It’s not an electrical component wear issue necessarily, though an extra cold cycle and reheat probably doesn’t help over time. For some reason ABS in particular tends to adhere really really well to PEI if you let it drop to room temperature and it doesn’t pop off from contraction, and reheating it doesn’t seem to release the bond as easily.It will still come off, it just seems to take more force to do so. I’m not sure if its a chemical bond at that point, or a mechanical one, but there is definitly some wierdness with letting it cool all the way and then reheat.
As I was told by some one that worked in the printer farm:
The adhesive is pushed and pulled by the different material expansion rates. So the cold print expands at a rate different than the glass bed, so you apply stresses to the bond. Which will lead to a quicker MTBF for the adhesive.
They pull a lot of prints off in the printer farm and have seen the results of the heat cycles to the adhesive. Along with the temp you remove the object at.
Any tips for the PEI replacement on a TAZ? (I too ruined my PEI sheet prying a part that cooled down too far.)
Disclaimer: I know nothing about G-code. (I do remember a little about programming from working with a couple of computer languages decades ago.)
Your code seems like a great idea. If the preferred method really is to not let it cool and then warm it back up, this would make a good addition to the standard included code.
I’m curious though, the stock Cura LB end G-code shuts the heated bed of entirely at the third step in the end code. Then moves to the cooling position, then waits for the bed to cool, then shuts off the heated bed again. Not sure why it’s necessary to shut it off twice.
If I’m following this correctly your code turns the heat back on after the move to cooling position. Is there some advantage to turning the heat entirely off up front and waiting for it to cool? Why not just set it to the removal temp in that third step, then move to cooling position and wait for it to cool down? Seems like less of an opportunity for an undershoot in temperature.
Poking around with some of this stuff is something I might be interested in. Are you guys using anything special to write the code? Is there any good reading I can do to learn about making temporary changes to code, or how to modify the default profiles and save them as a custom profile for Cura?
If your TAZ is still under warranty, contact Lulzbot and they will send you a new glass/heater/PEI assembly to replace. Very simple. If you’re out of warranty, Lulz has a step by step process on how to replace just teh PEI sheet on the glass.
Warranty replacement is the way to go…if you have it still.
once i started putting 1-2mm radius fillets on the bottom edges of everything i’ve printed, things just sort of auto-release for me when it cools down, and I’ve never had any more trouble taking ABS prints off the bed. I seldom retrieve my prints before the bed’s down to 20C since my house is so cold this time of year… it doesn’t take long.