Bed Leveling/Warped Glass

[mendells 51]

I have always been fighting getting the build platform level and finally made a dial indicator holder and wrote a program to help me level the bed. Now the leveling procedure initially checks positions as close to the adjustment screws as possible, then checks the same pattern but closer to the center of the build platform. After that I have it "scan" the bed in the X and Y directions. I have dialed the bed in as close as possible but it is very apparent that the glass is warped. We have 4x Ultimaker 2+ and all the beds are wrapped to some extent but this one is one of the worst. I have sourced some thicker/flatter borosilicate glass that hopefully should be here in two weeks. I will update again once I have the new glass.

 

[mendells 51]

For comparison here is our extended with a cheap borosilicate glass plate.

 

[Dim3nsioneer 360]

Is that cheap glass really Borosilicate?

I have recently been in contact with a manufacturer of Borosilicate glass quite well known in Europe and they told me that their borosilicate glass is not manufactured with the aim to get even surfaces.

Standard glass is often much flatter than borosilicate glass. And I have no doubt you can buy a 'cheap borosilicate glass' in China which would turn out to be standard glass if checked with appropriate methods.

One more remark to the test method: please be aware you are testing not only the flatness of the glass but also the straightness of the axes (although Ultimaker axes are very straight nowadays).

[mendells 51]

Yes I am aware that this method is susceptible to other factors including the rods being bent or the frame bring off but it does show the difference between the flat glass and the warped glass. I have checked both sheets on a grant slab with an indicator and the ultimaker glass is significantly warped compered to the borosilicate. You are correct in that the borosilicate glass is not manufactured specifically for flatness but is is significantly better than the stock glass regardless. I have also noticed a change in the flatness of the ultimaker glass at higher temperatures (60-100C), but this may be due to the aluminum it's mounted to not necessarily the glass itself.

Edited February 5, 2017 by Guest

[mendells 51]

I finally got the new glass and it is far better than the stock Ultimaker glass. The original glass varied by about .020" and the new glass only varies by about .004" (I'll get a new video when I can).

I have also found that the parts also stick much better to the glass. I'm not sure why exactly but I would guess that it is because there is more even pressure across the bottom layer as the part cools.