I added the magnetic plate to the aluminum bed plate on my Tech-1. The aluminum plate is very flat. Run a straight edge on it in any directions and it is good.
I am now finding that the magnetic plate has a bad crown in the center. It is like a mound that in the center moving toward all of the edges. The center of the build plate is significantly higher than at the edges. A rough measure puts it at about a 0.2mm change or drop from the center of the bed to the side edge.
The same straight edge placed on the bed, with out the spring steel part, will actually rock side to side.
This makes it near impossible to get a good first layer. The outer edges of trhe layer start to show gaps while the center area is mashed into the bed causing a wave pattern and accumulation of filament on the nozzle.
Material is PLA. I have tried from 90% first layer up to 120% so far. At 120% it is somewhat better but there is still an obvious problem.
Any ideas on this?