BIG Printer

[Ken Snyder]

Color me green!  $40k for this printer:

http://bigrep.com/

Ken

[John England]

Sounds like a challenge! ;-) Bet you could do it for $38k.

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[Elliot]

Good god. I would hate to have a 3 day print fail with only 8 hours left.

Actually, looking at the demo prints (the table), it looks like
they're using pretty low-resolution thick layers with a pretty big
nozzle, so maybe print times wouldn't be "that" bad after all.

However, how many spools would it take to build something that big? :)

[Ken Snyder]

I'd have to buy the 5lbs spools from Ultimachine and make a custom large nozzle or it would take days to print something big.  But it would be fun!

[wolfmanjm]

ken did you ever get a large nozzle to work?

I've been playing with a 0.75 nozzle printing at 0.5mm layer ht and 1mm width. The maximum speed i can print at is around 30mm/sec, any faster than that the PLA cools in the melt chamber due to the high flow, and even bumping temps upto 250°C doesn't help.

With the speed limited to 30mm/sec the advantage of a large nozzle is totally lost.

[Ken Snyder]

Hi Jim,

Sorry for the late reply.  I was using a 1.75mm filament 0.7 J-head at 200-220c going anywhere from 30-50mm/sec.  I wasn't going any faster not because of the hotend but for print quality.  The print bed was 1/8" x 20" x 20.5" aluminum + the same size glass.  If you get a bed that big moving too fast there is too much momentum.

You might want to drill it out larger and see how much faster you can go.  You could also try the SeeMeCNC hotend and EZStruder.  It has 2 heat resistors and might be able to transfer more heat to the plastic to keep it flowing at the desired speed.  I have 1.75mm filament one I could sell you with the Wednesday if you want to try it.

Ken

[wolfmanjm]

ok thanks, I  don't use 1.75mm filament, so I 'll pass on that :) but good to know it can work. The problem I have is the melt zone is not big enough, I have plenty of power in the heater cartridge and a solid copper heater block, its just the plastic flows through so fast it can;t heat up. It is not a jhead so may also be just plain bad, it is  a highly modified alustruder/magma with ptfe lining, and a drilled out melt zone so there is only about 0.5mm between the tip of the nozzle and the melt zone. That improved it a bit but still 30mm/sec is so slow it loses any advantage of using a large nozzle.

[Matthew Andrews]

I wonder if using a nozzle with a longer heated chamber something like the original reprap hotends where they would wrap a brass threaded rod or bolt with nichrome wire ahold help, giving the filament more time/distance to absorb heat over as it travels towards the nozzle. It might even be interesting to consider using a filament preheater which wouldn't get the filament all the way soft, but might lower the amount of heat you need to transfer to the filament at the nozzle. Of course you don't want to heat it enough that it deforms before entering the nozzle so you might not be able to preheat it enough to make much difference.

-Allie