Easy "Manual" ZProbe Calibration

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Easy "Manual" ZProbe Calibration

Post by artexmg »

Hi Folks, I am not sure if a "manual" Zprobe calibration method had been discussed before, but it is new to me, and worked like a charm!

I just finished building my Rostock Max V2 -Night Fury- (I need to update my building log: http://forum.seemecnc.com/viewtopic.php?f=42&t=5814" onclick="window.open(this.href);return false;), and started the daunting calibration process. But, instead of going down with the typical back and forward adjustment of the endstop screws, I used EXCLUSIVELY EEPROM values to get the bed flat.

Maybe I was just pure lucky, but after about 15 - 20 mins calibrating, I got it right. You can see, this is the first print EVER for my new Rostock. Take a look, the bed is FLAT. Never get this flat as easy with my old V1, using the original procedure. Of course, it has to be that the new V2 is more accurate in is build than V1 as well.
200m diameter calibration
200m diameter calibration
Here is what I did. It is very similar to Geneb's procedure, just using the EEPROM instead of screws and doing some simple calculations for Horizontal Radius.

Before anything, started by getting the Z-Height right (using geneb's procedure described in manual). Then, start the calibration with Z tower:

1. Ran the "Script 1" (or whatever script you are using for Tower Z) to get Z tower height. Yes, you should set Z5 or so the first time, just as a precaution to avoid hitting the borosilicate glass :-)
Script 1 (for tower Z)
Script 1 (for tower Z)
2. Using the "Z position" option from Advanced Settings menu, move the nozzle until you get it down to the bed (yes, use the paper method). Then write down the offset value for this tower. In my case, it was -1.15 mm.
Using the paper!
Using the paper!
offset in mm
offset in mm
3. Convert this offset value, from mm to steps. For this, get the "steps per mm" from the EEPROM (it is 80 for my V2), then, simple multiply this value by the offset in mm, then, invert the sign of the result (or, simple, multiply it by -1) this is

-1.15mm x 80steps/mm x -1 (just to invert the sign) = +92 steps

4. Get current value placed in EEPROM "Tower Z endstop offset [steps]", then, and add this to the value from step 3. For the first iteration, the original offset value would be ZERO. However, in the following calibrations, this value would be the previous offset entered. I was in my second calibration, then the original offset was 200 steps
current Z offset value in EEPROM
current Z offset value in EEPROM
The new offset value would be:

200 steps (original offset value) + 17.6 steps (current offset) = 217.6 steps (new offset)

Store this new offset in the EEPROM variable, overwriting the original value.

5. Re-run Script for Tower Z, and re-asses the offset. It should be zero, or very close to zero. If it is not zero, then get the offset value in mm (as in point 2) and then convert it to steps (as in point 3) and re-calculate the new offset value, as in step

After Tower Z is OK, repeat the same points from 1 to 5 for Towers Y and Z.

6. Now, run the Script 4 (or simple G28 followed by G0 Z0) to get the Z-height. As you know, it could be above or below 0 (NEVER zero :-) ). Use the "Z position" from Advanced Settings menu to get the offset value in mm. Write this value down, will be used in step 8.

Now, as explained in Geneb's manual, you have to modify the value in the EEPROM for "Horizontal Radius [mm]" by 0.5 (adding or subtracting it to the original Horizontal Radius).

7. Get back to re-calibrate the towers, but this time, you do not need to adjust one by one. You can get the three offset values first, and then enter all of them at once in the EEPROM (remember to invert the sign and to add this value to the original offset value in the EEPROM). You can do it one by one, but if you do it at once you can time.

8. Get the new Z-height (G28 + G0 Z0 or script 4). If not zero, then get the current offset (again, using "Z position" option). Then, get the variation in offset from the original one (from step 6), and the new one.

Delta = Z offset Step 6 - current Z offset (Important, get the absolute value => NO SIGN!)

Use this delta to calculate the new new Horizontal Radius:

New Horizontal Radius = (0.5 * current Z offset) x Delta

NOTE: this DELTA value is the mm that your nozzle will move with 0.5 variation in "Horizontal Delta Radius", it is important to write it down, as will help you to speed this process in the future.

9. For me, it was all, at this step my bed was flat.

I just finishing a second print (actually, the third, as the second ended when I tried to read the EEPROM to while printing :-) ). This calibration print was the larger one, not only 200mm as the first posted. You see two points were the print is messy, but believe me, it was due that I didn't spray enough aqua net, as the first layer (0.2mm at 100%) was printed perfectly over the entire bed!
New print calibration
New print calibration
and, here is the calibration cube -third print!- (25mmx24.95mm x 25.06mm):
Holly Cube!
Holly Cube!
Not bad For sub 30 mins calibration. I am loving my Night Fury!! ;-)


I will try this for my "old" printer and report back if works the same ... but has to be other day :-)

Cheers!
Art
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Re: Easy "Manual" ZProbe Calibration

Post by artexmg »

Well, I tried the same method in my "old" RM V1, and ... it worked as well!

I was able to refine the steps, so, in 6 iterations I was done, with the bed flat ... as flat as V1 allows, of course :-)

What I love is:

1- no need to touch the screws!
2- no need to go tower by tower, but all towers at one time
3- minimum guessing in Horizontal Radius, as you are able to get the ratio of mm per value (in my case, it is not 1:1)

So, I thing this could be incorporated in Matter Control and make life even easier?
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Re: Easy "Manual" ZProbe Calibration

Post by artexmg »

By the way, I do not know if it is only me, but while calibrating, I had noticed a consistent "buzz" that changes in tone as the nozzle gets close to the borosilicate plate. I had been able to notice the changes by the 0.01mm, once it is close enough (0.05 mm above the bed).

I get the same in both of my Rostock. I am using E3V6, so, maybe is the metal + heat + good waves (ok, this not)?

I had been able to get the nozzle at 0.1 (+-.05) consistently using only MY EAR ... as soon as I have some free time, I will try to get the waves in a sensor (sound? static? ultrasound?) and see if it couldbe use for leveling ... but, getting free time is almost impossible! :-)
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Re: Easy "Manual" ZProbe Calibration

Post by teoman »

Thank you very much for the writeup.

I was thinking there should be q computer based method to do the calibration. I will try this to finetune my printer when I get home.
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Re: Easy "Manual" ZProbe Calibration

Post by teoman »

Interesting.

So it works similarly to an afm probe.


Let us know how your experiments go OR, what you want experimented and I may be able to help out.
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Re: Easy "Manual" ZProbe Calibration

Post by artexmg »

teoman wrote:Thank you very much for the writeup.

I was thinking there should be q computer based method to do the calibration. I will try this to finetune my printer when I get home.
I will share (once at home, as I do not have it here) my spreadsheet. Nothing that you cannot create, but will help you to enter your data and get the idea faster; then you can create something more sophisticated.

It could, ultimately, be introduced as a routine in the firmware (oh, if just had enough time to deep dive into the code! :-) ), being you the "probe" and entering manually the results. Of course, an integrated probe is better, but, if not, this would be the second best option.
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Re: Easy "Manual" ZProbe Calibration

Post by artexmg »

teoman wrote:Interesting.

So it works similarly to an afm probe.


Let us know how your experiments go OR, what you want experimented and I may be able to help out.

Hey! that observation is very interesting, as one of the materials used to build AFM is, actually, borosilicate! ha!

So, probably the principle is something similar? , just in a bigger scale ( could we now start using the rostock for scanning nano-particles as well?? hahahaha, that would be awsome!!! :-))

not sure what experiments to do, but I was thinking, for starters, try to use all transducer I have at hand, and see if I can retrieve a signal.

I believe that just by "listening" at the surface of the borosilicate plate I could get something, but it is just my guts. It would be really good if you could test if you can detect by ear that vibration. I start listening when manipulating the Z-height with the dial, once the nozzle is 0.03 mm close to the bed, at temperatures BED 195 -200 Celsius and Nozzle 70 -75 (verified with external thermocouple). It changes (not sure if frequency or intensity, but definitely something changes) until it touches the glass. After that, I cannot distinguish a difference.

If you were able to listen to that, I will know, at least, that is not my imagination :-)

as I posted, I am using a hot end E3D V6 (all metal), with a nozzle 0.4mm (the one with the V6 version). I had not noticed anything before, when I was using a V5 of the same hot end, but that could be due to just I didn't pay enough attention.

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Re: Easy "Manual" ZProbe Calibration

Post by artexmg »

artexmg wrote:
teoman wrote:Interesting.

So it works similarly to an afm probe.


Let us know how your experiments go OR, what you want experimented and I may be able to help out.

Hey! that observation is very interesting, as one of the materials used to build AFM is, actually, borosilicate! ha!

So, probably the principle is something similar? , just in a bigger scale ( could we now start using the rostock for scanning nano-particles as well?? hahahaha, that would be awsome!!! :-))

not sure what experiments to do, but I was thinking, for starters, try to use all transducer I have at hand, and see if I can retrieve a signal.

I believe that just by "listening" at the surface of the borosilicate plate I could get something, but it is just my guts. It would be really good if you could test if you can detect by ear that vibration. I start listening when manipulating the Z-height with the dial, once the nozzle is 0.03 mm close to the bed, at temperatures BED 195 -200 Celsius and Nozzle 70 -75 (verified with external thermocouple). It changes (not sure if frequency or intensity, but definitely something changes) until it touches the glass. After that, I cannot distinguish a difference.

If you were able to listen to that, I will know, at least, that is not my imagination :-)

as I posted, I am using a hot end E3D V6 (all metal), with a nozzle 0.4mm (the one with the V6 version). I had not noticed anything before, when I was using a V5 of the same hot end, but that could be due to just I didn't pay enough attention.

Regards
Art
It sounds crazy! but, using the same principle as a Non Contact Atomic Force Microsocope (N-C AFM), it could be possible to put the signal trhough an amplifier and measuring FM or AM ... sounds like a nice project to have :-)
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Re: Easy "Manual" ZProbe Calibration

Post by artexmg »

Well, I tried to see if I could get anything from bare bone oscilloscope, and ... get nothing :-(

But, now I think that is something mechanical, if I touch the arms (I have the CF from tricklaser), I feel the vibrations coming from the base, so, this vibration is conducted to the nozzle (in a way, concentrated??). Probably, when the nozzle touches the glass, it creates a resonance effect?

Well, I do not know, I am just guessing, but I can hear (very, very weak though) something changes when the nozzle gets very close. It is more like a very low humming, that changes in tone/volumen. Am I just getting too much ABS dissolved in my brain? :-)

Cheers!
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Re: Easy "Manual" ZProbe Calibration

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I just downloaded an app called android spectral audio analyzer.

I will use it ehen I return from vacation.

That could help a lot.

Do you think you are hearing the pwm frequency?
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Re: Easy "Manual" ZProbe Calibration

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teoman wrote:I just downloaded an app called android spectral audio analyzer.

I will use it ehen I return from vacation.

That could help a lot.

Do you think you are hearing the pwm frequency?
Nice! i will download it myself and see what can I get.

Even though everything is possible, I do not thing that I am listening the pwm frequency, as it is audible only when getting close to the bed, and changes with every step in the manual dial. I am more inclined (I want to believe! :-) ) that it is the vibration generated by the Power Fan, transmitted by the towers, going through the arms, all the way to the tip of the nozzle, then, entering in resonance (maybe??) and amplified when touching the glass. But, it is a pure guess, nothing else :-)

Still, no matter what is it, if I am able to get a clear electrical signal out of that "sound", I could use it as my probe.
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Re: Easy "Manual" ZProbe Calibration

Post by teoman »

For some reason, the Z tower endstop offset is being ignored.

Because i am lazy i found a new trick (and being a dumbass this is probably the problem). Anyhow, if you are too low with the hot end, then you can just use the Repetier to move the hotend up, and it shows you how far above you are from the bed.

Every thime i was 0.4mm below the bed, sqeezing the paper, and i lifted it up by 0.4 mm (by 4 clicks on up 0.1mm) and got the tightness i wanted. However, after 5 repetitions of scrip1 and raise i noticed that i was too far down by 0.4mm every time. So i put a 1 in front of the offset value and repeated the process and again i was 0.4 mm too low. So something is not quite happening correctly.
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Re: Easy "Manual" ZProbe Calibration

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I tried the frequency analysis with my phone.

There is an artifact at approx 19kHz that goes up and down with every raise of 0.1mm. When the probe touches the hotbed it significantly decreases. However, the differences are not so great that it would be easy to detect it from the phone or software. Just by looking at the frequency analysis on the display i would not be able to determine the distance or determine contact.
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Re: Easy "Manual" ZProbe Calibration

Post by artexmg »

teoman wrote:For some reason, the Z tower endstop offset is being ignored.

Because i am lazy i found a new trick (and being a dumbass this is probably the problem). Anyhow, if you are too low with the hot end, then you can just use the Repetier to move the hotend up, and it shows you how far above you are from the bed.

Every thime i was 0.4mm below the bed, sqeezing the paper, and i lifted it up by 0.4 mm (by 4 clicks on up 0.1mm) and got the tightness i wanted. However, after 5 repetitions of scrip1 and raise i noticed that i was too far down by 0.4mm every time. So i put a 1 in front of the offset value and repeated the process and again i was 0.4 mm too low. So something is not quite happening correctly.
Humm .. probably you do not have the correct steps per mm set in firmware? I my "old" V1, the value was incorrect, and was not getting 0.1mm per click, until I changed the value.

Or probably is it something totally different, this is the beauty of playing with new technology, you never know!! :-)
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Re: Easy "Manual" ZProbe Calibration

Post by teoman »

I was set to 80, just like yours.

And it does seem like i am raising it about 0.4mm.


So i am a bit puzzled.


Are you using the newest firmware?
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Re: Easy "Manual" ZProbe Calibration

Post by teoman »

Trying the Y tower, and the offset also seems to be ignored.


Is there a way to enable the offsets?
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Re: Easy "Manual" ZProbe Calibration

Post by teoman »

Check your X tower offset.


I am still checking but it may be that it ignores negative values.

*** EDIT.


I used your method to calibrate my Rostock. Something had gone terribly wrong with my initial calibrations. The z height was off by 5 cm. Yet it still printed but proportions were off by %1 in x and Y and %10 in Z.

On my machine, the offsets only accept positive values. Putting in negative values is perceived as 0 by the software.


THANKS A LOT!
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Re: Easy "Manual" ZProbe Calibration

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teoman wrote:I tried the frequency analysis with my phone.

There is an artifact at approx 19kHz that goes up and down with every raise of 0.1mm. When the probe touches the hotbed it significantly decreases. However, the differences are not so great that it would be easy to detect it from the phone or software. Just by looking at the frequency analysis on the display i would not be able to determine the distance or determine contact.
But ... there is something that changes, it is good to know that I am not crazy! (that crazy, at least :-) )
Maybe with an amplifier ... will see ... time is so scarce! :-)
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Re: Easy "Manual" ZProbe Calibration

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teoman wrote:I was set to 80, just like yours.

And it does seem like i am raising it about 0.4mm.


So i am a bit puzzled.


Are you using the newest firmware?
I am using Repetier 0.91 firmware.

Regarding steps per mm, be careful, as it is not automatically 80, but it depends, you have that this parameter is given by

#define AXIS_STEPS_PER_MM ((float)(MICRO_STEPS * STEPS_PER_ROTATION) / PULLEY_CIRCUMFERENCE)

with

#define PULLEY_CIRCUMFERENCE (BELT_PITCH * PULLEY_TEETH)


In my "new" (or V2) I got 80, but in the "old" (or V1), the result is 106.6667.

This due to the pulleys are, in V1, 15 teeth, and in V2, 20 teeth. Everything else is the same.

So, rule of thumb, (assuming you have the stock Nema Motor with 200 steps/rotation, GT2 with pitch 2mm and 16 microsteps) if you have a 20 teeth pulley, then Steps per MM = 80, if 15, then Steps per MM = 106.666666667

I believe you are safe, as your built is not as "old" as mine (almost 1 year old!), but better safe than sorry.
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Re: Easy "Manual" ZProbe Calibration

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teoman wrote:Check your X tower offset.


I am still checking but it may be that it ignores negative values.

*** EDIT.


I used your method to calibrate my Rostock. Something had gone terribly wrong with my initial calibrations. The z height was off by 5 cm. Yet it still printed but proportions were off by %1 in x and Y and %10 in Z.

On my machine, the offsets only accept positive values. Putting in negative values is perceived as 0 by the software.


THANKS A LOT!
Glat that it helps!

It is weird that your machine does not accept negative values. It should be the firmware, for sure. I am using (as I wrote in the previous post) Repetier Firmware, 0.91. Probably you are using 0.8x
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Re: Easy "Manual" ZProbe Calibration

Post by artexmg »

teoman wrote:Check your X tower offset.


I am still checking but it may be that it ignores negative values.

*** EDIT.


I used your method to calibrate my Rostock. Something had gone terribly wrong with my initial calibrations. The z height was off by 5 cm. Yet it still printed but proportions were off by %1 in x and Y and %10 in Z.

On my machine, the offsets only accept positive values. Putting in negative values is perceived as 0 by the software.


THANKS A LOT!
Ah, by the way, I said I would share my spreadsheet, here it is.
Rostock Calibration Spreadsheet V0.1.xlsx
(18.15 KiB) Downloaded 411 times
Is silly, nothing complicated to do, but it helps me to get the thing calibrated very fast, 30 mins max, if I want to get fancy, down to the 0.01 mm :-)

You will need to change the initial values for your printer (Steps per mm and Horizontal Radius). My both printers have a "ratio" of 0.13mm per every change in 0.5 in Horizontal radius, so, you can start with this value. This is how it looks when you start

Before calibration, all offsets are zero.
Before calibration, all offsets are zero.
Then, you just have to enter the offset in mm, you will get the "new offset" value to set up in the EEPROM, script, get offset and repeat :-) This is how it looked in mine after the last time I used it
Screen after calibration is done.
Screen after calibration is done.

As you can see in this pic, I have a line in the spreadsheet. I put this only to get to know when the towers were aligned BEFORE I started changing the Horizontal Radius.

Once you get the three towers aligned and ready to modify the delta radius, you will use then the offset in mm in the "Height" section. It worked for me :-)

Cheers!
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Re: Easy "Manual" ZProbe Calibration

Post by teoman »

I should have the latest version of everything. Printer bought in June and I started assembling it on the 15th of July, downloaded all software on the 20th or so. Still printing the fan shroud.

And last night it was printing nicely until it decided to Picasso on me.
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Re: Easy "Manual" ZProbe Calibration

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teoman wrote:
....

And last night it was printing nicely until it decided to Picasso on me.
...

Hahaha ... it should be a verb, You've been Picassed ;-)
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Re: Easy "Manual" ZProbe Calibration

Post by artexmg »

teoman wrote:I should have the latest version of everything. Printer bought in June and I started assembling it on the 15th of July, downloaded all software on the 20th or so. Still printing the fan shroud.
...
It puzzles me that you cannot use negative values, if the firmware is the same, then the behavior should be the same.

Anyone there who knows if there is a setting to allow negative values?
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Re: Easy "Manual" ZProbe Calibration

Post by artexmg »

artexmg wrote:
teoman wrote:
....

And last night it was printing nicely until it decided to Picasso on me.
...

Hahaha ... it should be a verb, You've been Picassed ;-)
I bet that, if Picasso were alive, he would use a Rostock Max to create his prints ;-)
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