Custom Quantum/Hadron PCB Heated Build Plate

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Custom Quantum/Hadron PCB Heated Build Plate

Postby frob » Thu Feb 16, 2012 11:06 pm

So since i'm new to FDM style DIY 3D printers, please help me understand what is really needed here - for example:

What are the "ideal" temperature settings for the different materials available? PLA, ABS, other ?
Does this need to be adjusted for different situations like ambient temperature?
Are there any material that need more than 120 deg. C hot plate? any beyond 140 C ?

If there's really just one or 2 /3 obvious temperature settings, it could be self-regulating with a switch or digital 5V signal to pick which temp.

Do you mind if it's designed for 5V only or does it really need to be 12V ?

I'm thinking 5V x 30A from a cheap ATX PSU - that gives 150W cold to heat up fast -
then to to control the temperature,
maybe modulate the voltage by manipulating the PSU's remote voltage sense input -
That way you can even avoid the big mosfet - but it might be unnecessarily complicated.

Of course for anyone that just wants to use it as a heating element only that's fine too :)

It might be possible to make it work on either 5V or 12V with a clever arrangement of series or parallel heater circuits.

I was thinking of using right-angle 1/4" spade connectors (SMT style) for the power entry, does that work for you? or would you prefer to directly solder your own wires?
Last edited by frob on Fri Feb 17, 2012 12:17 am, edited 1 time in total.
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Re: Custom Quantum/Hadron PCB Heated Build Plate

Postby bdring » Fri Feb 17, 2012 12:14 am

Send me dimensions for your holes pattern so I am sure the platform matches.

I suggest using the MK1/MK2 hole pattern on Hadron. The Quantum uses the Thingamatic hole pattern, but that is somewhat limiting. I can add a second pattern for full width of Quantum.
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Re: Custom Quantum/Hadron PCB Heated Build Plate

Postby naPS » Fri Feb 17, 2012 1:05 am

I don't know how widely used it is, but there's heated platform options in skeinforge that enable a variety of things. One of them that I've been playing with (unsucessfully) has been varying the temperature of the heated bed the further you get away from it in the Z direction. I think there's also some function that slowly reduces the temperature based on an expected deg/minute drop as well. I'll try to look through it a little more tonight and glean whatever options I can pull out of it.

I've had the best luck with it just setting it at a specific temperature and letting it sit there for the duration of the print. About 120 has worked well for me. Putting a relay or something on the board that would allow the electronics to turn the heating element off at the end of a print could save a few pennies in electricity a year as well.
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Re: Custom Quantum/Hadron PCB Heated Build Plate

Postby bdring » Fri Feb 17, 2012 1:50 am

My setup turns off the bed and extruder at the end of each print. It is just GCode.
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Re: Custom Quantum/Hadron PCB Heated Build Plate

Postby frob » Fri Feb 17, 2012 1:53 am

bdring wrote:Send me dimensions for your holes pattern so I am sure the platform matches. I suggest using the MK1/MK2 hole pattern on Hadron.
The Quantum uses the Thingamatic hole pattern, but that is somewhat limiting. I can add a second pattern for full width of Quantum.

I'm planning to exactly follow the MK2 size hole pattern, but i haven't been able to find the center to center spacing of the holes anywhere -
I noticed the holes look awfully close to the edges, so there really isn't much meat to it on 2 sides, and it seems it would be a bit fragile -
I'd rather move them in a bit or enlarge the board so there's at least 60-100 thou of FR4 at the narrowest point.
Could the Quantum accommodate a full MK2, or would that start to limit the travel in the X direction?
Whats the most convenient point for you to have the cable come into the build plate ?
Also, i was wondering about thermal stress/distortion if all 4 corners are screwed down.
I was thinking a better option would be to have only one corner bolted down and have tight fitting slots riding tooling pins in the other 3 to allow the board to expand/contract.
But i may be worrying for nothing and over-engineering again :roll:
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Re: Custom Quantum/Hadron PCB Heated Build Plate

Postby bdring » Fri Feb 17, 2012 1:57 am

According to the Eagle file posted on Thingiverse, the M3 holes are spaced 209 mm


per http://reprap.org/wiki/PCB_Heatbed
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Re: Custom Quantum/Hadron PCB Heated Build Plate

Postby frob » Fri Feb 17, 2012 2:14 am

bdring wrote:
According to the Eagle file posted on Thingiverse, the M3 holes are spaced 209 mm

Thanks. thats one of the only formats Altium wont import
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Re: Custom Quantum/Hadron PCB Heated Build Plate

Postby frob » Fri Feb 17, 2012 6:28 am

Just doin a little back of the envellope math on this, its interesting :

Looking at thermal conductivity of Kapton tape, (assuming total 3mil thick or less) you get a conductivity over a 20x20 com area of ~ 68W/deg C which is like its not even there, practically -
And its thermal emissivity is pretty low, and transparency quite high in that thickness so maybe 20 watts or less lost through radiation, and about 8-10W thought the mount below, so steady state about 30 watts with a temp gradient of 1/2 degree C through the kapton.

now the same math on a 3mm thick piece of ordinary window glass:
thermal emissivity is high around 0.93 so same area, about 35W lost to the environment assuming surface at 125C and 25C surroundings .
thermal conductivity is lower @ 12.8W / C so about 3 deg C temp gradient through the glass and ~ 45W steady state.

Whats interesting is how the thermal emissivity really affects the power budget; if we could use a polished metal surface,
(with emissivity less than 0.05), you'd only need less than 10W to keep the whole plate that hot.
I will have to try that on polished copper or aluminum just to see if it sticks well enough
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Re: Custom Quantum/Hadron PCB Heated Build Plate

Postby Enraged » Fri Feb 17, 2012 6:49 am

would lapping the surface or using thermal paste (like on CPU heatsinks) help?
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Re: Custom Quantum/Hadron PCB Heated Build Plate

Postby nrp » Fri Feb 17, 2012 7:47 am

frob wrote:So since i'm new to FDM style DIY 3D printers, please help me understand what is really needed here - for example:

What are the "ideal" temperature settings for the different materials available? PLA, ABS, other ?
Does this need to be adjusted for different situations like ambient temperature?
Are there any material that need more than 120 deg. C hot plate? any beyond 140 C ?

If there's really just one or 2 /3 obvious temperature settings, it could be self-regulating with a switch or digital 5V signal to pick which temp.

Do you mind if it's designed for 5V only or does it really need to be 12V ?

I'm thinking 5V x 30A from a cheap ATX PSU - that gives 150W cold to heat up fast -
then to to control the temperature,
maybe modulate the voltage by manipulating the PSU's remote voltage sense input -
That way you can even avoid the big mosfet - but it might be unnecessarily complicated.

Of course for anyone that just wants to use it as a heating element only that's fine too :)

It might be possible to make it work on either 5V or 12V with a clever arrangement of series or parallel heater circuits.

I was thinking of using right-angle 1/4" spade connectors (SMT style) for the power entry, does that work for you? or would you prefer to directly solder your own wires?


For the sake of simplicity and expense, it makes sense just to use the existing RAMPS board for logic and switching. All you need is to do is connect to a thermistor or thermocouple stuck to the PCB and connect to the resistive element. That way you can choose the temperature programmatically, use PID, or even PWM if you want by just modifying the firmware on the AVR.

A MOSFET is the simplest way to go for control. A $1.00 one like the STP55NF06 can switch up to 50A continuously, which is way more than you'll ever need for a heated bed.

It would be interesting to be able to use either 5V or 12V by switching series traces to parallel, but since most people will be using RAMPS boards, it makes sense to just use the 12V that that uses anyway.
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