I’ve started printing more ABS, some of my models I use 100C bed temperature, mostly to try and raise the chamber temp more.
But my magnetic bed is very weak now, I remember when the machine was new it was super strong, a bit of a fight to get the plate off but now it’ so weak it is lifting from the magnet while the model is still stuck to the plate resulting in warped prints.
I’ve bought a new magnetic pad but wondered if other people have the same issue printing ABS? Maybe it’s all fine if the bed temp is 90 instead of 100C ?
I’ve lately been printing ABS on a heated bed at 120C. I haven’t noticed any drop in magnetism yet, but you raise an interesting point: am I perhaps gradually damaging the magnetism? But if so, what is the point of having a heated bed that’s rated for 120C? It seems incongruous to design it to heat to that temperature if it’s going to damage itself.
As a reference point I have over 1000 hours on my x/p series printers that I print pretty much exclusively with ABS and a bed temp of 100, I haven’t seen any change in magnetic adhesion.
Who (other than BBL) knows?, but it’s at least conceivable that maybe yours was constructed using differently sourced magnets, or maybe they’re different for some other reason entirely. When did you buy your X1C?
For that matter, I only think I’m printing with my build plate at 120C, because that’s what the printer is reporting. I should probably confirm it with an IR gun or thermocouple or something. same for you. Since you’re experiencing an issue, you should probably check it.
Actually, 50C is the most my chamber temperature ever reports also, and I’m setting my bed temperature to 120C. More often it reports something more like 47C or 48C. I’m also generally about 20C ambient.
Not that it proves anything, but it does give at least some reason for you to look into it.
A natural phenomenon with magnets concerns the loss of its magnetic fields if polls are not covered. I have no proof of the science, but I always leave my most common plate on the hot bed. I also have to admit it wasn’t my thought about magnets as much as forgetting to put a plate on the bed before starting a print.
A magnet can lose it’s magnetic field when heated. At which temperature (Curie Temperature) depends on the type of material the magnet is made out. For some magnets this temperature is around 80°C. But for neodymium magnets this is 150°C.
Besides temperature there are other factors that can demagnetize a magnet, things like shocks but also a broken magnet can cause this.
If bbl did their job well then your problem is caused by an incident.
I see very little mentioned in most posts regarding 3D printing before Bambu Lab hit the scene.
As Robert2 indicated, this is a known issue regarding heating magnetic surfaces.
Over time it will loose some of that ability. Besides playing with temps to see how long you can make them last, the only other thing to consider is replacing them every now and then.
Typically when ever I buy a print bed surface of any type I usually pick up two knowing the 1st will wear out eventually so why not be prepared.
What I sayd was that you need to go above a certain temperature to loose magnetic field. So if bbl used the right magnetic material, then it shouldn’t be a problem.
Magnets lose strength (“Coercivity”) as they heat up. If they do not exceed their maximum (“Curie Temperature”), the magnetism recovers when the temperature goes down. If they do exceed their Curie Temperature, Coercivity is permanently lost.
I’d like to think BBL did their homework on this and picked a material that was tolerant of the expected temperatures. But typically, flexible magnet sheet material has a Curie Temp of 100ºC.
There are no details of the material used on the BBL site so it’s anyone’s guess…
That being said, I’d argue the magnets are to keep the build plate from moving, and not to keep it from warping. ABS is very difficult to print without warping. It shrinks significantly as it cools (more than any other plastic, if I remember right). If you print something that goes edge-to-edge on the plate, unless you keep the build chamber good and hot, it’s going to warp. Either it’ll pull off the plate, or it’ll pull up the plate.
There are some 3D printable clips you can put around the perimeter of the build plate to help hold it down. But some blue painter’s tape works as well. But I bet if you do that, the print will come free instead.
Preheat the build chamber before starting the print. Get it to 45ºF at least. Run the Aux fan on high while you’re doing this, shut it off (as well as the chamber fan) completely for the print.
And if the area that is pulling up is near the front left or right sides, use more painter’s tape to seal up the seams around the door.
Lastly, consider ASA instead of ABS. It’s mechanically about the same, but it is much more UV resistant and it does not warp quite as much as ABS does.
Now that you’ve brought it up, something I only recently noticed was a couple of reverse settings which, if you tick them, claim to reduce warpage in ABS. Seems like a great idea. I don’t know how effective they are, but maybe someone reading this knows.
It’s under the overhangs section of the process settings. Reading the description of “reverse only internal perimeters” it sounds as though the scope may (?) be across the entire print and not just overhangs.
