Why not going a little bit bigger with your standard kit?

Hello everyone,

I m thinking about to build a fairly (L-W-H: 3.5m x 2.0m x 3.0m) big 3D Printer. So I started to look at my Prusa 3i (200mmx200mmx200mm) and the following adjustments:

The print bed will not move because it s going to be quite heavy. At each corner will be a column with a mechanic or belt to move the X and Y axis up and down (that s going to be the heaviest portable part).

I was thinking about to use the following parts, starting from my small Prusa 3i:

Mechanic parts = Aluminium (light is good)
Electronic Hardware = from my Prusa 3i (RAMPS 1.4 and MEGA 2560)
Motors = as big as I can go with my standard electronic hardware set
(heat) bed = a metalic plat (to heat that beast will be probably not that easy)

One major question I was asking myself is:

How much current can that standard RAMPS 1.4 output?
And does anyone has experience with building a little friend like this?

All the best,

Tom

So you want to build a i3 of that size?
I think you would be better of with an upscaled mendelmax 1.5 or even better a core xy design.
What is the torque of your nema 17 motors? For a printer that size you should go with nema 24 motors or really latge 17's.
I can also advice you to use the arduino duo 32 bit platform with a radds shield, it is much faster and multiple extruder ready, wich is a must for a printer of that size. What is the budget ?

Making a rigid frame that large will be costly, as will the large scale linear motion parts. It will be very heavy and require a lot of power/torque to move things. You won't be using 6mm wide GT2 belts to move things around! Unless the machine is made of aerogel there's no way that NEMA-17 motors are going to provide anywhere near the torque you'll need to move such a large, heavy mechanism unless you gear them down and drive at <1 mm/sec. Arduino/RAMPs can't drive motors that will be large enough. You will need external drivers, and since the motors will be large, they will be very noisy, so you'll want DSP based drivers to keep the noise down.

If you're going to use a heated bed you have multiple problems to solve. First and foremost is keeping it flat enough to print on. I assume you'll be using something at least a 3 mm or larger nozzle and printing in thick layers, otherwise, even if the bed is flat, it will be a very slow process to make a large print. Second, heating a bed that size will take a LOT of power unless you don't mind waiting a week for it to heat up. My printer has a 317x305 mm bed and with 0.5 W/cm^2 it gets to 105C in about 5 minutes. Scaling that to 7 m^2 takes you into multiple kW for similar performance.

I hope you have deep pockets and a lot of time on your hands...

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I love it when fantasy turns nightmare before the money is spent.
Its tough waking up broke.

A spare room in your house would be a good "frame" for a printer with such dimensions.

Sorry for the late response.

After doing some research about where to get the parts, I have to say that I must step back to 1.5mx3.0mx2.0m because the biggest aluminium bed I could find was a 1.5mx3.0m.

@ Govahnator: yes probably I will go for a Nema 24. Do you whether I can use it with my RAMPS 1.4? Thank you for the hint with the arduino duo 32 - I use that one. I hope I can realize it for 3.000 Euro, but my upper limit is 5.000 Euro. After the first draft I m optimistic that it could work with 3.000 Euro.

@ the_digital_dentist: I not plan to spend a lot for the frame. Some pillars and a frame on the top is what I want to use. If it s enough I can tell you hopefully at the end of next week. You say that things are getting really heavy. Right now if I take all the parts together of the biggest portable collection it weights around 15kg. I plan to use a 5mm alu plat. I will see how I can solve the heating issue. Last but not least money is available as well as time is.

@ o_lampe: It s going to be the garage.

I will keep you updated. I go shopping next Monday.

Quote
hello_tom
Sorry for the late response.

After doing some research about where to get the parts, I have to say that I must step back to 1.5mx3.0mx2.0m because the biggest aluminium bed I could find was a 1.5mx3.0m.

@ Govahnator: yes probably I will go for a Nema 24. Do you whether I can use it with my RAMPS 1.4? Thank you for the hint with the arduino duo 32 - I use that one. I hope I can realize it for 3.000 Euro, but my upper limit is 5.000 Euro. After the first draft I m optimistic that it could work with 3.000 Euro.

@ the_digital_dentist: I not plan to spend a lot for the frame. Some pillars and a frame on the top is what I want to use. If it s enough I can tell you hopefully at the end of next week. You say that things are getting really heavy. Right now if I take all the parts together of the biggest portable collection it weights around 15kg. I plan to use a 5mm alu plat. I will see how I can solve the heating issue. Last but not least money is available as well as time is.

@ o_lampe: It s going to be the garage.

I will keep you updated. I go shopping next Monday.

You can solve the heating by using a Mains fed Silicon heater pad which you would have to get custom made you would need around 22 kW of power in that for that size of bed. Also how do you propose to keep a 5mm thick slab of Aluminium flat once you suspend it by it's corners and then heat it up reckon you may get a considerable droop in the centre of that thing.

Think you need to look at good 32 bit electronics and external driver modules for it as well.

Anyway Good look to you.

Hello again,

I assembled the mechanics almost completely now.

Now I want to get the motors running: I bought M542T Drivers, RAMPS 1.4, and a MEGA 2560 (I want to try it with that one first, after moving to a SainSmart Due SAM3X8E 32-bit).

I will do the following:
- Connect the 4 wires of the RAMPS with the PUL+, PUL-, DIR+ and DIR- of the M542T
- Connect the Motor to A+,A-,B+ and B- of the M542T

Is that all? Just wiring the Driver in between. Do I still need the motor stepper at the RAMPS? What do I have to change in my Mendel firmware?

Thanks for help! or directing me to links/ post where someone already worked on that.

Tom

If you're build a printer of that size you don't want to use the lay-out of the Prusa i3.
Instead of that you better use a model where the Z-motors are driving along the Y-axle (the same way a portal-crane moves).
In that case you don't need a heavy printerbed and you save some square meters.

Just my thoughts,

Aad.