120V Heatbed
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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
Bed 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]. $10 per 12" bed, or $5 per 8" bed
- 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.
Tile
- Tile is a winner in terms of cost at $1/sf. 77 cents [7].
Pad
- Ultimaker beds are 500W - - [8]
- 8" bed on amazon is $84. [9]
- 8" bed on Aliexpress is $45 - [10]
- Expensive 12" on amazon - [11]
- Silicone rubber sheet - to 450F - [12] - $6/sf
- 10x10" heatbed aliexpress 500W - $10 - [13]
- 200W 8x8, $13 - [14]
Silicone Rubber Sheet
Double Sided Tape
- $3/sf - [17]
Single Sided Tape
- Kapton tape, 4"x100ft - $25 - [18]
- 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 - [19]
Sleeving
Rope Heater
- Up to 500C - [22]. Description: helical winding around core material, then insulating sleeve.
Helical Nichrome Coil
- Can be stretched - [23]
Carbon Fiber
- Carbon fiber is also used as a heating wire - [24]. Interesting. But it appears it can only do 15W/meter? Why is it limited? Limitation appears to be encapsulating materials - [25]
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. [26]
- Here is another at 12V, with 16 gauge - 10' long, going up only to 225C. [27]
.
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. [28]. Need to go thicker to handle the power.
- See Electronics Stack Exchange - [29]
Links
- Insulated Heatbed
- Hackaday article - [30]