Quote
Dust
You need a voltmeter to measure the voltage over the sense resistor, from the voltage you can work out the current.

The current sense resistors should be 0.1Ω

You need to know the current rating of your stepper motors.

Let say for this example you have 1.7amp stepper motors

Normally you only want to run about 70% of max current

The maths is Vref = I_TripMax / 2

Vref = (0.7 x 1.7A) / 2 = 0.595V

With the trimpot normally anti clockwises turns down the voltage and clockwise turns up the voltage, a good trimpot will have about 270 - 310 degrees of movement and physical stops to stop movement. Cheap ones will not and can turn right around.. do not spin them around and around, its pointless and can damage them.

You need to put the probes as pictured. (One probe on the trimpot, the other on negative.)
NB you do not need 12v on while doing this, is best if its off. That way you cant accidentally short 12v to anywhere its shouldn’t be.
Just power the mega from the usb plug. and Leave the ramps un powered.



So adjust and re measure and repeat, till you have the correct voltage.
And ill repeat, you really need a non conductive screwdriver here... a metal one you can short things and kill the driver.

Quote
cozmicray
quote Bigfilsing "It looks like there is some kind of cover shroud at the hot end
to stop the air from the fan hitting the heater block . Not very efficient at all."

Confusing Statement
Cooling heater block (melting filament) is not helping
just requiring more power to keep it at temperature

Yes -- cool above heater to keep filament solid so it can feed
Yes -- cool after extrusion to solidify part.

Black shroud is probably silicone insulator
more for prevention of burning flesh.


quote Bigfilsing "It looks like there is some kind of cover shroud at the hot end
to stop the air from the fan hitting the heater block . Not very efficient at all."

Quote
jepigepas

Quote
jepigepas
Hello,
Here is a pic of my hotted.
the fan in the foreground is attached to the first piece I printed

you can see that melted plastic came out the back of the nozzle and flow on heater wires.

Quote
jepigepas
Hello,
Here is a pic of my hotted.
the fan in the foreground is attached to the first piece I printed

Quote
jepigepas

Quote
jepigepas
Dear Bigfilsing,
I understand what you mean.
the diameter of hotend's nozzle is 0.4 mm
and
the filament I use is PLA

On the Arduino, I have let the predefined settings.

I have just enter heat settings in Slic3 following the wizard of the "electronic guide".
These settings are :
layer height 0.3 mm
first layer height 0.35

Speed :
perimeters 50 mm/s
small perimeters 50 mm/s or %
external perimeters 60%
Infill 50 mm/s
solid infill: 60 mm/s or %
top solid infill 50 mm/s or %
support material 60 mm/s
bridges 30 mm/s
gap fill 20 mm/s

travel 130 mm/s

first layer speed 30 mm/s or %

max print speed 80 mm/s

Filament:
diameter: 1.75 mm
extrusion multiplier: 1
Temperature: first layer 200°C ; other layers 200 °C
Bed: 0

printer settings:
Z Offset 0 mm

custom G-code:
G28; home all axes
G1 Z5 F5000; lift nozzle

End G-code:
G28 X0; home X axis
extruder:
nozzle diameter 0.4 mm
extruder offset (x: 0 ; y: 0 )

retraction:
length 0.7 mm
lift z 0
speed 15 mm/S
extra length on restart: 0
minimum travel after retraction 1 mm

That is all I see in the Slic3r.

Do you think I have any thing to change in the configuration.h ?

For the diameter of the nozzle, I must add that the 0.4 mm is the diameter of the wire coming out of the nozzle.

Quote
jepigepas
Dear Bigfilsing,
I understand what you mean.
the diameter of hotend's nozzle is 0.4 mm
and
the filament I use is PLA

On the Arduino, I have let the predefined settings.

I have just enter heat settings in Slic3 following the wizard of the "electronic guide".
These settings are :
layer height 0.3 mm
first layer height 0.35

Speed :
perimeters 50 mm/s
small perimeters 50 mm/s or %
external perimeters 60%
Infill 50 mm/s
solid infill: 60 mm/s or %
top solid infill 50 mm/s or %
support material 60 mm/s
bridges 30 mm/s
gap fill 20 mm/s

travel 130 mm/s

first layer speed 30 mm/s or %

max print speed 80 mm/s

Filament:
diameter: 1.75 mm
extrusion multiplier: 1
Temperature: first layer 200°C ; other layers 200 °C
Bed: 0

printer settings:
Z Offset 0 mm

custom G-code:
G28; home all axes
G1 Z5 F5000; lift nozzle

End G-code:
G28 X0; home X axis
extruder:
nozzle diameter 0.4 mm
extruder offset (x: 0 ; y: 0 )

retraction:
length 0.7 mm
lift z 0
speed 15 mm/S
extra length on restart: 0
minimum travel after retraction 1 mm

That is all I see in the Slic3r.

Do you think I have any thing to change in the configuration.h ?

Quote
bigfilsing

Quote
jepigepas
Hello all of you,
I must thank you very much for your help !
Thank you Dust,
Thank you Bigfilsing,
Thank you Cozmicray,
Thanks to you I was finally able to print my first pieces using PLA.
My bed heating is out of order, so I have used blue painter's tape that I have put on a removable plastic sheet. So it is very easy to pick up the piece after printing.
I just wonder if it possible to print with ABS without bed heating ?
thanks again and best regards,
Jack

You are welcome. Thanks for taking time out to say thanks. Many dont and i always appreciate it when people do.

ABS can be very tricky to get to stick . Thats why most slicer software has options to use a brim and/or a raft.
ABS can warp when printing so i dont think you can print without a heated bed im afraid.
E3D sells some filament called Polymax that prints like PLA but has similar properties to ABS but even that needs a heated bed.

SO i guess the easiest and best way forward is to be patient and order a replacement heated bed and save yourself a lot of wasted filament and frustration.
6 dollars on ebay ebay heated bed
or
7 dollars on banggood banggood heated bed ( Faster shipping)

Good luck

Quote
jepigepas
Hello all of you,
I must thank you very much for your help !
Thank you Dust,
Thank you Bigfilsing,
Thank you Cozmicray,
Thanks to you I was finally able to print my first pieces using PLA.
My bed heating is out of order, so I have used blue painter's tape that I have put on a removable plastic sheet. So it is very easy to pick up the piece after printing.
I just wonder if it possible to print with ABS without bed heating ?
thanks again and best regards,
Jack

Quote
jepigepas

Quote
bigfilsing
I think you may just have to accept that your heated bed is defect and source a new one before you damage the ramps board.
You can still print PLA without a heated bed ( using painters blue tape) so you could still experiment with your printer while you wait for a new heated bed!

Its normal for the thyristors to get warm/ hot, especially the one driving the heated bed but not hot enough to melt wire insulation.

I am concerned that you will do some irreparable damage to your ramps board.

Could you please precise what you mean (using painters bleu tape)?
Do you advise me to paint the glass of the heated bed?
Or do you mean of an adhesive tape which has to be glued on the bed?

Quote
bigfilsing
I think you may just have to accept that your heated bed is defect and source a new one before you damage the ramps board.
You can still print PLA without a heated bed ( using painters blue tape) so you could still experiment with your printer while you wait for a new heated bed!

Its normal for the thyristors to get warm/ hot, especially the one driving the heated bed but not hot enough to melt wire insulation.

I am concerned that you will do some irreparable damage to your ramps board.

Quote
bigfilsing

Quote
jepigepas
I have no LED on my bed resistance
I am manufacturing a resistance with pencil leads.
I'll put it in series with the bed restance in order to have an overall resistance of 2.5 Ohms.

I have no idea how that will work. If your heated bed is indeed defect then i think you may just have to buy a new one.

Quote
jepigepas
I have no LED on my bed resistance
I am manufacturing a resistance with pencil leads.
I'll put it in series with the bed restance in order to have an overall resistance of 2.5 Ohms.