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.

• Metal, glass, ceramic have been used successfully as heated beds.

• Ceramic - [1]
• Granite success and looks good -[2]
• Ceramic Floor Tile with Pictures - [3]. Addresses the melting of edges - edges remain cool.

Sourcing

Bed Plate

It is interesting to observe the performance of ceramics for heated beds. If heating time is acceptable, this could work.

Aluminum

• All with hefty shipping - 6" $3- [4]
• 12" $20 with ship for 1 [5], 8x16 $24 [6], 8x8 $13 [7] -
• 24" $43 [8]. $10 per 12" bed, or $5 per 8" bed
• McMaster stock - $13 + SH for 8" - [9]

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.

Tile

• Tile is a winner in terms of cost at $1/sf. 77 cents at 0.29" thick - [10].
• Granite - $2.50 - [11]
• Polished ceramic tile 69 cents - [12]
• Marble - 0.4" thick - [13]
• Porcelain - $1 - 9/32" thick - [14]
• 8x8 inch quarry tile, 1/2" thick - $1 - [15]
• 1/2" slate - $1.29 [16]
• 12x24 tile exists - [17]
• 36x36" tile exists - [18]

Pad

• Ultimaker beds are 500W - - [19]
• 8" bed on amazon is $84. [20]
• 8" bed on Aliexpress is $45 - [21]
• Expensive 12" on amazon - [22]
• Silicone rubber sheet - to 450F - [23] - $6/sf
• 10x10" heatbed aliexpress 500W - $10 - [24]
• 200W 8x8, $13 - [25]

Silicone Rubber Sheet

• Silicone rubber sheet - 20x20", 1 mm - $10 - [26]
• McMaster - <$5/sf for 1/32" thick - [27]

Double Sided Tape

• $3/sf - [28]

Single Sided Tape

• Kapton tape, 4"x100ft - $25 - [29]

• 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 - [30]

Sleeving

• 20 cents/foot, 1/16" ID - [31]. Specifically - 31 cents/foot 12 feet for May 2019 build of 120V hotbed. [32]
• Wire sleeving - [33] - 15 cents/foot for 16 gauge.

Rope Heater

• Up to 500C - [34]. Description: helical winding around core material, then insulating sleeve.

Helical Nichrome Coil

• Can be stretched - [35]

Carbon Fiber

• Carbon fiber is also used as a heating wire - [36]. Interesting. But it appears it can only do 15W/meter? Why is it limited? Limitation appears to be encapsulating materials - [37]

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. [38]

• Here is another at 12V, with 16 gauge - 10' long, going up only to 225C. [39]

.

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. [40]. Need to go thicker to handle the power.
• See Electronics Stack Exchange - [41]

Links

• Insulated Heatbed
• Hackaday article - [42]