Beautiful. So that confirms there is nothing in the heat bed assembly that would effect the field strength.
1 Like
At least not on my X1-C. The most my bed temps have seen is 57C. It could be higher temperatures demagnetize in the area of heaters though (I don’t know how high of bed temps the bed magnet sheet can take or where the heaters are in the plate bed or type).
See @korzenec post below - Build Plate Edge Lift - Check Mag Sheet Field Strength - #27 by korzenec
Note - the 71C temperature sure isn’t the same league as the high temperature sheet he found.
I was looking to find the maximum temperature for the sheet magnets and found something else that could maybe also be an issue especially with many using strong magnets in designs - you want to keep them off the build plate. They can apparently scramble a weaker magnet (or magnetic sheeting). So never test magnetic strength on the print bed with a strong neodymium magnet or similar.
1 Like
I just bought one of those 4x4 sheets and can confirm mine looks like yours. However, I tested over the top of my PEI plate, and it still looks like I have constant lines and strength. 
1 Like
I’m also curious about why the OP’s test lines run front to back and mine as well as @MZip lines run side to side. Could the OP have changed the pad out or is that a manufacturing occurrence.
1 Like
Good eye! I assume the magnetic sheets are the same since I’m counting the same number of stripes on the assumption the visualization sheets are the same. The build plate is square though. Could be they can be applied either way or the magnet sheet was applied to the heater sheet (if it’s a sheet) 90 degrees out? It’s interesting though.
The orientation of the magnetic sheet shouldn’t matter but might reveal a different production run or even person assembling the print beds?
1 Like
Given that stronger magnets will demagnetize the sheet, then the KIS-3D plate should definitely be avoided if you want to use it intermittently. Intermittently since it weighs 900 grams and may not be healthy for the X1 long term.
I can’t remember the original source for the image below, so I apologize in advance for not giving credit to the author.
Reference max operating temperature. Hopefully not 71C since most plates operate at 70C (or higher). One high temp sheet is Garaviflex 200 which is good for constant 120C. I have one and it has the same stripe pattern as the Bambu. The break strength (with 1 5/8" fender washer) is 650 grams vs my new Bambu sheet which is 750 grams.
1 Like
About the magnets and the temperature, good call. I bet they use something like that for the magnet sheet.
I have never heard of that plate with the embedded magnets. Is it a replacement or is it to lay on the stock build plate? But I have no idea. If it lays on the stock plate it would be interesting to see if it scrambles the field lines like magnets used to do with tube TVs.
The KIS-3D is a lay on top of the bambu magnetic sheet (to get a flat surface), then add your build plate of choice. I would expect it reeks havoc on the Bambu magnetic sheet.
I’d love to see a field image afterwards then! Who knows? Maybe it’s ok?
I have just looked on Amazon UK to see if I can grab one of these and I can only find 4" x 6" ones.
Does yours have a name I can look up?
This squarely falls into a want rather than a need. They look cool.
It’s ASIN B0952FJWNZ, from Oliver Electronics.
I got it at Amazon - 4” x 4” for $17. The 4” x 6” is $33. They are very cool.
2 Likes
This was an excellent post. Thanks!
For others suggesting heat as the cause, you all might consider the fact the heat is highest in the center and lowest in the corners, yet it’s the corners where the problem is. Seems very unlikely heat was the problem. I’d put my money on a defective mag. sheet right from the start.
1 Like
Amazon also has a 6" x 12" at an eye-watering $170. I like that I can move my 4x4 around the plate for an instant test. The $17 tester made it fun and worthwhile.
1 Like
Yep. I wasn’t sure how the plate was heated. Cartridge heaters would have localized heating around them to a higher level even with a heat spreader. But infrared images show very even bed heating so you are probably correct.
Maybe some new recruit was even using magnets to hold the stack together during assembly or something else bizarre?
Anyway, the magnetic field is obviously messed up in the original problem post and could easily be called defective and need a warranty replacement.
It’s cool, isn’t it? Like a magic window revealing a hidden world of sorts kind of like the sci-fi movie “They Live”.
1 Like
Replaced the mag sheet without a problem and noticed one additional issue but this one affects bed warp. See
“Print Bed Warp – Beware the plastic frame”
Good experiment.
The old mag plate was wrinkled but there was a good spot for testing. Photos 1 - 3 are with the Bambu magnetic sheet and Photo 4 is with a cheap magnetic sheet.
Photo 1 is the “virgin” area. Clean field lines
Photo 2 shows placing some rare earth magnets on the sheet and just letting them set for about 20 seconds. The small magnets are 6mm OD, the large magnets 20mm OD. I only saw a very minor field disruption after removing the magnets.
Photo 3 shows the field after rubbing the larger round magnet cross field on the sheet about 10 times. Now you can see definite field anomalies.
Photo 4 shows a cheap magnetic sheet after rubbing a magnet cross field. Big degradation.
So the Bambu magnetic sheet is affected by external magnetic fields but not nearly as much as a cheap magnetic plate.
Keeping magnets away is a definite good practice.
But it does not seem to explain why my sheet was in such bad shape.
1 Like
How am i just now hearing about these sheets? This is amazing.
2 Likes