(Group Buy) for 7"x7.5" Heated Bed

[TKL]

Time has come for chippin in for the Group buy. Please go here to make your payment:

http://heatbed.chipin.com/3d-printer-heatbed

It will only run for one week from today. After that the boards will be ordered and it will be too late to chip-in.

[michaellatif]

If we get to 25 boards or more count me in. At ~$15 plus shipping, that's a good deal, and I can use it for my second H-1 .

Edit: I am in for 3 (just got a friend tell me to add him one and a spare) if we hit 25 boards.

[drew]

Is there a proven design that we can use? I'm in for two at $15 if so.

[timothysvec]

I'm in.

[@CiDG]

I'm in, but I would like to know when a heated bed is needed. I'm printing just fine on glass with ABS Glue. Even with prints of plumbing parts that are narrow on the bottom and much wider on the top with little surface are holding it to the base.

[michaellatif]

I'm in, but I would like to know when a heated bed is needed. I'm printing just fine on glass with ABS Glue. Even with prints of plumbing parts that are narrow on the bottom and much wider on the top with little surface are holding it to the base.

I find that they only way for me to print a project case (something 4"x4" or larger) I need to run the heated bed because the edges curl up and the face/bottom of the print does not stay flat. With the heated bed, I can print large objects and get near glass finish.

[ALeander]

I too am in for 2 boards @ $15 or less.

[Eaglezsoar]

I'm in for two if they are around $15 each

[TKL]

Is there a proven design that we can use? I'm in for two at $15 if so.

There is, but it is too large for H-1 so the design will have to be adapted.

[kilroyo]

I kinda tired of trying to put together some homemade job, would much rather have something professional ... Count me In

[rotaone]

I'll take 2 if around $15.00 each and can be shipped to Australia, been hoping for one of these.

[TKL]

14 in so far as far as I can count. 11 to go to the 25 pcs price. I am considdering putting a 50-150* C thermostat on the board. It will be $4-5 for the components (25 pcs) including potentiometer and knob to mount outside the bed

[Eaglezsoar]

14 in so far as far as I can count. 11 to go to the 25 pcs price. I am considdering putting a 50-150* C thermostat on the board. It will be $4-5 for the components (25 pcs) including potentiometer and knob to mount outside the bed

I do not agree that putting the thermostat on the board is a good idea. It limits the functionality of the board and limits our abilities to use thermostats or digital devices that we may want to use.
Maybe I'm in the minority, what do others think?

[michaellatif]

I agree with Eaglezsoar - First rule of engineering KISS. I prefer to have standard hookup for thermistor/thermocouple and traces for heating. Maybe LED+resistor for on signal.

[rotaone]

I too would like to keep it to the minimum as i will be using a digital Azteeg board to control temp. LED and resistor for on indication would be good though.

[drew]

14 in so far as far as I can count. 11 to go to the 25 pcs price. I am considdering putting a 50-150* C thermostat on the board. It will be $4-5 for the components (25 pcs) including potentiometer and knob to mount outside the bed

Just in case I wasn't clear, I'm in for two. Also think it would be good to KISS. I'd like to use an arduino to control and display the temp.

[Eaglezsoar]

14 in so far as far as I can count. 11 to go to the 25 pcs price. I am considdering putting a 50-150* C thermostat on the board. It will be $4-5 for the components (25 pcs) including potentiometer and knob to mount outside the bed

I think the consensus is too keep it simple and leave off the on-board thermostat and make is so that it has the simple tracing along with the resistor and led, all designed for 12volts. (Hopefully, see below).

The silk screening should also be kept simple something like " Forum.SeeMeCNC.com Hotbed Group"

I say this because i would like to purchase the remaining number of boards that we need to reach 25 with the intent to resell the extra boards on Ebay or to members of this forum for cost plus shipping.

Before this can happen we need to produce one board of your design, test the ohms of the trace, determine the needed amperage at 12Volts and also find out the maximum temperature that this board can produce.
The MK1 for the bigger machines is a lot larger board with a lot of traces, my fear is that on a smaller board not enough traces can be designed so that the temperature is high enough. Using copper traces to create
heat is not the most efficient method, I am concerned that this cannot be done on a board of the size we are looking for. Can you produce the prototype board and put it through the testing? If a higher voltage is
needed we need to know this and cook the board in at the needed temperature to make sure the traces will not lift or disintegrate in some manner. Please respond as soon as possible, we are all anticipating the arrival
of these boards.

Regards, Carl.

[Polygonhell]

I'll take one @$15.

[michaellatif]

14 in so far as far as I can count. 11 to go to the 25 pcs price. I am considdering putting a 50-150* C thermostat on the board. It will be $4-5 for the components (25 pcs) including potentiometer and knob to mount outside the bed

I think the consensus is too keep it simple and leave off the on-board thermostat and make is so that it has the simple tracing along with the resistor and led, all designed for 12volts. (Hopefully, see below).

The silk screening should also be kept simple something like " Forum.SeeMeCNC.com Hotbed Group"

I say this because i would like to purchase the remaining number of boards that we need to reach 25 with the intent to resell the extra boards on Ebay or to members of this forum for cost plus shipping.

Before this can happen we need to produce one board of your design, test the ohms of the trace, determine the needed amperage at 12Volts and also find out the maximum temperature that this board can produce.
The MK1 for the bigger machines is a lot larger board with a lot of traces, my fear is that on a smaller board not enough traces can be designed so that the temperature is high enough. Using copper traces to create
heat is not the most efficient method, I am concerned that this cannot be done on a board of the size we are looking for. Can you produce the prototype board and put it through the testing? If a higher voltage is
needed we need to know this and cook the board in at the needed temperature to make sure the traces will not lift or disintegrate in some manner. Please respond as soon as possible, we are all anticipating the arrival
of these boards.

Regards, Carl.

Hey Carl,

Good point, the MK1 HBP is 8.4x8.4" (70.5 sq in). If we need 7x7.5(52.5 sq in), we are effectively removing 18 sq in (25%) of the surface area. I am thinking to compensate we will need to run the board at higher voltage.

Thoughts? Anyone versed in eagle design or whatever design software to create a proof of concept?

[Polygonhell]

Surely less space means less trace means lower resistance, means more current and as a result faster heating.
Isn't the issue going to be potentially drawing too much current?

[Eaglezsoar]

Surely less space means less trace means lower resistance, means more current and as a result faster heating.
Isn't the issue going to be potentially drawing too much current?

It is a bit more complicated than that. To obtain adequate heat, the board must be designed to have enough traces to obtain the
the correct current for that size of board. A smaller board would have thinner traces than a larger board but it is a balance of the
area of copper, the proper current and the breakdown of the traces depending on that current. Lesser amounts of traces does result
in reduced resistance and higher current but does this higher current adequately generate the proper temperatures without destroying
the traces? It is a balance of board size, width of the traces, thickness of the traces and how many traces. It needs to be created and
thoroughly tested for heating effectiveness and burned in at the proper temperatures to ensure the design does not cause melted or lifting
of the traces from the substrate.

Regards, Carl

[Dave_Sohlstrom]

There may be another option to building a heated bed using circuit boards with traces. The people that built this heating pad will build them to what ever wattage and voltage you need. This one is a 50watt at 3"x6" 12 VDC. I can check with my son in law and find out where he is getting these.

[img]http://i132.photobucket.com/albums/q3/D ... 0_1193.jpg[/img]

[Polygonhell]

Surely less space means less trace means lower resistance, means more current and as a result faster heating.
Isn't the issue going to be potentially drawing too much current?

It is a bit more complicated than that. To obtain adequate heat, the board must be designed to have enough traces to obtain the
the correct current for that size of board. A smaller board would have thinner traces than a larger board but it is a balance of the
area of copper, the proper current and the breakdown of the traces depending on that current. Lesser amounts of traces does result
in reduced resistance and higher current but does this higher current adequately generate the proper temperatures without destroying
the traces? It is a balance of board size, width of the traces, thickness of the traces and how many traces. It needs to be created and
thoroughly tested for heating effectiveness and burned in at the proper temperatures to ensure the design does not cause melted or lifting
of the traces from the substrate.

Regards, Carl

I agree entirely I misread the point of the original post.

[TKL]

Here it is (cobber layer only). The pads looks a bit wrong due to a missing apt file and the led is not added yet. The board is for 12 and 24V actually. The heating tracks are split into two 12V / 60W sections. You put them in parallel for 12V and series for 24V. Don't worry about the calculations; I am E-Engineer.

[Eaglezsoar]

Here it is (cobber layer only). The pads looks a bit wrong due to a missing apt file and the led is not added yet. The board is for 12 and 24V actually. The heating tracks are split into two 12V / 60W sections. You put them in parallel for 12V and series for 24V. Don't worry about the calculations; I am E-Engineer.

Are you able to create this board and test it before committing to purchasing the 25?