steps per unit??!!! SOLVED

My reprap prusa mendel assembly is finished, everything are working fine apart of my wades extruder!
Totally stuck on calibrating. i have standard parts : nema 17 1.8 deg, ramps 1.3 using merlin and pronterface, 2.5 belts and pulleys,
calculating x,y,z steps per unit makes no problems, but extruder is pain in a...s.
can somebody in simple language explain how to calculate extruder steps per unit (mm)?
classic wades geared extruder small gear 11t and big one 39t
trying with 1.75mm pla thru pronterface extrude 5mm and it extrudes 7 cm
googling in web found page where shown that extruder ( same one) has 700 steps per unit.
tried and still no success.

Was so happy that everything is assembled, and i will be able to do some test prints, but still no go
Thnx

Edited 1 time(s). Last edit at 05/04/2013 05:05AM by didzix.

you need to set the diameter of feedstock in software to 1.75. my extruder flow rate in firmware is between 800-900 steps per mm

Quote

can somebody in simple language explain how to calculate extruder steps per unit (mm)?

Assuming the extruder stepper runs at all it's simple:

1. Remove the hotend.

2. Put two markings on the filament, at a distance of 10 mm.

3. Command the extruder to forward 10 mm: G1 E10 F200

4. Measure how much filament it actually forwarded.

5. If it was more than 10 mm, raise the steps per mm. If it was less, reduce the number of steps/mm. Start with about 10% each time, or see below.

6. Repeat 2, 3 and 4 until the actual filament movement matches the command.

7. For mor precision, repeat with 100 mm commands.

To get faster results, you can calculate the new steps/mm value instead of going in 10% steps:

new value = old value * distance commanded / distance moved

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Like Traumflug said but....
There is no need to remove the hot end - mark a point on the filament which is say, 110mm from a fixed point on your extruder, command a move of 100mm and then measure the distance between the fixed point on the extruder and the mark which you have just made. If all is fine and dandy, this distance will now be 10mm. If more you need more steps per mm and if less, fewer steps per mm in your firmware. Use the formula which Traumflug gave in order to calculate the new value.

Alan

jamesdanielv Wrote:
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> you need to set the diameter of feedstock in
> software to 1.75. my extruder flow rate in
> firmware is between 800-900 steps per mm


I can't find any line consisting feedstock diameter

in slic3r it is under printer settings then filament. set diameter.


in pronterface go to settings and look for sfact setup.

in sfact change the following:
in DIMENSION set filament diameter to 1.75 or whatever your calipers measurements are.


I

Thnx for quick reply
Just switched on my printer, heated up hot end and tried steps described.
Motor in no more turning!!It screams and vibrates but is not turning,
Plugged different stepper, and the same
Replaced driver, same

One additional question.
Where can I disable function: prevent cold extrusion.
burning every time heater is no good

A bit confused.
There are my settings from marlin:

#define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,200*16/1.25,601.89} // default steps per unit for ultimaker
#define DEFAULT_MAX_FEEDRATE {500, 500, 5, 25} // (mm/sec)
#define DEFAULT_MAX_ACCELERATION {9000,9000,100,10000} // 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.

#define DEFAULT_ACCELERATION 3000 // X, Y, Z and E max acceleration in mm/s^2 for printing moves
#define DEFAULT_RETRACT_ACCELERATION 3000 // X, Y, Z and E max acceleration in mm/s^2 for r retracts


and there are previous :
#define DEFAULT_AXIS_STEPS_PER_UNIT {78.7402,78.7402,200*8/3,760*1.1} // default steps per unit for ultimaker
#define DEFAULT_MAX_FEEDRATE {500, 500, 5, 25} // (mm/sec)
#define DEFAULT_MAX_ACCELERATION {9000,9000,100,10000} // 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.

#define DEFAULT_ACCELERATION 3000 // X, Y, Z and E max acceleration in mm/s^2 for printing moves
#define DEFAULT_RETRACT_ACCELERATION 3000 // X, Y, Z and E max acceleration in mm/s^2 for r retracts


On Extruder value what mean last number (1.1)
I assume that 760 are steps per unit
Or i'm wrong!!??
in printerface extruding 5 mm, actual extrude are 7,9 cm

Edited 1 time(s). Last edit at 05/03/2013 06:31AM by didzix.

I got my stepper working by changing e feedrate under pronterface options

any further questions on this, can you mark this as solved in the subject line

there is a setting that will not allow extruding at a lower temp in configuration.h


line 123:

#define EXTRUDE_MINTEMP 170 // this sets lowest temp to extrude to 170

extrude 760*1.1 is 836 steps per mm

in pronterface change speed as well as length. say 60mm /m and extrude 5mm of feedstock, which is a lot more out of the hot end, as the hot end is narrower than the feedstock flowing in.

Edited 1 time(s). Last edit at 05/03/2013 06:56AM by jamesdanielv.

Thnx for reply,
will try it.

What about value in extruder steps per unit??
#define DEFAULT_AXIS_STEPS_PER_UNIT {78.7402,78.7402,200*8/3,760*1.1} // default steps per unit for ultimaker

Can somebody help with these values?
I was googling and googling, calculated steps per mm, still something is wrong, t feeds more than 10 times more than it should.
I'm guessing that number under steps per unit means something, what i need to change,
cant find any info!

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Wörth am Rhein, Germany
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change XXX.XX

#define DEFAULT_AXIS_STEPS_PER_UNIT {78.7402,78.7402,200*8/3,XXX.XX}


but also know that the feedrate is calculated on material going into extruder, not what comes out. measurements are more accurate that way.

Thank You guys for help,
quick overview what I done


based on formula Formula from wiki I calculated my theoretical extruder E steps per mm
Calculate E_steps = motor_steps_per_rev * driver_microstep * big_gear_teeth / small_gear_teeth / PI / hob_effective_diameter
in My case : I have a 51:11 pair on my gregstruder, so I calculate 200*16*51/11/3.14159/6 = 601.89

Entered 601.89 in marlin, compiled, uploaded to arduino
In pronterface entered 5mm to be extruded
it feeded 80 mm (measured infeed in extruder)

calculation shows :my steps (601.89) per 5 mm makes 3,009.45 steps
Calculated new value: 3,009.45 / 80 (actual filament going in extruder) = 37.6181

Entered value in Marlin, uploaded, measured again and its perfect. setting in pronterface to feed 150 mm it feeds 150 mm

Now I CAN SAY THAT MY PROBLEM IS SOLVED THANX TO YOU GUYS