first connection of my RAMPS V1.4

Yes sorry, I thought it was general,
in my case the nozzle is wrapped in a silicone insulation refractory to high temperatures.
I add that I use a black color filament, that had previously overflowed on the top of the nozzle.
As you have shown, I have set now a fan shroud that cools only the channel and not the nozzle.

Thanks to you, my printer can work since before yesterday.
It remains only a problem of esthetic:
I feel, that the successive layers are too visible.
But I must confess, that I still have not corrected the number of steps by mm of filament extruded in the config.h.

Thank you again for your precious help.

Good to hear its working.

You need to get the basic calibration of X,Y,Z & E ( extruder) 100% perfect before you even start to think about improving print quality.

The good thing is when you're done you shouldn't have to touch them again ( unless of course you change something major on the machine)

Each machine is different and many types & brands of filament have different properties. The only way to find what works best on your machine is to experiment.
The best way to do that is pick a simple calibration model ( something like a 20mm cube) and stay with it. SO when you do something different or get a different
brand of filament you can compare and start to get a feel for what works best on your machine.
Some people have different models to test different things like speed , flow layer height & temperature.

This is definitely a hobby where the more time and patience you put in the better results you get out!

a lot of people seem to focus on speed and that often brings problems with it. Would you rather have a 4 hour print that prints reliably every time or a 2 hour print that
looks bad and doesn't always work so you have to redo it!. Think about it.!!

Good luck

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.

drv8825-tuning.jpg

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.

Thanks for the great summary! I am also new to this, and I was hoping you could help me with an additional question. My Z axis has 2 stepper motors (both 0.4A) controlled by the same driver. According the formula you are using, the Vref for a single 0.4A motor should be:

Vref = (0.7 x 0.4) / 2 = 0.140V

Since there are 2 motors on the same driver should I double the Vref?

Vref = (0.7 x 0.4 x 2) / 2 = 0.280V?

if you allow me Acoffin,
I also have two engines for the vertical Z axis.
But these motors are connected in paralelle, so that they naturally have the same input voltage.

I also want to take this opportunity to express my best wishes to the team.
Without you I would not have been able to start my printer.
Now, thanks to you it works fine.
Thank you very much all of you and best regards,
JP

Most repraps do have the Z steppers in parallel (but there is nothing stopping running in series, and this can help if you exceed current limits)

Yes this means they get the same voltage, but although vref is shown as a voltage, its is a representation of the current settings

Yes you should double you vref for steppers in parallel, as long as it doesn’t exceed the drivers max of about 1.7 amp, since you running 0.4A steppers, this should be fine.

I am concerned about the steppers being such low current though... I suspect they will get quite warm.