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Hypercube - Heatbed

Posted: Thu Jul 06, 2017 9:45 pm
by MasterOfDesaster
Hi there :)

I am currently building a Hypercube based on the one by Tech2C.

Build volume approx 250x250x180 mm
Double Z-Axis with 12 mm rods

Duet Wifi
Nema17 2.5A
PSU: Corsair VS550 ATX (48A on 12V)
Mosfet for the heatbed

Sunon für the Nozzle
Noctua for the E3DV6 (perhaps an additional one for the DuetWifi, time will tell)

Now i am looking for a heatbed. I planned for a 210x210, but i fucked up my measurements (or math ^^ ) and it will not fit unless i use overlapping extrusions. But this will minimize the build height more. So i am thinking about aluminum plate and a silicone heatbed underneath.

But which one to buy?
How thick must the aluminium be? 5mm or less?

Minimum of the aluminium plate will be 250x250 mm, max size will be 280x320 mm. The plate will attached to the extrusions with silicone dampeners (i wanted to use them for the Heatbed of the Anet A8, but know i think this is a better use :) ) between extrusion and plate.

Silicone bed with 12V, 24V or 230V?

I will perhaps get another psu for the heatbed and i think the DuetWifi is capable of handling both 12V and 24V (Hotend and fans are 12V).

Any recommendations are welcome :) thx in advance :)

Re: Hypercube - Heatbed

Posted: Tue Aug 01, 2017 4:44 pm
by Narnash
OK I guess it's already to late for you since the post is now 2 months old and no one answered your questions

First things first the aluminium plate should be a cast (fine) milled aluminium plate that is very important, it results in a metal plate with a minimal on stress that expands evenly in all directions when heated up and should warp when hot. The thickness isn't that important, generally speaking are the downsides it takes a bit longer to heat up a thick buildplate, it's most of the time pricier and most important havier (a havier plate can cause problems with higher print speeds) than a thinner buildplate. The advantages of a thicker build plate is that it's easier to add a thermistor in a thicker sheet, it is of course stiffer but that shouldn't be a huge problem whith 3d printing, it doesn't cool down as fast when cleaned (wouldn't advice to clean it when it's hot in general) and sometimes availability (the thinnest and most afforable option for my own 310 mm x 310 mm buildplate was 8 mm).
I would recomand a 5 or 6 mm buildplate if you can find one, it's stiff enough and adding a thermistior isn't to difficult. BUT take a cast aluminium plate with a (fine) milled surface !

A silicone heater is absolutely prefered over a kapton or pcb heater, they heat up faster and more evenly, are safer, come with 3m tape to place them and often have a thermistor already which you can use if you want to (or you add one on your own), they are a bit pricier though. For availablity just search on ebay or aliexpress I hear keenovo are good quality one but most you will find should work.

If you use 12V, 24V or 230V most often depends on your used PSU on the controller and stepper motors, as you may expect you can find higher wattage heaters for 24V or 230V due safety reasons and to not have to use super thick and easy stressed cables. 230v heaters are abasicly a must for build volumes greater than 350 mm x 350 mm since you need 400W or mpre to heat up such a big aluminium sheet in a reasonable time and heaters in this size usually run on mains voltage. If you would use a 230V heater keep in mind that you would need a SSR to controll it through your DuetWifi. In your case with a 250 mm x 250 mm or 210 mm x 210 mm buildspace I would recomand a 24V heated bed since your DuetWifi's HB-Channel is rated for 18A so that you would be maxed out with only roughly 200W if you use 12V. This way you could choose a nice 300-400W silicone heater rated for 24V, your whole printer could easily run this way on 24V which is also a big plus for your stepper drivers since these run more efficent on higher voltages (less power usage and even more noticable much quieter operation!). (I think the Duet can run on 24V natively? ... otherwise a PSU with a 12V and a 24V powerrail. A new 24V heater cardridges for the hotend and 24V fans would also work)

PS: Iwould recomand a didicated PSU instead of an ATX one, as I said 24V would be ideal (reputable brand, with proper crimped cable management), to replace fans and heater cardridges isn't a big deal.