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current controlled DC motor by e-steps? (no replies)

January 25, 2018, 2:57 am
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Short story: could I use the extruder step signals to PWM-drive a dc motor? ( Mosfet driven of course )

Long story:
I made a few assumptions that led me to this question.
1. Slic3r is able to vary printspeed based on constant extruder feed rate
2. A current controlled DC motor would produce a steady amount of chamber pressure ( amount of extrusion= const. )
3. extruder temp and filament diameter are stable

The problem with dc driven extruders was the encoder. A closed loop control circuit was necessary.

A torque curve of a current controlled motor always looks the same: upto 50% of the no_load RPM the torque is constant, then it falls off more or less steep.
If we could find the sweet spot where the torque is just right to feed a steady amount of filament and the slicer is able to control printspeed accordingly, we wouldn't need an encoder anymore.
Acceleration and decceleration are reflected by e-steps, so the e-steps is the parameter that controls the dc-motors current/torque.
I know, that RRF is able to produce e-steps with a defined length, would that be enough to drive a MosFet the way we need?
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Cheapest nema 17 (1 reply)

January 29, 2018, 4:23 am
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Hey guy this is going to be a stupid question. I live in Australia and where are the cheapest nema 17 motors?
Please help.
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Unknown specification NEMA 17 stepper motor (5 replies)

August 25, 2017, 11:32 am
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Hi,
I found some used stepper motors from streets of our local electronics market, which are in working condition.
All I know about those motors are
1. NEMA 17 form factor
2. 2 phase bipolar (4 wire)
3. coil resistance 2.1 ohm.

Now as per Ohm's law if I assume that its current rating is ~1.5 A (which I think more of a standard in these types of motor), then the voltage rating comes as ~3.15 v (2.1*1.5).
I understand that I have to use constant current chopper driver, that would reduce the driver at standstill mode, and increase voltage while running.
The question is which driver I safely use to drive these motors. Can DRV8825 be an option? If so what psu I should use to drive it. Can I use a Computer SMPS?
Additionally I have a L293d shield. Can I use this shield at least to drive the motor to see it running. Can I add a small hi power resistance with the motor coil in series to achieve this?

Thanks in advance.
Debojit
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closed loop integrated steppers (no replies)

August 22, 2017, 10:32 am
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3d printer- STEPPER - HELP (4 replies)

September 9, 2017, 4:59 am
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hi
I tried to build a 3d printer by MARLIN firmware , but I have some problem. I'm in the first step I just connect 1 stepper to a ramp1.4 with a driver ( also i configured marlin ) but when I want to control the stepper in the first time, it doesn't move and just trembled but after 30 second it work while if I restart it or it stops for more than 1 min , again it doesnt work and I have to wait for some second which means that after any stop it doesnot run some first commend.
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Speed of my stepper motors (4 replies)

August 31, 2017, 1:31 pm
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Hi,

I'm building my first 3D printer, and I'm struggling with a challenge. I'm testing my stepper motors and, although I can make them move correctly, I can not make them move very quickly without them stalling. If I move the engine more than approx. 1500 mm/min in octoprint they stop moving and just make a terrible noise. The engines run freely, I have not yet put a load on them.

My printer is a CoreXY design, and I have only connected the x and y motors to my RAMPS 1.4 card. I am using DRV8825 drivers that are set to a voltage of 0.650V, which should give a current of 1.3A. I have until now only connected drivers to the x and y axis. The drivers are set for 1/16 microstepping. The power comes from a PC power supply and I have only connected the 12V to the 5A-port of the RAMPS.

The motors are RTTM 17HS8401:

[www.aliexpress.com]

Am I doing anything wrong, or can these motors not move faster?

Edit:
I just wanted to add that Marlin is set up to 100 steps/mm. :-)
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One of the Z motor not moving when auto home after first touch (1 reply)

October 7, 2017, 10:11 am
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As per subject title, I'm currently having an issue with the Z-axis motor. I used 2 motors for my Z-axis and they move fine pressing + and -Z from software. However, whenever it auto home, after the first touch of the Z-endstop, the other motor would not move in a slower speed like the working motor but instead it stopped moving. What problem am i facing.? Please help!
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Ramps and Nema 14 (1 reply)

October 5, 2017, 11:47 pm
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I have been given 5 Nema 14 stepper motors rated at 5.4 volts

Could these be driven from a ramps board as the PSU is 12 volts?
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Strange situation with stepper motor (6 replies)

November 1, 2017, 5:05 pm
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Hello to everybody,

I have a stepper driver shield (for Arduino UNO) and Arduino Mega2560 :D
(And use GRBL for mega2560)

I connected only one motor on z-axis for my tests and this is the result.

Connect pin for DIR and STEP, connect pins for clock and strobe, connect pin for enable.
Connect Vin and ground, 12V directly on the shield and USB to arduino for the logic.

All is ok and the stepper work great.

BUT

on arduino there is a 5V pin. I read many article on internet and this pins is needed to power the logic.
If I connect the stepper going into a freeze, if disconnect work fine.

How it's possible? I break my electronic if i leave it disconnected?

Link of schematics
[www.futurashop.it]

Thanks
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Z axis faster than xy axis (14 replies)

October 25, 2017, 4:45 pm
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Hello everyone, i'm strugling in feedrates and aceleration, cause I cant insert more than 5mm/s in xy feedrate and 5mm/s2 in aceleration(more than this value and i get skiping steps), but in z axis i can uise more and get no trouble, but they are same step motors.Im using drv8825 , 2,2 kgf stepmotors with no microsteps, and ramps 1.4.
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Stepper driver problem (1 reply)

October 23, 2017, 12:48 am
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Hi, this is a question that is related to the use of the TMC2208 silentstepstick and similar stepper drivers. When I apply 24v to the VM/ground pins, the driver chip gets fried. This happens regardless of whether I have an arduino connected to the step/dir pins or the enable pin grounded. This also happens regardless of where there is 5v going to the VIO pin or regardless of whether the stepper motor is connected. This motor power supply is a 24v dc unit rated at 5 amps. The actual chip itself gets fried as soon as the VM pin sees 24v. It feels like it is just instantly drawing a huge amount of current as soon as it's connected regardless of whatever else is connected. I tried a similar setup with a DRV8802 and the same thing happens. I have used these many times for different applications, 3d printers and other things and I have never had this problem. Any ideas? I have posted at stackexchange with a schematic which I will attach here. Thanks so much for any help.
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Dual Z single stepstick (2 replies)

October 24, 2017, 2:02 pm
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I am pre thinking how I am going to setup a hypercube evolution build I hope to make happen soon.

I want dual Z drive, I am likely to use an MKS Gen 1.4 board like I have in my baby cube I use now.
I have TMC2100 stepsticks and love them!! But they have pretty low current capacity...

IF I run dual Z motors in parallel on one step stick I think I am unlikely to have the power I need....

Suggestions?

Oh I plan two extruders so I cant use dual drivers on this setup.....

Maybe I should look at a Rumba so I can run six step sticks....

What other decent boards are there with six step sticks... Seems like there is always something I don't like on every one I look at....
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Which motor to choose? 1.8deg 59Ncm vs 0.9deg 46 Ncm (2 replies)

November 24, 2017, 9:51 am
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So, I'm building my second printer based on the AM8 plans on Thingiverse. I'm thinking of buying either these 0.9deg 46Ncm motors (here) or these 1.8deg 59Ncm motors (here). My current printer uses 1.8deg motors, and I was wondering if I could increase print quality with 0.9deg motors on all axes? To do so, I have to sacrifice 13Ncm of holding torque, and I'm not sure what holding torque value I should not fall under.

Any recommendations?
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Can i run DRV8825 with this NEMA motor :S (4 replies)

December 5, 2017, 1:09 pm
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Hi family , i want buy a stepper motor Nema 17 17HS4401

The current per phase is 1.7A i want know if i can run it with DRV8825 driver with any problem or burn the driver?
Thanks
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TMC2100 driving dual Z - thermal shutdown? (4 replies)

December 29, 2017, 1:11 am
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I have a Tevo Tarantula-style printer with dual Z (two identical motors connected to a single TMC2100 in parallel) with MKS Gen 1.4 board.

With Vref set to 1.2V, making RMS 1.2V*0.7A/V = 0.84A, which does not seem excessive.

Symptom: about 20-30 minutes into the print, Z axis stops moving. It's pretty easy to rotate by hand, you can feel the steps, but not much resistance.

Hypothesis: thermal shutdown?

Head scratchers:
1. Cancel the print, then immediately go to Control and move Z axis, it moves as if nothing was happening!
2. I run X and Y closer to 1.4V, and their motors get to 45C with no ill effects. Z motors are barely 28C (but there are two in parallel, remember!)
3. Measuring temperature optically through the cooling fins reports ~27C on Z driver, 28-29C on X and Y. Does not look anywhere close to panic levels.

Any ideas?
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extruder working but not XYZ (1 reply)

January 18, 2018, 5:53 pm
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Hello. I recently completed putting together a prusa i3 with RAMPS 1.4. I loaded it with the reprap test code found at (http://reprap.org/wiki/File:RAMPS1.4_TestCode.pde) everything works fine and all the motors move back and forth some. When I load it with Marlin firmware I am only able to make the extruder motor move. XYZ do not move and simply make noise. I am using Pronterface to run test commands. Any help would be appreciated and please assume I am stupid. Thank you
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current controlled DC motor by e-steps? (no replies)

January 25, 2018, 2:57 am
$
0
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Short story: could I use the extruder step signals to PWM-drive a dc motor? ( Mosfet driven of course )

Long story:
I made a few assumptions that led me to this question.
1. Slic3r is able to vary printspeed based on constant extruder feed rate
2. A current controlled DC motor would produce a steady amount of chamber pressure ( amount of extrusion= const. )
3. extruder temp and filament diameter are stable

The problem with dc driven extruders was the encoder. A closed loop control circuit was necessary.

A torque curve of a current controlled motor always looks the same: upto 50% of the no_load RPM the torque is constant, then it falls off more or less steep.
If we could find the sweet spot where the torque is just right to feed a steady amount of filament and the slicer is able to control printspeed accordingly, we wouldn't need an encoder anymore.
Acceleration and decceleration are reflected by e-steps, so the e-steps is the parameter that controls the dc-motors current/torque.
I know, that RRF is able to produce e-steps with a defined length, would that be enough to drive a MosFet the way we need?
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Cheapest nema 17 (6 replies)

February 1, 2018, 6:41 pm
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Hey guy this is going to be a stupid question. I live in Australia and where are the cheapest nema 17 motors?
Please help.
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RUMBA: stepper (&power) selection (1 reply)

February 8, 2018, 3:28 am
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Hi all,
I'm new to this forum, and quite new to automating machine projects :)

I am making a vertical drawing robot, much like Hektor / Makelangelo / OpenWall etc. For this I got a RUMBA board (+ DRV8825) as it seems the most reliable all-in-one board (and I'm looking to upscale the V-plotter).
My local electronics shop sells 2 kinds of stepper motors that could be fine for me:
- a lightweight 24V / 600mA stepper
- a NEMA17 12V / 350mA stepper

As the motors will be on board, the light 24V stepper is more appealing to me, along with its higher max. power and more favourable characteristics (less gearing needed). But does it require a 24V power supply on the RUMBA board as well, or is there some internal transfo? The information for the RUMBA board says it can power anything between 12-35V. But how do you set the voltage for the motors? Does the power supply have to match this exactly? Any other considerations when using a different voltage than the 'standard' 12V?

I have a 12V power supply ready to use and could probably go with the 12V stepper for now. But I'd really like to understand how it all works together on the board and drivers. So if you know a good information source, please kindly point me in the right direction.

Thanks!
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Linear stepper motors (75 replies)

April 29, 2018, 8:27 am
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I wanted to post a thread about linear stepper motors in the proper section of this forum to see how we could make these more affordable. They are very expensive; for example, a basic single axis linear stepper from H2W is $855 for a forcer, and $2,225 for a 48 in. long platen.

The platen is a piece of precision ground steel bar stock, and can be found at McMaster-Carr in lengths of 1.5 ft., 3 ft., and 6 ft. which is great. The bar stock isn't too badly priced. [www.mcmaster.com]

The platen needs teeth cut into it at a tooth pitch of 1mm, teeth width of 0.5mm, and a cut depth of 0.5mm.

I think the platen could easily be made at home with a wet tile saw and a jig. The jig would be a sled that places the bar stock at the proper cutting depth from the arc of the blade, and the jig will have a pin that sets the pitch of the teeth; for each cut made the previous tooth is placed over the pin in the jig.

The platen is the method of movement, the linear guide, and could also be used as the towers in a delta printer directly, making for a sweet setup.

The forcer will be more complicated to make; it is essentially a transformer split in half with a permanent magnet between the two and ball bearings that ride along the platen. The force of the permanent magnet means you can use the linear stepper in either a horizontal or vertical position. The ball bearings maintain a 25 micron air gap between platen and forcer.

Someone in another thread mentioned the moving wires in the forcer and that it would be better if the electromagnets were in the platen. While this is possible, it isn't feasible or cost effective to build in a multitude of electromagnets within the length of the platen as more machining would be involved.

Everything you could ever want to know about linear stepper motor theory and design is in this publication: [issuu.com]






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