Adjusting the Z height with the EEPROM and saving.

OK, First let me apologize if this is like basic 101 stuff. I am having a brain fart. so, here is my issue..i think.

With my Makerfarm pegasus 12, i have set up auto bed leveling and activated EEPROM settings. After the bed leveling program (witch works great) the print starts. the print head gets too close to the bed and almost blocks the filament from coming through. it's not for about 5-8 passes that i can see a good filament. I know I want to "squeeze" the first layer to the bed and in my slicer, I have first layer set to 95% to do that. I remember seeing a video or reading somewhere that to get a good spacing from the bed and extruder, check the z reading on the LCD for the first layer and see what it says. then adjust z offset in the eeprom, then save.

If I get -.10, do I then just add .10 to the z offset? or should I stop the print, leave the extruder where it is in X and Y, then, with the lcd, raise Z until a paper fits under it and then check THAT reading and adjust my z height?

Thank you for your patience on reading this, but I cannot seem to find the answer I am looking for probably because i can't figure out the correct question.

Happy Printing!

You will need to measure your Z offset (as you mentioned, by using a piece of paper, and checking the Z position on the LCD) AFTER you run the G-29 ABL command. I run a G-28 to home everything, run ABL, then position my nozzle at 150/150 for X/Y to center in my 12" bed. After this I place a piece of paper (mine is thick, measures .15mm) inbetween the nozzles and the bed. I lower the nozzle until the paper just barely clears (just barely enough resistance to be noticeable), and calculate my offset based on this number.

For example, if my Z offset is currently 4.00mm, and after homing and running ABL, I center the nozzles and slowly lower Z to 0 (.1mm increments). This is where you get Z offset adjustments.
- If Z > 0 on the LCD and you cannot get the paper under the nozzle, raise Z by .1mm until you can fit it under there. Then take the Z position, and subtract it from your current offset. Say if Z is .2mm on the LCD when you fit the paper under successfully, you would then set Z offset to 3.80mm (4 - 0.20)
- If Z = 0 on the LCD and the nozzle is nowhere close to the paper, you will need to raise your Z offset (i.e. add to the 4.00mm offset) until you get to the appropriate offset.

Make sure you save it in motion settings and then save settings to EEPROM to store your changes. I usually make note of mine to update my firmware for next time also, to save time.

If you are running a recent RC of Marlin, you might want to turn on Z-BabyStepping. You can just dial the nozzle up or down until everything is perfect. And you can then cross that number (for how much you changed the Z-Height) over to your Z_PROBE_OFFSET_FROM_EXTRUDER.

Clever! I will have to check out RC7, it seems Marlin updates to a new RC about the time I think I have a particular RC (I'm usually at least one behind) dialed in :p

Hi

Ok, using the *standard* old version of Marlin:

1) Do a manual adjust on the Z and get it within about 0.1 to 0.3 mm above the glass. This is all by adjusting the Z end stop.

2) Run the bed level on a heated machine (heated bed hot and hot end hot) Use a piece of paper, do it from the LCD

3) Do a G29 command from your computer. Record the numbers it spits back

4) Wait a bit and repeat the bed level, repeat the G29. The numbers should be the same, if not start digging into what's wrong with the printer

5) If the numbers repeat, save them using the "store memory" function under the "control" menu

At this point, the only thing you need to adjust for is the thickness of your paper. Unless you have a very unusual piece of paper, that will be in the -0.05 to -0.25 mm range. It has nothing to do with the data from the G29 it only relates to your paper. Make sure that your G code has the proper default info in it to run the bed level stuff. All of the details are in the Pegasus 12 instructions.

If you need to dig into the printer, I put up a monster long series of posts about how to do all of that.

Bob

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Originally Posted by dustmann

Clever! I will have to check out RC7, it seems Marlin updates to a new RC about the time I think I have a particular RC (I'm usually at least one behind) dialed in :p

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You can get ahead by bringing up the devel_UBL branch. That is going to be the code base for Version 1.1.1 You can edit the Z-Height of any position on the bed.

Hi

If you switch from the "stock" MakerFarm Marlin to something newer, be prepared to spend some quality time getting the config right. You are going up quite a ways in terms of Marlin versions. It's well worth doing, just don't try to do it without digging into the config's. While you are in there, set up the X,Y and Z limits to correspond to the ones on your actual build.

Bob

At the moment, the only thing you need to adjust the thickness of your paper. Unless you have a very unusual piece of paper, which will be in the range of -0.05 to -0.25 mm. It has nothing to do with the data from the G29. It relates only to your paper. Make sure your G code information in its appropriate default to run on these beds.

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Thanks Everyone. These instructions saved me quite a bit of time. All is good now, but I did come across one other little issue and I think I figured out how to solve it. After a coupe good test prints, I found my servo (g90) was jittering and during abl, Instead of going to rotation 155 (perfect straight up and down) it would go a little too far. This caused the micro switch to touch on the body first, flex the bed, then trigger the switch. This only happens during abl, so I beleave it is getting and interference signal from all the wires it's grouped with from the print head. I turned on the "servo off" setting in configuration H, but no change. I am thinking of adding a ferrite ring to the servo wire to see if that cancels out the jitter. At home when nothing is happening, I can send a prionterface command to raise and lower serve abl arm. 70, 155. It's perfect. Only while other things are running (filament heat and fan) does it not go perfectly into position.

does this make sense to add a ferrite ring?

Hi

What you describe is normal with a "cheap" servo. The jitter will change with temperature on many of them.

Bob

it was fairly cheap. I also found that it "over runs" a couple degrees. For example, my straight up and down is 155 in the servo support in Marlin configuration H. Using prionterface, I select m280 p0 s155 and the servo actually goes beyond like 157-158. If I run the command again, it straightens out to 155. If I repeatedly run the command, it "shakes". So, I was wondering what would be a good servo. I found this one on adafruit. https://www.adafruit.com/products/1143

any thoughts?

Hi

Back when I did my ABL stuff, I bought a variety of servos at a variety of prices. Eventually I found some expensive ones that did not randomly bounce around. They still had temperature sensitivity in my setup. I spent some quality time on the R/C forums digging into what others had seen on the same servos. Unfortunately that was after I had bought the majority of them. Seems that a lot of people see the same things on the same servos ...

My ultimate decision was that a fairly expensive (3X the price) servo was the way to go and that warming everything up for "a while" was part of what had to be done.

Quote:

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Originally Posted by Youngjedi

So, I was wondering what would be a good servo. I found this one on adafruit. https://www.adafruit.com/products/1143

any thoughts?

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All of the Tower Pro servos seem to jitter. Out of desperation, I bought different ones from different vendors. This one seems to work without jitter: http://www.ebay.com/itm/262564045761...%3AMEBIDX%3AIT

Odd with the jitter. I use the exact same model servo on my makerfarm 10 and it works fine after I set the power delay to 300 in the ramps configuration. for some reason, the Pegasus 12 has an issue with it. I am going to isolate the wiring from the servo to the ramps from all the other wires to see if that helps. Hopefully just adding a ferrite ring may do the trick as well.

Thanks Roxy for the Link...I'll check it out.

Hi

I would spend time grounding the printer frame and the rest of it before I'd go crazy with common mode chokes.

Bob

Well, It took an hour after I got home from work, But I think I solved it. My original config was to do the abl at the extended 155 servo number. Also turn off power to servo 300 Ms. After fussing around with it, I began to think that the servo was "overshooting the 155 mark by about 3 degrees. I said "to hell with the jitter, I don't care. I disabled the servo off command so there would be power to the servo all the time. I tried again and (with the jitter) it was still overshooting. I began to realize that maybe it's not overshooting, maybe that wrong angle is actually 155. So I changed it to 153, And ran 4 g29 commands. The servo jitters ever so slightly, but it is holding the correct position throughout the abl.

doing a test print now and it is looking great so far.

I want to thank everyone who help chime in on this. It took me in directions that I did not think about. If the print turns out nice, I'll post a picture.

This is a great forum (Makerfarm)...I hope more and more people join. Colin has a great product!

Charlie

Update....I printed an r2 cookie cutter. The ABL worked perfectly, and the print came out absolutely perfect. Being a cookie cutter, printed at a medium definition...nothing special.