Probed after heating shows upwards bow down the center
I managed to get the back corners within 0.021 of each other. However, when heating the bed, it warps. The warp is most noticeable in a line down the middle from front to back.
Biggest variance is in the back with the corners being lower than the center.
Leaving the bed heated for 10 minutes before probing in an attempt to get a more even temp throughout the bed makes no difference.
Bed is 500mm vcore 3. Pic is a shot from the back.
Any advice welcomed.
9 Replies
bed size? looks like common gantry bow. (absorbed heat, bi-metalic effect of aluminum gantry and steel linear rail)
it is the 500mm vcore 3
I was able to get under 0.2 with a cold bed. Is that not possible with a bed of this size when heated?
hot you can obtain better than .15 no problem. my 500, hot, is better than .115 It's a matter of sequence and how tight you did all the rail mount bolts.
Well.... I cheated though.... my bed supports... https://discord.com/channels/582187371529764864/1056263255842099331/1056263255842099331
sorry but i'm a bit confused as to what your bed support does. Does it eliminate the need for the rear z point at the back of the bed? those custom supports look like they are supporting the bed from the front.
I am also not sure how this would help with the bulge due to heat.
In that case, the 500 plate sag was corrected by spanning the Y axis, with a central pin support in the middle . (a bow on the Y axis is corrected)
For your mesh (linked above) It appears the bow is reversed from the norm! You have LESS distance in the middle compared to more, as is most common. That leads me to believe you have an air pocket trapped under your mag sheet. As it heats the air is lifting your print surface closer to the print head.
i'm not sure the air bubble theroy holds. When the bed is heated, the back corners drop relative to everything else. If it was an air bubble, I would expect he back corners to still be on the same plane as the front with a bulge that measures higher representing the air bubble.
New pic is a shot from down the X axis from the right.
This is common gantry bow, not air pocket. The alu extrusion has 2x the coefficient of expansion that the steel rail has. For a given change in temp, the alu will expand more than the steel and cause a downward bow in the gantry - seen as an upward bow in the mesh. The 500s are very susceptible to this and there have been various proposed solutions - probably the best being the dual rail mod.
fascinating-indigo•17mo ago
This doesn't explain why the mesh is worse at the back and almost straight at the front though.
I'm not trying to imply that gantry bow is the only issue, there may be others... But, if you can address the bow, you can move on to other issues if needed... Looking at that graph, its the first thing I'd look into