Beerwise, I replied to this from my tablet last night but it doesn't seem to have turned up. Not the first time that's happened from the tablet, but if a similar response appears from me you will know why.
I assume you're referring to the glass full-contact on the heated print bed, held in place with clips. Yeah, you can do that. It's a method that's pretty much gone out of fashion now. Things change incrementally as people find new and better ways to do things.
Glass and aluminium have different coefficients of thermal expansion, so any attempt to fix them together (clips etc) is risky. Gino pads are grippy but not adhesive, so the glass is free to "float" as it expands/contracts according to its own physical properties. Over the years many people using clips had the experience of seeing their glass crack or chip, and those stories soon spread through the various 3D printer communities.
Here is a shot of my own Wanhao Duplicator i3 showing the Gino pads in place, and then hidden by the mirror glass.
You really don't need to start digging into the physics of thermal properties of matter. The arrangement illustrated has been widely adopted because it works excellently and is extremely convenient in every respect. Many people who have used more than the four Gino pads have found no advantage in heat distribution, and usually discover that some of the pads don't touch the glass at all. Don't forget that the main purpose of using glass is to get a "perfectly" flat surface. Your print bed is almost certainly not nearly as flat -- in fact after some use (repeated expansion/contraction) it's almost guaranteed to have distortions. Thus it doesn't matter how many Gino pads you spread around, some of them will not be touching the glass.
Those pads that are touching the glass not only distribute the heat very efficiently, but provide the added advantage of helping to prevent vibration in the metal bed from spreading to the glass.
As to glass type...
I've been in discussions with people who get foaming-at-the-mouth rabid with any suggestion that you can use any glass other than borosilicate. There is often a lot of waffling on about Pyrex, borosilicate, rates of thermal expansion, and so on, and it's usually a load of uninformed crap. There was a point in time when things got quite messy in the world of these specialist glasses (https://en.wikipedia.org/wiki/Pyrex) which confused the issue somewhat. Anyway, I'm not getting into one of those discussions now, I'll just say this: there is a heap of evidence that much glass sold as borosilicate isn't borosilicate. That's point #1.
Next is the overwhelming evidence that plain glass is just fine; used day in and day out by thousands and thousands of people. One US professional I know buys window glass off-cuts from his local hardware store and cuts them to size himself to suit the various sized beds on the 20+ 3D printers he usually has on the go at any one time.
Yes, a lot of people use 3 mm plain glass, but my personal preference is for 4 mm mirror glass. I have a large Glass & Mirror company nearby so it was no trouble for me to get a sheet of mirror glass 213 mm x 213 mm, with the corners bevelled off. That is the exact size of my heated aluminium plate, which has a bolt head in each corner.
But as always, I can only tell you what I do. You are completely free to go your own way. No advantage to me either way.
I assume you're referring to the glass full-contact on the heated print bed, held in place with clips. Yeah, you can do that. It's a method that's pretty much gone out of fashion now. Things change incrementally as people find new and better ways to do things.
Glass and aluminium have different coefficients of thermal expansion, so any attempt to fix them together (clips etc) is risky. Gino pads are grippy but not adhesive, so the glass is free to "float" as it expands/contracts according to its own physical properties. Over the years many people using clips had the experience of seeing their glass crack or chip, and those stories soon spread through the various 3D printer communities.
Here is a shot of my own Wanhao Duplicator i3 showing the Gino pads in place, and then hidden by the mirror glass.
You really don't need to start digging into the physics of thermal properties of matter. The arrangement illustrated has been widely adopted because it works excellently and is extremely convenient in every respect. Many people who have used more than the four Gino pads have found no advantage in heat distribution, and usually discover that some of the pads don't touch the glass at all. Don't forget that the main purpose of using glass is to get a "perfectly" flat surface. Your print bed is almost certainly not nearly as flat -- in fact after some use (repeated expansion/contraction) it's almost guaranteed to have distortions. Thus it doesn't matter how many Gino pads you spread around, some of them will not be touching the glass.
Those pads that are touching the glass not only distribute the heat very efficiently, but provide the added advantage of helping to prevent vibration in the metal bed from spreading to the glass.
As to glass type...
I've been in discussions with people who get foaming-at-the-mouth rabid with any suggestion that you can use any glass other than borosilicate. There is often a lot of waffling on about Pyrex, borosilicate, rates of thermal expansion, and so on, and it's usually a load of uninformed crap. There was a point in time when things got quite messy in the world of these specialist glasses (https://en.wikipedia.org/wiki/Pyrex) which confused the issue somewhat. Anyway, I'm not getting into one of those discussions now, I'll just say this: there is a heap of evidence that much glass sold as borosilicate isn't borosilicate. That's point #1.
Next is the overwhelming evidence that plain glass is just fine; used day in and day out by thousands and thousands of people. One US professional I know buys window glass off-cuts from his local hardware store and cuts them to size himself to suit the various sized beds on the 20+ 3D printers he usually has on the go at any one time.
Yes, a lot of people use 3 mm plain glass, but my personal preference is for 4 mm mirror glass. I have a large Glass & Mirror company nearby so it was no trouble for me to get a sheet of mirror glass 213 mm x 213 mm, with the corners bevelled off. That is the exact size of my heated aluminium plate, which has a bolt head in each corner.
But as always, I can only tell you what I do. You are completely free to go your own way. No advantage to me either way.
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