Glass is awesome

I think the point is that the old bed was not level so some parts had nice strand spacing and others had big gaps. Now with glass the quality is consistent.

Yeah...I guess.. Ok! That's all I got from it, but I thought you may have been going for a grander point . 

So you say...."Solution to warped alu plate!......Add flat object, on top."

.

The aluminum bed will usually only be 2mm off or so, it shouldn't effect it too much with that small of a difference.  Depending on how flat mine is, I may do the glass mod right away too.  I noticed their competition in now order their tables a little larger then machining them down so they know they are flat.

So, I experimented with printing on glass for a few months, and here is what I found:

Pros: 
* Removable Surface so that multiple prints can be done without re-warming the bed.

Cons:
* Using Hairspray to get the plastic to stick is sort of a pain
* temperature differentials can eventually crack the glass
* You have to have something to keep the glass held firm while printing, and these clips will can get in the way of the extruder
* Glass is not conductive enough and doesn't heat up as fast as the aluminum (which I'm guessing is one reason you need hairspray)
* I could never get as solid a stick on glass as I could the heated bed.

So yesterday, I had my glass crack on me.  I think it was because I used the same piece of glass twice, so it underwent rapid cooling, then reheating once placed on the bed.  With glass, I always had problems getting a strong hold on parts.  Large flat parts were fine, but even then I saw corners peeling up where when I was printing on the heated bed that didn't happen.  Parts with small footprints would often come undone, no matter how much hairspray I put on. 

The other thing is that going from glass->bed or vice versa, I have to adjust that z-offset screw which, honestly, is a pain in the ass to reach (at least with the L-joint hex driver I have).  So have to adjust that then relevel the bed.  Does anyone else think the bed would be easier if it was a four point level instead of three?  It just feels that using a triangle to level a rectangle is more complicated than just leveling the four corners.  I need to print a harness for my dial indicator so that I can make sure everything is level.

So I'm going to go back to printing on the hot bed again and see if I'm just having rose-colored memories.  Has anyone tried printing on a sheet of metal instead?  It seems like you would have all the benefits of glass (removable), but it would be more durable and conduct heat better meaning you could forgo the hairspray if you just put some kapton on it.  Thoughts?

Are you enclosing your build environment.  I can't see having all these problems if you're in an enclosed environment.  So many others using glass with hairspray are having consistently excellent results, so I would look for other variables in your process to understand why you can't duplicate our results with the same setup.

I'm not sure, you're asking if it would fix a problem that doesn't exist for me.  What's better than working 100% of the time? 

Enclose your build environment, give glass another try and I'm certain you'll have better luck.  I just switched from the SD2 expert case to this yesterday.  Works just as well but I can access from any direction effortlessly.  Even cardboard will work just as well from what I hear. 

http://www.soliforum.com/topic/1306/cus … osure-mod/

Yep, I still use hairspray.  I much prefer it to kapton since that is more expensive and prone to ripping when the adhesion is strong.  The metal plates tend to warp under heat, but you can easily clamp it with binder clips or alligator clamps such that it becomes very flat on the bed. 

However, like cmetzel was saying, your problem is most likely from the background temperature - building a simple enclosure will hugely help reduce liftoff and warp.  Thermal gradients on the part can create massive stress that no build surface can fully compensate for.  So while metal and glass have great adhesion, it isn't enough to fix the problem completely.

Give an enclosure a try and see how it helps.

If you are cracking your glass, make sure you only clamp it down where it already makes contact with the bed.  If you put just a little bit of pressure on the glass so that it bends, it will crack pretty easily.

I've printed well with 65C and hairspray on the glass.  I think the addition of hairspray more than covers the lack of transferred heat through the glass.

Not sure just how much pressure is too much pressure, but I have had no issues with just using 2 clips at front and 2 rolls of coins that sit on the glass at the rear. The glass is cut at 8" deep so that the back edge butts up against the wood to brace the glass. The coins seem to add enough weight to the back end to keep the glass as flat as possible against the bed as the two front clips seem to lift the back end of the glass slightly up.