Auto_Bed_Leveling: Enhanced G29 command

[DarkAlchemist]

well, if 84 puts it up against the stop shouldn't 90 slam it into it where it will just stop shortly afterward?

[Tachout]

I am wondering if you could put an end stop on one side, and a simple ball catch on the other to that once it swings down, it locks into place and then as it rotates back up, it just pops over the ball catch. I am really thinking about this idea as I am about to undergo this change on mine.

[DarkAlchemist]

I am wondering if you could put an end stop on one side, and a simple ball catch on the other to that once it swings down, it locks into place and then as it rotates back up, it just pops over the ball catch. I am really thinking about this idea as I am about to undergo this change on mine.

Hmmmm, I am not sure it would have enough force to pop it out to move it up and if it did then the force to move down would be greater than the ball so it wouldn't catch it. What I know to be fact is that these servos are not very precise. I can do 84 and 85 but there is no measurable difference. I have to go by 5, so it seems, to get the slightest bit of change. Not sure if that is the servo, the Arduino, or the code driving the servo.

edit: This is what I was going to originally do but couldn't figure out a few steps and this guy did it exactly. https://www.youtube.com/watch?v=UPeNtwEEcww his page http://www.marcoantonini.eu/doku.php...tock:bed_level

[Roxy]

well, if 84 puts it up against the stop shouldn't 90 slam it into it where it will just stop shortly afterward?

You would think that... My experience is that won't give you the answer you are looking for. I tried that. It didn't work for me. First, when you tell it to go past where it can travel, you get vibration some times. But the other problem is as soon as the power is turned off, there is enough force pushing it that it kind of bounces and goes backwards into the part of the range where it can travel. So it doesn't end up at the end.

It might be worth while for you to play with the M280 command. That way you can figure out what will work for your servo.

Hmmmm, I am not sure it would have enough force to pop it out to move it up and if it did then the force to move down would be greater than the ball so it wouldn't catch it. What I know to be fact is that these servos are not very precise. I can do 84 and 85 but there is no measurable difference. I have to go by 5, so it seems, to get the slightest bit of change. Not sure if that is the servo, the Arduino, or the code driving the servo.

edit: This is what I was going to originally do but couldn't figure out a few steps and this guy did it exactly. https://www.youtube.com/watch?v=UPeNtwEEcww his page http://www.marcoantonini.eu/doku.php...tock:bed_level

I like Delta Printers! I want one! But my guess is you are going to have an easier time getting your Z-Probe right just using a normal switch. Those Hall Effect sensors are picky. (at least, that is what everybody tells me) Is there something you can have your probe leg hit before the servo is out of travel? Because if so, then you just have to make sure the part of the switch that probes the bed is offset a little bit so the force to press the switch also rotates the probe leg into the stop.

Can you post a couple pictures of you Z-Probe and how it is mounted to the extruder?

[DarkAlchemist]

So that tweak helped! What I did on mine was have that bump hit the main extruder block so the probe can't rotate any more. And then I positioned the switch such that when the lever is getting pressed, it tries to rotate the probe a little bit into the stop so it stays tight against the stop for all of the points.

After your responses I am lost as how to achieve this if what I described above isn't it. Could you elaborate?

Let me show you my design with the physical stop now.

[Roxy]

Where does the servo go? Where is the probe leg and the switch. Just a couple pictures of your actual printer with the Z-Probe up and down would be good.

[DarkAlchemist]

you are looking at the inside where the arm/switch goes. 84 drops it (should hit that physical end) and up is towards you. This mounts to a Prusa I3 Rework right under the big gear using the 2 screws that hold in the J-Head.

[AbuMaia]

Here's a brainteaser/stumper I just encountered. On my printer, I have my Z offset at -10.9, with a Raise Before Homing distance of 13. When I home Z, once it's done M114 shows Z position at 23.9. Seems right, 10.9 + 13.

HOWEVER

If I then extend the probe and move the Z axis down 13mm, one would think the switch would be triggered, right? Nope. I have to lower the Z axis another 4mm to 6.9 to toggle the switch. Which is weird, because a different Z-offset measurement procedure I read gives me an offset of -4.1.

1. Home the Z. It will be above the bed but will read as zero position.
2. Lower nozzle to bed position. Use paper to get the correct bed space.
3. Send M114 from Pronterface to read the position.
4. The reading shown on the screen will be the exact value to put in the firmware for the offset.

It gets better.

After doing a G29, once it's done probing, I use Pronterface to lower the nozzle to the bed, with a piece of paper to check it's at the right height. S̶a̶m̶e̶ ̶-̶1̶0̶.̶9̶ ̶o̶f̶f̶s̶e̶t̶,̶ ̶y̶e̶t̶ ̶w̶h̶e̶n̶ ̶t̶h̶e̶ ̶n̶o̶z̶z̶l̶e̶ ̶i̶s̶ ̶o̶n̶ ̶t̶h̶e̶ ̶p̶a̶p̶e̶r̶,̶ ̶M̶1̶1̶4̶ ̶g̶i̶v̶e̶s̶ ̶m̶e̶ ̶-̶1̶6̶.̶ Nevermind, I just ran it again, and the 16 is correct, with the 5mm Raise Before Probing distance.

I'm at a complete loss as to what's going on here. Can you help me figure this out?

[DarkAlchemist]

Well, here is something I have been wondering about for a while now but what is the purpose behind raising and lowering the arm between each probing? I see absolutely no reason for it and on a delta printer it doesn't do that. Makes very little sense to me to keep raising and lowering the arm/switch between probings when you can just lower the arm (before probing the first point), keep everything else the same, and after the last point is measured raise the arm.

[RobH2]

There is a post here that talks about that so you can stop that default action. I know this is a long thread but it's here somewhere. I used it and my arm lowers, takes 9 probes, and then goes up to begin printing.