12x24 Silicone Heater

I am Sourcing a 12" x 24" Silicone Heater for a new printer I am building

not sure how many watts I should look for 1000w?
I get the feeling my best choice is to use AC mains 110v
or am I better off getting two 12x12 heaters?

---

Makerparts.ca
Your Canadian source for V-Slot Extrusion, CNC and 3D Printing Parts and Accessories.
we are proud to be an official Openbuilds distributor.

I suggest you get a heater slightly smaller than the aluminium bed plate you will attach it to, to leave about 15mm margin around the edge for fixings etc. Heating power of 5kW per square metre is about right in my experience, which works out at 900W for that size bed. This company [www.aliexpress.com] will make you a custom heater at a very good price.

The advantage I can see of using two heaters is that you can leave a small gap between them, and attach a thermistor to the centre of the bed plate in the gap to get an accurate temperature reading. However, if the aluminium bed plate is thick enough then a thermistor mounted near the edge of it will be accurate enough. You can get a thermistor included in the silicone heater instead, but these tend to over-read due to their proximity to the heating wires - not a big problem, but you need to allow for it.

Be sure to take appropriate electrical safety precautions when using a 110V bed heater. In particular, ground the printer frame and the bed plate, use highly-flexible leads to feed power and ground to the moving bed (e.g. the type of wire used for multimeter test leads), and provide strain relief for these leads at both ends. You can use a SSR-25DA or SSR-40DA to control the bed heater from the electronics.

Edited 1 time(s). Last edit at 02/24/2016 04:13AM by dc42.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Found these Silicone heaters on ebay. they come prewired for 110v AC
also come with digital temp control

the idea of having a seperate control and not needing to control it in Gcode is appealing

[www.ebay.ca]

Thoughts?

---

Makerparts.ca
Your Canadian source for V-Slot Extrusion, CNC and 3D Printing Parts and Accessories.
we are proud to be an official Openbuilds distributor.

Surely controlling the bed heater in gcode is an advantage? You can ensure that the print doesn't start until the bed is hot, you can change the bed temperature at particular layers, and you can turn the bed heater off at the end of the print. Do you really want to have to do all of this manually?

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].