really? after posting here i made a small test after the normal print with 60 C bed temp, i lower it to 55C and it where a little better....
Ok now i will do a other test, which bed temp would you prefer for PLA
shiny bottoms i get every time when i work on the normal glass plate.... i wish i had this finish everywhere
Slightly higher temp is usually what you should try if warping is your problem.
I run all my PLA prints at 60C bed temperature with clean glass, and use glue stick if i need better adhesion.
Different brands of PLA does need slightly different temperatures for best bed adhesion tough, and some brands, especially the cheaper ones, are known to not adhere that well to clean glass.
Off-topic: @IRobertI, i know you have been using lots of blue tape for other stuff than printing tough... 
thank you guys for your help.
but for me as starter, about which higher temp do we speak now, changing it only 1-2°C up to 62, or do we speak about 10+ higher to 70 or even more?
i must get a feeling of this 
I would suggest that you change the bed temperature in steps of 5C or so
ok thank you...
but the test with the glue stick was very very bad now.... :(
the bottom was now with alot mistakes...
Consider posting some more info about the print model itself, eg. also a screenshot from Cura, this will help people give you more solid advice.
As an example, if at all possible, rounding off the corners of the object helps reduce warping.
Use very little glue. The layer should be so thin it is invisible. So for example if bed is completely cleaned first - then maybe put 2 full length stripes across teh bed - then wet a tissue and spread the glue around with the wet tissue to all corners. Then heat the bed and wait for the water to dry and it should become transparent.
60c is the ideal bed temp but 70C will help with warping issues (but cause other issues) so only go above 65C if you are desperate. Much more likely you aren't squishing the bottom layer enough. Try turning the 3 leveling knobs 1/2 turn CCW to get the glass closer to the nozzle. Don't mess with the leveling procedure - it tends to level to the "ideal" height such that the nozzle is .3mm off the bed when doing a .3mm bottom layer. But the problem with that is the part won't stick as well. So you want to be more like .2mm off the bed when doing a .3mm layer and then the part will stick very very well.
Ok back to this problem because I want to learn it
But honestly I have the reverse problem now.... All is to tight and I can't lose it
Ok back to topic
Tommy here are same pictures of the first layer with glue stick
And here perfect layer without glue 
Ok back to this problem because I want to learn it
But honestly I have the reverse problem now.... All is to tight and I can't lose it
For large prints I take the glass plate out and put it in the freezer when the print is done, come back 10 minutes later and it will have popped off by itself...
Smaller prints I can usually pry off by hand once the bed nears room temperature...
DONT use violence or force to pry off a print, you CAN damage the glass plate (ask me how I know)
What tommy said.
Ok back to this problem because I want to learn it
But honestly I have the reverse problem now.... All is to tight and I can't lose it
For large prints I take the glass plate out and put it in the freezer when the print is done, come back 10 minutes later and it will have popped off by itself...
Smaller prints I can usually pry off by hand once the bed nears room temperature...
DONT use violence or force to pry off a print, you CAN damage the glass plate (ask me how I know)
I've loosened prints by inverting canned air and using the propellant to cool the bed. Seems to work pretty well.
I would suggest you try wiping the glass plate with *salt water*, prior to printing PLA. Gently keep wiping with a moist tissue, until the water evaporates and leaves a thin mist of salt on the glass. This *greatly* improves bonding of PLA to heated glass. When the glass is hot (60°C), my prints bond rock-solid to it, I can't pull them off. But when cold after finishing, they come off without any force at all. So for me this is the perfect solution, much better than the "glue stick method" I tried before. And you don't need to remove the glass bed from the printer anymore. But it does require a heated glass bed, won't work on a cold bed.
Since I started using this "salt method" one year ago, I printed about 1000 parts, often very complex, long and 100% filled parts, without warping. (Only one inverted prism came off).
I tried different bed temperatures, and the default of 60°C seems to work best. At 50°C it still works, but you may get minor warping at corners of difficult objects (big, 100% filled, with chamfers). At 70°C bonding itself is better, but the PLA gets too flexible, so warping forces can easier peel it off. Thus 60°C seems to be the best balance for me.
See my manual (PDF-file) with lots of pictures at:
https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/
Hope this helps. This method probably only works for PLA, but I haven't tried any other materials. So I would be interested to know about other materials.
Geert
Edited by GuestSee my manual (PDF-file) with lots of pictures at:
https://www.uantwerpen.be/...rt-keteleer/manuals/
Geert
The link got mangled, the correct link is:
https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/
My (UM PLA) prints bond very good to clean glass at 60 degrees, but if I run into trouble I'll keep your 'salt' method in mind. I would like to lower the temp even further (for shorter cooling down times), I still have to look into that. 60 degrees seems enough, strange that Cura chooses 70 by default. But I've only tried UM PLA so far.
Higher the temp, try printing with a brim or skirt, and maybe use a raft.
Guys, some comments here are incorrect. LOWERING the bed temperature actually helps very often.
Try this: 60C initial layer, 50C subsequent layers. What lowering temperature does is this. It does not improve the "adhesive" properties of the material (actually makes it worse), BUT, it makes the bottom part more rigid on it's own. This helps reduce warping IN CERTAIN TYPES OF MODEL geometries, e.g. with corners.
If you increased bed temperature and warping got worse - try decreasing. You may be surprised.
Also, increasing print speed is known to reduce warping in some cases.
Edited by pavelr
MariMakes posted a topic in UltiMaker Cura,
ArunC posted a topic in UltiMaker 3D printers,
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IRobertI 521
Higher temp. Brim will help (consider increasing its size as well). A thin layer of glue can work wonders and if you spread it out with a damp cloth you still get shiny bottoms. I haven't used blue tape in 2+ years, well, at least not for printing.
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