I'm getting a little confused here trying to follow this discussion. (Maybe it's just me .. it usually is)! You refer to the 'bed', and re-leveling after changing it .. but are you actually talking about the glass plate that sits on top of the actual heated bed? (It would seem this is the case based on your earlier comments about printing on polyimide, sticking it in the freezer, etc.) Just trying to keep terminology straight.
Fwiw, I've run my machine probably hundreds on hours over the last eight months or so, and think I've only gone thru the Quick Start leveling/alignment process once since initial set up. Prior to getting the good advice of this collective group re: removing the glass prior to removing prints, I used to just pry 'em off while the glass was still on the bed. I no longer do that, but don't believe I've damaged the Y-axis bearings or caused something so significant as to require any re-leveling. Maybe I'm just lucky .. I just print .. the machine and leveling impresses me as very robust and forgiving.
To your specific questions .. A) yes, (I remove the glass .. not the bed) .. B) no.
Lossing Bed Level
Re: Lossing Bed Level
Thanks! That makes a lot more sense. I guess the official term for the glass is the "build surface". I'll try to be more precise in the future.
I'm still going to re-level things, just to see if wrestling my prints off with the glass installed has knocked anything out of whack. That should give me a good feel for the magnitude of the problem. My last print (which I knew would be really stuck) came out fine. I didn't attempt to do anything until I had the build surface off the heated bed. I managed to pop the print loose using a plastic razor blade, but I still ended up with a shallow dent in the polyimide where the print bent the edge of the razor blade down into the film.
After re-leveling tomorrow, my first project is to compare hairspray & glue stick to see if that helps getting the prints loose.
I'm still going to re-level things, just to see if wrestling my prints off with the glass installed has knocked anything out of whack. That should give me a good feel for the magnitude of the problem. My last print (which I knew would be really stuck) came out fine. I didn't attempt to do anything until I had the build surface off the heated bed. I managed to pop the print loose using a plastic razor blade, but I still ended up with a shallow dent in the polyimide where the print bent the edge of the razor blade down into the film.
After re-leveling tomorrow, my first project is to compare hairspray & glue stick to see if that helps getting the prints loose.
Re: Lossing Bed Level
I went through the bed leveling process just to check that I hadn't knocked things out of whack. I tried to figure out how out of level it might be by tracking the amount I had to raise the bed at each corner, but that was less than successful (see below). I started by running the nozzle up to temperature, retracting the filament 10mm, and then wiping/polishing the end of the nozzle with a piece of thin cardboard to make sure there was no residue to throw things off. I learned several things when I ran the Quick Start app:
1) It's hard to keep count of how much change you have applied with the buttons in the program. On my laptop, the touchpad/mouse drifts & you can move off the buttons while you are watching feeler gauge. You can click away with no effect, so just counting clicks doesn't work. You need to watch the Z-axis knob to see what is going on, and only count actual adjustments.
2) The slightest downward force on the build plate or upward force on the hex key & adjustment screw can flex the bed frame enough to give a false reading. You need to use a very light touch on the feeler gauge. Flexing it down under the nozzle from above the build plate is better than sliding it around with your finger tip holding the feeler gauge down on the build plate.
The program had me adjust several of the corner screws, but no more than ~ 1/8th of a turn. On a 3mm screw, that amounts to ~0.06 mm. Not a big deal for the 0.25 mm layer thickness I'm running, but it would be a problem if I was trying to print 50 micron layers. I suspect a lot of the error was due to lack of care the first time through the process more than distortion from removing prints with the build plate installed.
I re-ran a PETG test print that gave me fits removing from the build surface before, this time using glue stick on the polyimide. The skirt came up very easily, but the print itself is very firmly attached. I've got it in the freezer now to see if that will loosen it up.
1) It's hard to keep count of how much change you have applied with the buttons in the program. On my laptop, the touchpad/mouse drifts & you can move off the buttons while you are watching feeler gauge. You can click away with no effect, so just counting clicks doesn't work. You need to watch the Z-axis knob to see what is going on, and only count actual adjustments.
2) The slightest downward force on the build plate or upward force on the hex key & adjustment screw can flex the bed frame enough to give a false reading. You need to use a very light touch on the feeler gauge. Flexing it down under the nozzle from above the build plate is better than sliding it around with your finger tip holding the feeler gauge down on the build plate.
The program had me adjust several of the corner screws, but no more than ~ 1/8th of a turn. On a 3mm screw, that amounts to ~0.06 mm. Not a big deal for the 0.25 mm layer thickness I'm running, but it would be a problem if I was trying to print 50 micron layers. I suspect a lot of the error was due to lack of care the first time through the process more than distortion from removing prints with the build plate installed.
I re-ran a PETG test print that gave me fits removing from the build surface before, this time using glue stick on the polyimide. The skirt came up very easily, but the print itself is very firmly attached. I've got it in the freezer now to see if that will loosen it up.