Can't get Z axis close enough to head, Pre-assmbled Unit

[ttennebkram 0]

The bed often won't get close enough to the print head even if I loosen the screws a lot. I loosen the screws to where they almost fall out.

 

I tried jamming some folded paper between the plywood and plexiglass to force it, but I still can't get all 4 corners to touch at the same time.

 

I can get the left front corner OK, usually. Paper underneath helps.

 

The back left and back right are difficult to get at the same time. Getting a wad of paper under the back to help with the springs is hard. If I get one back corner set, the other is out off again.

 

Also, the back right corner adjustment screw is blocked by the print head, so you have to manually move it, which seems like it messes up what you're trying to accomplish.

 

The front right corner is the hardest, almost always floating in air.

 

More info:

 

This is a pre-assmebled unit bought from Ultimaker. The plywood of the bed holder in the front is a bit skewed. When I got it I figured the leveling screws would correct for that, but now I think they only correct so much.

 

Routinely when I loosen the screws the plexiglass doesn't rise up unless I also manually push it up, as if the springs aren't strong enough.

 

Taking the bed off to remove a printout is a sad event because I know it means that, when I put the bed back on, it won't be level, and will be hard to make it level.

 

I have managed to get one print, and there was one printout on it when it arrived. But the whole plywood bed / leveling screws / plexiglass seems really wobbly.

 

A question:

 

When properly leveled, should you be able to slide a piece of paper between the print head and bed or not? (This is from machine shop where we use paper) If a piece of paper were set there before adjusting, would it slide out easily, slide out with a tiny bit of pressure, be snug, or be impossible to remove?

 

[mostlyatomicbob 34]

Although I am still somewhat new to this printing game. It sounds like you need to adjust the 'Z' limit switch.

go to the bottom of the page here:

http://wiki.ultimaker.com/Ultimaker_rev.4_assembly:_Mounting_the_electronics

and follow the instructions and see if that helps.

It might also be worth adjusting the leveling scews on the Perpex bed to a mid point before doing the above, that way you have adjustment to raise or lower the plate when levevling.

Bob

 

[illuminarti 18]

Yes, Bob is right - it sounds like you need to adjust the top z-limit switch (on the top of the back panel, on the left as viewed from the front - behind the left most z-axis guide rod).

Regarding the problem with the plexiglass not moving up with the springs - make sure that the washers under the bed aren't getting caught in the keyhole slots. I don't know exactly what the current shipping configuration is, but when I first got mine, about a year ago, the washers were too small, and would partially catch in the slots, making bed leveling a nightmare. Adding slightly bigger washers on top of the existing ones made a huge difference. I too used to dread taking the bed off - now I do it all the time, and don't need to re-level afterwards.

Then adjust your z=0 level. With the power off, move the head to it's home x-y position, and screw all of the bed-leveling screws about half-way in, and then turn the coupler on the z-axis to move the bed, until the bed is just touching the tip of the nozzle (doesn't have to be perfect). Then adjust the z-axis limit switch so that it is just triggered in this position. Be careful not to strip the threads on the switch - they can be weak. This will give you the right z-axis home, and enough room to adjust the screws to get the bed level.

To level the bed, heat the head, and then auto-home it. Release the steppers if needed, and then move the head by hand to near the front left leveling screw (but leave yourself room to get to the screw with the driver). Slide a sheet of paper under the head in that position. Tighten the screw until you don't feel any tension on the paper as you move it around. Then unscrew it slowly, until you just start to feel the head catching on the paper. Then give an extra 1/8 turn out to make up for the thickness of the paper. You want your z=0 position to be literally with the head just touching the bed, but not deflecting the springs any further. Repeat this in all four corners, moving the head each time, and then go back and check the first corner, and continue until all are just touching.

 

[ttennebkram 0]

In moving the platform manually, the vertical threaded bar came out of the bottom holder.

What is the round cylinder at bottom of the Z-axis screw called? It's on the right hand side of this picture: http://www.flickr.com/photos/ultimaker/5488424600/

I reread the wiki page on installing the build platform, and near the bottom they talk about adding the M8 threaded rod, but they skip the one step about how it gets fastened to that thing at the bottom. I'm sure it's discussed on some other page, but short of rereading the entire site I couldn't find it.

I think I even had to secure this once before, but apparently didn't do it right. Also, there are 4 tiny holes. (this was a pre-assembled unit, so I don't know what's in there, impossible to look)

 

[owen 19]

Hi

The 4 holes in the coupling at the bottom contain screws which tighten up onto the z-screw and the motor below. You'll need a small allen key to do them up. Slide the z-screw all the way in.

 

[gr5 2,004]

What is the round cylinder at bottom of the Z-axis screw called?

I think it's called the z screw coupler.

Like owen said, make sure the z screw is all the way in. I messed that up when I built mine and so have others.

I'm sure it's discussed on some other page, but short of rereading the entire site I couldn't find it.

I was going to look it up for you until you said that. It will take you LESS THAN A MINUTE to scroll through all the photos in the entire build instructions. It took me 8 hours to build this thing but one can scroll through the 6 or so pages very quickly. Just look at the pictures.

 

[ttennebkram 0]

Ah, it's on the the first page, Frame Assembly, Step 4 Bottom Plate, http://wiki.ultimaker.com/Ultimaker_rev.4_assembly:_Frame#Step_4:_Preparing_the_bottom_plate It's 3 pages away from the Z-axis page, they might consider a back link ;-) The "official" name is the "Resiliert coupling"

 

[gr5 2,004]

e, they might consider a back link :wink:

 

It's a wiki. I strongly encourage you to create a free ultimaker wiki account and go in there and add the back link yourself.