Is 5 amp enough for my printer

I'm building a custom Kossel Mini and I found a supply that would JUST fit inside the bottom of my Kossel, which gives 12V 5amp.
I was wondering if this is enough for the stepper drivers (4) + hotend + fans.

I have a n E3D V6, which is 40 watts (so 3.33 amp), and I use the silent stepstick drivers, for which I set the ref-voltage to 0.6 / 0.7 V, and if I understand correctly the current is Vref * 0.71, so that gives about 0.5 amp pe rmotor (max?). 2 amp total
Then there is the fans, I don't know how much they use, and the RADDS controller and the Arduino due itself.
Also it drives a relay for the 220 volt heated bed.

So:
heater: 3.3 amp
motors: 2 amp
Fans: ??
Relay: ??
Others: ??

So that seems to be more than 5 amp, but I can also set the hot-end to use maximum of 75% for example, then heater= 2.5 amps, and together with the motor = 4.5 amp. Then there's 0.5 amp left for the rest...

Any thoughts about if this has a chance of working? Anyone have experience with using a power supply in a 3D printer which is rated close to what I theoretically will be drawing? Is it something that will definitely give me problems, or is there a chance it will work fine and I should just test it?

You can get a 30W heater for your hot end, which is entirely adequate for printing the common plastics. So that's 2.5A.

0.5A per motor is very low. You probably need more like 1A. However, the current drawn from the 12V supply is only about a quarter of the motor current, so that's 1A for all 4 motors.

12V fans draw about 200mA each, and the RADDS+Due without an LCD should be no more than 100mA.

For the bed heater you should use a zero crossing SSR, which draws only a few mA.

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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].

And when you heat up the hotend before you move any axis, only the heating phase from room temperature will need that much power, this would also reduce max power need.

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That's true. However, can I get up to 255 degrees with a 30 watt heater???

Yes, as long as you don't have a print cooling fan blowing a lot of cold air directly at the nozzle.

Edited 1 time(s). Last edit at 09/28/2016 02:49AM 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].

Sure, but you can do it also with 40W. You could regulate the output on most firmwares.

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Triffid Hunter's Calibration Guide

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Most important Gcode.

Okay should be doable with 5 amps then. Another idea I had: I can actually fit two 5 amp supplies in the base, and hook them up in parallel. I can't fit a single 10 amp though. I guess I'll first try it with only 1, and measure the amps, and see how hot the supply gets. One thing I'm worried about: the space in the base is a bit confined, and also houses 3 motors, and the arduino/rads, and on top of that is aluminium plate with heater under it. I did notice the motors didn't seem to get hot, but still I'm worried that if I draw 4 or 5 amps from a 5 amp supply, under a heated bed of 110 degrees it might get too hot. 2 supplies, which each a fan running might be better then?
Anyway I'll just have to try, thanks for all the input!

Connecting the outputs of 2 power supplies in parallel is not advisable. But you could use one for the hot end heater and the other for everything else.

Edited 1 time(s). Last edit at 09/28/2016 02:52AM 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].

What is the reason why connecting power supplies in parallel is bad?
And how would I hook up two power supplies to RADDS so that one is only used for the hotend?

Quote
BramV
What is the reason why connecting power supplies in parallel is bad?

The power supplies might fight each other leading to unstable regulation. Or one may have a slightly higher set point than the other, so it will end up supplying all (or most) of the power

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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 Thanks,

So seperating the power supplies between the hotend and the rest seems like a good idea, but also pretty hard. Do you know of an easy way to accomplish this on RADDS? Or do i have to start scratching out leaders on the pcb and soldering jumper wires?

It's probably just a matter of connecting the positive hot end heater wire to the positive output of the second supply instead of to the RADDS, and connecting the negative outputs of the two supplies together. But I am not very familiar with RADDS, so I'll leave it to someone else to fill in the details.

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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].