So I had tried heating the hot end.

Yes, got it to extrude some filament.

So all I got to do now is set up a computer and get it interfaced with a PC...

So I am still noodle scratching.

While I am happy with X,Y and Z axis running nicely, autohome anomolies have gone, I can only assume its a power problem when the system is in over current and the programming goes sideways.

Well that hasn't happened since rectifying the problem and ramping up the mVolts to give an ample 1.2 Amp at the motor output, seems to be ample for my needs.

Now the new issue.

The extruder is not working.

I had it running in a previous test, but since the change, I have also tried changing the driver socket and still, no movement at the motor, there seems to be no power getting to the motor.

However...

Testing the cable continuity -- Pass
Testing motor coils continuity -- Pass
Testing for voltage at the motor when testing axis movement -- Fail
** HOWEVER **
Testing the driver coil output pins for voltage -- Pass

I will understand if this makes no sense because cable - continutiy in the connections -- all OK BUT motor isn't energiuzed whren its prepped to move that motor and voltage IS on the pins of the output side of the driver AND the motor measures the same resistance as all the other motors that work.

I have tried moving driver IC to other port -- nothing
Moved connection to new port -- nothing
moved driver back -- nothing

So all combinations of driver chip and cable connect have been tried, there is 660mV at the driver vRef, voltage of 12 and 5v is getting to the chip, the chip has been put in another socket (exchanged) works fine.

The extruder has been run and I have felt it pull and retract before, however, the motor does not appear to have any "Enegized" state like the other motors that can't now be moved when the system is powered in a ready state to move motors.

So what am I missing...

Voltages where voltages should be but not where they should be ending up despite the cable and botors checking out.

1. Yes wiring, sadly I have to say that there is absolutely nothing wrong with the wiring.
2. There is no bad news...
3. I was tweaking the wrong driver... I double checked the plug out on the board and found that the Z axis The duplicate Z axis socket is turned 45 degrees to the rest. So this causes a problem with counting plugs and trace to the respective drivers.

https://youtu.be/hmGeD1n9n_w

Sorry guys, feel like I wasted peoples time.

Still, its a learning curve and what came out of this was simply that the Extruder driver is in the wrong socket, so It was a double discovery.

Had I not checked the wiring out and found it OK, the simple mistake wouldn't have been discovered.

I have now labelled up the various ports with the port it refers to like X, Y and Z axis and Extruder.

These Chinese parts are made cheap so no budget for quality control. And do not hot swap parts as this can cause driver failure.

As far as the computer thing there must be a driver you can load in your pc these things are fairly generic
As far as arduino 1.6.7 is is  the latest stable release to use with 3d printers. .

I have seen cases of mains plugs having the blue (neutral) And brown (hot) reversed. this is more of a safety issue than functional.
The point is you can not trust Chinese wiring/color codes.

I am thinking both motors running from one driver  so the driver is working. I doubt motor failure so check that wiring.

I am using the display unit that plugs in to the board, the menu system has various bits that allow you to input in the jog wheel movement in the desired axis.

I get good movement in all other axis except for the Z axis.

The motors came as part of a kit, the wires and everything is pre-wired and mostly a build that requires plugging cables in and screwing the off thing together, not rocket science in real terms, the probelm I am having is just getting proper movement.

I can't use a PC at teh moment because I have to build it..!

My computer and sons computer only have USB and the drivers for USB to COM port is not avaiable on the PC manufacuturers site, so I can't do anything from a PC.

So I need to buld one which I know will not have the same problem as its a generic Intel board.

Those drivers are installed when you install Arduino. Then if there some weird driver which there should not be they should have been on the disc or thumb driver that came with it.

I get good movement in all other axis except for the Z axis.

The motors came as part of a kit, the wires and everything is pre-wired and mostly a build that requires plugging cables in and screwing the off thing together, not rocket science in real terms, the probelm I am having is just getting proper movement.

I can't use a PC at teh moment because I have to build it..!

My computer and sons computer only have USB and the drivers for USB to COM port is not avaiable on the PC manufacuturers site, so I can't do anything from a PC.

So I need to buld one which I know will not have the same problem as its a generic Intel board.

Turn the VREF up till they spin correctly while calling for motion.  Even if you turn it all the way up it won’t hurt anything.
If once it’s turned up and things still don’t move.  Then look at acceleration being set too high. Or mismatch of coil pairs on one of the motors.  I’ve seen this several times with brand new motors so don’t assume just because the correct colors are in the correct place, that it’s correct. 
Are the motors connected in parallel or series?

He is doing all of this without a PC so he is not able to look at the firmware. I am not sure how he is making moves through the full travel of an axis without a PC but he is.

Mark, what you are doing should not be done without a PC. You need access to the firmware and it is critical and crucial. The firmware is the first place I would have went to to confirm the settings like acceleration and movement speed are correct. You also need to be able to send commands like M119 to confirm the endstops are functioning correctly and when they are supposed to as they can inhibit movement as well.

I would have not even thought of building a printer unless I had a PC first as you will need to to make things and need it to load the items to the printer.

When you say Arduino, I assume you are talking about the printers controller. Also you might want to know that once firmware is loaded it will no longer appear as an Arduino device on a PC, but instead it will be a USB COM port.

969mV should be 1 AMP or there abouts as one tutorial states that 869mv equals 1.1 Amp.

Therefore there should be ample current for the motors to turn.

This time you can see that the Z Axis travels more before it starts that binding thing.

Because the Z axis ended up skewed by 3.1 mm, you can hear a squeak in the video BUT the thing auto homes just fine.

The leads are as the lead screw nuts and anti back lash system has been oiled as have been all bearings with a light machine oil, the sort use in sewing machines as it is not thick enough to create friction because its too heavy like some greases that I have seen used. Linear rails are meant to be lightly oiled, mine have been properly lubricated and slide just beautifully.

The motors have been installed squarely, nothing is out of true but still, this problem persists.

So can some one say for sure if this is a current related problem or is it as indicated a possible config problem.

As this item has no manual, is their any way I can tweak the setting in the printer without having to connect to a PC?

I am using the machine as it is set up by the manufacturer, I tweaked all the drivers a bit.

I have to build a PC for the printer, the current systems I have lack the com ports via USB, other devices like printers that show up as USB devices on com ports work, however, Arduino is not picking up the Arduino hardware. So my only option is to dig out a windows 7 installer, build a system for the printer and hope that it sees the device on the com port.

I am more concerned with getting this problem of binding sorted as there is no rhyme or reason for it and what happened at the end, that was something it has never done before.

The board I have got has additional USB ports internally, they just need wiring up and I can then house the Arduino in the PC use the internal cooling fans to cool the stepper drivers.

The original setting on the stepper driver was a tad over 500mV, so if I ramp this up to 1 Amp then it should solve the problem, I really have no idea why it is binding like it is, both the lead scres work just fine, very smooth unlike the previous lead screws.

So, I will give it a try, see if that improves matters.

As for the tandem setup many printers are made that way and the current seen by the driver is double what it would normally be

that right there.. you need to basically double the voltage to get enough power to run both motors.

As for the tandem setup many printers are made that way and the current seen by the driver is double what it would normally be so you would need to double the setting that you would normally use for a single motor. One thing I found is the movement speed is sometimes set too high by default in the firmware which will make the motors buzz. If you could post your configuration.h here we could help you make sure there is  nothing in there causing issues.

Check the rated voltage and rated current for your step motor. I don't know the model of your printer and the step motor. Most of the printer i use use around 1A. I usually turn it down if it makes big noise.

Its a GeeTech clone of the i3.

The kit came with a 12 Volt 15 Amp supply which puts that in the 180 Watt range, allowing for some overhead, a working wattage of about 120 Watts is what I think is realistic.

The NEMA 17 Motors I guess all work on the supply delivered by the driver chip.

I know from watching other videos that problems with setups can be overcome where there is a bit of slop in the drive, this can be rectified by ramping up the current delivered to the motor, I understand this to be based on millivolts that the driver is set to.

The standard setting I understand is around the 0.500 ~ 0.600 mV range.

I have already ramp it up to 0.77mV

So, another play with it and this : https://youtu.be/NswuZmq7GDE happens.

Both motors are running from one driver chip, so I figure that this has got to be a power issue with the motors getting enough  current.

It is hard to know what these motors are rated for, I have seen NEMA17 motors with ratings up to 3.5 Amps. I will go with not very much for these as the PSU is a 12 Volt 15 Amp device. So we are talking low wattage and most of that will be taken up with the hot end and the hotbed, so I figure that I will be left with around 3 amps

Hot end is 12V at 40 watt which means a current draw of 3.5 Amps
Hot bed is 12V at 60 watt is about a 5 Amp draw
Assume 1.3 Amps on NEMA17, 5X 1.3 = 6.5 Amp
Allow 2 Amp for the GT2560 board

Total peak will likely be : 17 Amps.

As not all motors are on at the same time, hot bed will not draw much once at temperature... the total peak would be 17 Amps, the PSU is 15 Amp, so I figure that my calculations are pretty much spot on.

I will be upgrading the PSU for a larger wattage and higher amperage output and relegate the existing PSU to provision of power to the hotbed and hot end.

I found a comment about some driver "stepper driver default VREF voltage is 0.83VDC (equates to 1.3A drive)" and thought about it, If 500mV is 0.5 Amp motors, 830mV is for 1.3Amp then if I have 0.5 Amp motors and 2 on one driver need 1 Amp, that is the ???mV setting

I am not sure how the millivolts is calculated, it is in relation to the motor current and the voltage, and some dark majik voodoo involved, maybe a few incantations and the odd chicken is sacrificed, however, knowing how this is arrived at in a logical fashin is more preferable.