Big printer, any ideas for heat bed?

Hi. We are work on a big printer using h bot mecha. system. Can you offer me a few ideas about heat bed. We are desiging it which's printsize will be 50*50*50. Can we use 4 mk2/3 heatbed for it?

Sure, a few heatbeds could do it, just make sure to use a power supply that's powerful enough.

With a heatbed that big you will encounter some problems though, it's difficult to keep the temperature even over such a large surface so you might need temp sensors on each heatbed if you use four.

You could also build your own. [reprap.org]

Building something with mains power (110v/230v) is probably a good idea, as there will be a lot of current at 12v for such a large surface.

A build surface that big will also have issues with keeping the surface flat, and warping/lifting etc. You might need a build chamber.

---

--
-Nudel
Blog with RepRap Comic

Thanks for the reply Nudel. You have been really helpful.

large parts suffer a bit without the enclosure for the printer. Sure, your surface will be hot with a heated bed, but i'd guess that from 1" and up, the heat from the bed stops providing benefit at the print surface.
Internal stresses build, and you can get part fracture, de-lamination, warping etc. It is so dependent on many variables, and some have had success proving this opinion wrong.
I've seen people mention that even a breeze from walking by their machine caused the part to break free from the bed or split internally.

you can enclose and insulate the printer, and have a small air recirculating fan with a few power resistors and a temperature controller.
This method will be very low power. You can aim the fan for circular flow, or at the print head area.

Your machine can not have any printed PLA parts inside this enclosure. They will soften and deform after about 60C or so.
You can put your stepper motors inside, no issues.
The electronics can also survive, but having it outside the enclosure would be better.
You will have to wait 30 minutes or whatever, for the whole machine to heat up to 70-80C range (ABS printing).
If you have poor insulation or really low power to air exchange, you might not be able to reach the temp.

On my Stratasys, they use two small blowers and two small resistor heaters. When you first turn it on, you can not feel the heat added to the air by this arrangement.
It seems to be a very low power addition to the air. like a drop in a bucket.
Soon the bucket is full.

If you are trying to solve a problem of 50x50x50cm parts deforming during the build, then a scaled up heated bed might not fix everything.

[reprap.org]

I would consider mic6 plate with a few kapton heaters stuck on the bottom. It will be perfectly flat and evenly heated.

Heated build chambers can be simple, but there are a lot of subtleties as well. Many extruders (especially the all metal ones) rely on proper cooling to avoid jamming, which becomes harder when the ambient temperature is 70c. As well, many people include fans to help with detail, which again, becomes difficult in a heated build chamber.

Quote
691175002
I would consider mic6 plate with a few kapton heaters stuck on the bottom. It will be perfectly flat and evenly heated.

Have you done this?

I've started using 3mm aluminium sheets with a heap of heater cartridges strapped to the bottom, typically on my 200mmx400mm beds i use 6x30watt heater cartridges and it gets the bed up to 60c which is fine for pla, abs is a different story but even if it did get to 110c the size of the objects is still fundamentally limited

---

-=( blog )=- -=( thingiverse )=- -=( 3Dindustries )=- -=( Aluhotend - mostly metal hotend)=--=( Facebook )=-

I have done a heat table in size 700x450 with 4 heatmats a 185w eache power by 230V

Quote
vegasloki

Quote
691175002
I would consider mic6 plate with a few kapton heaters stuck on the bottom. It will be perfectly flat and evenly heated.

Have you done this?

Not yet, but I plan on having about 2KW of [www.omega.com] on the bottom of a 24" square plate of quarter inch mic6 this summer.

Quote
691175002
I plan on having about 2KW of [www.omega.com] on the bottom of a 24" square plate of quarter inch mic6 this summer.

Wow, do you have a 120V circuit at your place that can handle that much current? That's almost 17A, and most 120V circuits are rated for (and have a circuit breaker that trips above) 15A.