong
I use external stepper drivers which can easily be interfaced to the RAMPs step and direction lines. I bought these geckodrives for cheap on eBay. They can handle steppers up to 7amps. High performance drives that can easily spin nema23 motors well over 2000rpm. Overkill but I've been using similar drives on my big cnc and they never miss a beat. Parker compumotor and certain ones from leadshine are also very good drives. Keep on eye on eBay if you are interested in using external drivers with your 3d printer.

I'd like to see a video of your machine running with these drivers to my knowledge nobody's had good luck because of the pulse time and yes I know you can change this but still I have never seen anybody do this very well with these. Please show your machine running and show us how you set up the firmware

I don't have my 3d printer running yet, just bench testing the drivers out with the ramps board. I have 4 CNC's running external drivers with MACH3. One of them is spinning the axis at 300ipm or about 1500rpm. That's limitation of the computer. Not fast enough to run the drivers at a higher speed. With a external pulse generator they will spin upwards of 2000rpm or more. All I am saying that using good external stepper drivers, you can use higher rated nema23 motors and spin them as fast as your hardware will allow. I keep reading that nema23 motors can't run fast but with the right driver, power supply and low inductance stepper motors they can run pretty quick.

I got a few videos of my various cnc machines on youtube. Some are running servos, others steppers. Youtube search embeddedtronics

I should have my 3d printer running in a few weeks. I will be using nema23 motors and external drivers since I already have them in my pile of misc "junk". It's belt driven so I highly doubt the stepper will be spinning faster than 500rpm.

With Mach 3 of course every thing works fine that's what it was designed for but you said from the ramps the pulse for step and direction signal is to fast on the ramps this can be changed but I haven't seen anybody have good luck with it. I'm waiting to see how it goes there are ways to change the pulse by putting in delays in it will be interesting to see how it goes like I say to my knowledge nobody's had good luck with this. I have seen people on YouTube bench test ramps and run large stepper drivers but never seen a machine up and running with this set up

Edited 1 time(s). Last edit at 06/15/2014 06:24AM by cnc dick.

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jzatopa
The voltage of your power supply has a big effect on stepper performance

Sorry, but in this generalisation it's wrong.

Having a higher voltage doesn't add a single percent of torque at low speeds. The only effect you have, is, you can maintain (constant) torque up to higher RPMs. Wether you ever reach these speeds depends on your motors and you printer gearing.

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cnc dick
With Mach 3 of course every thing works fine that's what it was designed for but you said from the ramps the pulse for step and direction signal is to fast on the ramps this can be changed but I haven't seen anybody have good luck with it. I'm waiting to see how it goes there are ways to change the pulse by putting in delays in it will be interesting to see how it goes like I say to my knowledge nobody's had good luck with this. I have seen people on YouTube bench test ramps and run large stepper drivers but never seen a machine up and running with this set up

Ok I understand what you mean now, this is interesting if true. What is the setup time and minimum pulse width required by the ardiuno?

This is the specs of a gecko201 drive that I have. Like you said, spins on the test bench but I haven't done any specific benchmark testing.
Input Frequency 200kHz
Step Pulse “0” Time 2uS
Step Pulse “1” Time 1uS
Direction Setup (Before step rising edge) 200nS
Direction Setup (Hold after pulse rising edge) 200nS

This is taken from the pololu driver a4988 datasheet
STEP minimum, HIGH pulse width tA 1μs
STEP minimum, LOW pulse width tB 1μs
Setup time, input change to STEP tC 200ns
Hold time, input change to STEP tD 200ns

The only significant difference is the low pulse width, it's 2us on the gecko and 1us on the a4988. When I get around to it, I'll scope out the Arduino and see exactly what the pulse timing is. I have my doubts that the timing is that critical that a gecko won't work. Thanks for the info.

If there is a problem with the gecko timing, I have some industrial parker stepper motor E-DC drivers that lists minimum pulse width of 200ns. Good for 2mhz input frequency. If the Arduino can put out faster pulse timing than that, I'll be really surprised.

Jim

Edited 1 time(s). Last edit at 06/15/2014 08:55AM by Jim Fong.

I once had an issue with the tb6560 drivers which resulted in a modification to the marlin firmware which allowed the pulse output to be make longer by adding in a very short delay, i have re added the mod to my fork of marlin which also has a few other usefull goodies like hardware pwm capability and certain Mcodes are switched over to buffered

https://github.com/jgrjgr/Marlin currently the step pulse is set to 5us but it's changeable in stepper.cpp at line 243

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thejollygrimreaper
I once had an issue with the tb6560 drivers which resulted in a modification to the marlin firmware which allowed the pulse output to be make longer by adding in a very short delay, i have re added the mod to my fork of marlin which also has a few other usefull goodies like hardware pwm capability and certain Mcodes are switched over to buffered

https://github.com/jgrjgr/Marlin currently the step pulse is set to 5us but it's changeable in stepper.cpp at line 243

Do you recall what the unmodified firmware step pulse timing was? The tb6560 datasheet is not an easy read and it never really states what the minimum step pulse is. I haven't used one of those drivers but they seem to have not so good reviews on cnczone. Plenty of people do use them with excellent results though.

There has to be quite a few 3d printers using external stepper drivers.

Edited 1 time(s). Last edit at 06/15/2014 12:12PM by Jim Fong.

You said that there has to be many people that use external stepper drivers for 3-D printers I haven't found any if I remember right lobo CNC did on have their first 3-D printer and they have done away with it. If you find any case post a link or pictures video any thing. Anybody that is using external drivers seem to be running Mach 3 for their printer

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cnc dick
You said that there has to be many people that use external stepper drivers for 3-D printers I haven't found any if I remember right lobo CNC did on have their first 3-D printer and they have done away with it. If you find any case post a link or pictures video any thing. Anybody that is using external drivers seem to be running Mach 3 for their printer

the majority are using inexpensive pololu type drivers. Which in essence are really external stepper drivers in a plug in board. Jollygrimreaper has already stated that he used a tb6560 external driver with modified firmware.

Just because you haven't seen it doesn't mean it won't work. I like to think big.

Okay I'll be waiting to see how yours goes it will be nice if it works good I'm a big fan of the larger stepper drivers it is just to my knowledge other than bench test nobody's had good luck on a actual printer. And yes you can think of that way but the pulse for step and direction that they operate on is very fast compared to standard stepper drivers

Edited 1 time(s). Last edit at 06/15/2014 09:49PM by cnc dick.

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cnc dick
Okay I'll be waiting to see how yours goes it will be nice if it works good I'm a big fan of the larger stepper drivers it is just to my knowledge other than bench test nobody's had good luck on a actual printer. And yes you can think of that way but the pulse for step and direction that they operate on is very fast compared to standard stepper drivers

The older half step/full step chopper type stepper drivers were slow back in the day. I've used them in the past. You could barely get them to spin a stepper motor 200rpm if you were lucky. Resonance problems and were just plain noisy. The Parker drivers I have are industrial high performance CPLD/FPGA based which are far better performance wise than the single chip pololu drivers that everyone is using. Just one stepper drive cost more some complete 3d printers! I have 7 days off for vacation in July. I hope to have my printer completed then. I just finished my cnc conversion of my metal lathe so I can turn some of the custom parts needed in the build. Majority of the parts will be milled out on my bench mill.

This will be a interesting and fun project for me. I will be using a drv8825 pololu driver for the nema17 stepper extruder head just because I bought one to play around with several months ago. That geared stepper motor is only 1.5amps or so. I'm swapping out the steppers on my cnc gantry mill to servo motors and Applied Motion servo drivers. Another big project. I'll probably end up using these three steppers for the 3d printer. Those stepper motors are about 4amps, much to high for pololu's.

BTW I just looked up the minimum step timing requirements of a drv8825 chip used in the pololu driver and they are higher than a gecko step driver. If that works with arduino ramps board there's no reason a gecko driver won't. And certainly no problems for the much faster Parker drives that I also have.

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Traumflug

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jzatopa
The voltage of your power supply has a big effect on stepper performance

Sorry, but in this generalisation it's wrong.

Having a higher voltage doesn't add a single percent of torque at low speeds. The only effect you have, is, you can maintain (constant) torque up to higher RPMs. Wether you ever reach these speeds depends on your motors and you printer gearing.

My experiences and stepper speed torque curves like these have shown me my generalization is not wrong.

Please note that in the graph the speed is measured in half-steps per second and there are different graphs for different amperage.

A simple and unscientific way to test it is to hook up a 12V and 24V stepper setup and rotate them. Then see which one is harder to stop by hand. Even when they are idle you can feel a huge difference when you try to rotate them by hand.

Now you could say that just off idle the differences are small, but there is still a difference.

If there is something I am missing though I would love a link so I can learn what I am missing.

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The issue of whether voltage makes a difference or not is mostly affected by what you consider low speeds. For 3D printers low speeds are actually out to the right where the voltage does make a difference.

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cnc dick
You said that there has to be many people that use external stepper drivers for 3-D printers I haven't found any if I remember right lobo CNC did on have their first 3-D printer and they have done away with it. If you find any case post a link or pictures video any thing. Anybody that is using external drivers seem to be running Mach 3 for their printer

Here you go look up Buildersbot

[forums.reprap.org]

Using Arduino/ramps with nice external micro stepping drivers. Does both milling and 3d printing. Check out the videos.

Ok,
so could I use these kind of motors with actual setup for casual reprap with arduino using nema 17:

[www.automationtechnologiesinc.com]

and if yes, what will I need to make it work properly ?

AFAIK (and I'm a noob) the pololu drv8825 stepper drivers have about 2.5 ampere limits so switching to 24V from 12V allows you to output more watts / energy. Also a faster processor like the beaglebone with a cramps / bebopr shield might give more speed than the 8bit arduino boards, but I'm not really sure if that is relevant for speed.

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Arnold
Ok,
so could I use these kind of motors with actual setup for casual reprap with arduino using nema 17:

[www.automationtechnologiesinc.com]

and if yes, what will I need to make it work properly ?

These are rather high inductance stepper motors, 6.8mh when wired up bipolar parallel at 2.8amps. They would not run very fast speeds unless you have a high enough power supply to drive them, probably greater than 36volts (48volts or more would be better). That means a stepper driver that can operate at those voltage levels. ie gecko, leadshine etc.

If you really want to use a bigger nema23 stepper, this model is probably more suited for lower current/voltage drivers. Still not ideal though.
[www.automationtechnologiesinc.com] (3.6mh and 2.8amps. )

Unless there is a specific need for higher torque nema23 motors, your better off with a good 76oz-in nema17 stepper matched to pololu drivers for a 3d printer. Cheap and works.

I'm my case I already have nema23 steppers and compatible drivers so I will use them. If I had to buy new I would just use nema17/pololu and save a bundle of cash. Bigger stepper motors are not always better.

I would like to try CNC so that is why I dont want to use nema 17, no moving by belts, but threated rods.

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Arnold
I would like to try CNC so that is why I dont want to use nema 17, no moving by belts, but threated rods.

Not a expert but I've built several CNC's over the years. Don't rush on buying the stepper motors right away. It's best to look at the overall design first. These are some of the questions that need to be answered. It will help decide on what size stepper to buy. Like I said bigger is not always better. In most cases it can actually be worse. I am assuming you want to build some type of gantry/mill and not a 3d printer.

What size cnc
Materials to be cut
How fast do do you want the cnc to move ie rapid speed
What spindle do you plan to use
Threaded rod, acme (1,2 or 5 start) or ballscrew
Type of Linear rails

Edited 1 time(s). Last edit at 06/22/2014 11:18PM by Jim Fong.

Hi Jim,
I am thinking about at final 2x1,5m work area. I would like to cut just boards from wood, plastic, maybe aluminium. But firstly I want to make a little cnc for tests. Frame and linear rails will be aluminium, threated rods m8. Everything must be cheap so I dont plan to use some special components. I dont want to safe money on motors because I will sure make upgrade, so that is for future - I dont want to buy motors again. My idea for start is connect some strongs universal motors with arduino, but dunno how. I am total noob in electricity. Speed is now not so important but again, strong fast motors would be good for future upgrade. Spindle I would use some casual for wood at start, so no controling through pc. At the end I would like to choose special electronic for pure cnc working with mach3, but my vision for start is just testing with arduino.

I have found this:

[www.youtube.com]

Is it possible that it is going to work if I attach wiring from pololu a4988 I already have on arduino mega to this stepper driver ? And if yes, do I need 4 these boxes each for one motor or just 3 (one for X, one for double Y, one for Z) ?

Edited 1 time(s). Last edit at 06/23/2014 05:22PM by Arnold.