Insulated Heatbed
Hint: Integrate this with 120V Heatbed
Hint: Max continuous temperature of the OSE Insulated heatbed is 178C, which is the max temperature at which the PEI surface can remain at continuous duty. Without the PEI, the bed can probably go to 400C, with the limit being the temperature limit of the 200C wire junction inside the bed. This heat bed operates at 120V AC, which is dangerous high voltage (shocks occur above 48V). This bed can kill you. Do not use this heat bed unless you understand its design and function, and do not use this without a ground fault interrupter as shown in the BOM for D3D v19.06 - D3D_v19.06#BOM_2.
Contents
Requirements
- Insulated bed works with OSE Thermite Bed, 12/24V industry standard, and 8" silicone heatpad. Smaller bed may be used, such as 6 or 4 inch, and can work decently because of 2" insulation layer.
- Nichrome heater, butt connectors
OSE Build
Nichrome Heater Theory
- Nichrome Wire Calculator assumedly covers radiation loss only - as no information is given on conduction, or convection
- In a heated bed application, the real temperature will be determined by conduction to steel plate and convection to air. The complication comes from how much thermal insulation occurs due to the fiberglass coating of the wire.
8" and 12" Bed
- Considerations: using a belt-driven Z axis, we have 18 lb of holding torque per Nema 17 72 oz in motor. We use 2 motors per side. The bed weight should thus not be more than 50% of the holding torque to move bed up, or no heavier than 18 lb.
- Weight of insulated heatbed steel - 1/8" square, 8x8"; 1/16" square, 8x8"; [4] strips, 2"x7.5". Total weight is equivalent to an 8x8" square, 1/4" thick - or 4.4 lb based on Steel Weight. With the insulation and wiring, it should be about 5-6 lb.
- Weight of insulated heatbed - 12". 12" version should have a 12.5" surface. See 12" Heated Bed. Weight should be approximately 10 lb. This is also within the weight handling limit of 2 Nema 17 stepper motors - allowing for 8 lb of printed material at a time.
BOM
- Fiberglass sleeve - [1]
- Butt Crimp Connectors - [2]
- Binder Clips - [3]
- High temp wire - $13 for 100' - 200C - [4]
- Nichrome Wire, 26 ga - [5]
More
- Binder clips, 3/4" or 19mm - hold up to 1/3" - [6]
- Butt crimp connectors , uninsulated - [7]
- High temp butt connectors to 500C - [8]
- Insulate with Kapton tape or fiberglass sleeve after butt connectors
- High temp wire nuts - 50 cents - [9]
Links
- Materials sourcing - 120V Heatbed
- Check out different ways to do a heatbed - including resistors and nichrome - [10]
- RAMPS on 24V
