Heated bed mounting screws

[Rahere]

The bolt heads on the heated bed are dished, not flat, leaving them just slightly proud of the surface of the bed on my machine. Because I want to use a tempered glass surface for some output, the dish holds the glass about half a millimeter above the surface of the heated bed, making it unusable. I need either to grind them flat or to replace them. Does anyone know what the thread dimensions are?

[Ahaber]

What printer is this question about?

[Rahere]

Sorry. A Monoprice Maker Select V2. Having finally worked my way past their rubbish documentation, it’s clear that although the mechanicals are fine, the software’s a throwback to the stone age (fret not, so’m I) as the use of interpreted code is insane, imho. Plut a BT chip into the motherboard, for starters - mechanical connections are a recipe for a short life and a frustratingly merry one. And that then informs a whole raft of derivative follies, such as the need to replace the MOSFET interface. Fire Safety should have had this thing banned from Europe, and it’s still a moot point whether I simply use it to print something better and cannibalise it for the parts.

[Ahaber]

OK so do you care about the screws?

[Rahere]

I’m trying to fit a glass bed so I can swap different adhesion surfaces easily (different materials need different adhesions). The headache is that the screw fittings on the hotbed are proud of the surface by about 1 mm, which lifts the glass clear of the heated bed. Either I grind them flat, or replace them, or increase the depth of the countersunk socket, or…
I haven’t tried dismantling them yet, they look as if they may actually be rivetted in, which means the first option is en route to the second and third anyway. But, looking before I leap, the question is worth asking: has anyone tried it, what are the inevitable hidden traps to watch out for, and so on and so forth?

[cobnut]

How did the original surface fit if the screws are proud of the bed?

[Rahere]

They cut the corners out of the pad!

[cobnut]

That’s some excellent engineering planning! Could you get a local glass company to cut holes that fit where the screws are? You could probably then either put a PEI or other print bed sheet on top and there’d be enough resilience to still print over that area if necessary.

[Rahere]

Already done getting thin toughened glass for the pad - you can’t get holes that small.
It rather sounds as if this is new territory, perhaps the answer’s to cut 1mm alu to size and sandwich the lot, when you put it that way! Any preferences for glues?