24V 300x300 MK2A Heatbed

Hello! Sorry for my bad english!

I'm fairly new here in the 3D printing world and I just bought a Wanhao i3, but I was not really happy about the size so I build a 3D printer with a 300x300 MK2A Heatbed and dual (E3D V6 Extruders) I want to drive it at 24V?

Iv'e ordered a (BBP Fastbot) 3D Printer Controller Board
BBP1S
I calculated that it would draw somewhere about 15Amps at 24V (1.6 ~ Ohms)
each stepping motor (NEMA 17) rated for 1,7Amps each,
and I will use 6st step motors in total.
Stepper motor (42BYGHW609)

1x X axis GT2 Belt, and 20 teeth pulleys
1x Y axis GT2 Belt, and 20 teeth pulleys
2x Z axis 2x lead screws (8mm)
2x Bowden Extruders (E3D V6) (Mk8 Gear)
+
2x 24V 25W heater cartriges (E3D V6 Bowden)
2x 24V fans (extruder cooling Fans?)

will the (3D Printer Controller Board) Manage running (30 ~ A) or do I have to run a relay in parallel with the controller board?
Or is 30A even enough?


Sincerely

Edited 1 time(s). Last edit at 11/04/2015 04:18PM by Zuxztah.

I found a switched power supply (Mean Well RSP-750-24 751.2 W) but the biggest question is.. Will the controller board handle it?
The power supply is rated at 31,3 Amps. @ 24V

Edited 1 time(s). Last edit at 11/05/2015 01:35AM by Zuxztah.

Don't worry,
the stepper current of 1.7A is not the same current the driver is asking from the power supply.
I would try a 24V/19A PSU from Meanwell. Don't use a cloned one, I've seen they often miss some internal heatsinks.
-Olaf

Okey are you sure that it's a clone?
[www.conrad.se]π=1293156

It's a Swedish "website" but the description is in English.

Will the controller board manage to supply the heatbed wit 15-20 amp? Without pcb burn? Or components burning up?

Edited 1 time(s). Last edit at 11/05/2015 03:35AM by Zuxztah.

The fuse on the BBP1S board is 10A. If you are sure about the bed resistance of 1.6Ohm it won't be possible to use it directly.
-Olaf

Is there any other way to heat the heatbed without using BBP board? Is it possibleI to use a relay? What kind of relay?
I Don't really know how the heatbed electronics works in detail?

assuming it's a power mosfet that triggers the heatbed on/off until it reaches the desired temp?
No pwm signal?

Or I might be lowering the voltage to 20V (lowest possible for the power supply I bought) but still there will be 12,5~ Amps? On the HBP port?

Power supply >BBP> Heatbed power connector output > Relay (coil)
Powersupply + > relay pin 30 > relay pin 86 > Heatbed terminal +

Heatbed terminal - to Common grund on the power supply?

Would work if the HBP (HeatBedPlatform) output port puts out on/off signal?

You could use a standard 24V relais, but a DC-DC "SolidStateRelais" would be better. Search the forum for dc-dc ssr relay for details and sources.
-Olaf

Don't use a cheap DC-DC SSR. The cheap ones have too high a voltage drop so heating power is reduced (the SSR on the other hand gets very hot). The ones that are good enough cost about GBP65 or US$100.

This device [reprap.me] looks promising, but I don't have one, neither have I seen any reports on how well it works.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Hmm. Its not possible to use a overrated normal relay? Like 50-60 amps? Compared to the 25 amp draw?

Only the power supply Alone costs 167~ gbt then a ssr for another ~100gbt:/ wow...

I will buy one if I have to.

The Power expander looks very interesting! but there isn't any specifications.
Or maybe I'm just blind xD

You can use a normal relay if you can stand the constant clicking. The contacts may not last very long because of the amount of use. Be sure to connect a flyback diode across the relay coil.

The brief specification of the Power Expander is given on that page I linked to, however it didn't show up on my smartphone, only on my PC.

The draw of that bed heater should be about 15A, so in theory a SevenSwitch would just about handle it. However, the Power Expander looks a better bet because the ground wiring will be less critical, owing to the isolation it provides from the control input.

Personally, I use AC mains power to drive large heated beds, because that allows the use of a small power supply and a low-cost DC-AC SSR to switch the bed. However, use of AC mains power requires additional safety precautions to be taken, and I don't recommend it unless you are knowledgeable about AC mains wiring, protective grounding etc.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Okay I have some knowledge about ac power but didn't think about that erlier so I bought 3 cheap dc-dc ssr's anyway, better than nothing.

I will build a aluminum enclosure 5mm sheets for both power supply and controller board and mount the ssr to the inside wall with som thermal paste/glue and maybe add a 24V fan to cool it?

It's the heat from the ssr that's the problem? And maybe some power drop? Cause to slower heat up time? With the cheap ssr's?

Quote
Zuxztah
It's the heat from the ssr that's the problem? And maybe some power drop? Cause to slower heat up time? With the cheap ssr's?

Yes. Cheap DC-DC SSRs drop between 1.5V and 2V. If your bed heater draws 15A @ 24V, than that's between 22.5W and 30W of heat generated by the SSR that you need to get rid of, and up to 15% loss of bed heating power.

Edited 1 time(s). Last edit at 11/05/2015 03:09PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Ok. Thats not good!
What happens if the ssr breaks?
Worst case scenario?