Aluminium beds – some thoughts on levelling

The Wanhao printer bed is made of Aluminium, below this is a flexible heating element.

It’s been widely reported that the D9 doesn’t level very easilly, Here’s why people are having issues….

Aluminium expands when heated!

If you’re having ‘levelling issues’ ensure to do the electronic bed levelling whilst the bed is hot! – (pre-heat to typical printing temperature first)

 

Anyways, some math.

Here’s a datasheet for the Aluminium I purchased for my carriage upgrade

Two things I note here –

Physical Property Value
Density 2.71 g/cm³
Thermal Expansion 24 x10^-6 /K

Density – Steel (which the carriage is made of) is generally around the 7 – 8 g/cm³ – or Three times that of Aluminium! – win there, I can use a sheet of aluminium Three times thicker than the steel on the carriage and have the same weight (in theory)

Thermal Expansion – Translated this means that Aluminium expands by 24 micrometers per millikelvin. Also known as 0.000024 meters per degree

 

How does this affect the D9 Printbed?

When heated, the 325 x 325 x 2mm thick aluminium bed  becomes a bit larger

………How large?

 

Here follows some very rough calcuations……..

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