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aviphysics

Is it normal to need to level the bed before every print? (UM1)

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the answer is kinda yes.

the print bed of the ultimaker 1 is amazingly flexable and moves a lot.

After a big print, the wooden bed can easily be moved... Then when you start printing.. you notice that the pla forms differently on different sides of the bed... sometimes really flat... then sometimes maybe not even touching...

So I always would check the bed before an important print... just run the hotend around with your hand and see how it moves over the bed.

Maybe ultimaker could take the nice idea of the 3 point scress adjustment for the bed in the ultimaker2 and make that as a nice upgrade pack for the ultimaker 1 ?

Ian :-)

 

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It seems to be different depending on who you ask. Some people seem to re-level quite frequently while others, like myself, hardly ever need to touch it. The only times I had to re-level on mine was if I had to use brute force to get a part off the platform or when taking the head apart.

Since it is made of wood I imagine temperature and humidity may play a role. After all, we're talking about small fractions of a mm here. When printing a 0.1mm first layer you only have a very very small amount of room before the head is too far or too close to the bed.

You could also "fake it" a bit if you want to be lazy. As the first layer is being laid down (or even better as the brim or skirt is being laid down) you can manually adjust the height of the bed by twisting the z-screw. When you overpower the holding torque of the motor it will skip a small increment and raise or lower your bed by a small amount. This will not hurt the motor in any way.

 

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I am not. The last couple things I made were just 1 mm. What do you consider large?

 

Let's say larger than 5cm... 1mm is definitively not large... :wink:

I have the same effect as Ian. Interestingly (and fortunately!) the shift is always uniform over the whole bed size.

A possible solution would be to put the z top end switch somewhere, where the leveled bed and not the z stage triggers it.

 

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I usually only have to level once per day now but when it was newer I had to level every few hours. If the first layer is .3mm then you don't have to get it perfect but if you are printing say smart phone covers you will want the first layer perfect.

I have only levelled my UM2 on day one (a few times) and haven't touched levelling since!

 

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I had previously thought about wood expansion and shrinkage being a problem with this devices. That is one of the reasons I decided to lacquer the thing. It seems like for really high and consistent precision, the best solution is to avoid the wood framed printers altogether.

Will keep with it for the moment. Starting to think about selling it though and maybe getting a Type A Series 1 2014 (terrible name). At least they are located at a tech shop in my area, so I can visit them if I am having a problem. They have their own problems though. For example, the Type A team is really only interested in the kitchen friendly non-toxic plastics (like PLA and PET). Some of their members were almost hostile to the idea of 3D printing with stuff like Nylon. I wish their team was more interested in developing a machine for the garage then their whole 3D printer in the kitchen concept. I think it might be a result of the members living in city apartments without garages. Otherwise, it seemed like a pretty well built device.

I like a lot of things about the UM design, but it feels like a constant hassle.

 

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I level mine UM1 really seldom - maybe one a month...

If I do it, I have prepared a gcode-file on my main SD which sets the head as close to the screw positions as possible. After the first round, I make a second for fine-tune but that´s all...

On the other hand I thought of using some kind of struds or wiring between one of the screws holding the z-bushings and one of the scres holding the table... kind of tensioning the angle to stiffen the whole thing.

But don´t know if it would work... (too many ideas, too less time...)

 

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For my Ultimaker 1 I absolutely need to level it if I've transported the printer. As for normal printing at home I just look at the first layer (actually the skirt) and adjust the screws for the bed while the print head is out of the way (during the print). This way you can get a feel for how good the levelling is by eyeballing the height of the layer put down, and the color. At the moment most of my printing is done in white, which actually get kinda translucent when the hot end is too close to the bed.

The same goes for the form of the string of plastic being put down. If you're too far away from the bed, it really is like a string, and not really sticking to the bed. If you're too close it will be flat directly under the head, but with two 'pushed out bits' perpendicular to the direction the head was going. Ideally it is of a rectangular form, and firmly pressed into the bed.

It takes some time before you get a feel for what it should be like (I have so many aborted first layers in my scrap box), but my experience that this gives the best result. Beforehand I would cancel the print.. remove the print from the bed (screwing up the adjustment), relevelling the bed using a piece of paper, and restarting the print (which would often fail again: very frustrating!).

 

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It's like a wooden guitar. When you put new strings on it they stretch a little and you have to retune the guitar before every song. After a day you only have to retune once per day. After a month - if you don't play it - it keeps it's tuning for months.

Similarly for the bed - a brand new Ultimaker printer needs leveling more often.

The frame itself is fine - I don't think that needs any strengthening - it's just those 2 support arms and how they attach to the vertical rods.

Plus you get very good at levelling after a while. Like other's have said - you can level while it is printing the skirt. I've done that also. And most things don't have a super critical bottom layer height so for most things levelling isn't quite as crucial.

 

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Other things to check - make sure that the four leveling screws are engaged well into the delrin blocks, and that all the springs are not fully compressed in the z=0 position.

You might also want to add bigger washers to ensure that the edges of the washers don't get caught in the keyhole slots. Once you do that, and given just a little bit of time for things to bed in, you should get to the point where you rarely have to level the bed.

Also, print with a fairly thick first layer - 0.2 or 0.3mm - whenever possible, as it makes things a lot easier.

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