Glass Or Mirror For Ender 3 Bed?

Just wondering about this. Can one use a regular tempered piece of glass or mirror on an Ender 3 for printing on? I would take off the current mat that clips on with 4 clips in the corners and use a piece of glass. Or is there somathing special I am missing, such as does it have to be a specific type of glass? And if I was to do this, would I just measure the thickness and get something the same thickness?

If this was mentioned here before, I apologise as I did not find an answer myself. Thank you.

I haven’t tried regular glass or mirror, apparently it works, but the creality borosilicate glass bed is like 30$ at 3d printing and it’s awesome, I use it on my ender 5, and it has no sharp edges its nice and thick and holds heat really well

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Second that, Borosilicate glass! It is very forgiving of uneven heating and tolerates high temperature differences. Schott, pyrex, and duron are all Borosilicate glass there is a reason why they are used in heated applications. Other glasses are not.

wow spell check changes names of things constantly.

Thank you. If I may also ask. If switching out for a glass bed, do i have to readjust the switch on the side to compensate, or is it just the correct thickness that I do not have to do anything? This is just crossing my mind to try, and I hear pretty good things about it. I would probably switch it out for the regular mat when I use PETG.

I readjust the switch on the side (Z) when switching to glass and relevel manually but you can add the glass, measure the height and slice with an offset in Z if you are using Cura ( that’s the only slicer I am familiar with).

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Oh joy. So there is more to it than just swapping out the plate then. I was kind of hoping it would just swap out and be done. Now off to read about this measuring and slicing with an offset in ‘Z’, what this means and how to do such in case I do go to glass. Yes, I am using Cura. Thank you.

I just use a piece of window glass I cut to size. It’s fine.
There’s no engineering reason to expect a difference between that and a mirror; the silver/paint layer on the back of a mirror won’t make a measurable difference thermally.
Likewise, I don’t think that the temperature gradients involved are enough to really require Borosilicate glass. You might be able to break your bed if you put an ice cube on it when it’s hot, but in normal use, the stresses don’t get that bad.
I had wondered if the different shrinkage between soda glass and borosilicate would make a difference to how easily the print releases as the bed cools. Well, the coefficient of thermal expansion of PETG is around 7E-5. Soda glass is about 8E-6, and borosilicate about half that.
The shrinkage of the plastic is so much greater than that of the glass that you’ll never notice the difference.
…Not that I don’t like borosilicate glass. I produce honing rods for high-quality knives out of it (


I use different materials and take the glass off and put it on depending on what material I am printing with. If I just want to use the glass for a one or two prints I will use the z offset to save time. It is a short term solution.
In the build plate adhesion menu click on the gear/setting icon. Click on the Z offset box. If you hover over it there is a brief description of what it is.

Measure your glass and input that measurement in the z offset box that should now appear in the menu. If your glass is 10 mm input 10 mm. This raises the nozzle 10 mm from the bed where it thinks 0 is.

Slice and then try. You can also fine tune if your printer has Babystep Z in the tune menu. You can adjust up or down in small increments during the beginning of a print (anytime really). I use a purge across x and usually a skirt before the part.

If I am going to keep the glass on for a while and I will home the printer, disable the steppers (in LCD) and by hand turn the screw that raises the z axis until there is enough room to put the glass bed on. Move the table under the nozzle and lower it until it is just above the bed. I put the paper I use for leveling on the bed and when it touches stop.

Loosen the Z limit switch on slide up the side until it is fully makes contact. You will hear a click. Tighten the bolts holding the limit switch.

Enable steppers and then home the printer. Manually level from there or whatever you do to level.

Good luck.

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Thank you for both the replies and help. It is greatly appreciated.

I personally love glass make sure it’s good tempered level glass

No problem. I hope it helps.

The beauty of the BLTouch that replace the Z stop is I can swap from mag plate to glass because I do autolevel before every prints. But I still check once in a while the bed level by doing a manual leveling so that the BLTouch does not have to compensate too much.
So as soon as i change it i do a home the axis.

I like the stock glass (smooth side). I only use 2 clips, though; 1 on the front and 1 on the back. I also like to use a glue stick for better adhesion!