120V Heatbed

About

• OSE Reasons for using a nichrome 120V bed are scalability and lower cost for large beds.
• Reason for DIY nichrome beds is clear for larger beds on the basis of cost.
• Sound design is required a safe method:

• Do not use parts that melt at low temperature. Thus, use Nichrome C wire and braided fiberglass insulation.
• For connection, use high temp 200C wire, and simply wind them around each other. But wait... How to Connect Wire to Nichrome Heaters.

Sourcing

Metal Plate

Aluminum

• All with hefty shipping - 6" $3- [1], 12" $20 with ship for 1 [2], 8x16 $24 [3], 8x8 $13 [4]
• 24" $43 [5]
• McMaster stock - $13 + SH for 8" - [6]

Steel

• This would be interesting to CNC torch on a waterbed from 8" stock - or just cut with abrasive metal cutoff. Steel is under $1/lb - with a 1 square foot sheet weighing $5. So $5 is the baseline cost for 12" beds.
• If steel is torched, this should be done with water cooling to address warping
• Baseline cost is $5 vs. $10 for aluminum.

Pad

• Ultimaker beds are 500W - - [7]
• 8" bed on amazon is $84. [8]
• 8" bed on Aliexpress is $45 - [9]
• Expensive 12" on amazon - [10]
• Silicone rubber sheet - to 450F - [11] - $6/sf
• 10x10" heatbed aliexpress 500W - $10 - [12]
• 200W 8x8, $13 - [13]

Silicone Rubber Sheet

• Silicone rubber sheet - 20x20", 1 mm - $10 - [14]
• McMaster - <$5/sf for 1/32" thick - [15]

Double Sided Tape

• $3/sf - [16]

Single Sided Tape

• Kapton tape, 4"x100ft - $25 - [17]

• Enough for 300 small beds (4"), or 33 12" beds.

Coated Nichrome Wire

• Need 30 Ohms of wire, about 10' long
• See Nichrome Wire

Uncoated Nichrome Wire

• Need 30 Ohm resistance for the length of wire at 120V to get 480W, for P=IV, V=IR, I=V/R -> P=V^2/R = 120^2/30 according to Electrical Power Calculator.

High Temp Nichrome in Fiberglass

• Claim of 1200C - [18]

Sleeving

• 20 cents/foot, 1/16" ID - [19]
• Wire sleeving - [20] - 15 cents/foot for 16 gauge.

Rope Heater

• Up to 500C - [21]. Description: helical winding around core material, then insulating sleeve.

Helical Nichrome Coil

• Can be stretched - [22]

Carbon Fiber

• Carbon fiber is also used as a heating wire - [23]. Interesting. But it appears it can only do 15W/meter? Why is it limited? Limitation appears to be encapsulating materials - [24]

Example of a DIY Nichrome Heater

• Idea is to wind Nichrome around an inner core, as otherwise, the heater element gets too long. That is just a practical consideration for these types of heaters if running high voltage.
• Here is 31 ga and 19 feet - for 90W - at 115V. [25]

• Here is another at 12V, with 16 gauge - 10' long, going up only to 225C. [26]

.

Derivative for OSE + Calculations

• 31 ga, 19 feet long above
• Power to bring 31 ga up to 2000F is under 4A - so with full 500W, 31 ga wire would probably blow up. [27]. Need to go thicker to handle the power.
• See Electronics Stack Exchange - [28]

Links

• Insulated Heatbed
• Hackaday article - [29]