Due to the very large size of the heated build base, some analysis needed to be done. This was to ensure that the target temperature could be held across the plate and that it could be done with optimal cost-effectiveness.
The simplest way to heat a plate this large would be to buy one or two large rectangular flexible heaters (backed with high temperature pressure sensitive adhesive). The problem is, heaters that large get very expensive when trying to cover such a large area. So a solution that is less expensive and offers better heating coverage, would be to buy many smaller heaters. Their placement is then critical.
Thermal FEA of the Build Base
The above image is the result of a fairly coarse meshed Finite Element Analysis (FEA) on the build plate with the heaters in the final chosen placement. Different sizes and placements of heaters were tested and it was deiced to use eight, 1″ x 12″ flexible heaters with a pressure sensitive adhesive backing. At a target temperature of 100°C, the plate achieves approximately a 5.5°C spread across the plate, which is quite acceptable considering the high temperatures.
Underside of the Build Base During Heater Assembly
The above image is the underside of the build plate with the eight flexible heaters mounted in position. These heaters will pump 480W into the build plate. For now, the entire plate is heated no matter what size part is printed. On my to-do list is a zoned heating system which would only heat the part of the plate that is needed, in order to save energy.
Thermocouple and Cable Managment
Here you can see the cable management of all the wires and the thermocouple held mostly down with kapton tape. The J-type thermocouple is glued with high temperature epoxy to the plate for more accurate temperature response.
ULTEM Insulator Plate
To help prevent the high temperatures of the plate from heating the rest of the machine, a plate made of ULTEM is used as a thermal insulator between the build base and Y axis block. This is important because the linear ball bearings are rated to a maximum temperature of 70°C.
Looks awesome! Where do you get heaters like this?
Thanks Andreas. There are many vendors for flexible silicone rubber heaters; a google search should bring up a bunch. For example, Omega Engineering and McMaster-Carr carry them.
Ah, thanks. The key words “flexible silicone rubber heater” helped a lot for the search.
How did you get the surface temperature analysis recorded? I want to perform this, but i cannot find a cost effective way of doing this. I’ve been thinking of simply attaching a temperature probe to the carriage of my Mendel and dragging it accross the surface and manually documenting the temperature reading versus location and then putting this into an application to visualize the data.
Hi Cid, the surface temperature analysis was not recorded from the actual build plate. It was a computer simulation (Finite Element Analysis) of a model of the build plate with an optimal heater arrangement.