I have a variant of the Prusa I3 and I am wanting to update

(Mike Smith) #1

I have a variant of the Prusa I3 and I am wanting to update not only my heated bed but also my auto bed leveling. My current setup is a MK2 heated bed with a piece of 3mm borosilicate glass held on with binder clips and the auto bed leveling is a momentary switch that is activated by a solenoid whose pin touches the glass similar to the bltouch sensor. What I want to upgrade to is a silicone heater under 3mm glass or aluminum with high temp neodymium magnets placed on the underside of the bed and then use a piece of flexible sheet metal with a PEI sheet attached to it so that it is not only easy to remove the print surface but also easier to remove the print. the only question I have about this setup is whether to go with glass or the aluminum taking into consideration the thermal properties of both and also the deflection of both when heated to 100c. There other upgrade I want to do is to use a capacitance sensor to probe the bed but my concern is the magnets that will be used to hold the build surface down. I know that running the sensor directly over the magnet will have a drastic affect on when the sensor is tripped but what I don’t know is how far that magnetic field will radiate outward and still have an affect on the sensor and I also know that the steel sheet will reduce the magnets affect more than say a glass bed. Has anyone experimented with this type of setup and can maybe share your results of what worked or didn’t work. I know there is a lot of people that do not use auto bed leveling and even think it’s a bad idea to have but my experience with it has been fine and I would like to keep using it if at all possible but when it comes down to it my main priority is to upgrade the heated bed to the silicone heater with the magnetically held PEI build surface. TIA

(Eric Davies) #2

bear in mind that there is a difference between capacitive and inductive sensing. Magnets wouldn’t make a difference to a capacitive sensor, since you’d have them under the steel sheet. They would make a difference to an inductive sensor.