Z axis not homing correctly - PLEASE HELP -- [SOLVED]

PLEASE HELP! I am desperate with this issue.

Despite being a total newbie, I have bought HE3D Xi3 kit and after a couple of hickups, I managed to complete it. Instructions are dreadful, but that´s another story. Their support is just as bad, or even worse.

My main problem is that I cannot get the printer to home z axis correctly and consistently. Every time I tell the z axis to home, I get a different result :-( Please see my videos. Other axes work great. If it wasn´t for this z axis, i would be printing already.
I am running on Repetier firmware and I will also attach my configuration.h file here (which I think is setup wrong), but I don´t have it on this computer at the moment. The configuration.h file is coming directly from HE3D which I got after many requests.

The z axis homing is acting inconsistent no matter what I use to command it
- the LCD on the printer itself
- the Repetier Host software

I don´t have bed autoleveling of any kind.
I already surfed through tons of forums and I could not find a fix for my issue. I will appreciate ANY help, because I am out of ideas (maybe it is my lack of experience/knowledge)

z axis wont home correctly1
z axis wont home correctly2
z axis wont home correctly3

Edited 1 time(s). Last edit at 06/14/2016 04:35PM by VDX.

The z endstop may not be configured correctly. What does M119 show for the z endstop when it's not triggered?

it says z_min:L

which is correct, I think

when it is triggered it says z_min:H

Edited 1 time(s). Last edit at 05/11/2016 01:57PM by 79dusan.

Try this configuration file

I got an error while uploading

I got an error while uploading

This is newest configuration file. Download a hole map and upload it.
You can try your old config file to look like on the image.

You are maybe all the time in the triggered mode.
What is your endstop?

An update after watching your videos
[youtu.be]

when the nozzle is at the home position, grab upon paper 0.2mm
the lever of the z end stop switch (shown in the above link) should be just touching the printed part and show HIGH when triggered when printer is sent a M119
much the same as the x axis end stop

If the end stops are triggered "all the time" the axis won't move.
When triggered it should show high

The Z end stop is adjustable, you can move it up and down.

The way the z axis homes is this:

It's driven down until it hits the end stop, goes then just pass it, then comes up, at which point you should be able to get a "slight grab" upon a piece of paper

The trick is to place the end stop in the right place, so that a light touch is done on the print bed and it comes up to be the right height for a grab.

Printing this item from thingiverse makes the process much easier [www.thingiverse.com] and you can adjust the z-height with a screw driver
Further information here [reprap.org]

BEWARE, If end stop is too low you risk damage to the print bed, so be near the power switch so able to stop the motor

Uploading someone's config file could be a problem waiting to happen, I wouldn't advise it.

Edited 3 time(s). Last edit at 05/12/2016 12:09AM by orictosh.

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Supporting 3D Printers with Parts and Build services.
Printer: Ormerod 2 (528.4) Duel extruder set-up with Aluminium X-Rib, RRPro Firmware v1.11-ch (2016-04-08)

@bme My endstops are mechanical switches, per instructions wired to "C" (closed) and "NC" (normally closed) pins.

Quote
orictosh
An update after watching your videos
[youtu.be]

when the nozzle is at the home position, grab upon paper 0.2mm
the lever of the z end stop switch (shown in the above link) should be just touching the printed part and show HIGH when triggered when printer is sent a M119
much the same as the x axis end stop
- I did that a couple of times already, but no luck. It always homes differently.

If the end stops are triggered "all the time" the axis won't move.
When triggered it should show high
- when an endstop is triggered, it does show high

The Z end stop is adjustable, you can move it up and down.
- yes

The way the z axis homes is this:

It's driven down until it hits the end stop, goes then just pass it, then comes up, at which point you should be able to get a "slight grab" upon a piece of paper
- My axis home as follows (x axis for example):
1. it moves towards the endstop until pressed
2. then it retracts a few mm, just for the endstop to open
3. then it does a second check triggering the endstop again
4. then it retracts a few mm again and notes that position as zero (the printed part is just touching the endstop lever)
When you watch the 3rd video, you can hear 2 clicks at x and y axis.

The trick is to place the end stop in the right place, so that a light touch is done on the print bed and it comes up to be the right height for a grab.

Printing this item from thingiverse makes the process much easier [www.thingiverse.com] and you can adjust the z-height with a screw driver
Further information here [reprap.org]

BEWARE, If end stop is too low you risk damage to the print bed, so be near the power switch so able to stop the motor

Uploading someone's config file could be a problem waiting to happen, I wouldn't advise it.

- I agree, however I am desperate enough to even take that route. But, I want to understand it and fix it without doing so if possible, so all help here is appreciated.
- One more note, is really z motors cross talk significant enough that I should try to remove endstop cables away from cable organizer? I do not see that in x or y, so I am not sure...

The way you have described the X axis homing, is correct and working. It should be the same upon the Z axis.

If you hold down (Closed) the z axis end stop and at the same time send a M119 to the printer; Does it show triggered?

If not, check the wiring
If yes, then move the z axis end stop so it's a short distance away from the printed part. Then home z and be ready with the power switch in case it hits the bed.

I think you will find that once it hits the switch it will behave just like the x axis.
Currently there seems to be a safety measure when you home Z that's states "Haven't hit the switch, yet, so I better stop." and you need to move the switch up by about 5mm.
Upon the first time, it might be some distance away, so move it down a small bit so it's not triggered, re-home z.
You should find that it gets nearer the bed,
repeat move it down a bit, home z until the paper grabs with a slight pull.

When this occurs your z axis home position is set, so ensure that screw holding the end stop is tight and don't move it, just move Z up 5mm (aviods hitting anything, when you move x and y) and prep for print

If you go too far move the z axis off the end stop and move it up.

If I remember rightly the z end stop lever will be slightly above the print bed.

I don't think cross-talk would be a problem

Edited 2 time(s). Last edit at 05/12/2016 07:40AM by orictosh.

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Supporting 3D Printers with Parts and Build services.
Printer: Ormerod 2 (528.4) Duel extruder set-up with Aluminium X-Rib, RRPro Firmware v1.11-ch (2016-04-08)

yes, if I manually activate the switch, it does show triggered state.

I will try to do as you say and come back with feedback. Thanks for your comment regarding cross-talk.

BTW, do you think it makes sense to remove the small metal lever from the endstop? It was instructed so in build videos. I understand that it could eliminate some of the "extra" axis travel caused by the lever material bending. What is your experience?

So, here is how it went.
I lowered the endstop until z axis was perfect with the paper test.
Then I have pressed z-home in Repetier Host 12x times to check on consistency. No luck :-/

12x total
4x wrong
8x correct
- wrong leveling among correct ones, no pattern whatsoever.

Attached a video here

Evil machine, living its own life.
It seems that sometimes it enters this panic mode when it stops in the middle of homing sequence

Edited 1 time(s). Last edit at 05/12/2016 04:42PM by 79dusan.

Did you change anything in your config file? Can you attache the configuration file again? The file which is in your atmega2560 now.

Here is the image of your config file:

Edited 2 time(s). Last edit at 05/12/2016 05:26PM by bme.

Quote
bme
Did you change anything in your config file? Can you attache the configuration file again? The file which is in your atmega2560 now.

Here is the image of your config file:

@BME Doesn't need to change the config files, as it software and he has moved the z axis end stop (hardware) to it's correct position.

@79dusan
You don't need to keep homing z for consistency, it's homed at the start of each print and at power on and it will change, so home it once then print the adjustment part I linked to on thingiverse to make the adjustment easier.

Something that should have been checked before homing Z; Is that the bed is mechanically level and flat upon each corner; 4 point beds don't level that well but you should be able to get within 0.1-0.5mm of a known height. Using digital calliper measure a object say a bearing 10mm in diameter.
Now home all axis X, Y and Z then move z axis up to 12mm so that the bearing fits under the nozzle.

Move to position near an adjustment point, carefully move the z axis down to the fixed distance (10mm) and adjust the bed adjustment nut so the bearing has a slight grab.
Move to the next corner in rotation from the last and repeat; move up above 10mm, place bearing below nozzle, move down to 10mm and adjust the bed screw to get a slight grab.
As you go round, you should find that bed becomes level with nozzle in all 4 corners. what this means is as the nozzle moves round the print plate the thickness of the first layer will be uniform and have good contact with the print bed.

You can also do this be measuring the gap at each corner. You might find that you need to have adjustment screws need to be at the high settings (spring has gaps, not compressed)

You will also need to re check the z home position after doing the above, once you have the z -axis grab; the printer is ready to start printing.

Edited 1 time(s). Last edit at 05/12/2016 06:22PM by orictosh.

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Supporting 3D Printers with Parts and Build services.
Printer: Ormerod 2 (528.4) Duel extruder set-up with Aluminium X-Rib, RRPro Firmware v1.11-ch (2016-04-08)

I have this same issue, in a more working kinda way.
Mine will home correctly run a print and be perfect, then the very next print *without powering down* puts the Z home maybe .4mm - 1mm off.
Its much worse if I power down and rehome. Its completely inconsistent.

I thought it was the mechanical switch I was using so I designed and made a setup to use an optical switch instead and I get the same results.
The only thing I really hate about my printer is testing the Z home to get it right for about 5 minutes before I can actually print something.

Everything is rigid and doesnt move but somehow my Z home gets tossed out of whack.

orictosh@ Can you explain to me what you mean by software?

Could it be something wrong in his configuration file. He has enabled EEPROM SET1?

It could also be possible that the Z motors are missing steps due to low stepper voltage or they get desynchronized. That's a known problem with dual Z motor printers.

Quote
bme
orictosh@ Can you explain to me what you mean by software?

Could it be something wrong in his configuration file. He has enabled EEPROM SET1?

Software is code, scripts, apps, protocols (HTTP,TCP/IP, FTP SMTP), you can't see it, printer firmware; something that makes the hardware usable, digital files of music and designed items.

Hardware is the stuff you can touch, see, hold, motors, Led's, keyboards, mouse, serial programmers etc
There is relationship between them as you sort of need the software to be able to use the hardware in what ever form in comes in.
People have a better understanding of Hardware than Software or vice versa but IMHO you need a bit of both to make it work.

BME@ Can you explain what EEPROM SET1 does in relation to problem when getting the Z height correct ?

The printer in this topic is based upon a RepRap Prusa Mendel and to get a good working Z height.
The x-axis, together with the nozzle has to be parallel to print bed and 90 degrees to the print bed within 0.1mm or less

Sometime when you pair stepper motors as done on this set-up one can be higher/lower than the other; so you need to disable the motors and wind up/down each side so each side is at the same height within 0.1 or less.

Edited 1 time(s). Last edit at 05/13/2016 03:06AM by orictosh.

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Supporting 3D Printers with Parts and Build services.
Printer: Ormerod 2 (528.4) Duel extruder set-up with Aluminium X-Rib, RRPro Firmware v1.11-ch (2016-04-08)

@orictosh
1. I will level the bed by your instructions and reconfigure z home.
2. I will try to level the x axis with a digital caliper I just bought. I did "level" it indeed when building it, but using a simple construction ruler with bubble water level. Seeing the tolerance required, I realize the construction ruler is not quite appropriate for this.
3. I have printed the leveling tool (on a rental 3d printer) from thingiverse.com and I need to complete it with screws and washers.

@drmaestro

Quote
It could also be possible that the Z motors are missing steps due to low stepper voltage or they get desynchronized. That's a known problem with dual Z motor printers.

- how do I check that?

Edited 1 time(s). Last edit at 05/13/2016 05:48AM by 79dusan.

Hi,
I am new to this but just got myself Prusa i3 and because it's cheap Chineese pile of... wood, metal and plastic it gives me a lot of opportunities to learn while fixing stuff...
Anyway, to me it looks like you may have doggy Z axis endstop element. Now when you actually hit it did you try to swap it with one from X or Y axis for testing?
I know it closes the circuit but problem may be that it is doing it in various points translated to millimeters of difference in head position above the bed. Could be dirty or damaged somehow.
Simple test and can resolve the problem.

I can't speak for firmware but my printer doesn't seems to care about anything unless it hits endstop when homing and from that moment onward that's zero... so if endstop is consistent so should be homing end result...
Good luck

Hi all,

I made a significant progress over the last weekend. Leveling the x axis by adjusting z motors with digital caliper has helped greatly as far as the entire bed leveling process goes. I also leveled the bed in a way that paper test was perfect in all 4 corners.
Next thing I need to do is to get even more drag on the paper (either by raising the bed or by setting a z offset - which is by far quicker).

Sometimes my z axis home flies away, but then after a couple of home commands, it is ok. Satisfactory. One thing I noticed is that seldom, x and y axis have the same problem. But that occurs like 1x in 50 homing commands. Could my Arduino be busted?

I tried to print, but my ABS won´t stick to bed and there are countless threads on material sticking to bed. Not a big fan of acetone and ABS juice, I am going to try to put glass on my aluminium heat bed and apply UHU glue. If that fails, I am going to try hairspray.

@vladek7
I´d like to have the same behavior as you have - only hitting the endstop means 0. Swapping endstops won´t do much magic as I just replaced z endstop before posting to the forum. Build instructions I got were saying I should have removed the metal lever from z endstop, so I did that. Experience was even worse, so I replaced it with a new endstop with the metal lever.

Edited 1 time(s). Last edit at 05/16/2016 02:29AM by 79dusan.

Quote
79dusan
Hi all,

I made a significant progress over the last weekend. Leveling the x axis by adjusting z motors with digital caliper has helped greatly as far as the entire bed leveling process goes. I also leveled the bed in a way that paper test was perfect in all 4 corners.
Next thing I need to do is to get even more drag on the paper (either by raising the bed or by setting a z offset - which is by far quicker).

Sometimes my z axis home flies away, but then after a couple of home commands, it is ok. Satisfactory. One thing I noticed is that seldom, x and y axis have the same problem. But that occurs like 1x in 50 homing commands. Could my Arduino be busted?

No your Ardunio is not broken, your printer's alu plate will heat up and cool down which will cause it to move and put the Z height out. Having the right drag helps with the print sticking but too much and it will cause problems with extrusion and elephants foot upon the first layer.

Quote
79dusan
I tried to print, but my ABS won´t stick to bed and there are countless threads on material sticking to bed. Not a big fan of acetone and ABS juice, I am going to try to put glass on my aluminium heat bed and apply UHU glue. If that fails, I am going to try hairspray.

I haven't printed with ABS as my heat bed won't reach 110 degrees C so no methods able it to make it stick.
I use a glass plate and PVA glue and have found that the bed temperature plays a part in getting prints to stick. As I print with PETG and I found that the bed temp needed to be 70 degrees rather than PLA's 60 degrees C .The print bed also needs to be flat and cleaned with IPA or acetone before each print.

Quote
79dusan
@vladek7
I´d like to have the same behavior as you have - only hitting the endstop means 0. Swapping endstops won´t do much magic as I just replaced z endstop before posting to the forum. Build instructions I got were saying I should have removed the metal lever from z endstop, so I did that. Experience was even worse, so I replaced it with a new endstop with the metal lever.

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Supporting 3D Printers with Parts and Build services.
Printer: Ormerod 2 (528.4) Duel extruder set-up with Aluminium X-Rib, RRPro Firmware v1.11-ch (2016-04-08)

There are videos where people print over bare aluminium bed and it seems to work for them.
I tried with bed at 110 and extruder at 235 degrees, but no luck. I found out applying UHU glue stick to aluminium creates a thin layer of very slick area, nothing is able to stick to that, so I am getting glass to cover my alu bed.
With a rental XYZ printer, UHU glue on heated glass bed works like a charm, so I go down that route for starters.

So I was impatient and got hold of 2 photograph frames, removed the glass and put it onto printer bed. Set a z offset to 1.6 and heated to 110 (it went up sloooow), but in the end it has reached 109,6 which my printer evaluated as 110 and begun printing a 1x1cm test cube. Extruder at 240

Applying a bit of UHU glue and it sticks just great, thus this is gonna be my way. BUT...

In the middle of printing the printer either
- receives bad instructions OR
- is not 100% calibrated OR
- moving parts get stuck somehow OR
- it is just a pile of ... scrap?

See video here
It just moves away from the print and starts laying down material on totally different coordinates. Can you guys tell me what could be causing this? Or maybe point me to a thread where this was discussed?

The first cube printed (the one in the back) is the one looking like staircase So I assumed my x axis was not running smooth over one of my x axis rods (it came slightly bent and I was kinda worried this could be the effect). However, then I printed another cube (the one in the front) and my y axis went crazy together with x axis as well and it ends up looking like spiral staircase, so it is not the bent rod.

I guess I am learning the hard way

Edited 1 time(s). Last edit at 05/16/2016 04:22PM by 79dusan.

Slow down your accellaration in the firmware.

Quote
gforce1
Slow down your accellaration in the firmware.

will try that

you can also lower the travelspeed for non printing moves in your slicer

Quote
gforce1
Slow down your accellaration in the firmware.

which of these?
#define MAX_ACCELERATION_UNITS_PER_SQ_SECOND_X 1000
#define MAX_ACCELERATION_UNITS_PER_SQ_SECOND_Y 1000

#define MAX_TRAVEL_ACCELERATION_UNITS_PER_SQ_SECOND_X 1000
#define MAX_TRAVEL_ACCELERATION_UNITS_PER_SQ_SECOND_Y 1000

I have watched your video and i think the speed for non printing moves is to high.
What are your settings in your slicer? Set them at app. 30 mm/ sec if it works you can try raising them step by step.