Print bed not reaching temperature, very uneven across the bed
I have had a lot of trouble with bed adhesion since I moved to the Core One (pre-assembled). Even with PETG, and that was so sticky on my old MK3S+ that I had to do something to make it worse or it would pull the coating off the print sheet. It was especially bad when printing large parts that covered the whole bed - the front right and bottom left corners were lifting off.
Asked around and someone suggested to raise the bed temperature by 5°C, so I did and it solved my problem. But I also raised the chamber temperature by 5°C (which mostly turns the cooling fans off, so less draft I guess) and increased my first layer height to 0.25 mm from 0.2 mm.
I also ordered an infrared heat measurement "gun" and used it to measure temperatures at different spots of the bed during a print. The attached pictures show the print bed temperatures with the nominal set to 90°C. I am reaching 85 in one spot, in other spots it is barely 82 and especially around the edges it drops off a lot (to be expected if you know where the heated part ends, but still).
Is this normal? Where is the temperature of the bed measured by the controller? I feel like I should not have to set the bed temperature to 90°C to achieve 8° less than that in most places. And I never had this issue on my MK3S+ (in an enclosure). I should also be able to use the whole print area to print (with no space for a brim unfortunately).
I should add that this was measured during the "absorbing heat" phase, but while printing it does not become better.
RE: Print bed not reaching temperature, very uneven across the bed
This is the Core One L forum, looks like you have a Core One, you may have better answers reposting in the Core One forum.
Although we have different heat beds, my story is exactly the same as your, MK3S lack enclosure, I never had bed adhesion issues with PETG or PLA, never used brims. I have nothing but problems so far. I found I had to disable all venting and and no chamber fans. which helped alot. Also do live z test, just like you did for the Mk3S, this auto 1st layer isn't perfect.
RE: Print bed not reaching temperature, very uneven across the bed
Thanks, I reposted in the Core One forum. Will also raise this with support. maybe my temp sensor is doing something wrong (although I would expect temps to be higher than set if for example the connection was bad).