DIY Custom nichrome wire heated bed
Posted: Fri Apr 13, 2012 12:50 am
Here is my design (basic and common to others) for a custom nichrome wire heated bed for the H-1.
Most of the parts are available through a few sources and at your LHS.
Required parts to build heated bed:
Also, I will add instructions on how to mount the heated bed to the H-1
Heated bed specifications:
Next will be mounting and leveling (to be continued).
Below are more pictures of the heated bed assembled and being tested.
Most of the parts are available through a few sources and at your LHS.
Required parts to build heated bed:
- Nichrome wire x1 (sold per 5 foot section - ultimachine.com for $3.50 USD)
- 6"x6"x1/8" aluminium plate x1 (McMaster-Carr part number 88685K1 for $5.68 USD)
- 18"x6"x1/32 aluminium plate x1 (LHS - Home Depot ~$7.00 USD)
- 12"x6"x1/8" birch plywood (Found at your LHS or Michaels/Jo-Ann's/Art shops ~$4.00 USD)
- 6"x6"x1/8" heat-resistant borosilicate glass (McMaster-Carr part number 8476K161 for $13.58 USD)
- Copper wire (~24awg solid core is recommended)
- Thermistor - pick your favorite
- Kapton tape (several sizes will help with assembly - E-Bay)
- flat head phillips screws, lock-nuts and washers, M3 Size, 30mm Length x4 (any size will do, this is what I had on hand. Note the lock-nuts are important, they make keeping the bed together and leveling it easier)
Also, I will add instructions on how to mount the heated bed to the H-1
Heated bed specifications:
- Surface area: 6"x6"
- Resistance of attached nichrome wire: ~3.0 Ohms
- Voltage bed is run at: 12 Volts
- Current consumed: ~3.8 Amps
- Max bed temperature: 247F (non-insulated)
- Time it took to heat to 200F: 11 minutes
- Cut the 1/32" aluminum sheet into three equal 6x6 inch squares OR just cut off a 6x6 inch section for this purpose
- Cut the 1/8" birch plywood sheet into 6x6 inch sections
- Cut the nichrome wire into three 14-15" sections
- Bend nichrome wire into U shape, leave one leg about .25-.5" longer then the other - the size of the bottom of the U is approximately 1.5"
- Start by taping the middle of the three nichrome wires using kapton tape
Note: I built my HPB so that the three wires run in parallel giving me a resistance of approx 3Ohms (each 12" section is about 8Ohms) running at 12V/3.5Amps - You can decide to run them in series if you want, but in parallel, the HPB heats up faster. - Continue by taping the remaining two nichrome wires - Its important to leave the tips of the wires exposed for attaching the copper wire!
- Expose ~1/2-3/4" of an inch of the nichrome wire - this is difficult because the coating is adhered well - be careful because the wire can be damaged! Repeat for each end
Note: I did this by using an exacto knife run along the wire - with my thumb pinching the oppisite side. This technicque works well but if you are not careful you could cut yourself! - Now attach the copper wire to three of the six nichrome wire leads
Note: I use wire wrapping technique for this, in the past I have use brass crimps - Use kapton tape to cover the copper wire
- Use a DMM to test resistance, you should read ~3 Ohms - if you read higher, check your DMM, sometimes the DMM leads add 2-3Ohms.
- Repeat for second copper wire (remaining 3 nichrome wire leads)
- Now tape your thermistor to the center of the HPB and feed the leads out along the copper wire
Note: At this point I taped ALL of the sheet with kapton tape, this is optional, but assures me that everything is insulated well - Make a cut out/recess for your thermistor and leads in your 1/8" birch plywood (see picture for details)
Note: This is necessary only if your thermistor/leads protrude too far as mine did - Place second aluminum sheet on top of birch plywood and build plate
- Drill four holes in the corners of the bed, mine are 3/4" in from the edges
Note: I used binder clips to help hold everything together while I drilled the holes - Use bolts and lock-nuts to hold the sandwich of aluminum/birch/thinner aluminum together
Next will be mounting and leveling (to be continued).
Below are more pictures of the heated bed assembled and being tested.