Adding second glass plate with Garolite to UMO with heated bed kit

[lawrencejohnston 0]

I'm planning to pick up the UMO heated bed kit. In addition to the glass plate supplied with the kit, I was thinking of picking up another glass plate of the same size and gluing Garolite to it based on my http://umforum.ultimaker.com/index.php?/topic/8276-solution-for-being-unable-to-buy-un-warped-garolite-to-print-nylon-on/ printing Nylon on Garolite. I had a couple questions I wanted to get advice from everybody here on.

Is the glass supplied with the kit borosilicate glass?

 

It looks like the glass plate is just clipped onto the bed, so I shouldn't have any trouble attaching an alternate plate?

Will I be able to glue the garolite to the glass that way I did with my existing setup (linked above), or will the expansion of the glass during heating cause issues with that?

 

[gr5 898]

Printing on glass is such a wonderful experience for PLA. It's just wonderful.

The glass that UM supplies with the kit is "tempered" glass. Lawrence please update what country you are living in on your profile settings.

Tempered glass can be bought from most glass stores (there's one in every town in most parts of the world as there are lots of windows in most parts of the world - but many other parts of the world don't have very many glass windows at all).

Gluing something to glass and heating it sounds like a bad idea. Glass is very brittle and heating even just say the left side of a sheet of glass will make it shatter. Borosilicate glass indeed has low thermal expansion but I don't know what the thermal expansion of Garolite is and if they are different then that would be a problem. Also you want the thickness of the supplied plate exactly the same (exactly! - well within .01mm or about a tenth the thickness of a piece of paper. So, yeah, exactly) otherwise you have to level everytime you change beds. My favorite thing about the UM2 is I haven't levelled in many months. Same with UMO with HBK.

 

[gr5 898]

Maybe you could glue them together at a small 20mm square in the center and let the rest just sit on the glass. Or use a sheet of aluminum instead as that isn't so brittle and conducts heat even better than glass.

 

[meduza 185]

I would glue the garolite to a aluminium tooling plate instead, it is about as flat and conducts heat much better.

[lawrencejohnston 0]

Thank you both for the input. By aluminum tooling plate you mean something like this? (Found via a quick search, if you have a supplier to recommend please do.)

What thickness would you recommend? It looks like most sites I've found so far go down to 1/4", which still seems a bit thick compared to the 1/8" glass I'm using now.

I'm honestly not worried about this bed being a different thickness. What I've done for my current garolite bed is to create a shim that sits on the wood that triggers the Z-switch and adjusts the height to match without needing to re-level much if at all.

 

[meduza 185]

Yeah, you are probably right that cast tooling plate is seldom aviable in thinner gauge than 1/4", if you want a thinner one you can use Extruded aluminium sheeting of 7075 grade that is very hard and flat, but not guaranteed in flatness (tooling plate is ground to a very flat surface, but since you anyways will be gluing stuff to the surface that is probably OK).

 

[gr5 898]

By aluminum tooling plate you mean something like

 

Yes. MIC-6 is best. All the other common types of aluminum will warp if you repeatedly heat and cool it. Of the very common aluminum out there, MIC-6 is the most thermally stable. It warps the least. It's also a little harder to work with. Or maybe easier depending on your point of view. It's kind of soft and mush when you do things like cut it with a hack saw or drill it. It's really not bad though. Just different.

Because people usually want MIC-6 for a working surface it's hard to find it thinner than 1/4 inch because the whole point is to keep it from warping and 1/8 inch is getting to the point where it is less useful for typical needs (bends too easily).