Motors don't move RAMPs 1.4 + Arduino Mega 2560 + Sprinter Kliment + Pronterface

I know this is not an electronic issue but after installing today the heated bed, i felt the torqe on the Y axis decreased. I mean, I see the Y axis motor more "slow" and difficult to move.

I have a under plate 10x14cmx5mm of Methacrylate where the belt clamps are bolted, over this and screw to this one a 20x20cmx5mm of methacrylate, over this I bolted the heated bed MK1 wich is not plane compleatly so I put over this a 3mm glass piece with some bulldogs clips.

I don't have finished already the electronics (I didn't install yet the jumpers) but I think it won't affect to this. Does anyone felt this on his/her Y motor? Shoul I increase the current on Y pololu stepstick?

Thank you

You should check the voltage of your 12v rail. From what you mention it sounds as if the heated bed was loading in a way that output voltage was reduced (thus causing a reduced torque, that would affect all your steppers though).

misan

Edited 1 time(s). Last edit at 12/08/2011 05:26PM by misan.

I use my own firmware and software. I extrude ABS from reprapsource at 250C, higher than a lot of other ABS. It is whiter and less smelly than the common ABS that extrudes at lower temperatures.

265C is very hot for Reprap but UP and Stratasys use that sort of temperature. You probably need a stainless steel extruder for that. I think 250C is about the limit for PTFE and PEEK extruders.

Springs are the best way of tensioning the idler. They need to be strong though in my experience. If your filament is consistent diameter you can get away without springs and just set the distance just right.

Edited 1 time(s). Last edit at 12/08/2011 07:12PM by nophead.

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[www.hydraraptor.blogspot.com]

The 12v rail provides 11,97V measured with a multimeter. Maybe the Y axis needs more torque increassing the Pololu current?

I'll try with other ABS and decrease the extruder temperature to 245/250ºC. I don't know where is the problem yet, maybe not enought tensioning idler or not melting ABS in the nozzle so it doesn't flow down freely. Other problem is I just load a 10cm of ABS on the extruder, extruded a few cm and now I can't un-load the filament.. maybe heating the nozzle and taking it up..

I fail to see why one motor would slow down because you have your heated bed on. Your supply voltage seems ok.

Increasing the current till the rated current of the motor should cause no harm but some heat on both pololu and stepper. What I do is to rotate the potentiometer a bit more beyond the point where the motor ceases to skip steps.

To remove filament from the extruder, the extruder has to be hot, if not the cold solid plastic will be very difficult to get out and you can break something while trying to pull it out.

misan

I plugged on the heated bed + all motors + extruder heater and I get this V measured with a multimeter:

on steppers.. INPUT: 11V
on heatedbed.. INPUT: 10.75V

on extruder heater OUTPUT: -10.35V
on heatedbed OUTPUT: -10.30V

How do you see these values? It seems quite fine i think.. I'm using a 12V/20A Power supply.

About the Z axis, I have a new issue and I think it's because of the coupling. When I order to move it up or down +10 or +1 whatever, if then i change the order to the opposite direction, the right motor miss some steps and doesn't turn for a second or two or something like that, then if i still go on moving on this direction it moves correctly and freely but if then I change the order to move opposite again same..
I checked the couplings and they are very good tight as I squeeze them well and cleaned the plastic with methylated spirit.

About the extruder, I don't find the way to press the idle with the filament to be push it down trough the heater. When the heater sensor gets around 250º, the filament starts to come out a few milimeters itself without extrude it, If I press the extruder button on Pronterface, the filament doesn't go down, just motor gives turning to the pulley but not comming out the filament extruded.

> on steppers.. INPUT: 11V
> on heatedbed.. INPUT: 10.75V
>
> on extruder heater OUTPUT: -10.35V
> on heatedbed OUTPUT: -10.30V
>
> How do you see these values? It seems quite fine i
> think.. I'm using a 12V/20A Power supply.

It sounds right to me, a voltage reduction like this won't affect the torque of your motors as it is compensated for by the pololu.
>
> About the Z axis, I have a new issue and I think
> it's because of the coupling. When I order to move
> it up or down +10 or +1 whatever, if then i change
> the order to the opposite direction, the right
> motor miss some steps and doesn't turn for a
> second or two or something like that, then if i
> still go on moving on this direction it moves
> correctly and freely but if then I change the
> order to move opposite again same..
> I checked the couplings and they are very good
> tight as I squeeze them well and cleaned the
> plastic with methylated spirit.
>

It sounds like a mechanical problem, rods alignment and/or threaded rods oiling. You can check how it feels when you move the threaded rods by hand and fixing what you don't like.

> About the extruder, I don't find the way to press
> the idle with the filament to be push it down
> trough the heater. When the heater sensor gets

Extruder bearing should be pressing the filament against the hobbed bolt by the force of several springs.

> around 250º, the filament starts to come out a
> few milimeters itself without extrude it, If I

That is expected.

> press the extruder button on Pronterface, the
> filament doesn't go down, just motor gives turning
> to the pulley but not comming out the filament
> extruded.

You may need to press twice or three times the extrude button if most of the plastic has been oozing.
If extruder motor turns and nothing comes out, it may also happen your filament has been carved by the hobbed bolt. If that is the case you'll have to push it manually a bit to help it get new grip on the filament.

misan

yes, it seems like it's a threaded rod problen,maybe about the oil on that rod because I install a level on the X axis and it's horizontal. What do you use for this kind of works (oiling)? Currently I'm using a spray.. but maybe better using other correct products..

Misan, wich is your firmware and host soft combo?

A quick question that may have a "long" answer:

Wich are the most important parameters to have under controll about the extruder? This include firmware (Sprinter), hardware, host sofware (Pronterface).

Thanks to all

I've used machine oil I've got from a sewing machine. Your smooth rods need some lubricant too.

I'm using Pronterface + Slic3r on the PC and Sprinter firmware.

But I started using Repsnapper ... which maybe simpler to install.

Cheers,

misan

A configuration question (one more... sorry). On pronterface I set a heatedbed to 110ºC and it starts to heat it correctly. My thermistor is close to a corner so the temperature is much more lower than the central area because of the dropoff themperature. When does my heatedbed start to increase the temperature? Does it has a internal controll or does the heatedbed stop to increase the temperature till my thermistore arrives to the setted temperature even in the central area is higher??

Thanks!

I have no experience with a heated bed but my guess is that firmware controls the temperature the same way it does control the hot end temperature. It is just a second control loop with a different resistor element and thermistor.

This is getting crazy.. again the Z axis problem. Using Pronterface, if I order to move it down 1 or 10mm there is no problem. This come up when I order to move it UP any ammount. The axis becomes to move in steps in right motor and very oftenly stopping for a while and then moving again.

Well you need a bit more torque going up due to gravity, so it seems you have a little less torque than you need for reliable operation.

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[www.hydraraptor.blogspot.com]

How should i solve this torque issue? Power supply measures seems ok, should I change the Steps per unit? should I chante the power supply?

The power supply only affects torque at high speed. You can get more voltage on the 12V rail by applying more load on the 5v rail with a dummy load resistor.

You need to increase the current to get more torque at low speed.

No you should not change the steps per mm. That should be set so that it moves the correct distance, not to adjust the speed. You might want to lower the Z feed rate though as you might be trying to move too fast.

The Z axis shouldn't be this difficult. With the recommended 1.65A 0.44Nm motors and Pololu drivers I have plenty of torque and it is in no way marginal.

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[www.hydraraptor.blogspot.com]

This is my configuration.h maybe the feed rate is wrong. Anyway I'll wait till a few days and get the jumpers installed to see if the problem is solved itself, what do you think?

//// Calibration variables
// X, Y, Z, E steps per unit - Metric Prusa Mendel with Wade extruder:
float axis_steps_per_unit[] = {4.9, 4.819, 35, 42};
.
.
const bool min_software_endstops = false; //If true, axis won't move to coordinates less than zero.
const bool max_software_endstops = true; //If true, axis won't move to coordinates greater than the defined lengths below.
const int X_MAX_LENGTH = 175;
const int Y_MAX_LENGTH = 160;
const int Z_MAX_LENGTH = 95;

//// MOVEMENT SETTINGS
const int NUM_AXIS = 4; // The axis order in all axis related arrays is X, Y, Z, E
float max_feedrate[] = {200000, 200000, 240, 500000};
float homing_feedrate[] = {1500,1500,120};
bool axis_relative_modes[] = {false, false, false, false};

// Min step delay in microseconds. If you are experiencing missing steps, try to raise the delay microseconds, but be aware this
// If you enable this, make sure STEP_DELAY_RATIO is disabled.
//#define STEP_DELAY_MICROS 1

// Step delay over interval ratio. If you are still experiencing missing steps, try to uncomment the following line, but be aware this
// If you enable this, make sure STEP_DELAY_MICROS is disabled. (except for Gen6: both need to be enabled.)
//#define STEP_DELAY_RATIO 0.25

// Comment this to disable ramp acceleration
#define RAMP_ACCELERATION

//// Acceleration settings
#ifdef RAMP_ACCELERATION
// X, Y, Z, E maximum start speed for accelerated moves. E default values are good for skeinforge 40+, for older versions raise them a lot.
float max_start_speed_units_per_second[] = {25.0,25.0,0.2,10.0};
long max_acceleration_units_per_sq_second[] = {1000,1000,50,10000}; // X, Y, Z and E max acceleration in mm/s^2 for printing moves or retracts
long max_travel_acceleration_units_per_sq_second[] = {500,500,50,500}; // X, Y, Z max acceleration in mm/s^2 for travel moves
#endif

Thank you for your help.

What's the rating on the +12V rail on your power supply? I don't understand why this is not a power supply issue. The output drops from 12V to about 10V when all the heaters are on. If the headed bed resistance is around 1 ohm and there are no shorts in the wiring and there's a load in the 5V rail, then I think you should get another power supply.

I think the feed rate is determined by the host, not the firmware. It should be possible to run the Z axis reliably without micro stepping.

@brnrd
The PSU behaves like it doesn't have a load resistor on the 5V but the motors should be low voltage motors, so they should work at 10V and have the same torque as the drive is constant current.

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[www.hydraraptor.blogspot.com]

Quote
pikelo
//// Calibration variables
// X, Y, Z, E steps per unit - Metric Prusa Mendel with Wade extruder:
float axis_steps_per_unit[] = {4.9, 4.819, 35, 42};

Those numbers are way too small. Why did you change the default values for Prusa with 1/16 microstepping?

These are the default values in Sprinter:

float axis_steps_per_unit[] = {80, 80, 3200/1.25,700};

@nophead - Understood. But with only 10V, the heated bed won't get hot enough for ABS (110C and higher) so a load is needed on the +5V or a new power supply. I didn't see the current rating for the 12V rail so I thought it might be insufficient.

I have been decreasing the feed rate on pronterface to 30. Obviously rods are rotating more slow but still stopping and showing like not enough torque on those axis when I try to move them up. I don't know why.. I just wait till have installed the jumpers and see if it solves.

@brnrd It can't be a power supply problem because I just powered the 5V rail (just powering the motors with 20A) and they do exactly the same.

I changed because I don't have installed the jumpers yet on my RAMPs, so I divided those default values to adapt it without jumpers (microsteping).

float axis_steps_per_unit[] = {80, 80, 3200/1.25,700};

divided by 16:

float axis_steps_per_unit[] = {5, 5, 160, 43.75};

If I leave the 160 value, it doesn't move, just vibrate the motors because they try to move too fast, and they miss steps and don't move.

Why not install jumpers and go at least to 1/8 microstepping? Also, what's the current rating on the 12V output of your power supply? It needs to be around18A or more.

@brnrd, Yes 10V is too low for a heated bed for ABS. In fact I find 12V is too low and I use 17V. It doesn't explain why Z does not work. He hasn't installed the jumpers because he doesn't have any.

@pikelo,
You shouldn't control the speed with steps per mm as your model will come out the wrong size. You need to reduce the Z axis feed rate instead. Adding the jumpers won't change the torque. What sort of motors are you using?

Edited 1 time(s). Last edit at 12/10/2011 01:34PM by nophead.

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[www.hydraraptor.blogspot.com]

Nophead, wich PSU are you using (model), probably I'll need to buy a new one and power on different PSU steppers and extruder and other PSU to heated bed to reach the 110ºC for ABS.

The motors what I installed are from GRRF;

Stepper motor with 42x42mm distance over hubs, hybrid stepper motor, 1,8°

Technical data:
Installation Length: 47mm
Holding Torque: 43,15 Ncm
Rated Current: 1,68A
2 Phases, bipolar
Angular Shaped Construction, Distance Over Hubs 42x42mm (NEMA17)
Step Angle: 1,8°
Axis Diameter: 5mm
Axis Length: 22mm
Wiring: Black + Green, Red + Blue

Model: EL-M-SM1

What about after find the Z-axis problem, I add this PSU? What do you think? 12V-28A

[www.latiendadelordenador.com]

I use a PC power supply for the motors and one of these for the bed: [www.ebay.co.uk].

Those motors are the same spec as I use. With them wired in series and the current set to 1A I have plenty of torque and can run the Z axis at 5mm/s. As I don't need that much torque I may try them in parallel to get more speed.

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[www.hydraraptor.blogspot.com]

How could I measure the intensity (A) that arrives/gives the Z axis pololu?

Still trying different configurations but don't get them move firmly and clear..

Thousand of thanks!

You measure the voltage on the VREF pin and divide it by 0.4 to get the current in amps. There is a test pin on the board or you can measure the voltage on the wiper of the pot. See [picasaweb.google.com]

Edited 1 time(s). Last edit at 12/10/2011 05:26PM by nophead.

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[www.hydraraptor.blogspot.com]