New build, replace PEI or not?
I just finished build my MK2. This is my first 3d printer. Only got stuck a few times, but mostly due to me not reading carefully enough.
Anyways, I have printed 4 items from the supplied CD card. In this order: Prusa logo, frog, vase (isn't water proof), gears. Print quality appears great. Each time it was a pain to get the object off the bed. On the last one, the gears, it was especially hard. My scraper doesn't get under the object. Anyways after the gear was off, I noticed the bed in not flat any more. There are no gouges, but I saw tiny, tiny spots where the part was. If I run my finger across the side of the bed, it is smooth. If I run my finger tip across where the gear was printed, i few a slight dip where the gear was. If I do the same thing with the back of my finger nail, I feel nothing.
Does this slight dip warrant a pei replacement or not? When would I replace my pei?
Two other questions:
How else can I get my parts off the bed, I heard floss, but if a scraper doesn't work will floss?
Also, out of curiosity, how many hours can I print before belts, bearing, rods, or motors start to wear and need to be replaced?
Thank you!
Re: New build, replace PEI or not?
Its not uncommon for PEI to sink/rise in areas after a print. Its usually a very small amount that shouldn't affect any future prints.
As for the difficulty of getting prints off the bed. If you have the first layer too low, it will cause the print to secure itself to the bed VERY well. ABS is really bad for that. PLA isn't nearly as bad, but at least with PLA, you can use a small nylon hammer and tap the side of the object and it should just pop off. Haven't been able to use that technique with ABS.
I recommend that you reduce your Live Z setting until you get a nice first layer that doesn't looked too squished and doesn't have strings. You can check out some of the other posts that will help with Live Z.
Check out some of JeffJordan's posts about Live Z. He's got some really helpful information.
Re: New build, replace PEI or not?
...Does this slight dip warrant a pei replacement or not? When would I replace my pei?
these slight dips go away after a few prints or heatup/cooldown cycles. they are caused by the glue between pei sheet and heatbed pcb.
to assist the removing of prints with a large surface in contact with the printbed, it's allways a good idea to add mouse-ears to the print.
how much the print sticks to the pei surface is also influenced by the type of filament you use. so will biofila platec filament stick like hell to the printbed and some petg brands will do so as well.
there are a few things you can try to release a well sticking part:
use cooling spray
spill some ipa at the base of the part (so that some of it get's sucked under the part due to the capillar forces).
some people use an over saturated salt solution to treat the surface before printing pla (does NOT work for abs).
look around at this forum. you'll find good advice and can learn a lot. the search engine works quite well...but the results are only shown in threads, so you can't directly navigate to the posts with the keywords 😡 .
the problem is to find the balance between "sticking" and warping, getting loose or even popping off.
welcome to the hobby of 3d printing 
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