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Confused about Z-axis, platform, leveling and Autohome


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Posted · Confused about Z-axis, platform, leveling and Autohome

Newb with pre-assembled rig. Obviously I understand what the Z-axis is for, and how to adjust it with the front control. I've got both "print in air" and "rip into the paper" results, obviously I need some adjustments.

I'll try to spell out what's confusing me:

1: When you put the platform onto the 4 pegs, there's 2 ways it can fit. I assume there could be a slight difference (?), and I'm not sure which way it was calibrated when assembled. Is it "push down and slide left", or "push down and slide right" ?

2: My wooden platform is quite warped (lower on the left than the right), but it looks like the screws were adjusted to account for that. But is this normal?

3: I've tried the Autohome feature with both orientations (slide to left, slide to right) of the platform. In one of the orientations it doesn't seem to quite touch the platform after auto home (I can move paper in and out), but it does dig into the paper if I try to print. I seems like it touches it, then backs off, the goes back a bit.

But trying the platform the the other way, autohome seems to make contact and still try and push for a bit more. Also when I try to manually adjust the Z axis, it doesn't seem to go either way.

4: There seem like 3 or 4 logical limits on the Z-axis and this is likely my confusion.

* There's the limit switch

* There's what you get when you do Autohome

* Maybe there's also some adjustment that's done in Autostart?

* There's what you can adjust on each corner with the screws

* There's an option in the Prepare menu to "set new home" (I forget the wording)

* Then there's the level the software sets it to when it tries to print

* And all of this is potentially "x 2" depending on which 180 degree choice you make when putting the platform on

I haven't seem a really good complete explanation on the wiki about how all these things interact, and I'm guessing there's some critical wisdom that I'm missing. Also, there's probably a need for a separate discussion for people who bought a pre-assembled unit and what the state of it is, I'm not sure.

5: For a pre-assumbled unit, these are the assumptions I was making, but maybe one of them is wrong:

* I assume the limit switch and leveling screws were set correctly since there was a test print on the platform. I understand that I might need to make some adjustment over time?

* I assume the Autohome was "working", however it's setup or whatever it's rules, and that I'm supposed to use it.

* I thought that the software would leave the Z axis alone when I started printing, but it didn't. Later I did autohome on the control panel, then did a "reset axis", and that was the closest that I got to working. But shouldn't autohome do that anyway? I don't understand the coordination of Autohome, Autostart, "reset home" function, and what the software is doing.

Current status: I think manual control of the Z-axis is acting strangly, so I decided to stop and post.

When I manually try to move the Z-axis from the front panel it doesn't seem to move up or down anymore, but I do hear motors.

Oddly even increasing the Z-axis, to more the platform down, doesn't seem to move much.

*BUT* if I do Autohome it is able to move, so clearly there's still something working.

A final question / survey: When you put your plexiglass onto your screws, do you push down and then to the Left, or to the Right? And is there a standard for this?

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    Posted · Confused about Z-axis, platform, leveling and Autohome

    First, congratulations on one of the first pre-assembled Ultimakers.

    Both directions of platform fitting work. But it's best to always do it the same.

    Yes, the wood warps. It warps during assembly. But it also warps a bit over time due to moister getting in the wood. Wood always works a bit.

    Most likely, after transport, you will need to level out the platform again. We need to assemble a "user guide" explaining the first steps after unboxing your new pre-assembled printer. We noticed a bit late that this was a huge oversight from us and it's in the work.

    For the assumptions:

    * The limit switch should be right, but the bed will need some leveling again after transport. Cura should help you with this with the bed-leveling-wizard.

    * Autohome should put the printer-head to the front left corner with the nozzle on the printerbed

    * The "reset axes" really does nothing (it sets the current position as 0,0,0. But Autohome also does that in a better way), as well as "autostart", those are a bit of odd features and have no real use so ignore them. They will be left out from the menus in the next firmware.

    However, if I read your final bit as a "normal assembled" ultimaker, I would give the advice to check your Z screw coupler. It's the aluminum round bit that connects the motor and the screw. If you try to move the Z and you can hear the motor, check if you see the coupler rotating and the screw is not rotating. Or the motor rotating and the coupler not rotating. Because it really sounds like this part has come lose during transport.

    There should have been a small hex key with your machine to tighten the screws in there in case they came lose (they are the only smaller screws in the machine that cannot be tightened with the standard hex screwdriver)

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    Posted · Confused about Z-axis, platform, leveling and Autohome

    Thank you for the clarification of the various Z-axis functions.

    I didn't see a hex key in the packaging, just the one regular size tool, tape, etc.

    If you know the exact type / size of tool I can probably get it locally (I'm guessing metric)

    FYI: the reset axis did seem to act differently at one point than autohome, and was the closest I came to getting a print. I had been trying to print from Cura and had cancelled a bouple times. Then I had done autohome, and then printed from Cura. When Cura started printing, it moved the platform down and was printing "in air". So I cancelled printing, did autohome again, then this time "reset axis", then printed from Cura. It came a lot closer that time. Maybe Cura print / cancel / print / cancel puts the software in some odd state, so that autohome and reset axis act differently? Just a theory.

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    Posted · Confused about Z-axis, platform, leveling and Autohome

    When you print from cura, the code that runs does a autohome followed by a reset axis. Overriding anything you did from the LCD panel.

    You should have had this key with the kit:


    But it could also be that there is electrical interference on the bottom Z endstop. Which is pretty rare, but I've seen it before on one of our pre-assembled kits. You could try disconnecting the bottom Z endstop from the electronics.

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    Posted · Confused about Z-axis, platform, leveling and Autohome

    Make sure you are using Cura version 12.12. On the expert menu, select "Run bed leveling wizard..." It guides you through the adjustments. Basically, you turn each of the 4 screws at the corners of the bed in order to adjust the height of the four corners. When the corners are even, the middle will be even. That bed leveling wizard makes it easy to tell when they're even.

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    Posted · Confused about Z-axis, platform, leveling and Autohome

    Hi David,

    Re. the tool in picture


    If I got it, it's been misplaced. Can you tell me the spec? (would be good to know anyway)

    Or maybe to an Amazon product page?

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    Posted · Confused about Z-axis, platform, leveling and Autohome


    Looks like mine's a 1.5 mm so the smallest in that set ought to work...

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    Posted · Confused about Z-axis, platform, leveling and Autohome

    Ah, I may actually have one of those, thanks!

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