Help needed calculating power supply

G'day everyone,

I'm trying to figure out what power supply I need, but cannot for the life of me figure out how to calculate it. I have a 24v 350W power supply at home, which should run 14.5a.

Am i right in thinking that It'll power this silicon heat bed: [www.ebay.com.au]
and nothing else?

I'll also be running up to two hexagon hotends (https://www.bilby3d.com.au/DispProd.asp?CatID=&SubCatID=131&ProdID=ptHotEndHex175)

There's also the option of just getting a 240v silicon heater and running it with an SSR, but I'm going to try running a 24v heatbed through my Duetwifi first off.

Cheers in advance!

It won't even power that since the heater consumes 50W more than the maximum power output of the PSU.
In general you should stay within a reserve of 10-20% of a PSU, so for your 350W PSU you should stay below 300W.
Every heated hotend will add roughly 40W, the motors can use up to 30W per piece (in worst case, usually <20W) plus some power needed to run the controller board, lights etc.
I would go for the 240V heater with SSR. In that case you can continue to use the PSU.

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[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]

It depends if you want to bang-bang heat the hotbed or PWM it with P, I, D values.

If you PWM it, you will be limited to 7/8*100/1 = 87.5% duty cycle. Bang-Bang heating, putting full drain on a PSU, is called bang-bang for multiple reasons - it can make your PSU go bang (more of phut, really), and it's a term for digital / on off switch control, as opposed to proportional analogue control.

So you could use it, but it would heat less quickly than a unit fully capable of running at 100% permanently on Bang-Bang, but if using smoother PWM, it is just limited to how hard the PWM is. 50% is the regular value on Marlin, you can up that for quicker heating but usually less controlability.

Bang bang gives you least control, especially with a slow heat measurement device (themistor, thermocouple). You want fast feedback from the sensor, ideally. Sometimes you have to go that way and do bang bang on a hotbed, because PWM isn't an option. That's when you are glad that your PSU is full capacity, 100% duty cycle, and at least it won't be going "phut" or "bang".

There is guidance on working out how much power you need on the Duet3D wiki, at [duet3d.com].

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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].