Guys,

I tried to print some objects, but in one corner, it supposed to be flat, but when I finished printing, that corner was a bit bending up, not flat to Z = 0, why was it ?
Was it because of PLA shrinking ?

Thanks

This sounds like the plastic became detached as it was printing, causing the corner to curl up.

PLA does shrink, but if you have good bed adhesion, the corners should be able to overcome this problem.

Check that your adhesion method of choice is applied well (painters tape, hairspray, glue, etc) and try again.

I have found that hairspray on a warm bed (~50 degrees) works very well for me.

I use buildtak and not putting anything else on top...can I clean it first with alcohol?

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bianchi
I use buildtak and not putting anything else on top...can I clean it first with alcohol?

I use BuildTak too, you should clean it with alcohol, good and often. it is sensitive to grease and dirt.