Concave bed

Hi everyone,
I'm in the process of putting together my Mendel90 and I'm up to #26 Bed Levelling.

Unfortnately, it seems that the bed is concave. I measure the distance from the hot end to the bed in the middle at the back, using a bit of paper. Then raise the head 10 points upward, to ensure that it is unlikely to hit the bed if it is concave, move to the left back and attempt to move back down the 10 points, but it's about 2mm concave, so this is impossible.

Am I doing something wrong?

I don't know how to fix this, besides having to replace the bed. I would have thought that the glass on top would have removed any such possible minor convex/concave issues, but apparently not.

Any assistance will be greatly appreciated, I'm soo close to being able to print!!

Thank you.

Nathan

I can't see how a piece of glass can be 2mm concave. It would look curved and bending it that much would break it. I think you must simply have the left and right Z axes a long way out for each other.

Adjust the left Z screw until it just touches the bed. Then do the right one and keep alternating until the both just touch. Then see where the middle is. I can't imaging it can be 2mm lower when both sides are level.

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[www.hydraraptor.blogspot.com]

Hi Chris,

Thank you for the quick reply, greatly appreciated, I can't wait to print with your awesome machine!

I cannot understand how it could be so concave either.

I'll do as you suggested, tomorrow, and hopefully get things organised. I'll let you know how it goes.

How precise must it be? Microns out?

Thanks Chris.

Within about 0.05mm is usually good enough.

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[www.hydraraptor.blogspot.com]

By any chance could you post a picture? That might help someone spot the trouble?

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Sorry, I thought I'd responded to this.

I got it balanced, you were right Nophead, it was just way out.

Thank you.

Glad you got it figured.

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