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Bed Auto Leveling.. check this out

Posted by AlexBorro 
Re: Bed Auto Leveling.. check this out
May 17, 2014 05:07AM
Finally had time to remount my probe. But encountering some issues.

My probe position is (relative to the nozzle)
X: -30.6
Y: 5.9
Z: -15.5

I removed my Z-home magnetic switch and pluged in the switch from the probe (Z-min) on ramps.

But when i run G28, it homes the X, Y fine,
Then tries to lower the Z probe, but crashes it into the bed, doesnt seem to lift.
If i start up high enough for the probe to extend, it then homes all the way down.
Since my probe sits outside of the bed, the nozzle crashes into the bed when trying to home the Z axis.
I would think i need the nozzle to move to at least X:30.6mm before it tries to start homing.

Where can i set this?

Here's my current settings
#define X_PROBE_OFFSET_FROM_EXTRUDER -30.6
  #define Y_PROBE_OFFSET_FROM_EXTRUDER 5.9
  #define Z_PROBE_OFFSET_FROM_EXTRUDER -15.5

  #define Z_RAISE_BEFORE_HOMING 16       // (in mm) Raise Z before homing (G28) for Probe Clearance.
                                        // Be sure you have this distance over your Z_MAX_POS in case

  #define XY_TRAVEL_SPEED 3000         // X and Y axis travel speed between probes, in mm/min

  #define Z_RAISE_BEFORE_PROBING 16    //How much the extruder will be raised before traveling to the first probing point.
  #define Z_RAISE_BETWEEN_PROBINGS 5
Re: Bed Auto Leveling.. check this out
May 17, 2014 11:10AM
I tried a lot and read a lot about this and i'm near to get it working, But I just don't get the Nozzle to touch the Bed after Probing. It just stays where it was after the Probe triggered.
The Servo retract as it should, but after that the printer won't turn any lower.
And therefor prints into the air...
I added my config.h - maybe someone sees my stupid mistake?
I am using an (PRotos) like the old Prusa and recently updated it a little...

Thanks a lot
Attachments:
open | download - Configuration.h (30.9 KB)
edn
Re: Bed Auto Leveling.. check this out
May 17, 2014 12:30PM
Quote
derletztename
I tried a lot and read a lot about this and i'm near to get it working, But I just don't get the Nozzle to touch the Bed after Probing. It just stays where it was after the Probe triggered.
The Servo retract as it should, but after that the printer won't turn any lower.
And therefor prints into the air...
I added my config.h - maybe someone sees my stupid mistake?
I am using an (PRotos) like the old Prusa and recently updated it a little...

Thanks a lot

How confident are you on the Z_PROBE_OFFSET_FROM_EXTRUDER number? If you make that number more negative, it will be printing closer to the bed.
Re: Bed Auto Leveling.. check this out
May 17, 2014 02:29PM
Thanks for the answer
If I change the value of Z_PROBE_OFFSET_FROM_EXTRUDER nothing changes after probing.
The nozzle stays at the high it was during probing. And there it stays during printing.
The nozzle should be near to the bed after I perform a G28, right?
Re: Bed Auto Leveling.. check this out
May 17, 2014 02:49PM
After the G28 is finished, the head will be at the Z_PROBE_OFFSET_FROM_EXTRUDER height from the bed and in the center. For a G29, it'll be the same, but at the last probing position.

Send a G1 Z0 to the printer, it will move the head to the bed. If both are hot the head should be just touching the bed.

In slicer's custom g-code, I also have a G1 X120 Y115 Z5 F5000. To put the head in the center and 5mm off the bed. The 5mm is so I can keep the head clean of oozing while it finishes heating up.
edn
Re: Bed Auto Leveling.. check this out
May 17, 2014 02:52PM
Quote
derletztename
Thanks for the answer
If I change the value of Z_PROBE_OFFSET_FROM_EXTRUDER nothing changes after probing.
The nozzle stays at the high it was during probing. And there it stays during printing.
The nozzle should be near to the bed after I perform a G28, right?

I don't remember the specifics of what happens with the un-enhanced G29 code. If you go to

[3dprintboard.com]

And load the Enhanced G29 code, I'll be able to answer questions about whether it is doing the right thing.

But you should also check your

#define Z_RAISE_?????????

settings.

Edited 1 time(s). Last edit at 05/17/2014 02:55PM by edn.
Re: Bed Auto Leveling.. check this out
May 17, 2014 04:20PM
Okay, the G1 Z0 Command does help. But it varies where zero is.
Maybe there is some connection that after the probing the z-axis move faster than it could and therefore lose some steps sometimes. How can i get this slower? It doesn't seem to be affected by the homing speed settings in the config.h

Whats wrong with my #define Z_RAISE_... Has it to be bigger? As big as my "Stick" for the probe is?

Do I have to activate the EEPROM Settings for the leveling? Where else does it save the values?

And how can I test if the leveling did actually worked? Just via printing or should it even work while manually moving the x and y axis?

As I am no good with Software I did not want to install the Enhanced G29 code, before understanding the usually one...
edn
Re: Bed Auto Leveling.. check this out
May 17, 2014 05:47PM
Quote
derletztename
Okay, the G1 Z0 Command does help. But it varies where zero is.
Maybe there is some connection that after the probing the z-axis move faster than it could and therefore lose some steps sometimes. How can i get this slower? It doesn't seem to be affected by the homing speed settings in the config.h

Whats wrong with my #define Z_RAISE_... Has it to be bigger? As big as my "Stick" for the probe is?

Do I have to activate the EEPROM Settings for the leveling? Where else does it save the values?

And how can I test if the leveling did actually worked? Just via printing or should it even work while manually moving the x and y axis?

As I am no good with Software I did not want to install the Enhanced G29 code, before understanding the usually one...

You do not have to have the EEPROM stuff enabled for the Auto Bed leveling. However, if you do, you can just get the configuration.h settings close and use the EEPROM to compensate. Without the EEPROM stuff, all numbers are taken from the settings you have in Configuration.h

You can test if the G29 worked by looking at the Bed Level Matrix.

First, go check out this post.... This may solve your problem with the Z-Axis:

[forums.reprap.org]


The Enhanced G29 directions are very clear and simple to follow. The Enhanced version provides lots of debug information so it is much easier to tell where the problem is. If you still have problems and can't figure it out on your own with the Enhanced Bed Leveling code, open a thread over there and people will jump in and diagnose what is going on with your setup.

Edited 4 time(s). Last edit at 05/17/2014 07:13PM by edn.
Re: Bed Auto Leveling.. check this out
May 17, 2014 10:25PM
Do I understand this right? Z safe homing is supposed to move the nozzle somewhere to the middle of the board after finishing the X & Y homing on the G28 command?
Re: Bed Auto Leveling.. check this out
May 18, 2014 06:29AM
Yep - mine homes with the z switch in the middle of the bed.
Re: Bed Auto Leveling.. check this out
May 18, 2014 04:12PM
Okay, I did everything as you suggested. Probing takes more time now but seems to be accurate.
Theres just one thing i don't get. After G29 the nozzle is a little bit higher above the bed than after a G28 (I send a G1 Z0 after both).
How could that be?
The height after G28 is perfect, but after the G29 it's about 1mm to high...

A FAQ would be great btw. Than people could help themselfs... Or is there something like this?
edn
Re: Bed Auto Leveling.. check this out
May 18, 2014 04:54PM
Quote
derletztename
Okay, I did everything as you suggested. Probing takes more time now but seems to be accurate.
Theres just one thing i don't get. After G29 the nozzle is a little bit higher above the bed than after a G28 (I send a G1 Z0 after both).
How could that be?
The height after G28 is perfect, but after the G29 it's about 1mm to high...

A FAQ would be great btw. Than people could help themselfs... Or is there something like this?

After the G29, all the position coordinates are corrected. It is possible the nozzle is at the correct location. Can you cut and past the whole dialog generated during the G29. I presume you are using the enhanced code. If so, do this: G29 n 5 v 4

And then, with that information, we will start giving it M114 commands and such to figure out exactly what is going on.

Edited 1 time(s). Last edit at 05/18/2014 06:18PM by edn.
Re: Bed Auto Leveling.. check this out
May 28, 2014 06:36PM
Quote
derletztename
Okay, I did everything as you suggested. Probing takes more time now but seems to be accurate.
Theres just one thing i don't get. After G29 the nozzle is a little bit higher above the bed than after a G28 (I send a G1 Z0 after both).
How could that be?
The height after G28 is perfect, but after the G29 it's about 1mm to high...

A FAQ would be great btw. Than people could help themselfs... Or is there something like this?

I've been having some problems with setting up auto bed levelling and I believe there is some new code on GitHub that will correct the G28 G29 difference [github.com]

Also if anyone is having trouble getting the nozzle to move down after a G28 or G29 send an M114 first. Repertier Host doesn't update the manual controls without it and seems to also block direct commands. Sending M114 seems to help me but seems like an odd thing to have to do.

Also if like me you would prefer to have your z move up before it retracts the probe on a G28 and keep the probe down during a G29 only deploying once before bed levelling and once at the end of the sequence try [github.com]

I still need to implement this last one but I'm hoping it will save my probe from scraping the bed when it retracts.
This is my first post so sorry if anyone has already said any of this.
Re: Bed Auto Leveling.. check this out
May 28, 2014 07:16PM
I have made microswitch sensor operated by electromagnet for auto bed levelling. Has anybody managed to control electromagnet instead of a servo? Especially on Melzi - using a fan switch transistor to do that?
I would appreciate any suggestions.
Re: Bed Auto Leveling.. check this out
May 28, 2014 07:38PM
Quote
otas
I have made microswitch sensor operated by electromagnet for auto bed levelling. Has anybody managed to control electromagnet instead of a servo? Especially on Melzi - using a fan switch transistor to do that?
I would appreciate any suggestions.

Go to this forum and ask there, it is more to do with this subject than here I think.
[3dprintboard.com]


[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci
Re: Bed Auto Leveling.. check this out
May 29, 2014 07:50PM
Thanks, but not much luck there. Never mind, I will perservere. I think the servo is a bit too wobbly and microswitch too inaccurate for this purpose for an accurate measurement. I am working now on optical, contactless switch, which does not need moving parts and retraction. So far I managed on the prototype 10mm clearance gap, 1 micron accuracy with 30 micron hysteresis. The idea is to mount it 4 mm above the nozzle level, leaving 6mm below the nozzle for the table clearance. Still need more work on the electronics. But in principle I am there.
Re: Bed Auto Leveling.. check this out
May 29, 2014 09:05PM
Quote
otas
Thanks, but not much luck there. Never mind, I will perservere. I think the servo is a bit too wobbly and microswitch too inaccurate for this purpose for an accurate measurement. I am working now on optical, contactless switch, which does not need moving parts and retraction. So far I managed on the prototype 10mm clearance gap, 1 micron accuracy with 30 micron hysteresis. The idea is to mount it 4 mm above the nozzle level, leaving 6mm below the nozzle for the table clearance. Still need more work on the electronics. But in principle I am there.

I would be very interested in your method, I would like to try that too Have you any more details that you can share?


[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci
Re: Bed Auto Leveling.. check this out
May 30, 2014 04:08AM
Thanks for your interest. I will shoot a short video and perhaps put it on Kikstarter as a component, to see what interest it generates. Then I will reveal it.
Re: Bed Auto Leveling.. check this out
May 30, 2014 06:14PM
You guys might like to check out some threads on the Ormerod forum. There has been a lot of work on height sensors for z-homing and auto bed levelling there. Here is a selection of threads on the subject:

[forums.reprap.org] (my original hack to the unmodulated IR height sensor supplied with the Ormerod, to add modulation)
[forums.reprap.org] (ultrasonic height sensing)
[forums.reprap.org] (capacitive height sensing)
[forums.reprap.org] (discusses several height sensing methods including inductive sensing, solenoid-operated contact probe, force-sensitive resistor, and differential IR)
[forums.reprap.org] (my original IR + ultrasonic + fan control + illumination hot end board, design files are at [github.com])
[forums.reprap.org] (test results on prototype differential IR sensor)
[forums.reprap.org] (my new differential IR + fan control + illumination hot end board)



Large delta printer [miscsolutions.wordpress.com], Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Bed Auto Leveling.. check this out
June 08, 2014 10:53AM
HI, My z0 is not adding the Z offset, ie the print head remains at the probe level, any ideas what I have missed?
Heres my config.h
and this is the output from the G29
SENDING:G29
SENDING:G1 F2000 X95 Y95
Bed x: 50.00 y: 50.00 z: 0.13
Bed x: 150.00 y: 50.00 z: 0.12
Bed x: 150.00 y: 150.00 z: 0.06
Bed x: 50.00 y: 150.00 z: 0.07
Eqn coefficients: a: -0.00 b: -0.00 d: 0.17
planeNormal x: 0.00 y: 0.00 z: 1.00
echo:endstops hit: Z:0.07

My z offset is -6.6
Re: Bed Auto Leveling.. check this out
June 09, 2014 11:59PM
Anyway to implement BAL with Melzi board? there isn't any port for servo on Melzi board..sad smiley

Edited 1 time(s). Last edit at 06/09/2014 11:59PM by zonerx.
Re: Bed Auto Leveling.. check this out
June 10, 2014 12:23AM
Quote
zonerx
Anyway to implement BAL with Melzi board? there isn't any port for servo on Melzi board..sad smiley

Have a look in the SmartRap forum, we are using no servo Auto Bed Leveing now. You may be able to do something similar.
SmartRap forum


[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci
Re: Bed Auto Leveling.. check this out
June 10, 2014 01:42AM
Quote
regpye
Quote
zonerx
Anyway to implement BAL with Melzi board? there isn't any port for servo on Melzi board..sad smiley

Have a look in the SmartRap forum, we are using no servo Auto Bed Leveing now. You may be able to do something similar.
SmartRap forum

Thanks Regpye, will check them out.
Re: Bed Auto Leveling.. check this out
June 10, 2014 06:34AM
Hi regpye could you possible link to how your servo less system works? Had a quick look in the forum but can only see the post which asks who's servo less and who isn't. No info on how it works. I know there are several ways to go servo less, just wondered how yours works, thanks.
Re: Bed Auto Leveling.. check this out
June 10, 2014 10:32AM
Have a look at this build, it will show you the whole machine being built. The details of the servoless system are a part of it.

Full build here of SmartRap servoless.


[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci
Re: Bed Auto Leveling.. check this out
June 10, 2014 12:13PM
Thanks regpye if I'd tried looking a bit harder I probably would have found it, not so easy navigating on my iPhone while my laptop is broken. Strangely you seem to have had the exact same idea I had for my mendelmax. I made a j head mount with a hinge and spring and used the hotend as the probe. I use hall o sensors as they can be set extremely sensitive so the slightest touch will activate the endstop, problem was I don't currently use a Bowden hotend and the retract was moving the hotend up and down. I hadn't spent much time designing it so I could probably improve the way it works with a bit more effort. I've switched to a servo activated probe for the moment but I'm trying to design a new lightweight x carriage/extruder that doesn't have a stepper motor on it and doesn't use a Bowden cable. Not sure if it's going to work yet but I'm hoping it will be a good alternative to my current set up.
Re: Bed Auto Leveling.. check this out
June 10, 2014 07:48PM
Quote
Brainscan
Thanks regpye if I'd tried looking a bit harder I probably would have found it, not so easy navigating on my iPhone while my laptop is broken. Strangely you seem to have had the exact same idea I had for my mendelmax. I made a j head mount with a hinge and spring and used the hotend as the probe. I use hall o sensors as they can be set extremely sensitive so the slightest touch will activate the endstop, problem was I don't currently use a Bowden hotend and the retract was moving the hotend up and down. I hadn't spent much time designing it so I could probably improve the way it works with a bit more effort. I've switched to a servo activated probe for the moment but I'm trying to design a new lightweight x carriage/extruder that doesn't have a stepper motor on it and doesn't use a Bowden cable. Not sure if it's going to work yet but I'm hoping it will be a good alternative to my current set up.

Sounds like a challenging idea but well worth following.
The only thing about using a Bowden is that it is light weight, otherwise I would be using it directly with an extruder and hotend combined.
How does the hall o sensor work? Is it magnetic?


[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci
Re: Bed Auto Leveling.. check this out
June 11, 2014 02:51AM
Quote
regpye

Sounds like a challenging idea but well worth following.
The only thing about using a Bowden is that it is light weight, otherwise I would be using it directly with an extruder and hotend combined.
How does the hall o sensor work? Is it magnetic?

I like how lightweight Bowden setups are and my nozzle probe would have worked a treat if I'd been using one as the retraction wouldn't pull and push the hotend up and down (I'm only talking 0.1-0.2mm) but it was enough to affect print quality. I don't want to switch to a Bowden as I want to be able to use soft filaments like ninja flex. I'm hoping to mount the extruder stepper on an x end and have a lightweight x carriage/extruder/probe combo so I can up my print speed.

Yes hall o sensors are tiny and very cheap and detect magnetic fields, they are also extremely accurate and don't wear out. I use them on the boards designed by rrd but you can just plug them into a servo lead and away you go. There are a couple of articles showing how they can be set up like that.

Edited 1 time(s). Last edit at 06/11/2014 02:52AM by Brainscan.
Re: Bed Auto Leveling.. check this out
June 11, 2014 03:21AM
Quote
Brainscan
Quote
regpye

Sounds like a challenging idea but well worth following.
The only thing about using a Bowden is that it is light weight, otherwise I would be using it directly with an extruder and hotend combined.
How does the hall o sensor work? Is it magnetic?

I like how lightweight Bowden setups are and my nozzle probe would have worked a treat if I'd been using one as the retraction wouldn't pull and push the hotend up and down (I'm only talking 0.1-0.2mm) but it was enough to affect print quality. I don't want to switch to a Bowden as I want to be able to use soft filaments like ninja flex. I'm hoping to mount the extruder stepper on an x end and have a lightweight x carriage/extruder/probe combo so I can up my print speed.

Yes hall o sensors are tiny and very cheap and detect magnetic fields, they are also extremely accurate and don't wear out. I use them on the boards designed by rrd but you can just plug them into a servo lead and away you go. There are a couple of articles showing how they can be set up like that.

Yes I have been using hall effect sensors for some time now, but never for the Z axis with auto bed leveling. I haven't worked out a good way to do it yet. Still thinking about that.


[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci
Re: Bed Auto Leveling.. check this out
June 11, 2014 05:04AM
I cobbled a prototype together from a bic pen, m4 bolt, m4 nut, spring and mounted it on a servo horn. Sorry I don't have any pictures but it's just a small spring loaded bolt with a magnet on the nut so when the bolt head touches the plate it moves the magnet closer to the hall o board which is mounted on the servo. I can fine tune it from the length of bolt and trim pot so i can make it really sensitive or have a few mm before it activates. It's surprisingly accurate even though it's quite crude at the moment. I'm going to try making a micro probe with a 1.7g linear servo once my laptop is working again.
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